diff --git a/php/ext/google/protobuf/package.xml b/php/ext/google/protobuf/package.xml
index e0d25c8..400176a 100644
--- a/php/ext/google/protobuf/package.xml
+++ b/php/ext/google/protobuf/package.xml
@@ -45,6 +45,8 @@
     <file baseinstalldir="/" name="php-upb.h" role="src"/>
     <file baseinstalldir="/" name="protobuf.c" role="src"/>
     <file baseinstalldir="/" name="protobuf.h" role="src"/>
+    <file baseinstalldir="/" name="third_party/wyhash/wyhash.h" role="src"/>
+    <file baseinstalldir="/" name="third_party/wyhash/LICENSE" role="doc"/>
     <file baseinstalldir="/" name="LICENSE" role="doc"/>
   </dir>
  </contents>
diff --git a/php/ext/google/protobuf/php-upb.c b/php/ext/google/protobuf/php-upb.c
index d1fc366..a8945a5 100644
--- a/php/ext/google/protobuf/php-upb.c
+++ b/php/ext/google/protobuf/php-upb.c
@@ -22,6 +22,15 @@
 *
 * This file is private and must not be included by users!
 */
+
+#if !(__STDC_VERSION__ >= 199901L || __cplusplus >= 201103L)
+#error upb requires C99 or C++11
+#endif
+
+#if (defined(_MSC_VER) && _MSC_VER < 1900)
+#error upb requires MSVC >= 2015.
+#endif
+
 #include <stdint.h>
 #include <stddef.h>
 
@@ -70,66 +79,21 @@
 #define UPB_UNLIKELY(x) (x)
 #endif
 
-/* Define UPB_BIG_ENDIAN manually if you're on big endian and your compiler
- * doesn't provide these preprocessor symbols. */
-#if defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)
-#define UPB_BIG_ENDIAN
-#endif
-
 /* Macros for function attributes on compilers that support them. */
 #ifdef __GNUC__
 #define UPB_FORCEINLINE __inline__ __attribute__((always_inline))
 #define UPB_NOINLINE __attribute__((noinline))
 #define UPB_NORETURN __attribute__((__noreturn__))
+#elif defined(_MSC_VER)
+#define UPB_NOINLINE
+#define UPB_FORCEINLINE
+#define UPB_NORETURN __declspec(noreturn)
 #else  /* !defined(__GNUC__) */
 #define UPB_FORCEINLINE
 #define UPB_NOINLINE
 #define UPB_NORETURN
 #endif
 
-#if __STDC_VERSION__ >= 199901L || __cplusplus >= 201103L
-/* C99/C++11 versions. */
-#include <stdio.h>
-#define _upb_snprintf snprintf
-#define _upb_vsnprintf vsnprintf
-#define _upb_va_copy(a, b) va_copy(a, b)
-#elif defined(_MSC_VER)
-/* Microsoft C/C++ versions. */
-#include <stdarg.h>
-#include <stdio.h>
-#if _MSC_VER < 1900
-int msvc_snprintf(char* s, size_t n, const char* format, ...);
-int msvc_vsnprintf(char* s, size_t n, const char* format, va_list arg);
-#define UPB_MSVC_VSNPRINTF
-#define _upb_snprintf msvc_snprintf
-#define _upb_vsnprintf msvc_vsnprintf
-#else
-#define _upb_snprintf snprintf
-#define _upb_vsnprintf vsnprintf
-#endif
-#define _upb_va_copy(a, b) va_copy(a, b)
-#elif defined __GNUC__
-/* A few hacky workarounds for functions not in C89.
- * For internal use only!
- * TODO(haberman): fix these by including our own implementations, or finding
- * another workaround.
- */
-#define _upb_snprintf __builtin_snprintf
-#define _upb_vsnprintf __builtin_vsnprintf
-#define _upb_va_copy(a, b) __va_copy(a, b)
-#else
-#error Need implementations of [v]snprintf and va_copy
-#endif
-
-#ifdef __cplusplus
-#if __cplusplus >= 201103L || defined(__GXX_EXPERIMENTAL_CXX0X__) || \
-    (defined(_MSC_VER) && _MSC_VER >= 1900)
-/* C++11 is present */
-#else
-#error upb requires C++11 for C++ support
-#endif
-#endif
-
 #define UPB_MAX(x, y) ((x) > (y) ? (x) : (y))
 #define UPB_MIN(x, y) ((x) < (y) ? (x) : (y))
 
@@ -143,7 +107,7 @@
 #elif defined _MSC_VER
 #define UPB_ASSUME(expr) if (!(expr)) __assume(0)
 #else
-#define UPB_ASSUME(expr) do {} if (false && (expr))
+#define UPB_ASSUME(expr) do {} while (false && (expr))
 #endif
 #else
 #define UPB_ASSUME(expr) assert(expr)
@@ -157,55 +121,62 @@
 #define UPB_ASSERT(expr) assert(expr)
 #endif
 
-/* UPB_ASSERT_DEBUGVAR(): assert that uses functions or variables that only
- * exist in debug mode.  This turns into regular assert. */
-#define UPB_ASSERT_DEBUGVAR(expr) assert(expr)
-
 #if defined(__GNUC__) || defined(__clang__)
 #define UPB_UNREACHABLE() do { assert(0); __builtin_unreachable(); } while(0)
 #else
 #define UPB_UNREACHABLE() do { assert(0); } while(0)
 #endif
 
-/* UPB_INFINITY representing floating-point positive infinity. */
-#include <math.h>
-#ifdef INFINITY
-#define UPB_INFINITY INFINITY
-#else
-#define UPB_INFINITY (1.0 / 0.0)
+#if defined(__SANITIZE_ADDRESS__)
+#define UPB_ASAN 1
+#ifdef __cplusplus
+extern "C" {
 #endif
-#ifdef NAN
-#define UPB_NAN NAN
-#else
-#define UPB_NAN (0.0 / 0.0)
+void __asan_poison_memory_region(void const volatile *addr, size_t size);
+void __asan_unpoison_memory_region(void const volatile *addr, size_t size);
+#ifdef __cplusplus
+}  /* extern "C" */
 #endif
+#define UPB_POISON_MEMORY_REGION(addr, size) \
+  __asan_poison_memory_region((addr), (size))
+#define UPB_UNPOISON_MEMORY_REGION(addr, size) \
+  __asan_unpoison_memory_region((addr), (size))
+#else
+#define UPB_ASAN 0
+#define UPB_POISON_MEMORY_REGION(addr, size) \
+  ((void)(addr), (void)(size))
+#define UPB_UNPOISON_MEMORY_REGION(addr, size) \
+  ((void)(addr), (void)(size))
+#endif 
+
 
 #include <setjmp.h>
 #include <string.h>
 
 
+/* Must be last. */
 
-/* Maps descriptor type -> upb field type.  */
-static const uint8_t desctype_to_fieldtype[] = {
+/* Maps descriptor type -> elem_size_lg2.  */
+static const uint8_t desctype_to_elem_size_lg2[] = {
     -1,               /* invalid descriptor type */
-    UPB_TYPE_DOUBLE,  /* DOUBLE */
-    UPB_TYPE_FLOAT,   /* FLOAT */
-    UPB_TYPE_INT64,   /* INT64 */
-    UPB_TYPE_UINT64,  /* UINT64 */
-    UPB_TYPE_INT32,   /* INT32 */
-    UPB_TYPE_UINT64,  /* FIXED64 */
-    UPB_TYPE_UINT32,  /* FIXED32 */
-    UPB_TYPE_BOOL,    /* BOOL */
-    UPB_TYPE_STRING,  /* STRING */
-    UPB_TYPE_MESSAGE, /* GROUP */
-    UPB_TYPE_MESSAGE, /* MESSAGE */
-    UPB_TYPE_BYTES,   /* BYTES */
-    UPB_TYPE_UINT32,  /* UINT32 */
-    UPB_TYPE_ENUM,    /* ENUM */
-    UPB_TYPE_INT32,   /* SFIXED32 */
-    UPB_TYPE_INT64,   /* SFIXED64 */
-    UPB_TYPE_INT32,   /* SINT32 */
-    UPB_TYPE_INT64,   /* SINT64 */
+    3,  /* DOUBLE */
+    2,   /* FLOAT */
+    3,   /* INT64 */
+    3,  /* UINT64 */
+    2,   /* INT32 */
+    3,  /* FIXED64 */
+    2,  /* FIXED32 */
+    0,    /* BOOL */
+    UPB_SIZE(3, 4),  /* STRING */
+    UPB_SIZE(2, 3),  /* GROUP */
+    UPB_SIZE(2, 3),  /* MESSAGE */
+    UPB_SIZE(3, 4),  /* BYTES */
+    2,  /* UINT32 */
+    2,    /* ENUM */
+    2,   /* SFIXED32 */
+    3,   /* SFIXED64 */
+    2,   /* SINT32 */
+    3,   /* SINT64 */
 };
 
 /* Maps descriptor type -> upb map size.  */
@@ -314,20 +285,22 @@
 
 /* Data pertaining to the parse. */
 typedef struct {
-  const char *limit;       /* End of delimited region or end of buffer. */
-  upb_arena *arena;
+  const char *end;         /* Can read up to 16 bytes slop beyond this. */
+  const char *limit_ptr;   /* = end + UPB_MIN(limit, 0) */
+  int limit;               /* Submessage limit relative to end. */
   int depth;
   uint32_t end_group; /* Set to field number of END_GROUP tag, if any. */
+  bool alias;
+  char patch[32];
+  upb_arena arena;
   jmp_buf err;
 } upb_decstate;
 
 typedef union {
   bool bool_val;
-  int32_t int32_val;
-  int64_t int64_val;
   uint32_t uint32_val;
   uint64_t uint64_val;
-  upb_strview str_val;
+  uint32_t size;
 } wireval;
 
 static const char *decode_msg(upb_decstate *d, const char *ptr, upb_msg *msg,
@@ -371,47 +344,54 @@
 
 static bool decode_reserve(upb_decstate *d, upb_array *arr, size_t elem) {
   bool need_realloc = arr->size - arr->len < elem;
-  if (need_realloc && !_upb_array_realloc(arr, arr->len + elem, d->arena)) {
+  if (need_realloc && !_upb_array_realloc(arr, arr->len + elem, &d->arena)) {
     decode_err(d);
   }
   return need_realloc;
 }
 
+typedef struct {
+  const char *ptr;
+  uint64_t val;
+} decode_vret;
+
 UPB_NOINLINE
-static const char *decode_longvarint64(upb_decstate *d, const char *ptr,
-                                       const char *limit, uint64_t *val) {
-  uint8_t byte;
-  int bitpos = 0;
-  uint64_t out = 0;
-
-  do {
-    if (bitpos >= 70 || ptr == limit) decode_err(d);
-    byte = *ptr;
-    out |= (uint64_t)(byte & 0x7F) << bitpos;
-    ptr++;
-    bitpos += 7;
-  } while (byte & 0x80);
-
-  *val = out;
-  return ptr;
+static decode_vret decode_longvarint64(const char *ptr, uint64_t val) {
+  decode_vret ret = {NULL, 0};
+  uint64_t byte;
+  int i;
+  for (i = 1; i < 10; i++) {
+    byte = (uint8_t)ptr[i];
+    val += (byte - 1) << (i * 7);
+    if (!(byte & 0x80)) {
+      ret.ptr = ptr + i + 1;
+      ret.val = val;
+      return ret;
+    }
+  }
+  return ret;
 }
 
 UPB_FORCEINLINE
 static const char *decode_varint64(upb_decstate *d, const char *ptr,
-                                   const char *limit, uint64_t *val) {
-  if (UPB_LIKELY(ptr < limit && (*ptr & 0x80) == 0)) {
-    *val = (uint8_t)*ptr;
+                                   uint64_t *val) {
+  uint64_t byte = (uint8_t)*ptr;
+  if (UPB_LIKELY((byte & 0x80) == 0)) {
+    *val = byte;
     return ptr + 1;
   } else {
-    return decode_longvarint64(d, ptr, limit, val);
+    decode_vret res = decode_longvarint64(ptr, byte);
+    if (!res.ptr) decode_err(d);
+    *val = res.val;
+    return res.ptr;
   }
 }
 
 UPB_FORCEINLINE
 static const char *decode_varint32(upb_decstate *d, const char *ptr,
-                                   const char *limit, uint32_t *val) {
+                                   uint32_t *val) {
   uint64_t u64;
-  ptr = decode_varint64(d, ptr, limit, &u64);
+  ptr = decode_varint64(d, ptr, &u64);
   if (u64 > UINT32_MAX) decode_err(d);
   *val = (uint32_t)u64;
   return ptr;
@@ -424,14 +404,21 @@
       break;
     case UPB_DESCRIPTOR_TYPE_SINT32: {
       uint32_t n = val->uint32_val;
-      val->int32_val = (n >> 1) ^ -(int32_t)(n & 1);
+      val->uint32_val = (n >> 1) ^ -(int32_t)(n & 1);
       break;
     }
     case UPB_DESCRIPTOR_TYPE_SINT64: {
       uint64_t n = val->uint64_val;
-      val->int64_val = (n >> 1) ^ -(int64_t)(n & 1);
+      val->uint64_val = (n >> 1) ^ -(int64_t)(n & 1);
       break;
     }
+    case UPB_DESCRIPTOR_TYPE_INT32:
+    case UPB_DESCRIPTOR_TYPE_UINT32:
+      if (!_upb_isle()) {
+        /* The next stage will memcpy(dst, &val, 4) */
+        val->uint32_val = val->uint64_val;
+      }
+      break;
   }
 }
 
@@ -454,20 +441,85 @@
 static upb_msg *decode_newsubmsg(upb_decstate *d, const upb_msglayout *layout,
                                  const upb_msglayout_field *field) {
   const upb_msglayout *subl = layout->submsgs[field->submsg_index];
-  return _upb_msg_new(subl, d->arena);
+  return _upb_msg_new_inl(subl, &d->arena);
 }
 
-static void decode_tosubmsg(upb_decstate *d, upb_msg *submsg,
-                            const upb_msglayout *layout,
-                            const upb_msglayout_field *field, upb_strview val) {
+static int decode_pushlimit(upb_decstate *d, const char *ptr, int size) {
+  int limit = size + (int)(ptr - d->end);
+  int delta = d->limit - limit;
+  d->limit = limit;
+  d->limit_ptr = d->end + UPB_MIN(0, limit);
+  return delta;
+}
+
+static void decode_poplimit(upb_decstate *d, int saved_delta) {
+  d->limit += saved_delta;
+  d->limit_ptr = d->end + UPB_MIN(0, d->limit);
+}
+
+typedef struct {
+  bool ok;
+  const char *ptr;
+} decode_doneret;
+
+UPB_NOINLINE
+static const char *decode_isdonefallback(upb_decstate *d, const char *ptr,
+                                         int overrun) {
+  if (overrun < d->limit) {
+    /* Need to copy remaining data into patch buffer. */
+    UPB_ASSERT(overrun < 16);
+    memset(d->patch + 16, 0, 16);
+    memcpy(d->patch, d->end, 16);
+    ptr = &d->patch[0] + overrun;
+    d->end = &d->patch[16];
+    d->limit -= 16;
+    d->limit_ptr = d->end + d->limit;
+    d->alias = false;
+    UPB_ASSERT(ptr < d->limit_ptr);
+    return ptr;
+  } else {
+    decode_err(d);
+  }
+}
+
+UPB_FORCEINLINE
+static bool decode_isdone(upb_decstate *d, const char **ptr) {
+  int overrun = *ptr - d->end;
+  if (UPB_LIKELY(*ptr < d->limit_ptr)) {
+    return false;
+  } else if (UPB_LIKELY(overrun == d->limit)) {
+    return true;
+  } else {
+    *ptr = decode_isdonefallback(d, *ptr, overrun);
+    return false;
+  }
+}
+
+static const char *decode_readstr(upb_decstate *d, const char *ptr, int size,
+                                  upb_strview *str) {
+  if (d->alias) {
+    str->data = ptr;
+  } else {
+    char *data =  upb_arena_malloc(&d->arena, size);
+    if (!data) decode_err(d);
+    memcpy(data, ptr, size);
+    str->data = data;
+  }
+  str->size = size;
+  return ptr + size;
+}
+
+static const char *decode_tosubmsg(upb_decstate *d, const char *ptr,
+                                   upb_msg *submsg, const upb_msglayout *layout,
+                                   const upb_msglayout_field *field, int size) {
   const upb_msglayout *subl = layout->submsgs[field->submsg_index];
-  const char *saved_limit = d->limit;
+  int saved_delta = decode_pushlimit(d, ptr, size);
   if (--d->depth < 0) decode_err(d);
-  d->limit = val.data + val.size;
-  decode_msg(d, val.data, submsg, subl);
-  d->limit = saved_limit;
+  ptr = decode_msg(d, ptr, submsg, subl);
+  decode_poplimit(d, saved_delta);
   if (d->end_group != 0) decode_err(d);
   d->depth++;
+  return ptr;
 }
 
 static const char *decode_group(upb_decstate *d, const char *ptr,
@@ -496,15 +548,15 @@
   upb_array *arr = *arrp;
   void *mem;
 
-  if (!arr) {
-    upb_fieldtype_t type = desctype_to_fieldtype[field->descriptortype];
-    arr = _upb_array_new(d->arena, type);
+  if (arr) {
+    decode_reserve(d, arr, 1);
+  } else {
+    size_t lg2 = desctype_to_elem_size_lg2[field->descriptortype];
+    arr = _upb_array_new(&d->arena, 4, lg2);
     if (!arr) decode_err(d);
     *arrp = arr;
   }
 
-  decode_reserve(d, arr, 1);
-
   switch (op) {
     case OP_SCALAR_LG2(0):
     case OP_SCALAR_LG2(2):
@@ -515,15 +567,14 @@
       memcpy(mem, &val, 1 << op);
       return ptr;
     case OP_STRING:
-      decode_verifyutf8(d, val.str_val.data, val.str_val.size);
+      decode_verifyutf8(d, ptr, val.size);
       /* Fallthrough. */
-    case OP_BYTES:
+    case OP_BYTES: {
       /* Append bytes. */
-      mem =
-          UPB_PTR_AT(_upb_array_ptr(arr), arr->len * sizeof(upb_strview), void);
+      upb_strview *str = (upb_strview*)_upb_array_ptr(arr) + arr->len;
       arr->len++;
-      memcpy(mem, &val, sizeof(upb_strview));
-      return ptr;
+      return decode_readstr(d, ptr, val.size, str);
+    }
     case OP_SUBMSG: {
       /* Append submessage / group. */
       upb_msg *submsg = decode_newsubmsg(d, layout, field);
@@ -531,26 +582,25 @@
           submsg;
       arr->len++;
       if (UPB_UNLIKELY(field->descriptortype == UPB_DTYPE_GROUP)) {
-        ptr = decode_togroup(d, ptr, submsg, layout, field);
+        return decode_togroup(d, ptr, submsg, layout, field);
       } else {
-        decode_tosubmsg(d, submsg, layout, field, val.str_val);
+        return decode_tosubmsg(d, ptr, submsg, layout, field, val.size);
       }
-      return ptr;
     }
     case OP_FIXPCK_LG2(2):
     case OP_FIXPCK_LG2(3): {
       /* Fixed packed. */
       int lg2 = op - OP_FIXPCK_LG2(0);
       int mask = (1 << lg2) - 1;
-      size_t count = val.str_val.size >> lg2;
-      if ((val.str_val.size & mask) != 0) {
+      size_t count = val.size >> lg2;
+      if ((val.size & mask) != 0) {
         decode_err(d); /* Length isn't a round multiple of elem size. */
       }
       decode_reserve(d, arr, count);
       mem = UPB_PTR_AT(_upb_array_ptr(arr), arr->len << lg2, void);
       arr->len += count;
-      memcpy(mem, val.str_val.data, val.str_val.size);
-      return ptr;
+      memcpy(mem, ptr, val.size);  /* XXX: ptr boundary. */
+      return ptr + val.size;
     }
     case OP_VARPCK_LG2(0):
     case OP_VARPCK_LG2(2):
@@ -558,12 +608,11 @@
       /* Varint packed. */
       int lg2 = op - OP_VARPCK_LG2(0);
       int scale = 1 << lg2;
-      const char *ptr = val.str_val.data;
-      const char *end = ptr + val.str_val.size;
+      int saved_limit = decode_pushlimit(d, ptr, val.size);
       char *out = UPB_PTR_AT(_upb_array_ptr(arr), arr->len << lg2, void);
-      while (ptr < end) {
+      while (!decode_isdone(d, &ptr)) {
         wireval elem;
-        ptr = decode_varint64(d, ptr, end, &elem.uint64_val);
+        ptr = decode_varint64(d, ptr, &elem.uint64_val);
         decode_munge(field->descriptortype, &elem);
         if (decode_reserve(d, arr, 1)) {
           out = UPB_PTR_AT(_upb_array_ptr(arr), arr->len << lg2, void);
@@ -572,7 +621,7 @@
         memcpy(out, &elem, scale);
         out += scale;
       }
-      if (ptr != end) decode_err(d);
+      decode_poplimit(d, saved_limit);
       return ptr;
     }
     default:
@@ -580,9 +629,9 @@
   }
 }
 
-static void decode_tomap(upb_decstate *d, upb_msg *msg,
-                         const upb_msglayout *layout,
-                         const upb_msglayout_field *field, wireval val) {
+static const char *decode_tomap(upb_decstate *d, const char *ptr, upb_msg *msg,
+                                const upb_msglayout *layout,
+                                const upb_msglayout_field *field, wireval val) {
   upb_map **map_p = UPB_PTR_AT(msg, field->offset, upb_map *);
   upb_map *map = *map_p;
   upb_map_entry ent;
@@ -597,7 +646,7 @@
     char val_size = desctype_to_mapsize[val_field->descriptortype];
     UPB_ASSERT(key_field->offset == 0);
     UPB_ASSERT(val_field->offset == sizeof(upb_strview));
-    map = _upb_map_new(d->arena, key_size, val_size);
+    map = _upb_map_new(&d->arena, key_size, val_size);
     *map_p = map;
   }
 
@@ -607,13 +656,12 @@
   if (entry->fields[1].descriptortype == UPB_DESCRIPTOR_TYPE_MESSAGE ||
       entry->fields[1].descriptortype == UPB_DESCRIPTOR_TYPE_GROUP) {
     /* Create proactively to handle the case where it doesn't appear. */
-    ent.v.val.val = (uint64_t)_upb_msg_new(entry->submsgs[0], d->arena);
+    ent.v.val = upb_value_ptr(_upb_msg_new(entry->submsgs[0], &d->arena));
   }
 
-  decode_tosubmsg(d, &ent.k, layout, field, val.str_val);
-
-  /* Insert into map. */
-  _upb_map_set(map, &ent.k, map->key_size, &ent.v, map->val_size, d->arena);
+  ptr = decode_tosubmsg(d, ptr, &ent.k, layout, field, val.size);
+  _upb_map_set(map, &ent.k, map->key_size, &ent.v, map->val_size, &d->arena);
+  return ptr;
 }
 
 static const char *decode_tomsg(upb_decstate *d, const char *ptr, upb_msg *msg,
@@ -647,16 +695,15 @@
       if (UPB_UNLIKELY(type == UPB_DTYPE_GROUP)) {
         ptr = decode_togroup(d, ptr, submsg, layout, field);
       } else {
-        decode_tosubmsg(d, submsg, layout, field, val.str_val);
+        ptr = decode_tosubmsg(d, ptr, submsg, layout, field, val.size);
       }
       break;
     }
     case OP_STRING:
-      decode_verifyutf8(d, val.str_val.data, val.str_val.size);
+      decode_verifyutf8(d, ptr, val.size);
       /* Fallthrough. */
     case OP_BYTES:
-      memcpy(mem, &val, sizeof(upb_strview));
-      break;
+      return decode_readstr(d, ptr, val.size, mem);
     case OP_SCALAR_LG2(3):
       memcpy(mem, &val, 8);
       break;
@@ -675,7 +722,7 @@
 
 static const char *decode_msg(upb_decstate *d, const char *ptr, upb_msg *msg,
                               const upb_msglayout *layout) {
-  while (ptr < d->limit) {
+  while (!decode_isdone(d, &ptr)) {
     uint32_t tag;
     const upb_msglayout_field *field;
     int field_number;
@@ -684,7 +731,7 @@
     wireval val;
     int op;
 
-    ptr = decode_varint32(d, ptr, d->limit, &tag);
+    ptr = decode_varint32(d, ptr, &tag);
     field_number = tag >> 3;
     wire_type = tag & 7;
 
@@ -692,40 +739,36 @@
 
     switch (wire_type) {
       case UPB_WIRE_TYPE_VARINT:
-        ptr = decode_varint64(d, ptr, d->limit, &val.uint64_val);
+        ptr = decode_varint64(d, ptr, &val.uint64_val);
         op = varint_ops[field->descriptortype];
         decode_munge(field->descriptortype, &val);
         break;
       case UPB_WIRE_TYPE_32BIT:
-        if (d->limit - ptr < 4) decode_err(d);
-        memcpy(&val, ptr, 4);
+        memcpy(&val.uint32_val, ptr, 4);
+        val.uint32_val = _upb_be_swap32(val.uint32_val);
         ptr += 4;
         op = OP_SCALAR_LG2(2);
         if (((1 << field->descriptortype) & fixed32_ok) == 0) goto unknown;
         break;
       case UPB_WIRE_TYPE_64BIT:
-        if (d->limit - ptr < 8) decode_err(d);
-        memcpy(&val, ptr, 8);
+        memcpy(&val.uint64_val, ptr, 8);
+        val.uint64_val = _upb_be_swap64(val.uint64_val);
         ptr += 8;
         op = OP_SCALAR_LG2(3);
         if (((1 << field->descriptortype) & fixed64_ok) == 0) goto unknown;
         break;
       case UPB_WIRE_TYPE_DELIMITED: {
-        uint32_t size;
         int ndx = field->descriptortype;
         if (_upb_isrepeated(field)) ndx += 18;
-        ptr = decode_varint32(d, ptr, d->limit, &size);
-        if (size >= INT32_MAX || (size_t)(d->limit - ptr) < size) {
+        ptr = decode_varint32(d, ptr, &val.size);
+        if (val.size >= INT32_MAX || ptr - d->end + val.size > d->limit) {
           decode_err(d); /* Length overflow. */
         }
-        val.str_val.data = ptr;
-        val.str_val.size = size;
-        ptr += size;
         op = delim_ops[ndx];
         break;
       }
       case UPB_WIRE_TYPE_START_GROUP:
-        val.int32_val = field_number;
+        val.uint32_val = field_number;
         op = OP_SUBMSG;
         if (field->descriptortype != UPB_DTYPE_GROUP) goto unknown;
         break;
@@ -744,7 +787,7 @@
           ptr = decode_toarray(d, ptr, msg, layout, field, val, op);
           break;
         case _UPB_LABEL_MAP:
-          decode_tomap(d, msg, layout, field, val);
+          ptr = decode_tomap(d, ptr, msg, layout, field, val);
           break;
         default:
           ptr = decode_tomsg(d, ptr, msg, layout, field, val, op);
@@ -758,32 +801,55 @@
         ptr = decode_group(d, ptr, NULL, NULL, field_number);
       }
       if (msg) {
+        if (wire_type == UPB_WIRE_TYPE_DELIMITED) ptr += val.size;
         if (!_upb_msg_addunknown(msg, field_start, ptr - field_start,
-                                 d->arena)) {
+                                 &d->arena)) {
           decode_err(d);
         }
       }
     }
   }
 
-  if (ptr != d->limit) decode_err(d);
   return ptr;
 }
 
 bool upb_decode(const char *buf, size_t size, void *msg, const upb_msglayout *l,
                 upb_arena *arena) {
+  bool ok;
   upb_decstate state;
-  state.limit = buf + size;
-  state.arena = arena;
+
+  if (size == 0) {
+    return true;
+  } else if (size < 16) {
+    memset(&state.patch, 0, 32);
+    memcpy(&state.patch, buf, size);
+    buf = state.patch;
+    state.end = buf + size;
+    state.limit = 0;
+    state.alias = false;
+  } else {
+    state.end = buf + size - 16;
+    state.limit = 16;
+    state.alias = true;
+  }
+
+  state.limit_ptr = state.end;
   state.depth = 64;
   state.end_group = 0;
+  state.arena.head = arena->head;
+  state.arena.last_size = arena->last_size;
+  state.arena.parent = arena;
 
-  if (setjmp(state.err)) return false;
+  if (UPB_UNLIKELY(setjmp(state.err))) {
+    ok = false;
+  } else {
+    decode_msg(&state, buf, msg, l);
+    ok = state.end_group == 0;
+  }
 
-  if (size == 0) return true;
-  decode_msg(&state, buf, msg, l);
-
-  return state.end_group == 0;
+  arena->head.ptr = state.arena.head.ptr;
+  arena->head.end = state.arena.head.end;
+  return ok;
 }
 
 #undef OP_SCALAR_LG2
@@ -794,30 +860,30 @@
 /* We encode backwards, to avoid pre-computing lengths (one-pass encode). */
 
 
+#include <setjmp.h>
 #include <string.h>
 
 
 
 #define UPB_PB_VARINT_MAX_LEN 10
-#define CHK(x) do { if (!(x)) { return false; } } while(0)
 
-static size_t upb_encode_varint(uint64_t val, char *buf) {
-  size_t i;
-  if (val < 128) { buf[0] = val; return 1; }
-  i = 0;
-  while (val) {
+UPB_NOINLINE
+static size_t encode_varint64(uint64_t val, char *buf) {
+  size_t i = 0;
+  do {
     uint8_t byte = val & 0x7fU;
     val >>= 7;
     if (val) byte |= 0x80U;
     buf[i++] = byte;
-  }
+  } while (val);
   return i;
 }
 
-static uint32_t upb_zzencode_32(int32_t n) { return ((uint32_t)n << 1) ^ (n >> 31); }
-static uint64_t upb_zzencode_64(int64_t n) { return ((uint64_t)n << 1) ^ (n >> 63); }
+static uint32_t encode_zz32(int32_t n) { return ((uint32_t)n << 1) ^ (n >> 31); }
+static uint64_t encode_zz64(int64_t n) { return ((uint64_t)n << 1) ^ (n >> 63); }
 
 typedef struct {
+  jmp_buf err;
   upb_alloc *alloc;
   char *buf, *ptr, *limit;
 } upb_encstate;
@@ -830,11 +896,15 @@
   return ret;
 }
 
-static bool upb_encode_growbuffer(upb_encstate *e, size_t bytes) {
+UPB_NORETURN static void encode_err(upb_encstate *e) { longjmp(e->err, 1); }
+
+UPB_NOINLINE
+static void encode_growbuffer(upb_encstate *e, size_t bytes) {
   size_t old_size = e->limit - e->buf;
   size_t new_size = upb_roundup_pow2(bytes + (e->limit - e->ptr));
   char *new_buf = upb_realloc(e->alloc, e->buf, old_size, new_size);
-  CHK(new_buf);
+
+  if (!new_buf) encode_err(e);
 
   /* We want previous data at the end, realloc() put it at the beginning. */
   if (old_size > 0) {
@@ -844,99 +914,115 @@
   e->ptr = new_buf + new_size - (e->limit - e->ptr);
   e->limit = new_buf + new_size;
   e->buf = new_buf;
-  return true;
+
+  e->ptr -= bytes;
 }
 
 /* Call to ensure that at least "bytes" bytes are available for writing at
  * e->ptr.  Returns false if the bytes could not be allocated. */
-static bool upb_encode_reserve(upb_encstate *e, size_t bytes) {
-  CHK(UPB_LIKELY((size_t)(e->ptr - e->buf) >= bytes) ||
-      upb_encode_growbuffer(e, bytes));
+UPB_FORCEINLINE
+static void encode_reserve(upb_encstate *e, size_t bytes) {
+  if ((size_t)(e->ptr - e->buf) < bytes) {
+    encode_growbuffer(e, bytes);
+    return;
+  }
 
   e->ptr -= bytes;
-  return true;
 }
 
 /* Writes the given bytes to the buffer, handling reserve/advance. */
-static bool upb_put_bytes(upb_encstate *e, const void *data, size_t len) {
-  if (len == 0) return true;
-  CHK(upb_encode_reserve(e, len));
+static void encode_bytes(upb_encstate *e, const void *data, size_t len) {
+  if (len == 0) return;  /* memcpy() with zero size is UB */
+  encode_reserve(e, len);
   memcpy(e->ptr, data, len);
-  return true;
 }
 
-static bool upb_put_fixed64(upb_encstate *e, uint64_t val) {
-  /* TODO(haberman): byte-swap for big endian. */
-  return upb_put_bytes(e, &val, sizeof(uint64_t));
+static void encode_fixed64(upb_encstate *e, uint64_t val) {
+  val = _upb_be_swap64(val);
+  encode_bytes(e, &val, sizeof(uint64_t));
 }
 
-static bool upb_put_fixed32(upb_encstate *e, uint32_t val) {
-  /* TODO(haberman): byte-swap for big endian. */
-  return upb_put_bytes(e, &val, sizeof(uint32_t));
+static void encode_fixed32(upb_encstate *e, uint32_t val) {
+  val = _upb_be_swap32(val);
+  encode_bytes(e, &val, sizeof(uint32_t));
 }
 
-static bool upb_put_varint(upb_encstate *e, uint64_t val) {
+UPB_NOINLINE
+static void encode_longvarint(upb_encstate *e, uint64_t val) {
   size_t len;
   char *start;
-  CHK(upb_encode_reserve(e, UPB_PB_VARINT_MAX_LEN));
-  len = upb_encode_varint(val, e->ptr);
+
+  encode_reserve(e, UPB_PB_VARINT_MAX_LEN);
+  len = encode_varint64(val, e->ptr);
   start = e->ptr + UPB_PB_VARINT_MAX_LEN - len;
   memmove(start, e->ptr, len);
   e->ptr = start;
-  return true;
 }
 
-static bool upb_put_double(upb_encstate *e, double d) {
+UPB_FORCEINLINE
+static void encode_varint(upb_encstate *e, uint64_t val) {
+  if (val < 128 && e->ptr != e->buf) {
+    --e->ptr;
+    *e->ptr = val;
+  } else {
+    encode_longvarint(e, val);
+  }
+}
+
+static void encode_double(upb_encstate *e, double d) {
   uint64_t u64;
   UPB_ASSERT(sizeof(double) == sizeof(uint64_t));
   memcpy(&u64, &d, sizeof(uint64_t));
-  return upb_put_fixed64(e, u64);
+  encode_fixed64(e, u64);
 }
 
-static bool upb_put_float(upb_encstate *e, float d) {
+static void encode_float(upb_encstate *e, float d) {
   uint32_t u32;
   UPB_ASSERT(sizeof(float) == sizeof(uint32_t));
   memcpy(&u32, &d, sizeof(uint32_t));
-  return upb_put_fixed32(e, u32);
+  encode_fixed32(e, u32);
 }
 
-static bool upb_put_tag(upb_encstate *e, int field_number, int wire_type) {
-  return upb_put_varint(e, (field_number << 3) | wire_type);
+static void encode_tag(upb_encstate *e, int field_number, int wire_type) {
+  encode_varint(e, (field_number << 3) | wire_type);
 }
 
-static bool upb_put_fixedarray(upb_encstate *e, const upb_array *arr,
+static void encode_fixedarray(upb_encstate *e, const upb_array *arr,
                                size_t elem_size, uint32_t tag) {
   size_t bytes = arr->len * elem_size;
   const char* data = _upb_array_constptr(arr);
   const char* ptr = data + bytes - elem_size;
   if (tag) {
     while (true) {
-      CHK(upb_put_bytes(e, ptr, elem_size) && upb_put_varint(e, tag));
+      encode_bytes(e, ptr, elem_size);
+      encode_varint(e, tag);
       if (ptr == data) break;
       ptr -= elem_size;
     }
-    return true;
   } else {
-    return upb_put_bytes(e, data, bytes) && upb_put_varint(e, bytes);
+    encode_bytes(e, data, bytes);
   }
 }
 
-bool upb_encode_message(upb_encstate *e, const char *msg,
-                        const upb_msglayout *m, size_t *size);
+static void encode_message(upb_encstate *e, const char *msg,
+                           const upb_msglayout *m, size_t *size);
 
-static bool upb_encode_scalarfield(upb_encstate *e, const void *_field_mem,
-                                   const upb_msglayout *m,
-                                   const upb_msglayout_field *f,
-                                   bool skip_zero_value) {
+static void encode_scalar(upb_encstate *e, const void *_field_mem,
+                          const upb_msglayout *m, const upb_msglayout_field *f,
+                          bool skip_zero_value) {
   const char *field_mem = _field_mem;
-#define CASE(ctype, type, wire_type, encodeval) do { \
-  ctype val = *(ctype*)field_mem; \
-  if (skip_zero_value && val == 0) { \
-    return true; \
-  } \
-  return upb_put_ ## type(e, encodeval) && \
-      upb_put_tag(e, f->number, wire_type); \
-} while(0)
+  int wire_type;
+
+#define CASE(ctype, type, wtype, encodeval) \
+  {                                         \
+    ctype val = *(ctype *)field_mem;        \
+    if (skip_zero_value && val == 0) {      \
+      return;                               \
+    }                                       \
+    encode_##type(e, encodeval);            \
+    wire_type = wtype;                      \
+    break;                                  \
+  }
 
   switch (f->descriptortype) {
     case UPB_DESCRIPTOR_TYPE_DOUBLE:
@@ -960,90 +1046,91 @@
     case UPB_DESCRIPTOR_TYPE_BOOL:
       CASE(bool, varint, UPB_WIRE_TYPE_VARINT, val);
     case UPB_DESCRIPTOR_TYPE_SINT32:
-      CASE(int32_t, varint, UPB_WIRE_TYPE_VARINT, upb_zzencode_32(val));
+      CASE(int32_t, varint, UPB_WIRE_TYPE_VARINT, encode_zz32(val));
     case UPB_DESCRIPTOR_TYPE_SINT64:
-      CASE(int64_t, varint, UPB_WIRE_TYPE_VARINT, upb_zzencode_64(val));
+      CASE(int64_t, varint, UPB_WIRE_TYPE_VARINT, encode_zz64(val));
     case UPB_DESCRIPTOR_TYPE_STRING:
     case UPB_DESCRIPTOR_TYPE_BYTES: {
       upb_strview view = *(upb_strview*)field_mem;
       if (skip_zero_value && view.size == 0) {
-        return true;
+        return;
       }
-      return upb_put_bytes(e, view.data, view.size) &&
-          upb_put_varint(e, view.size) &&
-          upb_put_tag(e, f->number, UPB_WIRE_TYPE_DELIMITED);
+      encode_bytes(e, view.data, view.size);
+      encode_varint(e, view.size);
+      wire_type = UPB_WIRE_TYPE_DELIMITED;
+      break;
     }
     case UPB_DESCRIPTOR_TYPE_GROUP: {
       size_t size;
       void *submsg = *(void **)field_mem;
       const upb_msglayout *subm = m->submsgs[f->submsg_index];
       if (submsg == NULL) {
-        return true;
+        return;
       }
-      return upb_put_tag(e, f->number, UPB_WIRE_TYPE_END_GROUP) &&
-          upb_encode_message(e, submsg, subm, &size) &&
-          upb_put_tag(e, f->number, UPB_WIRE_TYPE_START_GROUP);
+      encode_tag(e, f->number, UPB_WIRE_TYPE_END_GROUP);
+      encode_message(e, submsg, subm, &size);
+      wire_type = UPB_WIRE_TYPE_START_GROUP;
+      break;
     }
     case UPB_DESCRIPTOR_TYPE_MESSAGE: {
       size_t size;
       void *submsg = *(void **)field_mem;
       const upb_msglayout *subm = m->submsgs[f->submsg_index];
       if (submsg == NULL) {
-        return true;
+        return;
       }
-      return upb_encode_message(e, submsg, subm, &size) &&
-          upb_put_varint(e, size) &&
-          upb_put_tag(e, f->number, UPB_WIRE_TYPE_DELIMITED);
+      encode_message(e, submsg, subm, &size);
+      encode_varint(e, size);
+      wire_type = UPB_WIRE_TYPE_DELIMITED;
+      break;
     }
+    default:
+      UPB_UNREACHABLE();
   }
 #undef CASE
-  UPB_UNREACHABLE();
+
+  encode_tag(e, f->number, wire_type);
 }
 
-static bool upb_encode_array(upb_encstate *e, const char *field_mem,
-                             const upb_msglayout *m,
-                             const upb_msglayout_field *f) {
+static void encode_array(upb_encstate *e, const char *field_mem,
+                         const upb_msglayout *m, const upb_msglayout_field *f) {
   const upb_array *arr = *(const upb_array**)field_mem;
   bool packed = f->label == _UPB_LABEL_PACKED;
+  size_t pre_len = e->limit - e->ptr;
 
   if (arr == NULL || arr->len == 0) {
-    return true;
+    return;
   }
 
 #define VARINT_CASE(ctype, encode)                                       \
   {                                                                      \
     const ctype *start = _upb_array_constptr(arr);                       \
     const ctype *ptr = start + arr->len;                                 \
-    size_t pre_len = e->limit - e->ptr;                                  \
     uint32_t tag = packed ? 0 : (f->number << 3) | UPB_WIRE_TYPE_VARINT; \
     do {                                                                 \
       ptr--;                                                             \
-      CHK(upb_put_varint(e, encode));                                    \
-      if (tag) CHK(upb_put_varint(e, tag));                              \
+      encode_varint(e, encode);                                          \
+      if (tag) encode_varint(e, tag);                                    \
     } while (ptr != start);                                              \
-    if (!tag) CHK(upb_put_varint(e, e->limit - e->ptr - pre_len));       \
   }                                                                      \
-  break;                                                                 \
-  do {                                                                   \
-    ;                                                                    \
-  } while (0)
+  break;
 
 #define TAG(wire_type) (packed ? 0 : (f->number << 3 | wire_type))
 
   switch (f->descriptortype) {
     case UPB_DESCRIPTOR_TYPE_DOUBLE:
-      CHK(upb_put_fixedarray(e, arr, sizeof(double), TAG(UPB_WIRE_TYPE_64BIT)));
+      encode_fixedarray(e, arr, sizeof(double), TAG(UPB_WIRE_TYPE_64BIT));
       break;
     case UPB_DESCRIPTOR_TYPE_FLOAT:
-      CHK(upb_put_fixedarray(e, arr, sizeof(float), TAG(UPB_WIRE_TYPE_32BIT)));
+      encode_fixedarray(e, arr, sizeof(float), TAG(UPB_WIRE_TYPE_32BIT));
       break;
     case UPB_DESCRIPTOR_TYPE_SFIXED64:
     case UPB_DESCRIPTOR_TYPE_FIXED64:
-      CHK(upb_put_fixedarray(e, arr, sizeof(uint64_t), TAG(UPB_WIRE_TYPE_64BIT)));
+      encode_fixedarray(e, arr, sizeof(uint64_t), TAG(UPB_WIRE_TYPE_64BIT));
       break;
     case UPB_DESCRIPTOR_TYPE_FIXED32:
     case UPB_DESCRIPTOR_TYPE_SFIXED32:
-      CHK(upb_put_fixedarray(e, arr, sizeof(uint32_t), TAG(UPB_WIRE_TYPE_32BIT)));
+      encode_fixedarray(e, arr, sizeof(uint32_t), TAG(UPB_WIRE_TYPE_32BIT));
       break;
     case UPB_DESCRIPTOR_TYPE_INT64:
     case UPB_DESCRIPTOR_TYPE_UINT64:
@@ -1056,20 +1143,20 @@
     case UPB_DESCRIPTOR_TYPE_BOOL:
       VARINT_CASE(bool, *ptr);
     case UPB_DESCRIPTOR_TYPE_SINT32:
-      VARINT_CASE(int32_t, upb_zzencode_32(*ptr));
+      VARINT_CASE(int32_t, encode_zz32(*ptr));
     case UPB_DESCRIPTOR_TYPE_SINT64:
-      VARINT_CASE(int64_t, upb_zzencode_64(*ptr));
+      VARINT_CASE(int64_t, encode_zz64(*ptr));
     case UPB_DESCRIPTOR_TYPE_STRING:
     case UPB_DESCRIPTOR_TYPE_BYTES: {
       const upb_strview *start = _upb_array_constptr(arr);
       const upb_strview *ptr = start + arr->len;
       do {
         ptr--;
-        CHK(upb_put_bytes(e, ptr->data, ptr->size) &&
-            upb_put_varint(e, ptr->size) &&
-            upb_put_tag(e, f->number, UPB_WIRE_TYPE_DELIMITED));
+        encode_bytes(e, ptr->data, ptr->size);
+        encode_varint(e, ptr->size);
+        encode_tag(e, f->number, UPB_WIRE_TYPE_DELIMITED);
       } while (ptr != start);
-      return true;
+      return;
     }
     case UPB_DESCRIPTOR_TYPE_GROUP: {
       const void *const*start = _upb_array_constptr(arr);
@@ -1078,11 +1165,11 @@
       do {
         size_t size;
         ptr--;
-        CHK(upb_put_tag(e, f->number, UPB_WIRE_TYPE_END_GROUP) &&
-            upb_encode_message(e, *ptr, subm, &size) &&
-            upb_put_tag(e, f->number, UPB_WIRE_TYPE_START_GROUP));
+        encode_tag(e, f->number, UPB_WIRE_TYPE_END_GROUP);
+        encode_message(e, *ptr, subm, &size);
+        encode_tag(e, f->number, UPB_WIRE_TYPE_START_GROUP);
       } while (ptr != start);
-      return true;
+      return;
     }
     case UPB_DESCRIPTOR_TYPE_MESSAGE: {
       const void *const*start = _upb_array_constptr(arr);
@@ -1091,31 +1178,30 @@
       do {
         size_t size;
         ptr--;
-        CHK(upb_encode_message(e, *ptr, subm, &size) &&
-            upb_put_varint(e, size) &&
-            upb_put_tag(e, f->number, UPB_WIRE_TYPE_DELIMITED));
+        encode_message(e, *ptr, subm, &size);
+        encode_varint(e, size);
+        encode_tag(e, f->number, UPB_WIRE_TYPE_DELIMITED);
       } while (ptr != start);
-      return true;
+      return;
     }
   }
 #undef VARINT_CASE
 
   if (packed) {
-    CHK(upb_put_tag(e, f->number, UPB_WIRE_TYPE_DELIMITED));
+    encode_varint(e, e->limit - e->ptr - pre_len);
+    encode_tag(e, f->number, UPB_WIRE_TYPE_DELIMITED);
   }
-  return true;
 }
 
-static bool upb_encode_map(upb_encstate *e, const char *field_mem,
-                           const upb_msglayout *m,
-                           const upb_msglayout_field *f) {
+static void encode_map(upb_encstate *e, const char *field_mem,
+                       const upb_msglayout *m, const upb_msglayout_field *f) {
   const upb_map *map = *(const upb_map**)field_mem;
   const upb_msglayout *entry = m->submsgs[f->submsg_index];
   const upb_msglayout_field *key_field = &entry->fields[0];
   const upb_msglayout_field *val_field = &entry->fields[1];
   upb_strtable_iter i;
   if (map == NULL) {
-    return true;
+    return;
   }
 
   upb_strtable_begin(&i, &map->table);
@@ -1127,59 +1213,57 @@
     upb_map_entry ent;
     _upb_map_fromkey(key, &ent.k, map->key_size);
     _upb_map_fromvalue(val, &ent.v, map->val_size);
-    CHK(upb_encode_scalarfield(e, &ent.v, entry, val_field, false));
-    CHK(upb_encode_scalarfield(e, &ent.k, entry, key_field, false));
+    encode_scalar(e, &ent.v, entry, val_field, false);
+    encode_scalar(e, &ent.k, entry, key_field, false);
     size = (e->limit - e->ptr) - pre_len;
-    CHK(upb_put_varint(e, size));
-    CHK(upb_put_tag(e, f->number, UPB_WIRE_TYPE_DELIMITED));
+    encode_varint(e, size);
+    encode_tag(e, f->number, UPB_WIRE_TYPE_DELIMITED);
   }
-
-  return true;
 }
 
+static void encode_scalarfield(upb_encstate *e, const char *msg,
+                               const upb_msglayout *m,
+                               const upb_msglayout_field *f) {
+  bool skip_empty = false;
+  if (f->presence == 0) {
+    /* Proto3 presence. */
+    skip_empty = true;
+  } else if (f->presence > 0) {
+    /* Proto2 presence: hasbit. */
+    if (!_upb_hasbit_field(msg, f)) return;
+  } else {
+    /* Field is in a oneof. */
+    if (_upb_getoneofcase_field(msg, f) != f->number) return;
+  }
+  encode_scalar(e, msg + f->offset, m, f, skip_empty);
+}
 
-bool upb_encode_message(upb_encstate *e, const char *msg,
-                        const upb_msglayout *m, size_t *size) {
-  int i;
+static void encode_message(upb_encstate *e, const char *msg,
+                           const upb_msglayout *m, size_t *size) {
   size_t pre_len = e->limit - e->ptr;
   const char *unknown;
   size_t unknown_size;
+  const upb_msglayout_field *f = &m->fields[m->field_count];
+  const upb_msglayout_field *first = &m->fields[0];
 
   unknown = upb_msg_getunknown(msg, &unknown_size);
 
   if (unknown) {
-    upb_put_bytes(e, unknown, unknown_size);
+    encode_bytes(e, unknown, unknown_size);
   }
 
-  for (i = m->field_count - 1; i >= 0; i--) {
-    const upb_msglayout_field *f = &m->fields[i];
-
+  while (f != first) {
+    f--;
     if (_upb_isrepeated(f)) {
-      CHK(upb_encode_array(e, msg + f->offset, m, f));
+      encode_array(e, msg + f->offset, m, f);
     } else if (f->label == _UPB_LABEL_MAP) {
-      CHK(upb_encode_map(e, msg + f->offset, m, f));
+      encode_map(e, msg + f->offset, m, f);
     } else {
-      bool skip_empty = false;
-      if (f->presence == 0) {
-        /* Proto3 presence. */
-        skip_empty = true;
-      } else if (f->presence > 0) {
-        /* Proto2 presence: hasbit. */
-        if (!_upb_hasbit_field(msg, f)) {
-          continue;
-        }
-      } else {
-        /* Field is in a oneof. */
-        if (_upb_getoneofcase_field(msg, f) != f->number) {
-          continue;
-        }
-      }
-      CHK(upb_encode_scalarfield(e, msg + f->offset, m, f, skip_empty));
+      encode_scalarfield(e, msg, m, f);
     }
   }
 
   *size = (e->limit - e->ptr) - pre_len;
-  return true;
 }
 
 char *upb_encode(const void *msg, const upb_msglayout *m, upb_arena *arena,
@@ -1190,11 +1274,13 @@
   e.limit = NULL;
   e.ptr = NULL;
 
-  if (!upb_encode_message(&e, msg, m, size)) {
+  if (setjmp(e.err)) {
     *size = 0;
     return NULL;
   }
 
+  encode_message(&e, msg, m, size);
+
   *size = e.limit - e.ptr;
 
   if (*size == 0) {
@@ -1206,113 +1292,72 @@
   }
 }
 
-#undef CHK
-
 
 
 
 /** upb_msg *******************************************************************/
 
-static const char _upb_fieldtype_to_sizelg2[12] = {
-  0,
-  0,  /* UPB_TYPE_BOOL */
-  2,  /* UPB_TYPE_FLOAT */
-  2,  /* UPB_TYPE_INT32 */
-  2,  /* UPB_TYPE_UINT32 */
-  2,  /* UPB_TYPE_ENUM */
-  UPB_SIZE(2, 3),  /* UPB_TYPE_MESSAGE */
-  3,  /* UPB_TYPE_DOUBLE */
-  3,  /* UPB_TYPE_INT64 */
-  3,  /* UPB_TYPE_UINT64 */
-  UPB_SIZE(3, 4),  /* UPB_TYPE_STRING */
-  UPB_SIZE(3, 4),  /* UPB_TYPE_BYTES */
-};
-
-static uintptr_t tag_arrptr(void* ptr, int elem_size_lg2) {
-  UPB_ASSERT(elem_size_lg2 <= 4);
-  return (uintptr_t)ptr | elem_size_lg2;
-}
-
-static int upb_msg_internalsize(const upb_msglayout *l) {
-  return sizeof(upb_msg_internal) - l->extendable * sizeof(void *);
-}
-
-static size_t upb_msg_sizeof(const upb_msglayout *l) {
-  return l->size + upb_msg_internalsize(l);
-}
+static const size_t overhead = sizeof(upb_msg_internal);
 
 static const upb_msg_internal *upb_msg_getinternal_const(const upb_msg *msg) {
   ptrdiff_t size = sizeof(upb_msg_internal);
   return UPB_PTR_AT(msg, -size, upb_msg_internal);
 }
 
-static upb_msg_internal *upb_msg_getinternal(upb_msg *msg) {
-  return (upb_msg_internal*)upb_msg_getinternal_const(msg);
+upb_msg *_upb_msg_new(const upb_msglayout *l, upb_arena *a) {
+  return _upb_msg_new_inl(l, a);
 }
 
 void _upb_msg_clear(upb_msg *msg, const upb_msglayout *l) {
-  ptrdiff_t internal = upb_msg_internalsize(l);
-  void *mem = UPB_PTR_AT(msg, -internal, char);
-  memset(mem, 0, l->size + internal);
-}
-
-upb_msg *_upb_msg_new(const upb_msglayout *l, upb_arena *a) {
-  void *mem = upb_arena_malloc(a, upb_msg_sizeof(l));
-  upb_msg *msg;
-
-  if (!mem) {
-    return NULL;
-  }
-
-  msg = UPB_PTR_AT(mem, upb_msg_internalsize(l), upb_msg);
-  _upb_msg_clear(msg, l);
-  return msg;
+  void *mem = UPB_PTR_AT(msg, -sizeof(upb_msg_internal), char);
+  memset(mem, 0, upb_msg_sizeof(l));
 }
 
 bool _upb_msg_addunknown(upb_msg *msg, const char *data, size_t len,
                          upb_arena *arena) {
+
   upb_msg_internal *in = upb_msg_getinternal(msg);
-  if (len > in->unknown_size - in->unknown_len) {
-    upb_alloc *alloc = upb_arena_alloc(arena);
-    size_t need = in->unknown_size + len;
-    size_t newsize = UPB_MAX(in->unknown_size * 2, need);
-    void *mem = upb_realloc(alloc, in->unknown, in->unknown_size, newsize);
-    if (!mem) return false;
-    in->unknown = mem;
-    in->unknown_size = newsize;
+  if (!in->unknown) {
+    size_t size = 128;
+    while (size < len) size *= 2;
+    in->unknown = upb_arena_malloc(arena, size + overhead);
+    if (!in->unknown) return false;
+    in->unknown->size = size;
+    in->unknown->len = 0;
+  } else if (in->unknown->size - in->unknown->len < len) {
+    size_t need = in->unknown->len + len;
+    size_t size = in->unknown->size;
+    while (size < need)  size *= 2;
+    in->unknown = upb_arena_realloc(
+        arena, in->unknown, in->unknown->size + overhead, size + overhead);
+    if (!in->unknown) return false;
+    in->unknown->size = size;
   }
-  memcpy(in->unknown + in->unknown_len, data, len);
-  in->unknown_len += len;
+  memcpy(UPB_PTR_AT(in->unknown + 1, in->unknown->len, char), data, len);
+  in->unknown->len += len;
   return true;
 }
 
 void _upb_msg_discardunknown_shallow(upb_msg *msg) {
   upb_msg_internal *in = upb_msg_getinternal(msg);
-  in->unknown_len = 0;
+  if (in->unknown) {
+    in->unknown->len = 0;
+  }
 }
 
 const char *upb_msg_getunknown(const upb_msg *msg, size_t *len) {
   const upb_msg_internal *in = upb_msg_getinternal_const(msg);
-  *len = in->unknown_len;
-  return in->unknown;
+  if (in->unknown) {
+    *len = in->unknown->len;
+    return (char*)(in->unknown + 1);
+  } else {
+    *len = 0;
+    return NULL;
+  }
 }
 
 /** upb_array *****************************************************************/
 
-upb_array *_upb_array_new(upb_arena *a, upb_fieldtype_t type) {
-  upb_array *arr = upb_arena_malloc(a, sizeof(upb_array));
-
-  if (!arr) {
-    return NULL;
-  }
-
-  arr->data = tag_arrptr(NULL, _upb_fieldtype_to_sizelg2[type]);
-  arr->len = 0;
-  arr->size = 0;
-
-  return arr;
-}
-
 bool _upb_array_realloc(upb_array *arr, size_t min_size, upb_arena *arena) {
   size_t new_size = UPB_MAX(arr->size, 4);
   int elem_size_lg2 = arr->data & 7;
@@ -1330,16 +1375,16 @@
     return false;
   }
 
-  arr->data = tag_arrptr(ptr, elem_size_lg2);
+  arr->data = _upb_tag_arrptr(ptr, elem_size_lg2);
   arr->size = new_size;
   return true;
 }
 
-static upb_array *getorcreate_array(upb_array **arr_ptr, upb_fieldtype_t type,
+static upb_array *getorcreate_array(upb_array **arr_ptr, int elem_size_lg2,
                                     upb_arena *arena) {
   upb_array *arr = *arr_ptr;
   if (!arr) {
-    arr = _upb_array_new(arena, type);
+    arr = _upb_array_new(arena, 4, elem_size_lg2);
     if (!arr) return NULL;
     *arr_ptr = arr;
   }
@@ -1347,22 +1392,22 @@
 }
 
 void *_upb_array_resize_fallback(upb_array **arr_ptr, size_t size,
-                                 upb_fieldtype_t type, upb_arena *arena) {
-  upb_array *arr = getorcreate_array(arr_ptr, type, arena);
-  return arr && _upb_array_resize(arr, size, arena) ? _upb_array_ptr(arr) : NULL;
+                                 int elem_size_lg2, upb_arena *arena) {
+  upb_array *arr = getorcreate_array(arr_ptr, elem_size_lg2, arena);
+  return arr && _upb_array_resize(arr, size, arena) ? _upb_array_ptr(arr)
+                                                    : NULL;
 }
 
 bool _upb_array_append_fallback(upb_array **arr_ptr, const void *value,
-                                upb_fieldtype_t type, upb_arena *arena) {
-  upb_array *arr = getorcreate_array(arr_ptr, type, arena);
+                                int elem_size_lg2, upb_arena *arena) {
+  upb_array *arr = getorcreate_array(arr_ptr, elem_size_lg2, arena);
   size_t elem = arr->len;
-  int lg2 = _upb_fieldtype_to_sizelg2[type];
   char *data;
 
   if (!arr || !_upb_array_resize(arr, elem + 1, arena)) return false;
 
   data = _upb_array_ptr(arr);
-  memcpy(data + (elem << lg2), value, 1 << lg2);
+  memcpy(data + (elem << elem_size_lg2), value, 1 << elem_size_lg2);
   return true;
 }
 
@@ -1375,7 +1420,7 @@
     return NULL;
   }
 
-  upb_strtable_init2(&map->table, UPB_CTYPE_INT32, upb_arena_alloc(a));
+  upb_strtable_init2(&map->table, UPB_CTYPE_INT32, 4, upb_arena_alloc(a));
   map->key_size = key_size;
   map->val_size = value_size;
 
@@ -1387,9 +1432,11 @@
 ** Implementation is heavily inspired by Lua's ltable.c.
 */
 
-
 #include <string.h>
 
+#include "third_party/wyhash/wyhash.h"
+
+/* Must be last. */
 
 #define UPB_MAXARRSIZE 16  /* 64k. */
 
@@ -1468,11 +1515,7 @@
 }
 
 static bool isfull(upb_table *t) {
-  if (upb_table_size(t) == 0) {
-    return true;
-  } else {
-    return ((double)(t->count + 1) / upb_table_size(t)) > MAX_LOAD;
-  }
+  return t->count == t->max_count;
 }
 
 static bool init(upb_table *t, uint8_t size_lg2, upb_alloc *a) {
@@ -1481,6 +1524,7 @@
   t->count = 0;
   t->size_lg2 = size_lg2;
   t->mask = upb_table_size(t) ? upb_table_size(t) - 1 : 0;
+  t->max_count = upb_table_size(t) * MAX_LOAD;
   bytes = upb_table_size(t) * sizeof(upb_tabent);
   if (bytes > 0) {
     t->entries = upb_malloc(a, bytes);
@@ -1496,9 +1540,17 @@
   upb_free(a, mutable_entries(t));
 }
 
-static upb_tabent *emptyent(upb_table *t) {
-  upb_tabent *e = mutable_entries(t) + upb_table_size(t);
-  while (1) { if (upb_tabent_isempty(--e)) return e; UPB_ASSERT(e > t->entries); }
+static upb_tabent *emptyent(upb_table *t, upb_tabent *e) {
+  upb_tabent *begin = mutable_entries(t);
+  upb_tabent *end = begin + upb_table_size(t);
+  for (e = e + 1; e < end; e++) {
+    if (upb_tabent_isempty(e)) return e;
+  }
+  for (e = begin; e < end; e++) {
+    if (upb_tabent_isempty(e)) return e;
+  }
+  UPB_ASSERT(false);
+  return NULL;
 }
 
 static upb_tabent *getentry_mutable(upb_table *t, uint32_t hash) {
@@ -1554,7 +1606,7 @@
     our_e->next = NULL;
   } else {
     /* Collision. */
-    upb_tabent *new_e = emptyent(t);
+    upb_tabent *new_e = emptyent(t, mainpos_e);
     /* Head of collider's chain. */
     upb_tabent *chain = getentry_mutable(t, hashfunc(mainpos_e->key));
     if (chain == mainpos_e) {
@@ -1649,10 +1701,14 @@
   return (uintptr_t)str;
 }
 
+static uint32_t table_hash(const char *p, size_t n) {
+  return wyhash(p, n, 0, _wyp);
+}
+
 static uint32_t strhash(upb_tabkey key) {
   uint32_t len;
   char *str = upb_tabstr(key, &len);
-  return upb_murmur_hash2(str, len, 0);
+  return table_hash(str, len);
 }
 
 static bool streql(upb_tabkey k1, lookupkey_t k2) {
@@ -1661,9 +1717,14 @@
   return len == k2.str.len && (len == 0 || memcmp(str, k2.str.str, len) == 0);
 }
 
-bool upb_strtable_init2(upb_strtable *t, upb_ctype_t ctype, upb_alloc *a) {
+bool upb_strtable_init2(upb_strtable *t, upb_ctype_t ctype,
+                        size_t expected_size, upb_alloc *a) {
   UPB_UNUSED(ctype);  /* TODO(haberman): rm */
-  return init(&t->t, 2, a);
+  // Multiply by approximate reciprocal of MAX_LOAD (0.85), with pow2 denominator.
+  size_t need_entries = (expected_size + 1) * 1204 / 1024;
+  UPB_ASSERT(need_entries >= expected_size * 0.85);
+  int size_lg2 = _upb_lg2ceil(need_entries);
+  return init(&t->t, size_lg2, a);
 }
 
 void upb_strtable_clear(upb_strtable *t) {
@@ -1714,20 +1775,20 @@
   tabkey = strcopy(key, a);
   if (tabkey == 0) return false;
 
-  hash = upb_murmur_hash2(key.str.str, key.str.len, 0);
+  hash = table_hash(key.str.str, key.str.len);
   insert(&t->t, key, tabkey, v, hash, &strhash, &streql);
   return true;
 }
 
 bool upb_strtable_lookup2(const upb_strtable *t, const char *key, size_t len,
                           upb_value *v) {
-  uint32_t hash = upb_murmur_hash2(key, len, 0);
+  uint32_t hash = table_hash(key, len);
   return lookup(&t->t, strkey2(key, len), v, hash, &streql);
 }
 
 bool upb_strtable_remove3(upb_strtable *t, const char *key, size_t len,
                          upb_value *val, upb_alloc *alloc) {
-  uint32_t hash = upb_murmur_hash2(key, len, 0);
+  uint32_t hash = table_hash(key, len);
   upb_tabkey tabkey;
   if (rm(&t->t, strkey2(key, len), val, &tabkey, hash, &streql)) {
     if (alloc) {
@@ -2081,185 +2142,6 @@
          i1->array_part == i2->array_part;
 }
 
-#if defined(UPB_UNALIGNED_READS_OK) || defined(__s390x__)
-/* -----------------------------------------------------------------------------
- * MurmurHash2, by Austin Appleby (released as public domain).
- * Reformatted and C99-ified by Joshua Haberman.
- * Note - This code makes a few assumptions about how your machine behaves -
- *   1. We can read a 4-byte value from any address without crashing
- *   2. sizeof(int) == 4 (in upb this limitation is removed by using uint32_t
- * And it has a few limitations -
- *   1. It will not work incrementally.
- *   2. It will not produce the same results on little-endian and big-endian
- *      machines. */
-uint32_t upb_murmur_hash2(const void *key, size_t len, uint32_t seed) {
-  /* 'm' and 'r' are mixing constants generated offline.
-   * They're not really 'magic', they just happen to work well. */
-  const uint32_t m = 0x5bd1e995;
-  const int32_t r = 24;
-
-  /* Initialize the hash to a 'random' value */
-  uint32_t h = seed ^ len;
-
-  /* Mix 4 bytes at a time into the hash */
-  const uint8_t * data = (const uint8_t *)key;
-  while(len >= 4) {
-    uint32_t k;
-    memcpy(&k, data, sizeof(k));
-
-    k *= m;
-    k ^= k >> r;
-    k *= m;
-
-    h *= m;
-    h ^= k;
-
-    data += 4;
-    len -= 4;
-  }
-
-  /* Handle the last few bytes of the input array */
-  switch(len) {
-    case 3: h ^= data[2] << 16;
-    case 2: h ^= data[1] << 8;
-    case 1: h ^= data[0]; h *= m;
-  };
-
-  /* Do a few final mixes of the hash to ensure the last few
-   * bytes are well-incorporated. */
-  h ^= h >> 13;
-  h *= m;
-  h ^= h >> 15;
-
-  return h;
-}
-
-#else /* !UPB_UNALIGNED_READS_OK */
-
-/* -----------------------------------------------------------------------------
- * MurmurHashAligned2, by Austin Appleby
- * Same algorithm as MurmurHash2, but only does aligned reads - should be safer
- * on certain platforms.
- * Performance will be lower than MurmurHash2 */
-
-#define MIX(h,k,m) { k *= m; k ^= k >> r; k *= m; h *= m; h ^= k; }
-
-uint32_t upb_murmur_hash2(const void * key, size_t len, uint32_t seed) {
-  const uint32_t m = 0x5bd1e995;
-  const int32_t r = 24;
-  const uint8_t * data = (const uint8_t *)key;
-  uint32_t h = (uint32_t)(seed ^ len);
-  uint8_t align = (uintptr_t)data & 3;
-
-  if(align && (len >= 4)) {
-    /* Pre-load the temp registers */
-    uint32_t t = 0, d = 0;
-    int32_t sl;
-    int32_t sr;
-
-    switch(align) {
-      case 1: t |= data[2] << 16;  /* fallthrough */
-      case 2: t |= data[1] << 8;   /* fallthrough */
-      case 3: t |= data[0];
-    }
-
-    t <<= (8 * align);
-
-    data += 4-align;
-    len -= 4-align;
-
-    sl = 8 * (4-align);
-    sr = 8 * align;
-
-    /* Mix */
-
-    while(len >= 4) {
-      uint32_t k;
-
-      d = *(uint32_t *)data;
-      t = (t >> sr) | (d << sl);
-
-      k = t;
-
-      MIX(h,k,m);
-
-      t = d;
-
-      data += 4;
-      len -= 4;
-    }
-
-    /* Handle leftover data in temp registers */
-
-    d = 0;
-
-    if(len >= align) {
-      uint32_t k;
-
-      switch(align) {
-        case 3: d |= data[2] << 16;  /* fallthrough */
-        case 2: d |= data[1] << 8;   /* fallthrough */
-        case 1: d |= data[0];        /* fallthrough */
-      }
-
-      k = (t >> sr) | (d << sl);
-      MIX(h,k,m);
-
-      data += align;
-      len -= align;
-
-      /* ----------
-       * Handle tail bytes */
-
-      switch(len) {
-        case 3: h ^= data[2] << 16;    /* fallthrough */
-        case 2: h ^= data[1] << 8;     /* fallthrough */
-        case 1: h ^= data[0]; h *= m;  /* fallthrough */
-      };
-    } else {
-      switch(len) {
-        case 3: d |= data[2] << 16;  /* fallthrough */
-        case 2: d |= data[1] << 8;   /* fallthrough */
-        case 1: d |= data[0];        /* fallthrough */
-        case 0: h ^= (t >> sr) | (d << sl); h *= m;
-      }
-    }
-
-    h ^= h >> 13;
-    h *= m;
-    h ^= h >> 15;
-
-    return h;
-  } else {
-    while(len >= 4) {
-      uint32_t k = *(uint32_t *)data;
-
-      MIX(h,k,m);
-
-      data += 4;
-      len -= 4;
-    }
-
-    /* ----------
-     * Handle tail bytes */
-
-    switch(len) {
-      case 3: h ^= data[2] << 16; /* fallthrough */
-      case 2: h ^= data[1] << 8;  /* fallthrough */
-      case 1: h ^= data[0]; h *= m;
-    };
-
-    h ^= h >> 13;
-    h *= m;
-    h ^= h >> 15;
-
-    return h;
-  }
-}
-#undef MIX
-
-#endif /* UPB_UNALIGNED_READS_OK */
-
 
 #include <errno.h>
 #include <stdarg.h>
@@ -2299,7 +2181,7 @@
 void upb_status_vseterrf(upb_status *status, const char *fmt, va_list args) {
   if (!status) return;
   status->ok = false;
-  _upb_vsnprintf(status->msg, sizeof(status->msg), fmt, args);
+  vsnprintf(status->msg, sizeof(status->msg), fmt, args);
   status->msg[UPB_STATUS_MAX_MESSAGE - 1] = '\0';
 }
 
@@ -2308,7 +2190,7 @@
   if (!status) return;
   status->ok = false;
   len = strlen(status->msg);
-  _upb_vsnprintf(status->msg + len, sizeof(status->msg) - len, fmt, args);
+  vsnprintf(status->msg + len, sizeof(status->msg) - len, fmt, args);
   status->msg[UPB_STATUS_MAX_MESSAGE - 1] = '\0';
 }
 
@@ -2332,37 +2214,18 @@
 
 /* Be conservative and choose 16 in case anyone is using SSE. */
 
-typedef struct mem_block {
+struct mem_block {
   struct mem_block *next;
   uint32_t size;
   uint32_t cleanups;
   /* Data follows. */
-} mem_block;
+};
 
 typedef struct cleanup_ent {
   upb_cleanup_func *cleanup;
   void *ud;
 } cleanup_ent;
 
-struct upb_arena {
-  _upb_arena_head head;
-  uint32_t *cleanups;
-
-  /* Allocator to allocate arena blocks.  We are responsible for freeing these
-   * when we are destroyed. */
-  upb_alloc *block_alloc;
-  uint32_t last_size;
-
-  /* When multiple arenas are fused together, each arena points to a parent
-   * arena (root points to itself). The root tracks how many live arenas
-   * reference it. */
-  uint32_t refcount;  /* Only used when a->parent == a */
-  struct upb_arena *parent;
-
-  /* Linked list of blocks to free/cleanup. */
-  mem_block *freelist, *freelist_tail;
-};
-
 static const size_t memblock_reserve = UPB_ALIGN_UP(sizeof(mem_block), 16);
 
 static upb_arena *arena_findroot(upb_arena *a) {
@@ -2376,9 +2239,9 @@
   return a;
 }
 
-static void upb_arena_addblock(upb_arena *a, void *ptr, size_t size) {
+static void upb_arena_addblock(upb_arena *a, upb_arena *root, void *ptr,
+                               size_t size) {
   mem_block *block = ptr;
-  upb_arena *root = arena_findroot(a);
 
   /* The block is for arena |a|, but should appear in the freelist of |root|. */
   block->next = root->freelist;
@@ -2392,26 +2255,22 @@
   a->head.end = UPB_PTR_AT(block, size, char);
   a->cleanups = &block->cleanups;
 
-  /* TODO(haberman): ASAN poison. */
+  UPB_POISON_MEMORY_REGION(a->head.ptr, a->head.end - a->head.ptr);
 }
 
 static bool upb_arena_allocblock(upb_arena *a, size_t size) {
+  upb_arena *root = arena_findroot(a);
   size_t block_size = UPB_MAX(size, a->last_size * 2) + memblock_reserve;
-  mem_block *block = upb_malloc(a->block_alloc, block_size);
+  mem_block *block = upb_malloc(root->block_alloc, block_size);
 
   if (!block) return false;
-  upb_arena_addblock(a, block, block_size);
+  upb_arena_addblock(a, root, block, block_size);
   return true;
 }
 
-static bool arena_has(upb_arena *a, size_t size) {
-  _upb_arena_head *h = (_upb_arena_head*)a;
-  return (size_t)(h->end - h->ptr) >= size;
-}
-
 void *_upb_arena_slowmalloc(upb_arena *a, size_t size) {
   if (!upb_arena_allocblock(a, size)) return NULL;  /* Out of memory. */
-  UPB_ASSERT(arena_has(a, size));
+  UPB_ASSERT(_upb_arenahas(a, size));
   return upb_arena_malloc(a, size);
 }
 
@@ -2443,7 +2302,7 @@
   a->freelist = NULL;
   a->freelist_tail = NULL;
 
-  upb_arena_addblock(a, mem, n);
+  upb_arena_addblock(a, a, mem, n);
 
   return a;
 }
@@ -2506,14 +2365,15 @@
 bool upb_arena_addcleanup(upb_arena *a, void *ud, upb_cleanup_func *func) {
   cleanup_ent *ent;
 
-  if (!a->cleanups || !arena_has(a, sizeof(cleanup_ent))) {
+  if (!a->cleanups || !_upb_arenahas(a, sizeof(cleanup_ent))) {
     if (!upb_arena_allocblock(a, 128)) return false;  /* Out of memory. */
-    UPB_ASSERT(arena_has(a, sizeof(cleanup_ent)));
+    UPB_ASSERT(_upb_arenahas(a, sizeof(cleanup_ent)));
   }
 
   a->head.end -= sizeof(cleanup_ent);
   ent = (cleanup_ent*)a->head.end;
   (*a->cleanups)++;
+  UPB_UNPOISON_MEMORY_REGION(ent, sizeof(cleanup_ent));
 
   ent->cleanup = func;
   ent->ud = ud;
@@ -2599,7 +2459,7 @@
   UPB_SIZE(64, 128), 12, false,
 };
 
-static const upb_msglayout *const google_protobuf_DescriptorProto_submsgs[8] = {
+static const upb_msglayout *const google_protobuf_DescriptorProto_submsgs[7] = {
   &google_protobuf_DescriptorProto_msginit,
   &google_protobuf_DescriptorProto_ExtensionRange_msginit,
   &google_protobuf_DescriptorProto_ReservedRange_msginit,
@@ -2674,23 +2534,23 @@
 };
 
 static const upb_msglayout_field google_protobuf_FieldDescriptorProto__fields[11] = {
-  {1, UPB_SIZE(36, 40), 6, 0, 12, 1},
-  {2, UPB_SIZE(44, 56), 7, 0, 12, 1},
-  {3, UPB_SIZE(24, 24), 3, 0, 5, 1},
-  {4, UPB_SIZE(8, 8), 1, 0, 14, 1},
-  {5, UPB_SIZE(16, 16), 2, 0, 14, 1},
-  {6, UPB_SIZE(52, 72), 8, 0, 12, 1},
-  {7, UPB_SIZE(60, 88), 9, 0, 12, 1},
-  {8, UPB_SIZE(76, 120), 11, 0, 11, 1},
-  {9, UPB_SIZE(28, 28), 4, 0, 5, 1},
-  {10, UPB_SIZE(68, 104), 10, 0, 12, 1},
-  {17, UPB_SIZE(32, 32), 5, 0, 8, 1},
+  {1, UPB_SIZE(24, 24), 6, 0, 12, 1},
+  {2, UPB_SIZE(32, 40), 7, 0, 12, 1},
+  {3, UPB_SIZE(12, 12), 3, 0, 5, 1},
+  {4, UPB_SIZE(4, 4), 1, 0, 14, 1},
+  {5, UPB_SIZE(8, 8), 2, 0, 14, 1},
+  {6, UPB_SIZE(40, 56), 8, 0, 12, 1},
+  {7, UPB_SIZE(48, 72), 9, 0, 12, 1},
+  {8, UPB_SIZE(64, 104), 11, 0, 11, 1},
+  {9, UPB_SIZE(16, 16), 4, 0, 5, 1},
+  {10, UPB_SIZE(56, 88), 10, 0, 12, 1},
+  {17, UPB_SIZE(20, 20), 5, 0, 8, 1},
 };
 
 const upb_msglayout google_protobuf_FieldDescriptorProto_msginit = {
   &google_protobuf_FieldDescriptorProto_submsgs[0],
   &google_protobuf_FieldDescriptorProto__fields[0],
-  UPB_SIZE(80, 128), 11, false,
+  UPB_SIZE(72, 112), 11, false,
 };
 
 static const upb_msglayout *const google_protobuf_OneofDescriptorProto_submsgs[1] = {
@@ -2796,33 +2656,33 @@
 };
 
 static const upb_msglayout_field google_protobuf_FileOptions__fields[21] = {
-  {1, UPB_SIZE(28, 32), 11, 0, 12, 1},
-  {8, UPB_SIZE(36, 48), 12, 0, 12, 1},
-  {9, UPB_SIZE(8, 8), 1, 0, 14, 1},
-  {10, UPB_SIZE(16, 16), 2, 0, 8, 1},
-  {11, UPB_SIZE(44, 64), 13, 0, 12, 1},
-  {16, UPB_SIZE(17, 17), 3, 0, 8, 1},
-  {17, UPB_SIZE(18, 18), 4, 0, 8, 1},
-  {18, UPB_SIZE(19, 19), 5, 0, 8, 1},
-  {20, UPB_SIZE(20, 20), 6, 0, 8, 1},
-  {23, UPB_SIZE(21, 21), 7, 0, 8, 1},
-  {27, UPB_SIZE(22, 22), 8, 0, 8, 1},
-  {31, UPB_SIZE(23, 23), 9, 0, 8, 1},
-  {36, UPB_SIZE(52, 80), 14, 0, 12, 1},
-  {37, UPB_SIZE(60, 96), 15, 0, 12, 1},
-  {39, UPB_SIZE(68, 112), 16, 0, 12, 1},
-  {40, UPB_SIZE(76, 128), 17, 0, 12, 1},
-  {41, UPB_SIZE(84, 144), 18, 0, 12, 1},
-  {42, UPB_SIZE(24, 24), 10, 0, 8, 1},
-  {44, UPB_SIZE(92, 160), 19, 0, 12, 1},
-  {45, UPB_SIZE(100, 176), 20, 0, 12, 1},
-  {999, UPB_SIZE(108, 192), 0, 0, 11, 3},
+  {1, UPB_SIZE(20, 24), 11, 0, 12, 1},
+  {8, UPB_SIZE(28, 40), 12, 0, 12, 1},
+  {9, UPB_SIZE(4, 4), 1, 0, 14, 1},
+  {10, UPB_SIZE(8, 8), 2, 0, 8, 1},
+  {11, UPB_SIZE(36, 56), 13, 0, 12, 1},
+  {16, UPB_SIZE(9, 9), 3, 0, 8, 1},
+  {17, UPB_SIZE(10, 10), 4, 0, 8, 1},
+  {18, UPB_SIZE(11, 11), 5, 0, 8, 1},
+  {20, UPB_SIZE(12, 12), 6, 0, 8, 1},
+  {23, UPB_SIZE(13, 13), 7, 0, 8, 1},
+  {27, UPB_SIZE(14, 14), 8, 0, 8, 1},
+  {31, UPB_SIZE(15, 15), 9, 0, 8, 1},
+  {36, UPB_SIZE(44, 72), 14, 0, 12, 1},
+  {37, UPB_SIZE(52, 88), 15, 0, 12, 1},
+  {39, UPB_SIZE(60, 104), 16, 0, 12, 1},
+  {40, UPB_SIZE(68, 120), 17, 0, 12, 1},
+  {41, UPB_SIZE(76, 136), 18, 0, 12, 1},
+  {42, UPB_SIZE(16, 16), 10, 0, 8, 1},
+  {44, UPB_SIZE(84, 152), 19, 0, 12, 1},
+  {45, UPB_SIZE(92, 168), 20, 0, 12, 1},
+  {999, UPB_SIZE(100, 184), 0, 0, 11, 3},
 };
 
 const upb_msglayout google_protobuf_FileOptions_msginit = {
   &google_protobuf_FileOptions_submsgs[0],
   &google_protobuf_FileOptions__fields[0],
-  UPB_SIZE(112, 208), 21, false,
+  UPB_SIZE(104, 192), 21, false,
 };
 
 static const upb_msglayout *const google_protobuf_MessageOptions_submsgs[1] = {
@@ -2848,19 +2708,19 @@
 };
 
 static const upb_msglayout_field google_protobuf_FieldOptions__fields[7] = {
-  {1, UPB_SIZE(8, 8), 1, 0, 14, 1},
-  {2, UPB_SIZE(24, 24), 3, 0, 8, 1},
-  {3, UPB_SIZE(25, 25), 4, 0, 8, 1},
-  {5, UPB_SIZE(26, 26), 5, 0, 8, 1},
-  {6, UPB_SIZE(16, 16), 2, 0, 14, 1},
-  {10, UPB_SIZE(27, 27), 6, 0, 8, 1},
-  {999, UPB_SIZE(28, 32), 0, 0, 11, 3},
+  {1, UPB_SIZE(4, 4), 1, 0, 14, 1},
+  {2, UPB_SIZE(12, 12), 3, 0, 8, 1},
+  {3, UPB_SIZE(13, 13), 4, 0, 8, 1},
+  {5, UPB_SIZE(14, 14), 5, 0, 8, 1},
+  {6, UPB_SIZE(8, 8), 2, 0, 14, 1},
+  {10, UPB_SIZE(15, 15), 6, 0, 8, 1},
+  {999, UPB_SIZE(16, 16), 0, 0, 11, 3},
 };
 
 const upb_msglayout google_protobuf_FieldOptions_msginit = {
   &google_protobuf_FieldOptions_submsgs[0],
   &google_protobuf_FieldOptions__fields[0],
-  UPB_SIZE(32, 40), 7, false,
+  UPB_SIZE(20, 24), 7, false,
 };
 
 static const upb_msglayout *const google_protobuf_OneofOptions_submsgs[1] = {
@@ -2928,15 +2788,15 @@
 };
 
 static const upb_msglayout_field google_protobuf_MethodOptions__fields[3] = {
-  {33, UPB_SIZE(16, 16), 2, 0, 8, 1},
-  {34, UPB_SIZE(8, 8), 1, 0, 14, 1},
-  {999, UPB_SIZE(20, 24), 0, 0, 11, 3},
+  {33, UPB_SIZE(8, 8), 2, 0, 8, 1},
+  {34, UPB_SIZE(4, 4), 1, 0, 14, 1},
+  {999, UPB_SIZE(12, 16), 0, 0, 11, 3},
 };
 
 const upb_msglayout google_protobuf_MethodOptions_msginit = {
   &google_protobuf_MethodOptions_submsgs[0],
   &google_protobuf_MethodOptions__fields[0],
-  UPB_SIZE(24, 32), 3, false,
+  UPB_SIZE(16, 24), 3, false,
 };
 
 static const upb_msglayout *const google_protobuf_UninterpretedOption_submsgs[1] = {
@@ -3093,7 +2953,7 @@
   &google_protobuf_GeneratedCodeInfo_Annotation_msginit,
 };
 
-static const char descriptor[7619] = {'\n', ' ', 'g', 'o', 'o', 'g', 'l', 'e', '/', 'p', 'r', 'o', 't', 'o', 'b', 'u', 'f', '/', 'd', 'e', 's', 'c', 'r', 'i', 'p', 
+static const char descriptor[7601] = {'\n', ' ', 'g', 'o', 'o', 'g', 'l', 'e', '/', 'p', 'r', 'o', 't', 'o', 'b', 'u', 'f', '/', 'd', 'e', 's', 'c', 'r', 'i', 'p', 
 't', 'o', 'r', '.', 'p', 'r', 'o', 't', 'o', '\022', '\017', 'g', 'o', 'o', 'g', 'l', 'e', '.', 'p', 'r', 'o', 't', 'o', 'b', 'u', 
 'f', '\"', 'M', '\n', '\021', 'F', 'i', 'l', 'e', 'D', 'e', 's', 'c', 'r', 'i', 'p', 't', 'o', 'r', 'S', 'e', 't', '\022', '8', '\n', 
 '\004', 'f', 'i', 'l', 'e', '\030', '\001', ' ', '\003', '(', '\013', '2', '$', '.', 'g', 'o', 'o', 'g', 'l', 'e', '.', 'p', 'r', 'o', 't', 
@@ -3391,13 +3251,13 @@
 'n', '\022', '\026', '\n', '\004', 'p', 'a', 't', 'h', '\030', '\001', ' ', '\003', '(', '\005', 'B', '\002', '\020', '\001', 'R', '\004', 'p', 'a', 't', 'h', 
 '\022', '\037', '\n', '\013', 's', 'o', 'u', 'r', 'c', 'e', '_', 'f', 'i', 'l', 'e', '\030', '\002', ' ', '\001', '(', '\t', 'R', '\n', 's', 'o', 
 'u', 'r', 'c', 'e', 'F', 'i', 'l', 'e', '\022', '\024', '\n', '\005', 'b', 'e', 'g', 'i', 'n', '\030', '\003', ' ', '\001', '(', '\005', 'R', '\005', 
-'b', 'e', 'g', 'i', 'n', '\022', '\020', '\n', '\003', 'e', 'n', 'd', '\030', '\004', ' ', '\001', '(', '\005', 'R', '\003', 'e', 'n', 'd', 'B', '\217', 
-'\001', '\n', '\023', 'c', 'o', 'm', '.', 'g', 'o', 'o', 'g', 'l', 'e', '.', 'p', 'r', 'o', 't', 'o', 'b', 'u', 'f', 'B', '\020', 'D', 
-'e', 's', 'c', 'r', 'i', 'p', 't', 'o', 'r', 'P', 'r', 'o', 't', 'o', 's', 'H', '\001', 'Z', '>', 'g', 'i', 't', 'h', 'u', 'b', 
-'.', 'c', 'o', 'm', '/', 'g', 'o', 'l', 'a', 'n', 'g', '/', 'p', 'r', 'o', 't', 'o', 'b', 'u', 'f', '/', 'p', 'r', 'o', 't', 
-'o', 'c', '-', 'g', 'e', 'n', '-', 'g', 'o', '/', 'd', 'e', 's', 'c', 'r', 'i', 'p', 't', 'o', 'r', ';', 'd', 'e', 's', 'c', 
-'r', 'i', 'p', 't', 'o', 'r', '\370', '\001', '\001', '\242', '\002', '\003', 'G', 'P', 'B', '\252', '\002', '\032', 'G', 'o', 'o', 'g', 'l', 'e', '.', 
-'P', 'r', 'o', 't', 'o', 'b', 'u', 'f', '.', 'R', 'e', 'f', 'l', 'e', 'c', 't', 'i', 'o', 'n', 
+'b', 'e', 'g', 'i', 'n', '\022', '\020', '\n', '\003', 'e', 'n', 'd', '\030', '\004', ' ', '\001', '(', '\005', 'R', '\003', 'e', 'n', 'd', 'B', '~', 
+'\n', '\023', 'c', 'o', 'm', '.', 'g', 'o', 'o', 'g', 'l', 'e', '.', 'p', 'r', 'o', 't', 'o', 'b', 'u', 'f', 'B', '\020', 'D', 'e', 
+'s', 'c', 'r', 'i', 'p', 't', 'o', 'r', 'P', 'r', 'o', 't', 'o', 's', 'H', '\001', 'Z', '-', 'g', 'o', 'o', 'g', 'l', 'e', '.', 
+'g', 'o', 'l', 'a', 'n', 'g', '.', 'o', 'r', 'g', '/', 'p', 'r', 'o', 't', 'o', 'b', 'u', 'f', '/', 't', 'y', 'p', 'e', 's', 
+'/', 'd', 'e', 's', 'c', 'r', 'i', 'p', 't', 'o', 'r', 'p', 'b', '\370', '\001', '\001', '\242', '\002', '\003', 'G', 'P', 'B', '\252', '\002', '\032', 
+'G', 'o', 'o', 'g', 'l', 'e', '.', 'P', 'r', 'o', 't', 'o', 'b', 'u', 'f', '.', 'R', 'e', 'f', 'l', 'e', 'c', 't', 'i', 'o', 
+'n', 
 };
 
 static upb_def_init *deps[1] = {
@@ -3408,12 +3268,13 @@
   deps,
   layouts,
   "google/protobuf/descriptor.proto",
-  UPB_STRVIEW_INIT(descriptor, 7619)
+  UPB_STRVIEW_INIT(descriptor, 7601)
 };
 
 
 #include <ctype.h>
 #include <errno.h>
+#include <setjmp.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ -3423,15 +3284,6 @@
   char str[1];  /* Null-terminated string data follows. */
 } str_t;
 
-static str_t *newstr(upb_alloc *alloc, const char *data, size_t len) {
-  str_t *ret = upb_malloc(alloc, sizeof(*ret) + len);
-  if (!ret) return NULL;
-  ret->len = len;
-  if (len) memcpy(ret->str, data, len);
-  ret->str[len] = '\0';
-  return ret;
-}
-
 struct upb_fielddef {
   const upb_filedef *file;
   const upb_msgdef *msgdef;
@@ -3498,7 +3350,9 @@
 struct upb_oneofdef {
   const upb_msgdef *parent;
   const char *full_name;
-  uint32_t index;
+  int field_count;
+  bool synthetic;
+  const upb_fielddef **fields;
   upb_strtable ntof;
   upb_inttable itof;
 };
@@ -3525,6 +3379,7 @@
   upb_arena *arena;
   upb_strtable syms;  /* full_name -> packed def ptr */
   upb_strtable files;  /* file_name -> upb_filedef* */
+  size_t bytes_loaded;
 };
 
 /* Inside a symtab we store tagged pointers to specific def types. */
@@ -3563,38 +3418,6 @@
   return upb_isletter(c) || upb_isbetween(c, '0', '9');
 }
 
-static bool upb_isident(upb_strview name, bool full, upb_status *s) {
-  const char *str = name.data;
-  size_t len = name.size;
-  bool start = true;
-  size_t i;
-  for (i = 0; i < len; i++) {
-    char c = str[i];
-    if (c == '.') {
-      if (start || !full) {
-        upb_status_seterrf(s, "invalid name: unexpected '.' (%s)", str);
-        return false;
-      }
-      start = true;
-    } else if (start) {
-      if (!upb_isletter(c)) {
-        upb_status_seterrf(
-            s, "invalid name: path components must start with a letter (%s)",
-            str);
-        return false;
-      }
-      start = false;
-    } else {
-      if (!upb_isalphanum(c)) {
-        upb_status_seterrf(s, "invalid name: non-alphanumeric character (%s)",
-                           str);
-        return false;
-      }
-    }
-  }
-  return !start;
-}
-
 static const char *shortdefname(const char *fullname) {
   const char *p;
 
@@ -3654,85 +3477,6 @@
   upb_status_seterrmsg(status, "out of memory");
 }
 
-static bool assign_msg_indices(upb_msgdef *m, upb_status *s) {
-  /* Sort fields.  upb internally relies on UPB_TYPE_MESSAGE fields having the
-   * lowest indexes, but we do not publicly guarantee this. */
-  upb_msg_field_iter j;
-  int i;
-  uint32_t selector;
-  int n = upb_msgdef_numfields(m);
-  upb_fielddef **fields;
-
-  if (n == 0) {
-    m->selector_count = UPB_STATIC_SELECTOR_COUNT;
-    m->submsg_field_count = 0;
-    return true;
-  }
-
-  fields = upb_gmalloc(n * sizeof(*fields));
-  if (!fields) {
-    upb_status_setoom(s);
-    return false;
-  }
-
-  m->submsg_field_count = 0;
-  for(i = 0, upb_msg_field_begin(&j, m);
-      !upb_msg_field_done(&j);
-      upb_msg_field_next(&j), i++) {
-    upb_fielddef *f = upb_msg_iter_field(&j);
-    UPB_ASSERT(f->msgdef == m);
-    if (upb_fielddef_issubmsg(f)) {
-      m->submsg_field_count++;
-    }
-    fields[i] = f;
-  }
-
-  qsort(fields, n, sizeof(*fields), cmp_fields);
-
-  selector = UPB_STATIC_SELECTOR_COUNT + m->submsg_field_count;
-  for (i = 0; i < n; i++) {
-    upb_fielddef *f = fields[i];
-    f->index_ = i;
-    f->selector_base = selector + upb_handlers_selectorbaseoffset(f);
-    selector += upb_handlers_selectorcount(f);
-  }
-  m->selector_count = selector;
-
-  upb_gfree(fields);
-  return true;
-}
-
-static bool check_oneofs(upb_msgdef *m, upb_status *s) {
-  int i;
-  int first_synthetic = -1;
-  upb_oneofdef *mutable_oneofs = (upb_oneofdef*)m->oneofs;
-
-  for (i = 0; i < m->oneof_count; i++) {
-    mutable_oneofs[i].index = i;
-
-    if (upb_oneofdef_issynthetic(&mutable_oneofs[i])) {
-      if (first_synthetic == -1) {
-        first_synthetic = i;
-      }
-    } else {
-      if (first_synthetic != -1) {
-        upb_status_seterrf(
-            s, "Synthetic oneofs must be after all other oneofs: %s",
-            upb_oneofdef_name(&mutable_oneofs[i]));
-        return false;
-      }
-    }
-  }
-
-  if (first_synthetic == -1) {
-    m->real_oneof_count = m->oneof_count;
-  } else {
-    m->real_oneof_count = first_synthetic;
-  }
-
-  return true;
-}
-
 static void assign_msg_wellknowntype(upb_msgdef *m) {
   const char *name = upb_msgdef_fullname(m);
   if (name == NULL) {
@@ -4135,15 +3879,32 @@
   return m->real_oneof_count;
 }
 
+int upb_msgdef_fieldcount(const upb_msgdef *m) {
+  return m->field_count;
+}
+
+int upb_msgdef_oneofcount(const upb_msgdef *m) {
+  return m->oneof_count;
+}
+
+int upb_msgdef_realoneofcount(const upb_msgdef *m) {
+  return m->real_oneof_count;
+}
+
 const upb_msglayout *upb_msgdef_layout(const upb_msgdef *m) {
   return m->layout;
 }
 
-const upb_fielddef *_upb_msgdef_field(const upb_msgdef *m, int i) {
-  if (i >= m->field_count) return NULL;
+const upb_fielddef *upb_msgdef_field(const upb_msgdef *m, int i) {
+  UPB_ASSERT(i >= 0 && i < m->field_count);
   return &m->fields[i];
 }
 
+const upb_oneofdef *upb_msgdef_oneof(const upb_msgdef *m, int i) {
+  UPB_ASSERT(i >= 0 && i < m->oneof_count);
+  return &m->oneofs[i];
+}
+
 bool upb_msgdef_mapentry(const upb_msgdef *m) {
   return m->map_entry;
 }
@@ -4231,22 +3992,25 @@
   return o->parent;
 }
 
+int upb_oneofdef_fieldcount(const upb_oneofdef *o) {
+  return o->field_count;
+}
+
+const upb_fielddef *upb_oneofdef_field(const upb_oneofdef *o, int i) {
+  UPB_ASSERT(i < o->field_count);
+  return o->fields[i];
+}
+
 int upb_oneofdef_numfields(const upb_oneofdef *o) {
-  return (int)upb_strtable_count(&o->ntof);
+  return o->field_count;
 }
 
 uint32_t upb_oneofdef_index(const upb_oneofdef *o) {
-  return o->index;
+  return o - o->parent->oneofs;
 }
 
 bool upb_oneofdef_issynthetic(const upb_oneofdef *o) {
-  upb_inttable_iter iter;
-  const upb_fielddef *f;
-  upb_inttable_begin(&iter, &o->itof);
-  if (upb_oneofdef_numfields(o) != 1) return false;
-  f = upb_value_getptr(upb_inttable_iter_value(&iter));
-  UPB_ASSERT(f);
-  return f->proto3_optional_;
+  return o->synthetic;
 }
 
 const upb_fielddef *upb_oneofdef_ntof(const upb_oneofdef *o,
@@ -4282,7 +4046,185 @@
   upb_inttable_iter_setdone(iter);
 }
 
-/* Dynamic Layout Generation. *************************************************/
+/* upb_filedef ****************************************************************/
+
+const char *upb_filedef_name(const upb_filedef *f) {
+  return f->name;
+}
+
+const char *upb_filedef_package(const upb_filedef *f) {
+  return f->package;
+}
+
+const char *upb_filedef_phpprefix(const upb_filedef *f) {
+  return f->phpprefix;
+}
+
+const char *upb_filedef_phpnamespace(const upb_filedef *f) {
+  return f->phpnamespace;
+}
+
+upb_syntax_t upb_filedef_syntax(const upb_filedef *f) {
+  return f->syntax;
+}
+
+int upb_filedef_msgcount(const upb_filedef *f) {
+  return f->msg_count;
+}
+
+int upb_filedef_depcount(const upb_filedef *f) {
+  return f->dep_count;
+}
+
+int upb_filedef_enumcount(const upb_filedef *f) {
+  return f->enum_count;
+}
+
+const upb_filedef *upb_filedef_dep(const upb_filedef *f, int i) {
+  return i < 0 || i >= f->dep_count ? NULL : f->deps[i];
+}
+
+const upb_msgdef *upb_filedef_msg(const upb_filedef *f, int i) {
+  return i < 0 || i >= f->msg_count ? NULL : &f->msgs[i];
+}
+
+const upb_enumdef *upb_filedef_enum(const upb_filedef *f, int i) {
+  return i < 0 || i >= f->enum_count ? NULL : &f->enums[i];
+}
+
+void upb_symtab_free(upb_symtab *s) {
+  upb_arena_free(s->arena);
+  upb_gfree(s);
+}
+
+upb_symtab *upb_symtab_new(void) {
+  upb_symtab *s = upb_gmalloc(sizeof(*s));
+  upb_alloc *alloc;
+
+  if (!s) {
+    return NULL;
+  }
+
+  s->arena = upb_arena_new();
+  s->bytes_loaded = 0;
+  alloc = upb_arena_alloc(s->arena);
+
+  if (!upb_strtable_init2(&s->syms, UPB_CTYPE_CONSTPTR, 32, alloc) ||
+      !upb_strtable_init2(&s->files, UPB_CTYPE_CONSTPTR, 4, alloc)) {
+    upb_arena_free(s->arena);
+    upb_gfree(s);
+    s = NULL;
+  }
+  return s;
+}
+
+const upb_msgdef *upb_symtab_lookupmsg(const upb_symtab *s, const char *sym) {
+  upb_value v;
+  return upb_strtable_lookup(&s->syms, sym, &v) ?
+      unpack_def(v, UPB_DEFTYPE_MSG) : NULL;
+}
+
+const upb_msgdef *upb_symtab_lookupmsg2(const upb_symtab *s, const char *sym,
+                                        size_t len) {
+  upb_value v;
+  return upb_strtable_lookup2(&s->syms, sym, len, &v) ?
+      unpack_def(v, UPB_DEFTYPE_MSG) : NULL;
+}
+
+const upb_enumdef *upb_symtab_lookupenum(const upb_symtab *s, const char *sym) {
+  upb_value v;
+  return upb_strtable_lookup(&s->syms, sym, &v) ?
+      unpack_def(v, UPB_DEFTYPE_ENUM) : NULL;
+}
+
+const upb_filedef *upb_symtab_lookupfile(const upb_symtab *s, const char *name) {
+  upb_value v;
+  return upb_strtable_lookup(&s->files, name, &v) ? upb_value_getconstptr(v)
+                                                  : NULL;
+}
+
+const upb_filedef *upb_symtab_lookupfile2(
+    const upb_symtab *s, const char *name, size_t len) {
+  upb_value v;
+  return upb_strtable_lookup2(&s->files, name, len, &v) ?
+      upb_value_getconstptr(v) : NULL;
+}
+
+int upb_symtab_filecount(const upb_symtab *s) {
+  return (int)upb_strtable_count(&s->files);
+}
+
+/* Code to build defs from descriptor protos. *********************************/
+
+/* There is a question of how much validation to do here.  It will be difficult
+ * to perfectly match the amount of validation performed by proto2.  But since
+ * this code is used to directly build defs from Ruby (for example) we do need
+ * to validate important constraints like uniqueness of names and numbers. */
+
+#define CHK_OOM(x) if (!(x)) { symtab_oomerr(ctx); }
+
+typedef struct {
+  upb_symtab *symtab;
+  upb_filedef *file;              /* File we are building. */
+  upb_arena *file_arena;          /* Allocate defs here. */
+  upb_alloc *alloc;               /* Alloc of file_arena, for tables. */
+  const upb_msglayout **layouts;  /* NULL if we should build layouts. */
+  upb_status *status;             /* Record errors here. */
+  jmp_buf err;                    /* longjmp() on error. */
+} symtab_addctx;
+
+UPB_NORETURN UPB_NOINLINE
+static void symtab_errf(symtab_addctx *ctx, const char *fmt, ...) {
+  va_list argp;
+  va_start(argp, fmt);
+  upb_status_vseterrf(ctx->status, fmt, argp);
+  va_end(argp);
+  longjmp(ctx->err, 1);
+}
+
+UPB_NORETURN UPB_NOINLINE
+static void symtab_oomerr(symtab_addctx *ctx) {
+  upb_status_setoom(ctx->status);
+  longjmp(ctx->err, 1);
+}
+
+void *symtab_alloc(symtab_addctx *ctx, size_t bytes) {
+  void *ret = upb_arena_malloc(ctx->file_arena, bytes);
+  if (!ret) symtab_oomerr(ctx);
+  return ret;
+}
+
+static void check_ident(symtab_addctx *ctx, upb_strview name, bool full) {
+  const char *str = name.data;
+  size_t len = name.size;
+  bool start = true;
+  size_t i;
+  for (i = 0; i < len; i++) {
+    char c = str[i];
+    if (c == '.') {
+      if (start || !full) {
+        symtab_errf(ctx, "invalid name: unexpected '.' (%.*s)", (int)len, str);
+      }
+      start = true;
+    } else if (start) {
+      if (!upb_isletter(c)) {
+        symtab_errf(
+            ctx,
+            "invalid name: path components must start with a letter (%.*s)",
+            (int)len, str);
+      }
+      start = false;
+    } else {
+      if (!upb_isalphanum(c)) {
+        symtab_errf(ctx, "invalid name: non-alphanumeric character (%.*s)",
+                    (int)len, str);
+      }
+    }
+  }
+  if (start) {
+    symtab_errf(ctx, "invalid name: empty part (%.*s)", (int)len, str);
+  }
+}
 
 static size_t div_round_up(size_t n, size_t d) {
   return (n + d - 1) / d;
@@ -4349,7 +4291,7 @@
 
 /* This function is the dynamic equivalent of message_layout.{cc,h} in upbc.
  * It computes a dynamic layout for all of the fields in |m|. */
-static bool make_layout(const upb_symtab *symtab, const upb_msgdef *m) {
+static void make_layout(symtab_addctx *ctx, const upb_msgdef *m) {
   upb_msglayout *l = (upb_msglayout*)m->layout;
   upb_msg_field_iter it;
   upb_msg_oneof_iter oit;
@@ -4357,18 +4299,11 @@
   size_t submsg_count = m->submsg_field_count;
   const upb_msglayout **submsgs;
   upb_msglayout_field *fields;
-  upb_alloc *alloc = upb_arena_alloc(symtab->arena);
 
   memset(l, 0, sizeof(*l));
 
-  fields = upb_malloc(alloc, upb_msgdef_numfields(m) * sizeof(*fields));
-  submsgs = upb_malloc(alloc, submsg_count * sizeof(*submsgs));
-
-  if ((!fields && upb_msgdef_numfields(m)) ||
-      (!submsgs && submsg_count)) {
-    /* OOM. */
-    return false;
-  }
+  fields = symtab_alloc(ctx, upb_msgdef_numfields(m) * sizeof(*fields));
+  submsgs = symtab_alloc(ctx, submsg_count * sizeof(*submsgs));
 
   l->field_count = upb_msgdef_numfields(m);
   l->fields = fields;
@@ -4398,7 +4333,7 @@
     l->field_count = 2;
     l->size = 2 * sizeof(upb_strview);
     l->size = UPB_ALIGN_UP(l->size, 8);
-    return true;
+    return;
   }
 
   /* Allocate data offsets in three stages:
@@ -4510,31 +4445,52 @@
   /* Sort fields by number. */
   qsort(fields, upb_msgdef_numfields(m), sizeof(*fields), field_number_cmp);
   assign_layout_indices(m, fields);
-
-  return true;
 }
 
-/* Code to build defs from descriptor protos. *********************************/
+static void assign_msg_indices(symtab_addctx *ctx, upb_msgdef *m) {
+  /* Sort fields.  upb internally relies on UPB_TYPE_MESSAGE fields having the
+   * lowest indexes, but we do not publicly guarantee this. */
+  upb_msg_field_iter j;
+  int i;
+  uint32_t selector;
+  int n = upb_msgdef_numfields(m);
+  upb_fielddef **fields;
 
-/* There is a question of how much validation to do here.  It will be difficult
- * to perfectly match the amount of validation performed by proto2.  But since
- * this code is used to directly build defs from Ruby (for example) we do need
- * to validate important constraints like uniqueness of names and numbers. */
+  if (n == 0) {
+    m->selector_count = UPB_STATIC_SELECTOR_COUNT;
+    m->submsg_field_count = 0;
+    return;
+  }
 
-#define CHK(x) if (!(x)) { return false; }
-#define CHK_OOM(x) if (!(x)) { upb_status_setoom(ctx->status); return false; }
+  fields = upb_gmalloc(n * sizeof(*fields));
 
-typedef struct {
-  const upb_symtab *symtab;
-  upb_filedef *file;              /* File we are building. */
-  upb_alloc *alloc;               /* Allocate defs here. */
-  upb_alloc *tmp;                 /* Alloc for addtab and any other tmp data. */
-  upb_strtable *addtab;           /* full_name -> packed def ptr for new defs */
-  const upb_msglayout **layouts;  /* NULL if we should build layouts. */
-  upb_status *status;             /* Record errors here. */
-} symtab_addctx;
+  m->submsg_field_count = 0;
+  for(i = 0, upb_msg_field_begin(&j, m);
+      !upb_msg_field_done(&j);
+      upb_msg_field_next(&j), i++) {
+    upb_fielddef *f = upb_msg_iter_field(&j);
+    UPB_ASSERT(f->msgdef == m);
+    if (upb_fielddef_issubmsg(f)) {
+      m->submsg_field_count++;
+    }
+    fields[i] = f;
+  }
 
-static char* strviewdup(const symtab_addctx *ctx, upb_strview view) {
+  qsort(fields, n, sizeof(*fields), cmp_fields);
+
+  selector = UPB_STATIC_SELECTOR_COUNT + m->submsg_field_count;
+  for (i = 0; i < n; i++) {
+    upb_fielddef *f = fields[i];
+    f->index_ = i;
+    f->selector_base = selector + upb_handlers_selectorbaseoffset(f);
+    selector += upb_handlers_selectorcount(f);
+  }
+  m->selector_count = selector;
+
+  upb_gfree(fields);
+}
+
+static char *strviewdup(symtab_addctx *ctx, upb_strview view) {
   return upb_strdup2(view.data, view.size, ctx->alloc);
 }
 
@@ -4546,13 +4502,12 @@
   return streql2(view.data, view.size, b);
 }
 
-static const char *makefullname(const symtab_addctx *ctx, const char *prefix,
+static const char *makefullname(symtab_addctx *ctx, const char *prefix,
                                 upb_strview name) {
   if (prefix) {
     /* ret = prefix + '.' + name; */
     size_t n = strlen(prefix);
-    char *ret = upb_malloc(ctx->alloc, n + name.size + 2);
-    CHK_OOM(ret);
+    char *ret = symtab_alloc(ctx, n + name.size + 2);
     strcpy(ret, prefix);
     ret[n] = '.';
     memcpy(&ret[n + 1], name.data, name.size);
@@ -4563,6 +4518,41 @@
   }
 }
 
+static void finalize_oneofs(symtab_addctx *ctx, upb_msgdef *m) {
+  int i;
+  int synthetic_count = 0;
+  upb_oneofdef *mutable_oneofs = (upb_oneofdef*)m->oneofs;
+
+  for (i = 0; i < m->oneof_count; i++) {
+    upb_oneofdef *o = &mutable_oneofs[i];
+
+    if (o->synthetic && o->field_count != 1) {
+      symtab_errf(ctx, "Synthetic oneofs must have one field, not %d: %s",
+                  o->field_count, upb_oneofdef_name(o));
+    }
+
+    if (o->synthetic) {
+      synthetic_count++;
+    } else if (synthetic_count != 0) {
+      symtab_errf(ctx, "Synthetic oneofs must be after all other oneofs: %s",
+                  upb_oneofdef_name(o));
+    }
+
+    o->fields = symtab_alloc(ctx, sizeof(upb_fielddef *) * o->field_count);
+    o->field_count = 0;
+  }
+
+  for (i = 0; i < m->field_count; i++) {
+    const upb_fielddef *f = &m->fields[i];
+    upb_oneofdef *o = (upb_oneofdef*)f->oneof;
+    if (o) {
+      o->fields[o->field_count++] = f;
+    }
+  }
+
+  m->real_oneof_count = m->oneof_count - synthetic_count;
+}
+
 size_t getjsonname(const char *name, char *buf, size_t len) {
   size_t src, dst = 0;
   bool ucase_next = false;
@@ -4601,76 +4591,57 @@
 #undef WRITE
 }
 
-static char* makejsonname(const char* name, upb_alloc *alloc) {
+static char* makejsonname(symtab_addctx *ctx, const char* name) {
   size_t size = getjsonname(name, NULL, 0);
-  char* json_name = upb_malloc(alloc, size);
+  char* json_name = symtab_alloc(ctx, size);
   getjsonname(name, json_name, size);
   return json_name;
 }
 
-static bool symtab_add(const symtab_addctx *ctx, const char *name,
-                       upb_value v) {
-  upb_value tmp;
-  if (upb_strtable_lookup(ctx->addtab, name, &tmp) ||
-      upb_strtable_lookup(&ctx->symtab->syms, name, &tmp)) {
-    upb_status_seterrf(ctx->status, "duplicate symbol '%s'", name);
-    return false;
+static void symtab_add(symtab_addctx *ctx, const char *name, upb_value v) {
+  if (upb_strtable_lookup(&ctx->symtab->syms, name, NULL)) {
+    symtab_errf(ctx, "duplicate symbol '%s'", name);
   }
-
-  CHK_OOM(upb_strtable_insert3(ctx->addtab, name, strlen(name), v, ctx->tmp));
-  return true;
+  upb_alloc *alloc = upb_arena_alloc(ctx->symtab->arena);
+  size_t len = strlen(name);
+  CHK_OOM(upb_strtable_insert3(&ctx->symtab->syms, name, len, v, alloc));
 }
 
 /* Given a symbol and the base symbol inside which it is defined, find the
  * symbol's definition in t. */
-static bool resolvename(const upb_strtable *t, const upb_fielddef *f,
-                        const char *base, upb_strview sym,
-                        upb_deftype_t type, upb_status *status,
-                        const void **def) {
-  if(sym.size == 0) return false;
+static const void *symtab_resolve(symtab_addctx *ctx, const upb_fielddef *f,
+                                  const char *base, upb_strview sym,
+                                  upb_deftype_t type) {
+  const upb_strtable *t = &ctx->symtab->syms;
+  if(sym.size == 0) goto notfound;
   if(sym.data[0] == '.') {
     /* Symbols starting with '.' are absolute, so we do a single lookup.
      * Slice to omit the leading '.' */
     upb_value v;
     if (!upb_strtable_lookup2(t, sym.data + 1, sym.size - 1, &v)) {
-      return false;
+      goto notfound;
     }
 
-    *def = unpack_def(v, type);
-
-    if (!*def) {
-      upb_status_seterrf(status,
-                         "type mismatch when resolving field %s, name %s",
-                         f->full_name, sym.data);
-      return false;
+    const void *ret = unpack_def(v, type);
+    if (!ret) {
+      symtab_errf(ctx, "type mismatch when resolving field %s, name %s",
+                  f->full_name, sym.data);
     }
-
-    return true;
+    return ret;
   } else {
     /* Remove components from base until we find an entry or run out.
      * TODO: This branch is totally broken, but currently not used. */
     (void)base;
     UPB_ASSERT(false);
-    return false;
+    goto notfound;
   }
+
+notfound:
+  symtab_errf(ctx, "couldn't resolve name '%s'", sym.data);
 }
 
-const void *symtab_resolve(const symtab_addctx *ctx, const upb_fielddef *f,
-                           const char *base, upb_strview sym,
-                           upb_deftype_t type) {
-  const void *ret;
-  if (!resolvename(ctx->addtab, f, base, sym, type, ctx->status, &ret) &&
-      !resolvename(&ctx->symtab->syms, f, base, sym, type, ctx->status, &ret)) {
-    if (upb_ok(ctx->status)) {
-      upb_status_seterrf(ctx->status, "couldn't resolve name '%s'", sym.data);
-    }
-    return false;
-  }
-  return ret;
-}
-
-static bool create_oneofdef(
-    const symtab_addctx *ctx, upb_msgdef *m,
+static void create_oneofdef(
+    symtab_addctx *ctx, upb_msgdef *m,
     const google_protobuf_OneofDescriptorProto *oneof_proto) {
   upb_oneofdef *o;
   upb_strview name = google_protobuf_OneofDescriptorProto_name(oneof_proto);
@@ -4679,18 +4650,27 @@
   o = (upb_oneofdef*)&m->oneofs[m->oneof_count++];
   o->parent = m;
   o->full_name = makefullname(ctx, m->full_name, name);
+  o->field_count = 0;
+  o->synthetic = false;
 
   v = pack_def(o, UPB_DEFTYPE_ONEOF);
-  CHK_OOM(symtab_add(ctx, o->full_name, v));
+  symtab_add(ctx, o->full_name, v);
   CHK_OOM(upb_strtable_insert3(&m->ntof, name.data, name.size, v, ctx->alloc));
 
   CHK_OOM(upb_inttable_init2(&o->itof, UPB_CTYPE_CONSTPTR, ctx->alloc));
-  CHK_OOM(upb_strtable_init2(&o->ntof, UPB_CTYPE_CONSTPTR, ctx->alloc));
-
-  return true;
+  CHK_OOM(upb_strtable_init2(&o->ntof, UPB_CTYPE_CONSTPTR, 4, ctx->alloc));
 }
 
-static bool parse_default(const symtab_addctx *ctx, const char *str, size_t len,
+static str_t *newstr(symtab_addctx *ctx, const char *data, size_t len) {
+  str_t *ret = symtab_alloc(ctx, sizeof(*ret) + len);
+  if (!ret) return NULL;
+  ret->len = len;
+  if (len) memcpy(ret->str, data, len);
+  ret->str[len] = '\0';
+  return ret;
+}
+
+static void parse_default(symtab_addctx *ctx, const char *str, size_t len,
                           upb_fielddef *f) {
   char *end;
   char nullz[64];
@@ -4705,7 +4685,7 @@
     case UPB_TYPE_FLOAT:
       /* Standard C number parsing functions expect null-terminated strings. */
       if (len >= sizeof(nullz) - 1) {
-        return false;
+        symtab_errf(ctx, "Default too long: %.*s", (int)len, str);
       }
       memcpy(nullz, str, len);
       nullz[len] = '\0';
@@ -4718,47 +4698,61 @@
   switch (upb_fielddef_type(f)) {
     case UPB_TYPE_INT32: {
       long val = strtol(str, &end, 0);
-      CHK(val <= INT32_MAX && val >= INT32_MIN && errno != ERANGE && !*end);
+      if (val > INT32_MAX || val < INT32_MIN || errno == ERANGE || *end) {
+        goto invalid;
+      }
       f->defaultval.sint = val;
       break;
     }
     case UPB_TYPE_ENUM: {
       const upb_enumdef *e = f->sub.enumdef;
       int32_t val;
-      CHK(upb_enumdef_ntoi(e, str, len, &val));
+      if (!upb_enumdef_ntoi(e, str, len, &val)) {
+        goto invalid;
+      }
       f->defaultval.sint = val;
       break;
     }
     case UPB_TYPE_INT64: {
       /* XXX: Need to write our own strtoll, since it's not available in c89. */
       int64_t val = strtol(str, &end, 0);
-      CHK(val <= INT64_MAX && val >= INT64_MIN && errno != ERANGE && !*end);
+      if (val > INT64_MAX || val < INT64_MIN || errno == ERANGE || *end) {
+        goto invalid;
+      }
       f->defaultval.sint = val;
       break;
     }
     case UPB_TYPE_UINT32: {
       unsigned long val = strtoul(str, &end, 0);
-      CHK(val <= UINT32_MAX && errno != ERANGE && !*end);
+      if (val > UINT32_MAX || errno == ERANGE || *end) {
+        goto invalid;
+      }
       f->defaultval.uint = val;
       break;
     }
     case UPB_TYPE_UINT64: {
       /* XXX: Need to write our own strtoull, since it's not available in c89. */
       uint64_t val = strtoul(str, &end, 0);
-      CHK(val <= UINT64_MAX && errno != ERANGE && !*end);
+      if (val > UINT64_MAX || errno == ERANGE || *end) {
+        goto invalid;
+      }
       f->defaultval.uint = val;
       break;
     }
     case UPB_TYPE_DOUBLE: {
       double val = strtod(str, &end);
-      CHK(errno != ERANGE && !*end);
+      if (errno == ERANGE || *end) {
+        goto invalid;
+      }
       f->defaultval.dbl = val;
       break;
     }
     case UPB_TYPE_FLOAT: {
       /* XXX: Need to write our own strtof, since it's not available in c89. */
       float val = strtod(str, &end);
-      CHK(errno != ERANGE && !*end);
+      if (errno == ERANGE || *end) {
+        goto invalid;
+      }
       f->defaultval.flt = val;
       break;
     }
@@ -4768,25 +4762,30 @@
       } else if (streql2(str, len, "true")) {
         f->defaultval.boolean = true;
       } else {
-        return false;
       }
       break;
     }
     case UPB_TYPE_STRING:
-      f->defaultval.str = newstr(ctx->alloc, str, len);
+      f->defaultval.str = newstr(ctx, str, len);
       break;
     case UPB_TYPE_BYTES:
       /* XXX: need to interpret the C-escaped value. */
-      f->defaultval.str = newstr(ctx->alloc, str, len);
+      f->defaultval.str = newstr(ctx, str, len);
       break;
     case UPB_TYPE_MESSAGE:
       /* Should not have a default value. */
-      return false;
+      symtab_errf(ctx, "Message should not have a default (%s)",
+                  upb_fielddef_fullname(f));
   }
-  return true;
+
+  return;
+
+invalid:
+  symtab_errf(ctx, "Invalid default '%.*s' for field %f", (int)len, str,
+              upb_fielddef_fullname(f));
 }
 
-static void set_default_default(const symtab_addctx *ctx, upb_fielddef *f) {
+static void set_default_default(symtab_addctx *ctx, upb_fielddef *f) {
   switch (upb_fielddef_type(f)) {
     case UPB_TYPE_INT32:
     case UPB_TYPE_INT64:
@@ -4803,7 +4802,7 @@
       break;
     case UPB_TYPE_STRING:
     case UPB_TYPE_BYTES:
-      f->defaultval.str = newstr(ctx->alloc, NULL, 0);
+      f->defaultval.str = newstr(ctx, NULL, 0);
       break;
     case UPB_TYPE_BOOL:
       f->defaultval.boolean = false;
@@ -4813,8 +4812,8 @@
   }
 }
 
-static bool create_fielddef(
-    const symtab_addctx *ctx, const char *prefix, upb_msgdef *m,
+static void create_fielddef(
+    symtab_addctx *ctx, const char *prefix, upb_msgdef *m,
     const google_protobuf_FieldDescriptorProto *field_proto) {
   upb_alloc *alloc = ctx->alloc;
   upb_fielddef *f;
@@ -4826,12 +4825,11 @@
   uint32_t field_number;
 
   if (!google_protobuf_FieldDescriptorProto_has_name(field_proto)) {
-    upb_status_seterrmsg(ctx->status, "field has no name");
-    return false;
+    symtab_errf(ctx, "field has no name (%s)", upb_msgdef_fullname(m));
   }
 
   name = google_protobuf_FieldDescriptorProto_name(field_proto);
-  CHK(upb_isident(name, false, ctx->status));
+  check_ident(ctx, name, false);
   full_name = makefullname(ctx, prefix, name);
   shortname = shortdefname(full_name);
 
@@ -4839,14 +4837,13 @@
     json_name = strviewdup(
         ctx, google_protobuf_FieldDescriptorProto_json_name(field_proto));
   } else {
-    json_name = makejsonname(shortname, ctx->alloc);
+    json_name = makejsonname(ctx, shortname);
   }
 
   field_number = google_protobuf_FieldDescriptorProto_number(field_proto);
 
   if (field_number == 0 || field_number > UPB_MAX_FIELDNUMBER) {
-    upb_status_seterrf(ctx->status, "invalid field number (%u)", field_number);
-    return false;
+    symtab_errf(ctx, "invalid field number (%u)", field_number);
   }
 
   if (m) {
@@ -4859,19 +4856,15 @@
     f->is_extension_ = false;
 
     if (upb_strtable_lookup(&m->ntof, shortname, NULL)) {
-      upb_status_seterrf(ctx->status, "duplicate field name (%s)", shortname);
-      return false;
+      symtab_errf(ctx, "duplicate field name (%s)", shortname);
     }
 
     if (upb_strtable_lookup(&m->ntof, json_name, NULL)) {
-      upb_status_seterrf(ctx->status, "duplicate json_name (%s)", json_name);
-      return false;
+      symtab_errf(ctx, "duplicate json_name (%s)", json_name);
     }
 
     if (upb_inttable_lookup(&m->itof, field_number, NULL)) {
-      upb_status_seterrf(ctx->status, "duplicate field number (%u)",
-                         field_number);
-      return false;
+      symtab_errf(ctx, "duplicate field number (%u)", field_number);
     }
 
     field_v = pack_def(f, UPB_DEFTYPE_FIELD);
@@ -4905,7 +4898,7 @@
     /* extension field. */
     f = (upb_fielddef*)&ctx->file->exts[ctx->file->ext_count++];
     f->is_extension_ = true;
-    CHK_OOM(symtab_add(ctx, full_name, pack_def(f, UPB_DEFTYPE_FIELD)));
+    symtab_add(ctx, full_name, pack_def(f, UPB_DEFTYPE_FIELD));
   }
 
   f->full_name = full_name;
@@ -4924,9 +4917,7 @@
   f->sub.unresolved = field_proto;
 
   if (f->label_ == UPB_LABEL_REQUIRED && f->file->syntax == UPB_SYNTAX_PROTO3) {
-    upb_status_seterrf(ctx->status, "proto3 fields cannot be required (%s)",
-                       f->full_name);
-    return false;
+    symtab_errf(ctx, "proto3 fields cannot be required (%s)", f->full_name);
   }
 
   if (google_protobuf_FieldDescriptorProto_has_oneof_index(field_proto)) {
@@ -4936,32 +4927,34 @@
     upb_value v = upb_value_constptr(f);
 
     if (upb_fielddef_label(f) != UPB_LABEL_OPTIONAL) {
-      upb_status_seterrf(ctx->status,
-                         "fields in oneof must have OPTIONAL label (%s)",
-                         f->full_name);
-      return false;
+      symtab_errf(ctx, "fields in oneof must have OPTIONAL label (%s)",
+                  f->full_name);
     }
 
     if (!m) {
-      upb_status_seterrf(ctx->status,
-                         "oneof_index provided for extension field (%s)",
-                         f->full_name);
-      return false;
+      symtab_errf(ctx, "oneof_index provided for extension field (%s)",
+                  f->full_name);
     }
 
     if (oneof_index >= m->oneof_count) {
-      upb_status_seterrf(ctx->status, "oneof_index out of range (%s)",
-                         f->full_name);
-      return false;
+      symtab_errf(ctx, "oneof_index out of range (%s)", f->full_name);
     }
 
     oneof = (upb_oneofdef*)&m->oneofs[oneof_index];
     f->oneof = oneof;
 
-    CHK(upb_inttable_insert2(&oneof->itof, f->number_, v, alloc));
-    CHK(upb_strtable_insert3(&oneof->ntof, name.data, name.size, v, alloc));
+    oneof->field_count++;
+    if (f->proto3_optional_) {
+      oneof->synthetic = true;
+    }
+    CHK_OOM(upb_inttable_insert2(&oneof->itof, f->number_, v, alloc));
+    CHK_OOM(upb_strtable_insert3(&oneof->ntof, name.data, name.size, v, alloc));
   } else {
     f->oneof = NULL;
+    if (f->proto3_optional_) {
+      symtab_errf(ctx, "field with proto3_optional was not in a oneof (%s)",
+                  f->full_name);
+    }
   }
 
   options = google_protobuf_FieldDescriptorProto_has_options(field_proto) ?
@@ -4980,12 +4973,10 @@
   } else {
     f->lazy_ = false;
   }
-
-  return true;
 }
 
-static bool create_enumdef(
-    const symtab_addctx *ctx, const char *prefix,
+static void create_enumdef(
+    symtab_addctx *ctx, const char *prefix,
     const google_protobuf_EnumDescriptorProto *enum_proto) {
   upb_enumdef *e;
   const google_protobuf_EnumValueDescriptorProto *const *values;
@@ -4993,25 +4984,22 @@
   size_t i, n;
 
   name = google_protobuf_EnumDescriptorProto_name(enum_proto);
-  CHK(upb_isident(name, false, ctx->status));
+  check_ident(ctx, name, false);
 
   e = (upb_enumdef*)&ctx->file->enums[ctx->file->enum_count++];
   e->full_name = makefullname(ctx, prefix, name);
-  CHK_OOM(symtab_add(ctx, e->full_name, pack_def(e, UPB_DEFTYPE_ENUM)));
+  symtab_add(ctx, e->full_name, pack_def(e, UPB_DEFTYPE_ENUM));
 
-  CHK_OOM(upb_strtable_init2(&e->ntoi, UPB_CTYPE_INT32, ctx->alloc));
+  values = google_protobuf_EnumDescriptorProto_value(enum_proto, &n);
+  CHK_OOM(upb_strtable_init2(&e->ntoi, UPB_CTYPE_INT32, n, ctx->alloc));
   CHK_OOM(upb_inttable_init2(&e->iton, UPB_CTYPE_CSTR, ctx->alloc));
 
   e->file = ctx->file;
   e->defaultval = 0;
 
-  values = google_protobuf_EnumDescriptorProto_value(enum_proto, &n);
-
   if (n == 0) {
-    upb_status_seterrf(ctx->status,
-                       "enums must contain at least one value (%s)",
-                       e->full_name);
-    return false;
+    symtab_errf(ctx, "enums must contain at least one value (%s)",
+                e->full_name);
   }
 
   for (i = 0; i < n; i++) {
@@ -5022,15 +5010,12 @@
     upb_value v = upb_value_int32(num);
 
     if (i == 0 && e->file->syntax == UPB_SYNTAX_PROTO3 && num != 0) {
-      upb_status_seterrf(ctx->status,
-                         "for proto3, the first enum value must be zero (%s)",
-                         e->full_name);
-      return false;
+      symtab_errf(ctx, "for proto3, the first enum value must be zero (%s)",
+                  e->full_name);
     }
 
     if (upb_strtable_lookup(&e->ntoi, name2, NULL)) {
-      upb_status_seterrf(ctx->status, "duplicate enum label '%s'", name2);
-      return false;
+      symtab_errf(ctx, "duplicate enum label '%s'", name2);
     }
 
     CHK_OOM(name2)
@@ -5044,11 +5029,9 @@
   }
 
   upb_inttable_compact2(&e->iton, ctx->alloc);
-
-  return true;
 }
 
-static bool create_msgdef(symtab_addctx *ctx, const char *prefix,
+static void create_msgdef(symtab_addctx *ctx, const char *prefix,
                           const google_protobuf_DescriptorProto *msg_proto) {
   upb_msgdef *m;
   const google_protobuf_MessageOptions *options;
@@ -5056,18 +5039,22 @@
   const google_protobuf_FieldDescriptorProto *const *fields;
   const google_protobuf_EnumDescriptorProto *const *enums;
   const google_protobuf_DescriptorProto *const *msgs;
-  size_t i, n;
+  size_t i, n_oneof, n_field, n;
   upb_strview name;
 
   name = google_protobuf_DescriptorProto_name(msg_proto);
-  CHK(upb_isident(name, false, ctx->status));
+  check_ident(ctx, name, false);
 
   m = (upb_msgdef*)&ctx->file->msgs[ctx->file->msg_count++];
   m->full_name = makefullname(ctx, prefix, name);
-  CHK_OOM(symtab_add(ctx, m->full_name, pack_def(m, UPB_DEFTYPE_MSG)));
+  symtab_add(ctx, m->full_name, pack_def(m, UPB_DEFTYPE_MSG));
+
+  oneofs = google_protobuf_DescriptorProto_oneof_decl(msg_proto, &n_oneof);
+  fields = google_protobuf_DescriptorProto_field(msg_proto, &n_field);
 
   CHK_OOM(upb_inttable_init2(&m->itof, UPB_CTYPE_CONSTPTR, ctx->alloc));
-  CHK_OOM(upb_strtable_init2(&m->ntof, UPB_CTYPE_CONSTPTR, ctx->alloc));
+  CHK_OOM(upb_strtable_init2(&m->ntof, UPB_CTYPE_CONSTPTR, n_oneof + n_field,
+                             ctx->alloc));
 
   m->file = ctx->file;
   m->map_entry = false;
@@ -5083,25 +5070,23 @@
     ctx->layouts++;
   } else {
     /* Allocate now (to allow cross-linking), populate later. */
-    m->layout = upb_malloc(ctx->alloc, sizeof(*m->layout));
+    m->layout = symtab_alloc(ctx, sizeof(*m->layout));
   }
 
-  oneofs = google_protobuf_DescriptorProto_oneof_decl(msg_proto, &n);
   m->oneof_count = 0;
-  m->oneofs = upb_malloc(ctx->alloc, sizeof(*m->oneofs) * n);
-  for (i = 0; i < n; i++) {
-    CHK(create_oneofdef(ctx, m, oneofs[i]));
+  m->oneofs = symtab_alloc(ctx, sizeof(*m->oneofs) * n_oneof);
+  for (i = 0; i < n_oneof; i++) {
+    create_oneofdef(ctx, m, oneofs[i]);
   }
 
-  fields = google_protobuf_DescriptorProto_field(msg_proto, &n);
   m->field_count = 0;
-  m->fields = upb_malloc(ctx->alloc, sizeof(*m->fields) * n);
-  for (i = 0; i < n; i++) {
-    CHK(create_fielddef(ctx, m->full_name, m, fields[i]));
+  m->fields = symtab_alloc(ctx, sizeof(*m->fields) * n_field);
+  for (i = 0; i < n_field; i++) {
+    create_fielddef(ctx, m->full_name, m, fields[i]);
   }
 
-  CHK(assign_msg_indices(m, ctx->status));
-  CHK(check_oneofs(m, ctx->status));
+  assign_msg_indices(ctx, m);
+  finalize_oneofs(ctx, m);
   assign_msg_wellknowntype(m);
   upb_inttable_compact2(&m->itof, ctx->alloc);
 
@@ -5109,93 +5094,78 @@
 
   enums = google_protobuf_DescriptorProto_enum_type(msg_proto, &n);
   for (i = 0; i < n; i++) {
-    CHK(create_enumdef(ctx, m->full_name, enums[i]));
+    create_enumdef(ctx, m->full_name, enums[i]);
   }
 
   msgs = google_protobuf_DescriptorProto_nested_type(msg_proto, &n);
   for (i = 0; i < n; i++) {
-    CHK(create_msgdef(ctx, m->full_name, msgs[i]));
+    create_msgdef(ctx, m->full_name, msgs[i]);
   }
-
-  return true;
 }
 
-typedef struct {
-  int msg_count;
-  int enum_count;
-  int ext_count;
-} decl_counts;
-
 static void count_types_in_msg(const google_protobuf_DescriptorProto *msg_proto,
-                               decl_counts *counts) {
+                               upb_filedef *file) {
   const google_protobuf_DescriptorProto *const *msgs;
   size_t i, n;
 
-  counts->msg_count++;
+  file->msg_count++;
 
   msgs = google_protobuf_DescriptorProto_nested_type(msg_proto, &n);
   for (i = 0; i < n; i++) {
-    count_types_in_msg(msgs[i], counts);
+    count_types_in_msg(msgs[i], file);
   }
 
   google_protobuf_DescriptorProto_enum_type(msg_proto, &n);
-  counts->enum_count += n;
+  file->enum_count += n;
 
   google_protobuf_DescriptorProto_extension(msg_proto, &n);
-  counts->ext_count += n;
+  file->ext_count += n;
 }
 
 static void count_types_in_file(
     const google_protobuf_FileDescriptorProto *file_proto,
-    decl_counts *counts) {
+    upb_filedef *file) {
   const google_protobuf_DescriptorProto *const *msgs;
   size_t i, n;
 
   msgs = google_protobuf_FileDescriptorProto_message_type(file_proto, &n);
   for (i = 0; i < n; i++) {
-    count_types_in_msg(msgs[i], counts);
+    count_types_in_msg(msgs[i], file);
   }
 
   google_protobuf_FileDescriptorProto_enum_type(file_proto, &n);
-  counts->enum_count += n;
+  file->enum_count += n;
 
   google_protobuf_FileDescriptorProto_extension(file_proto, &n);
-  counts->ext_count += n;
+  file->ext_count += n;
 }
 
-static bool resolve_fielddef(const symtab_addctx *ctx, const char *prefix,
+static void resolve_fielddef(symtab_addctx *ctx, const char *prefix,
                              upb_fielddef *f) {
   upb_strview name;
   const google_protobuf_FieldDescriptorProto *field_proto = f->sub.unresolved;
 
   if (f->is_extension_) {
     if (!google_protobuf_FieldDescriptorProto_has_extendee(field_proto)) {
-      upb_status_seterrf(ctx->status,
-                         "extension for field '%s' had no extendee",
-                         f->full_name);
-      return false;
+      symtab_errf(ctx, "extension for field '%s' had no extendee",
+                  f->full_name);
     }
 
     name = google_protobuf_FieldDescriptorProto_extendee(field_proto);
     f->msgdef = symtab_resolve(ctx, f, prefix, name, UPB_DEFTYPE_MSG);
-    CHK(f->msgdef);
   }
 
   if ((upb_fielddef_issubmsg(f) || f->type_ == UPB_DESCRIPTOR_TYPE_ENUM) &&
       !google_protobuf_FieldDescriptorProto_has_type_name(field_proto)) {
-    upb_status_seterrf(ctx->status, "field '%s' is missing type name",
-                       f->full_name);
-    return false;
+    symtab_errf(ctx, "field '%s' is missing type name", f->full_name);
   }
 
   name = google_protobuf_FieldDescriptorProto_type_name(field_proto);
 
   if (upb_fielddef_issubmsg(f)) {
     f->sub.msgdef = symtab_resolve(ctx, f, prefix, name, UPB_DEFTYPE_MSG);
-    CHK(f->sub.msgdef);
   } else if (f->type_ == UPB_DESCRIPTOR_TYPE_ENUM) {
     f->sub.enumdef = symtab_resolve(ctx, f, prefix, name, UPB_DEFTYPE_ENUM);
-    CHK(f->sub.enumdef);
   }
 
   /* Have to delay resolving of the default value until now because of the enum
@@ -5205,54 +5175,36 @@
         google_protobuf_FieldDescriptorProto_default_value(field_proto);
 
     if (f->file->syntax == UPB_SYNTAX_PROTO3) {
-      upb_status_seterrf(ctx->status,
-                         "proto3 fields cannot have explicit defaults (%s)",
-                         f->full_name);
-      return false;
+      symtab_errf(ctx, "proto3 fields cannot have explicit defaults (%s)",
+                  f->full_name);
     }
 
     if (upb_fielddef_issubmsg(f)) {
-      upb_status_seterrf(ctx->status,
-                         "message fields cannot have explicit defaults (%s)",
-                         f->full_name);
-      return false;
+      symtab_errf(ctx, "message fields cannot have explicit defaults (%s)",
+                  f->full_name);
     }
 
-    if (!parse_default(ctx, defaultval.data, defaultval.size, f)) {
-      upb_status_seterrf(ctx->status,
-                         "couldn't parse default '" UPB_STRVIEW_FORMAT
-                         "' for field (%s)",
-                         UPB_STRVIEW_ARGS(defaultval), f->full_name);
-      return false;
-    }
+    parse_default(ctx, defaultval.data, defaultval.size, f);
   } else {
     set_default_default(ctx, f);
   }
-
-  return true;
 }
 
-static bool build_filedef(
+static void build_filedef(
     symtab_addctx *ctx, upb_filedef *file,
     const google_protobuf_FileDescriptorProto *file_proto) {
-  upb_alloc *alloc = ctx->alloc;
   const google_protobuf_FileOptions *file_options_proto;
   const google_protobuf_DescriptorProto *const *msgs;
   const google_protobuf_EnumDescriptorProto *const *enums;
   const google_protobuf_FieldDescriptorProto *const *exts;
   const upb_strview* strs;
   size_t i, n;
-  decl_counts counts = {0, 0, 0};
 
-  count_types_in_file(file_proto, &counts);
+  count_types_in_file(file_proto, file);
 
-  file->msgs = upb_malloc(alloc, sizeof(*file->msgs) * counts.msg_count);
-  file->enums = upb_malloc(alloc, sizeof(*file->enums) * counts.enum_count);
-  file->exts = upb_malloc(alloc, sizeof(*file->exts) * counts.ext_count);
-
-  CHK_OOM(counts.msg_count == 0 || file->msgs);
-  CHK_OOM(counts.enum_count == 0 || file->enums);
-  CHK_OOM(counts.ext_count == 0 || file->exts);
+  file->msgs = symtab_alloc(ctx, sizeof(*file->msgs) * file->msg_count);
+  file->enums = symtab_alloc(ctx, sizeof(*file->enums) * file->enum_count);
+  file->exts = symtab_alloc(ctx, sizeof(*file->exts) * file->ext_count);
 
   /* We increment these as defs are added. */
   file->msg_count = 0;
@@ -5260,8 +5212,7 @@
   file->ext_count = 0;
 
   if (!google_protobuf_FileDescriptorProto_has_name(file_proto)) {
-    upb_status_seterrmsg(ctx->status, "File has no name");
-    return false;
+    symtab_errf(ctx, "File has no name");
   }
 
   file->name =
@@ -5272,7 +5223,7 @@
   if (google_protobuf_FileDescriptorProto_has_package(file_proto)) {
     upb_strview package =
         google_protobuf_FileDescriptorProto_package(file_proto);
-    CHK(upb_isident(package, true, ctx->status));
+    check_ident(ctx, package, true);
     file->package = strviewdup(ctx, package);
   } else {
     file->package = NULL;
@@ -5287,9 +5238,8 @@
     } else if (streql_view(syntax, "proto3")) {
       file->syntax = UPB_SYNTAX_PROTO3;
     } else {
-      upb_status_seterrf(ctx->status, "Invalid syntax '" UPB_STRVIEW_FORMAT "'",
-                         UPB_STRVIEW_ARGS(syntax));
-      return false;
+      symtab_errf(ctx, "Invalid syntax '" UPB_STRVIEW_FORMAT "'",
+                  UPB_STRVIEW_ARGS(syntax));
     }
   } else {
     file->syntax = UPB_SYNTAX_PROTO2;
@@ -5311,19 +5261,17 @@
 
   /* Verify dependencies. */
   strs = google_protobuf_FileDescriptorProto_dependency(file_proto, &n);
-  file->deps = upb_malloc(alloc, sizeof(*file->deps) * n) ;
-  CHK_OOM(n == 0 || file->deps);
+  file->deps = symtab_alloc(ctx, sizeof(*file->deps) * n);
 
   for (i = 0; i < n; i++) {
     upb_strview dep_name = strs[i];
     upb_value v;
     if (!upb_strtable_lookup2(&ctx->symtab->files, dep_name.data,
                               dep_name.size, &v)) {
-      upb_status_seterrf(ctx->status,
-                         "Depends on file '" UPB_STRVIEW_FORMAT
-                         "', but it has not been loaded",
-                         UPB_STRVIEW_ARGS(dep_name));
-      return false;
+      symtab_errf(ctx,
+                  "Depends on file '" UPB_STRVIEW_FORMAT
+                  "', but it has not been loaded",
+                  UPB_STRVIEW_ARGS(dep_name));
     }
     file->deps[i] = upb_value_getconstptr(v);
   }
@@ -5331,193 +5279,92 @@
   /* Create messages. */
   msgs = google_protobuf_FileDescriptorProto_message_type(file_proto, &n);
   for (i = 0; i < n; i++) {
-    CHK(create_msgdef(ctx, file->package, msgs[i]));
+    create_msgdef(ctx, file->package, msgs[i]);
   }
 
   /* Create enums. */
   enums = google_protobuf_FileDescriptorProto_enum_type(file_proto, &n);
   for (i = 0; i < n; i++) {
-    CHK(create_enumdef(ctx, file->package, enums[i]));
+    create_enumdef(ctx, file->package, enums[i]);
   }
 
   /* Create extensions. */
   exts = google_protobuf_FileDescriptorProto_extension(file_proto, &n);
-  file->exts = upb_malloc(alloc, sizeof(*file->exts) * n);
-  CHK_OOM(n == 0 || file->exts);
+  file->exts = symtab_alloc(ctx, sizeof(*file->exts) * n);
   for (i = 0; i < n; i++) {
-    CHK(create_fielddef(ctx, file->package, NULL, exts[i]));
+    create_fielddef(ctx, file->package, NULL, exts[i]);
   }
 
   /* Now that all names are in the table, build layouts and resolve refs. */
   for (i = 0; i < (size_t)file->ext_count; i++) {
-    CHK(resolve_fielddef(ctx, file->package, (upb_fielddef*)&file->exts[i]));
+    resolve_fielddef(ctx, file->package, (upb_fielddef*)&file->exts[i]);
   }
 
   for (i = 0; i < (size_t)file->msg_count; i++) {
     const upb_msgdef *m = &file->msgs[i];
     int j;
     for (j = 0; j < m->field_count; j++) {
-      CHK(resolve_fielddef(ctx, m->full_name, (upb_fielddef*)&m->fields[j]));
+      resolve_fielddef(ctx, m->full_name, (upb_fielddef*)&m->fields[j]);
     }
   }
 
   if (!ctx->layouts) {
     for (i = 0; i < (size_t)file->msg_count; i++) {
       const upb_msgdef *m = &file->msgs[i];
-      make_layout(ctx->symtab, m);
+      make_layout(ctx, m);
     }
   }
+}
 
-  return true;
- }
-
-static bool upb_symtab_addtotabs(upb_symtab *s, symtab_addctx *ctx) {
-  const upb_filedef *file = ctx->file;
+static void remove_filedef(upb_symtab *s, upb_filedef *file) {
   upb_alloc *alloc = upb_arena_alloc(s->arena);
-  upb_strtable_iter iter;
-
-  CHK_OOM(upb_strtable_insert3(&s->files, file->name, strlen(file->name),
-                               upb_value_constptr(file), alloc));
-
-  upb_strtable_begin(&iter, ctx->addtab);
-  for (; !upb_strtable_done(&iter); upb_strtable_next(&iter)) {
-    upb_strview key = upb_strtable_iter_key(&iter);
-    upb_value value = upb_strtable_iter_value(&iter);
-    CHK_OOM(upb_strtable_insert3(&s->syms, key.data, key.size, value, alloc));
+  int i;
+  for (i = 0; i < file->msg_count; i++) {
+    const char *name = file->msgs[i].full_name;
+    upb_strtable_remove3(&s->syms, name, strlen(name), NULL, alloc);
   }
-
-  return true;
-}
-
-/* upb_filedef ****************************************************************/
-
-const char *upb_filedef_name(const upb_filedef *f) {
-  return f->name;
-}
-
-const char *upb_filedef_package(const upb_filedef *f) {
-  return f->package;
-}
-
-const char *upb_filedef_phpprefix(const upb_filedef *f) {
-  return f->phpprefix;
-}
-
-const char *upb_filedef_phpnamespace(const upb_filedef *f) {
-  return f->phpnamespace;
-}
-
-upb_syntax_t upb_filedef_syntax(const upb_filedef *f) {
-  return f->syntax;
-}
-
-int upb_filedef_msgcount(const upb_filedef *f) {
-  return f->msg_count;
-}
-
-int upb_filedef_depcount(const upb_filedef *f) {
-  return f->dep_count;
-}
-
-int upb_filedef_enumcount(const upb_filedef *f) {
-  return f->enum_count;
-}
-
-const upb_filedef *upb_filedef_dep(const upb_filedef *f, int i) {
-  return i < 0 || i >= f->dep_count ? NULL : f->deps[i];
-}
-
-const upb_msgdef *upb_filedef_msg(const upb_filedef *f, int i) {
-  return i < 0 || i >= f->msg_count ? NULL : &f->msgs[i];
-}
-
-const upb_enumdef *upb_filedef_enum(const upb_filedef *f, int i) {
-  return i < 0 || i >= f->enum_count ? NULL : &f->enums[i];
-}
-
-void upb_symtab_free(upb_symtab *s) {
-  upb_arena_free(s->arena);
-  upb_gfree(s);
-}
-
-upb_symtab *upb_symtab_new(void) {
-  upb_symtab *s = upb_gmalloc(sizeof(*s));
-  upb_alloc *alloc;
-
-  if (!s) {
-    return NULL;
+  for (i = 0; i < file->enum_count; i++) {
+    const char *name = file->enums[i].full_name;
+    upb_strtable_remove3(&s->syms, name, strlen(name), NULL, alloc);
   }
-
-  s->arena = upb_arena_new();
-  alloc = upb_arena_alloc(s->arena);
-
-  if (!upb_strtable_init2(&s->syms, UPB_CTYPE_CONSTPTR, alloc) ||
-      !upb_strtable_init2(&s->files, UPB_CTYPE_CONSTPTR, alloc)) {
-    upb_arena_free(s->arena);
-    upb_gfree(s);
-    s = NULL;
+  for (i = 0; i < file->ext_count; i++) {
+    const char *name = file->exts[i].full_name;
+    upb_strtable_remove3(&s->syms, name, strlen(name), NULL, alloc);
   }
-  return s;
-}
-
-const upb_msgdef *upb_symtab_lookupmsg(const upb_symtab *s, const char *sym) {
-  upb_value v;
-  return upb_strtable_lookup(&s->syms, sym, &v) ?
-      unpack_def(v, UPB_DEFTYPE_MSG) : NULL;
-}
-
-const upb_msgdef *upb_symtab_lookupmsg2(const upb_symtab *s, const char *sym,
-                                        size_t len) {
-  upb_value v;
-  return upb_strtable_lookup2(&s->syms, sym, len, &v) ?
-      unpack_def(v, UPB_DEFTYPE_MSG) : NULL;
-}
-
-const upb_enumdef *upb_symtab_lookupenum(const upb_symtab *s, const char *sym) {
-  upb_value v;
-  return upb_strtable_lookup(&s->syms, sym, &v) ?
-      unpack_def(v, UPB_DEFTYPE_ENUM) : NULL;
-}
-
-const upb_filedef *upb_symtab_lookupfile(const upb_symtab *s, const char *name) {
-  upb_value v;
-  return upb_strtable_lookup(&s->files, name, &v) ? upb_value_getconstptr(v)
-                                                  : NULL;
-}
-
-const upb_filedef *upb_symtab_lookupfile2(
-    const upb_symtab *s, const char *name, size_t len) {
-  upb_value v;
-  return upb_strtable_lookup2(&s->files, name, len, &v) ?
-      upb_value_getconstptr(v) : NULL;
-}
-
-int upb_symtab_filecount(const upb_symtab *s) {
-  return (int)upb_strtable_count(&s->files);
 }
 
 static const upb_filedef *_upb_symtab_addfile(
     upb_symtab *s, const google_protobuf_FileDescriptorProto *file_proto,
     const upb_msglayout **layouts, upb_status *status) {
-  upb_arena *tmparena = upb_arena_new();
-  upb_strtable addtab;
-  upb_alloc *alloc = upb_arena_alloc(s->arena);
-  upb_filedef *file = upb_malloc(alloc, sizeof(*file));
-  bool ok;
+  upb_arena *file_arena = upb_arena_new();
+  upb_filedef *file = upb_arena_malloc(file_arena, sizeof(*file));
+  bool ok = true;
   symtab_addctx ctx;
 
   ctx.file = file;
   ctx.symtab = s;
-  ctx.alloc = alloc;
-  ctx.tmp = upb_arena_alloc(tmparena);
-  ctx.addtab = &addtab;
+  ctx.file_arena = file_arena;
+  ctx.alloc = upb_arena_alloc(file_arena);
   ctx.layouts = layouts;
   ctx.status = status;
 
-  ok = file && upb_strtable_init2(&addtab, UPB_CTYPE_CONSTPTR, ctx.tmp) &&
-       build_filedef(&ctx, file, file_proto) && upb_symtab_addtotabs(s, &ctx);
+  file->msg_count = 0;
+  file->enum_count = 0;
+  file->ext_count = 0;
 
-  upb_arena_free(tmparena);
+  if (UPB_UNLIKELY(setjmp(ctx.err))) {
+    UPB_ASSERT(!upb_ok(status));
+    ok = false;
+    remove_filedef(s, file);
+  } else {
+    build_filedef(&ctx, file, file_proto);
+    upb_strtable_insert3(&s->files, file->name, strlen(file->name),
+                         upb_value_constptr(file), ctx.alloc);
+    UPB_ASSERT(upb_ok(status));
+    upb_arena_fuse(s->arena, file_arena);
+  }
+
+  upb_arena_free(file_arena);
   return ok ? file : NULL;
 }
 
@@ -5552,6 +5399,7 @@
 
   file = google_protobuf_FileDescriptorProto_parse(
       init->descriptor.data, init->descriptor.size, arena);
+  s->bytes_loaded += init->descriptor.size;
 
   if (!file) {
     upb_status_seterrf(
@@ -5574,7 +5422,10 @@
   return false;
 }
 
-#undef CHK
+size_t _upb_symtab_bytesloaded(const upb_symtab *s) {
+  return s->bytes_loaded;
+}
+
 #undef CHK_OOM
 
 
@@ -5622,6 +5473,21 @@
   0,  /* UPB_TYPE_BYTES */
 };
 
+static const char _upb_fieldtype_to_sizelg2[12] = {
+  0,
+  0,  /* UPB_TYPE_BOOL */
+  2,  /* UPB_TYPE_FLOAT */
+  2,  /* UPB_TYPE_INT32 */
+  2,  /* UPB_TYPE_UINT32 */
+  2,  /* UPB_TYPE_ENUM */
+  UPB_SIZE(2, 3),  /* UPB_TYPE_MESSAGE */
+  3,  /* UPB_TYPE_DOUBLE */
+  3,  /* UPB_TYPE_INT64 */
+  3,  /* UPB_TYPE_UINT64 */
+  UPB_SIZE(3, 4),  /* UPB_TYPE_STRING */
+  UPB_SIZE(3, 4),  /* UPB_TYPE_BYTES */
+};
+
 /** upb_msg *******************************************************************/
 
 upb_msg *upb_msg_new(const upb_msgdef *m, upb_arena *a) {
@@ -5655,24 +5521,17 @@
 
 const upb_fielddef *upb_msg_whichoneof(const upb_msg *msg,
                                        const upb_oneofdef *o) {
-  upb_oneof_iter i;
-  const upb_fielddef *f;
-  const upb_msglayout_field *field;
-  const upb_msgdef *m = upb_oneofdef_containingtype(o);
-  uint32_t oneof_case;
-
-  /* This is far from optimal. */
-  upb_oneof_begin(&i, o);
-  if (upb_oneof_done(&i)) return false;
-  f = upb_oneof_iter_field(&i);
-  field = upb_fielddef_layout(f);
-  if (in_oneof(field)) {
-    oneof_case = _upb_getoneofcase_field(msg, field);
+  const upb_fielddef *f = upb_oneofdef_field(o, 0);
+  if (upb_oneofdef_issynthetic(o)) {
+    UPB_ASSERT(upb_oneofdef_fieldcount(o) == 1);
+    return upb_msg_has(msg, f) ? f : NULL;
   } else {
-    return _upb_hasbit_field(msg, field) ? f : NULL;
+    const upb_msglayout_field *field = upb_fielddef_layout(f);
+    uint32_t oneof_case = _upb_getoneofcase_field(msg, field);
+    f = oneof_case ? upb_oneofdef_itof(o, oneof_case) : NULL;
+    UPB_ASSERT((f != NULL) == (oneof_case != 0));
+    return f;
   }
-
-  return oneof_case ? upb_msgdef_itof(m, oneof_case) : NULL;
 }
 
 upb_msgval upb_msg_get(const upb_msg *msg, const upb_fielddef *f) {
@@ -5785,11 +5644,12 @@
 bool upb_msg_next(const upb_msg *msg, const upb_msgdef *m,
                   const upb_symtab *ext_pool, const upb_fielddef **out_f,
                   upb_msgval *out_val, size_t *iter) {
-  size_t i = *iter;
+  int i = *iter;
+  int n = upb_msgdef_fieldcount(m);
   const upb_msgval zero = {0};
-  const upb_fielddef *f;
   UPB_UNUSED(ext_pool);
-  while ((f = _upb_msgdef_field(m, (int)++i)) != NULL) {
+  while (++i < n) {
+    const upb_fielddef *f = upb_msgdef_field(m, i);
     upb_msgval val = _upb_msg_getraw(msg, f);
 
     /* Skip field if unset or empty. */
@@ -5874,7 +5734,7 @@
 /** upb_array *****************************************************************/
 
 upb_array *upb_array_new(upb_arena *a, upb_fieldtype_t type) {
-  return _upb_array_new(a, type);
+  return _upb_array_new(a, 4, _upb_fieldtype_to_sizelg2[type]);
 }
 
 size_t upb_array_size(const upb_array *arr) {
@@ -5998,6 +5858,7 @@
 #include <float.h>
 #include <inttypes.h>
 #include <limits.h>
+#include <math.h>
 #include <setjmp.h>
 #include <stdlib.h>
 #include <string.h>
@@ -6032,6 +5893,19 @@
   return str.size == strlen(lit) && memcmp(str.data, lit, str.size) == 0;
 }
 
+static bool jsondec_isnullvalue(const upb_fielddef *f) {
+  return upb_fielddef_type(f) == UPB_TYPE_ENUM &&
+         strcmp(upb_enumdef_fullname(upb_fielddef_enumsubdef(f)),
+                "google.protobuf.NullValue") == 0;
+}
+
+static bool jsondec_isvalue(const upb_fielddef *f) {
+  return (upb_fielddef_type(f) == UPB_TYPE_MESSAGE &&
+          upb_msgdef_wellknowntype(upb_fielddef_msgsubdef(f)) ==
+              UPB_WELLKNOWN_VALUE) ||
+         jsondec_isnullvalue(f);
+}
+
 UPB_NORETURN static void jsondec_err(jsondec *d, const char *msg) {
   upb_status_seterrf(d->status, "Error parsing JSON @%d:%d: %s", d->line,
                      (int)(d->ptr - d->line_begin), msg);
@@ -6724,11 +6598,11 @@
     case JD_STRING:
       str = jsondec_string(d);
       if (jsondec_streql(str, "NaN")) {
-        val.double_val = UPB_NAN;
+        val.double_val = NAN;
       } else if (jsondec_streql(str, "Infinity")) {
-        val.double_val = UPB_INFINITY;
+        val.double_val = INFINITY;
       } else if (jsondec_streql(str, "-Infinity")) {
-        val.double_val = -UPB_INFINITY;
+        val.double_val = -INFINITY;
       } else {
         val.double_val = strtod(str.data, NULL);
       }
@@ -6738,7 +6612,7 @@
   }
 
   if (upb_fielddef_type(f) == UPB_TYPE_FLOAT) {
-    if (val.double_val != UPB_INFINITY && val.double_val != -UPB_INFINITY &&
+    if (val.double_val != INFINITY && val.double_val != -INFINITY &&
         (val.double_val > FLT_MAX || val.double_val < -FLT_MAX)) {
       jsondec_err(d, "Float out of range");
     }
@@ -6759,21 +6633,32 @@
 }
 
 static upb_msgval jsondec_enum(jsondec *d, const upb_fielddef *f) {
-  if (jsondec_peek(d) == JD_STRING) {
-    const upb_enumdef *e = upb_fielddef_enumsubdef(f);
-    upb_strview str = jsondec_string(d);
-    upb_msgval val;
-    if (!upb_enumdef_ntoi(e, str.data, str.size, &val.int32_val)) {
-      if (d->options & UPB_JSONDEC_IGNOREUNKNOWN) {
+  switch (jsondec_peek(d)) {
+    case JD_STRING: {
+      const upb_enumdef *e = upb_fielddef_enumsubdef(f);
+      upb_strview str = jsondec_string(d);
+      upb_msgval val;
+      if (!upb_enumdef_ntoi(e, str.data, str.size, &val.int32_val)) {
+        if (d->options & UPB_JSONDEC_IGNOREUNKNOWN) {
+          val.int32_val = 0;
+        } else {
+          jsondec_errf(d, "Unknown enumerator: '" UPB_STRVIEW_FORMAT "'",
+                       UPB_STRVIEW_ARGS(str));
+        }
+      }
+      return val;
+    }
+    case JD_NULL: {
+      if (jsondec_isnullvalue(f)) {
+        upb_msgval val;
+        jsondec_null(d);
         val.int32_val = 0;
-      } else {
-        jsondec_errf(d, "Unknown enumerator: '" UPB_STRVIEW_FORMAT "'",
-                     UPB_STRVIEW_ARGS(str));
+        return val;
       }
     }
-    return val;
-  } else {
-    return jsondec_int(d, f);
+      /* Fallthrough. */
+    default:
+      return jsondec_int(d, f);
   }
 }
 
@@ -6857,12 +6742,6 @@
   return val;
 }
 
-static bool jsondec_isvalue(const upb_fielddef *f) {
-  return upb_fielddef_type(f) == UPB_TYPE_MESSAGE &&
-         upb_msgdef_wellknowntype(upb_fielddef_msgsubdef(f)) ==
-             UPB_WELLKNOWN_VALUE;
-}
-
 static void jsondec_field(jsondec *d, upb_msg *msg, const upb_msgdef *m) {
   upb_strview name;
   const upb_fielddef *f;
@@ -7068,6 +6947,7 @@
   upb_strview str = jsondec_string(d);
   const char *ptr = str.data;
   const char *end = ptr + str.size;
+  const int64_t max = (uint64_t)3652500 * 86400;
 
   /* "3.000000001s", "3s", etc. */
   ptr = jsondec_buftoint64(d, ptr, end, &seconds.int64_val);
@@ -7077,7 +6957,7 @@
     jsondec_err(d, "Malformed duration");
   }
 
-  if (seconds.int64_val < -315576000000LL || seconds.int64_val > 315576000000LL) {
+  if (seconds.int64_val < -max || seconds.int64_val > max) {
     jsondec_err(d, "Duration out of range");
   }
 
@@ -7414,12 +7294,14 @@
 #include <ctype.h>
 #include <float.h>
 #include <inttypes.h>
+#include <math.h>
+#include <setjmp.h>
 #include <stdarg.h>
 #include <stdio.h>
 #include <string.h>
-#include <setjmp.h>
 
 
+/* Must be last. */
 
 typedef struct {
   char *buf, *ptr, *end;
@@ -7483,7 +7365,7 @@
   va_list args;
 
   va_start(args, fmt);
-  n = _upb_vsnprintf(e->ptr, have, fmt, args);
+  n = vsnprintf(e->ptr, have, fmt, args);
   va_end(args);
 
   if (UPB_LIKELY(have > n)) {
@@ -7574,12 +7456,17 @@
 
 static void jsonenc_enum(int32_t val, const upb_fielddef *f, jsonenc *e) {
   const upb_enumdef *e_def = upb_fielddef_enumsubdef(f);
-  const char *name = upb_enumdef_iton(e_def, val);
 
-  if (name) {
-    jsonenc_printf(e, "\"%s\"", name);
+  if (strcmp(upb_enumdef_fullname(e_def), "google.protobuf.NullValue") == 0) {
+    jsonenc_putstr(e, "null");
   } else {
-    jsonenc_printf(e, "%" PRId32, val);
+    const char *name = upb_enumdef_iton(e_def, val);
+
+    if (name) {
+      jsonenc_printf(e, "\"%s\"", name);
+    } else {
+      jsonenc_printf(e, "%" PRId32, val);
+    }
   }
 }
 
@@ -7670,9 +7557,9 @@
 }
 
 static void jsonenc_double(jsonenc *e, const char *fmt, double val) {
-  if (val == UPB_INFINITY) {
+  if (val == INFINITY) {
     jsonenc_putstr(e, "\"Infinity\"");
-  } else if (val == -UPB_INFINITY) {
+  } else if (val == -INFINITY) {
     jsonenc_putstr(e, "\"-Infinity\"");
   } else if (val != val) {
     jsonenc_putstr(e, "\"NaN\"");
@@ -8055,10 +7942,10 @@
 
   if (e->options & UPB_JSONENC_EMITDEFAULTS) {
     /* Iterate over all fields. */
-    upb_msg_field_iter i;
-    for (upb_msg_field_begin(&i, m); !upb_msg_field_done(&i);
-         upb_msg_field_next(&i)) {
-      f = upb_msg_iter_field(&i);
+    int i = 0;
+    int n = upb_msgdef_fieldcount(m);
+    for (i = 0; i < n; i++) {
+      f = upb_msgdef_field(m, i);
       jsonenc_fieldval(e, f, upb_msg_get(msg, f), &first);
     }
   } else {
@@ -8127,11 +8014,7 @@
 #undef UPB_UNUSED
 #undef UPB_ASSUME
 #undef UPB_ASSERT
-#undef UPB_ASSERT_DEBUGVAR
 #undef UPB_UNREACHABLE
-#undef UPB_INFINITY
-#undef UPB_NAN
-#undef UPB_MSVC_VSNPRINTF
-#undef _upb_snprintf
-#undef _upb_vsnprintf
-#undef _upb_va_copy
+#undef UPB_POISON_MEMORY_REGION
+#undef UPB_UNPOISON_MEMORY_REGION
+#undef UPB_ASAN
diff --git a/php/ext/google/protobuf/php-upb.h b/php/ext/google/protobuf/php-upb.h
index 666ec76..ba5ef87 100644
--- a/php/ext/google/protobuf/php-upb.h
+++ b/php/ext/google/protobuf/php-upb.h
@@ -21,6 +21,15 @@
 *
 * This file is private and must not be included by users!
 */
+
+#if !(__STDC_VERSION__ >= 199901L || __cplusplus >= 201103L)
+#error upb requires C99 or C++11
+#endif
+
+#if (defined(_MSC_VER) && _MSC_VER < 1900)
+#error upb requires MSVC >= 2015.
+#endif
+
 #include <stdint.h>
 #include <stddef.h>
 
@@ -69,66 +78,21 @@
 #define UPB_UNLIKELY(x) (x)
 #endif
 
-/* Define UPB_BIG_ENDIAN manually if you're on big endian and your compiler
- * doesn't provide these preprocessor symbols. */
-#if defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)
-#define UPB_BIG_ENDIAN
-#endif
-
 /* Macros for function attributes on compilers that support them. */
 #ifdef __GNUC__
 #define UPB_FORCEINLINE __inline__ __attribute__((always_inline))
 #define UPB_NOINLINE __attribute__((noinline))
 #define UPB_NORETURN __attribute__((__noreturn__))
+#elif defined(_MSC_VER)
+#define UPB_NOINLINE
+#define UPB_FORCEINLINE
+#define UPB_NORETURN __declspec(noreturn)
 #else  /* !defined(__GNUC__) */
 #define UPB_FORCEINLINE
 #define UPB_NOINLINE
 #define UPB_NORETURN
 #endif
 
-#if __STDC_VERSION__ >= 199901L || __cplusplus >= 201103L
-/* C99/C++11 versions. */
-#include <stdio.h>
-#define _upb_snprintf snprintf
-#define _upb_vsnprintf vsnprintf
-#define _upb_va_copy(a, b) va_copy(a, b)
-#elif defined(_MSC_VER)
-/* Microsoft C/C++ versions. */
-#include <stdarg.h>
-#include <stdio.h>
-#if _MSC_VER < 1900
-int msvc_snprintf(char* s, size_t n, const char* format, ...);
-int msvc_vsnprintf(char* s, size_t n, const char* format, va_list arg);
-#define UPB_MSVC_VSNPRINTF
-#define _upb_snprintf msvc_snprintf
-#define _upb_vsnprintf msvc_vsnprintf
-#else
-#define _upb_snprintf snprintf
-#define _upb_vsnprintf vsnprintf
-#endif
-#define _upb_va_copy(a, b) va_copy(a, b)
-#elif defined __GNUC__
-/* A few hacky workarounds for functions not in C89.
- * For internal use only!
- * TODO(haberman): fix these by including our own implementations, or finding
- * another workaround.
- */
-#define _upb_snprintf __builtin_snprintf
-#define _upb_vsnprintf __builtin_vsnprintf
-#define _upb_va_copy(a, b) __va_copy(a, b)
-#else
-#error Need implementations of [v]snprintf and va_copy
-#endif
-
-#ifdef __cplusplus
-#if __cplusplus >= 201103L || defined(__GXX_EXPERIMENTAL_CXX0X__) || \
-    (defined(_MSC_VER) && _MSC_VER >= 1900)
-/* C++11 is present */
-#else
-#error upb requires C++11 for C++ support
-#endif
-#endif
-
 #define UPB_MAX(x, y) ((x) > (y) ? (x) : (y))
 #define UPB_MIN(x, y) ((x) < (y) ? (x) : (y))
 
@@ -142,7 +106,7 @@
 #elif defined _MSC_VER
 #define UPB_ASSUME(expr) if (!(expr)) __assume(0)
 #else
-#define UPB_ASSUME(expr) do {} if (false && (expr))
+#define UPB_ASSUME(expr) do {} while (false && (expr))
 #endif
 #else
 #define UPB_ASSUME(expr) assert(expr)
@@ -156,28 +120,33 @@
 #define UPB_ASSERT(expr) assert(expr)
 #endif
 
-/* UPB_ASSERT_DEBUGVAR(): assert that uses functions or variables that only
- * exist in debug mode.  This turns into regular assert. */
-#define UPB_ASSERT_DEBUGVAR(expr) assert(expr)
-
 #if defined(__GNUC__) || defined(__clang__)
 #define UPB_UNREACHABLE() do { assert(0); __builtin_unreachable(); } while(0)
 #else
 #define UPB_UNREACHABLE() do { assert(0); } while(0)
 #endif
 
-/* UPB_INFINITY representing floating-point positive infinity. */
-#include <math.h>
-#ifdef INFINITY
-#define UPB_INFINITY INFINITY
-#else
-#define UPB_INFINITY (1.0 / 0.0)
+#if defined(__SANITIZE_ADDRESS__)
+#define UPB_ASAN 1
+#ifdef __cplusplus
+extern "C" {
 #endif
-#ifdef NAN
-#define UPB_NAN NAN
-#else
-#define UPB_NAN (0.0 / 0.0)
+void __asan_poison_memory_region(void const volatile *addr, size_t size);
+void __asan_unpoison_memory_region(void const volatile *addr, size_t size);
+#ifdef __cplusplus
+}  /* extern "C" */
 #endif
+#define UPB_POISON_MEMORY_REGION(addr, size) \
+  __asan_poison_memory_region((addr), (size))
+#define UPB_UNPOISON_MEMORY_REGION(addr, size) \
+  __asan_unpoison_memory_region((addr), (size))
+#else
+#define UPB_ASAN 0
+#define UPB_POISON_MEMORY_REGION(addr, size) \
+  ((void)(addr), (void)(size))
+#define UPB_UNPOISON_MEMORY_REGION(addr, size) \
+  ((void)(addr), (void)(size))
+#endif 
 /*
 ** upb_decode: parsing into a upb_msg using a upb_msglayout.
 */
@@ -213,7 +182,7 @@
 ** store pointers or integers of at least 32 bits (upb isn't really useful on
 ** systems where sizeof(void*) < 4).
 **
-** The table must be homogeneous (all values of the same type).  In debug
+** The table must be homogenous (all values of the same type).  In debug
 ** mode, we check this on insert and lookup.
 */
 
@@ -384,17 +353,35 @@
 
 UPB_INLINE upb_alloc *upb_arena_alloc(upb_arena *a) { return (upb_alloc*)a; }
 
+UPB_INLINE bool _upb_arenahas(upb_arena *a, size_t size) {
+  _upb_arena_head *h = (_upb_arena_head*)a;
+  return (size_t)(h->end - h->ptr) >= size;
+}
+
 UPB_INLINE void *upb_arena_malloc(upb_arena *a, size_t size) {
   _upb_arena_head *h = (_upb_arena_head*)a;
   void* ret;
   size = UPB_ALIGN_MALLOC(size);
 
-  if (UPB_UNLIKELY((size_t)(h->end - h->ptr) < size)) {
+  if (UPB_UNLIKELY(!_upb_arenahas(a, size))) {
     return _upb_arena_slowmalloc(a, size);
   }
 
   ret = h->ptr;
   h->ptr += size;
+  UPB_UNPOISON_MEMORY_REGION(ret, size);
+
+#if UPB_ASAN
+  {
+    size_t guard_size = 32;
+    if (_upb_arenahas(a, guard_size)) {
+      h->ptr += guard_size;
+    } else {
+      h->ptr = h->end;
+    }
+  }
+#endif
+
   return ret;
 }
 
@@ -496,6 +483,39 @@
 
 #define UPB_MAP_BEGIN ((size_t)-1)
 
+UPB_INLINE bool _upb_isle(void) {
+  int x = 1;
+  return *(char*)&x == 1;
+}
+
+UPB_INLINE uint32_t _upb_be_swap32(uint32_t val) {
+  if (_upb_isle()) {
+    return val;
+  } else {
+    return ((val & 0xff) << 24) | ((val & 0xff00) << 8) |
+           ((val & 0xff0000) >> 8) | ((val & 0xff000000) >> 24);
+  }
+}
+
+UPB_INLINE uint64_t _upb_be_swap64(uint64_t val) {
+  if (_upb_isle()) {
+    return val;
+  } else {
+    return ((uint64_t)_upb_be_swap32(val) << 32) | _upb_be_swap32(val >> 32);
+  }
+}
+
+UPB_INLINE int _upb_lg2ceil(int x) {
+  if (x == 0) return 0;
+#ifdef __GNUC__
+  return 32 - __builtin_clz(x - 1);
+#else
+  int lg2 = 0;
+  while (1 << lg2 < x) lg2++;
+  return lg2;
+#endif
+}
+
 
 #ifdef __cplusplus
 }  /* extern "C" */
@@ -649,7 +669,8 @@
 
 typedef struct {
   size_t count;          /* Number of entries in the hash part. */
-  size_t mask;           /* Mask to turn hash value -> bucket. */
+  uint32_t mask;         /* Mask to turn hash value -> bucket. */
+  uint32_t max_count;    /* Max count before we hit our load limit. */
   uint8_t size_lg2;      /* Size of the hashtable part is 2^size_lg2 entries. */
 
   /* Hash table entries.
@@ -708,7 +729,8 @@
 /* Initialize and uninitialize a table, respectively.  If memory allocation
  * failed, false is returned that the table is uninitialized. */
 bool upb_inttable_init2(upb_inttable *table, upb_ctype_t ctype, upb_alloc *a);
-bool upb_strtable_init2(upb_strtable *table, upb_ctype_t ctype, upb_alloc *a);
+bool upb_strtable_init2(upb_strtable *table, upb_ctype_t ctype,
+                        size_t expected_size, upb_alloc *a);
 void upb_inttable_uninit2(upb_inttable *table, upb_alloc *a);
 void upb_strtable_uninit2(upb_strtable *table, upb_alloc *a);
 
@@ -717,7 +739,7 @@
 }
 
 UPB_INLINE bool upb_strtable_init(upb_strtable *table, upb_ctype_t ctype) {
-  return upb_strtable_init2(table, ctype, &upb_alloc_global);
+  return upb_strtable_init2(table, ctype, 4, &upb_alloc_global);
 }
 
 UPB_INLINE void upb_inttable_uninit(upb_inttable *table) {
@@ -989,25 +1011,41 @@
  * compatibility.  We put these before the user's data.  The user's upb_msg*
  * points after the upb_msg_internal. */
 
+typedef struct {
+  uint32_t len;
+  uint32_t size;
+  /* Data follows. */
+} upb_msg_unknowndata;
+
 /* Used when a message is not extendable. */
 typedef struct {
-  char *unknown;
-  size_t unknown_len;
-  size_t unknown_size;
+  upb_msg_unknowndata *unknown;
 } upb_msg_internal;
 
-/* Used when a message is extendable. */
-typedef struct {
-  upb_inttable *extdict;
-  upb_msg_internal base;
-} upb_msg_internal_withext;
-
 /* Maps upb_fieldtype_t -> memory size. */
 extern char _upb_fieldtype_to_size[12];
 
+UPB_INLINE size_t upb_msg_sizeof(const upb_msglayout *l) {
+  return l->size + sizeof(upb_msg_internal);
+}
+
+UPB_INLINE upb_msg *_upb_msg_new_inl(const upb_msglayout *l, upb_arena *a) {
+  size_t size = upb_msg_sizeof(l);
+  void *mem = upb_arena_malloc(a, size);
+  upb_msg *msg;
+  if (UPB_UNLIKELY(!mem)) return NULL;
+  msg = UPB_PTR_AT(mem, sizeof(upb_msg_internal), upb_msg);
+  memset(mem, 0, size);
+  return msg;
+}
+
 /* Creates a new messages with the given layout on the given arena. */
 upb_msg *_upb_msg_new(const upb_msglayout *l, upb_arena *a);
 
+UPB_INLINE upb_msg_internal *upb_msg_getinternal(upb_msg *msg) {
+  return UPB_PTR_AT(msg, -sizeof(upb_msg_internal), upb_msg_internal);
+}
+
 /* Clears the given message. */
 void _upb_msg_clear(upb_msg *msg, const upb_msglayout *l);
 
@@ -1110,17 +1148,30 @@
   return (void*)_upb_array_constptr(arr);
 }
 
-/* Creates a new array on the given arena. */
-upb_array *_upb_array_new(upb_arena *a, upb_fieldtype_t type);
+UPB_INLINE uintptr_t _upb_tag_arrptr(void* ptr, int elem_size_lg2) {
+  UPB_ASSERT(elem_size_lg2 <= 4);
+  return (uintptr_t)ptr | (unsigned)elem_size_lg2;
+}
+
+UPB_INLINE upb_array *_upb_array_new(upb_arena *a, size_t init_size,
+                                     int elem_size_lg2) {
+  const size_t bytes = sizeof(upb_array) + (init_size << elem_size_lg2);
+  upb_array *arr = (upb_array*)upb_arena_malloc(a, bytes);
+  if (!arr) return NULL;
+  arr->data = _upb_tag_arrptr(arr + 1, elem_size_lg2);
+  arr->len = 0;
+  arr->size = init_size;
+  return arr;
+}
 
 /* Resizes the capacity of the array to be at least min_size. */
 bool _upb_array_realloc(upb_array *arr, size_t min_size, upb_arena *arena);
 
 /* Fallback functions for when the accessors require a resize. */
 void *_upb_array_resize_fallback(upb_array **arr_ptr, size_t size,
-                                 upb_fieldtype_t type, upb_arena *arena);
+                                 int elem_size_lg2, upb_arena *arena);
 bool _upb_array_append_fallback(upb_array **arr_ptr, const void *value,
-                                upb_fieldtype_t type, upb_arena *arena);
+                                int elem_size_lg2, upb_arena *arena);
 
 UPB_INLINE bool _upb_array_reserve(upb_array *arr, size_t size,
                                    upb_arena *arena) {
@@ -1159,29 +1210,28 @@
   }
 }
 
-UPB_INLINE void *_upb_array_resize_accessor(void *msg, size_t ofs, size_t size,
-                                            upb_fieldtype_t type,
-                                            upb_arena *arena) {
-  upb_array **arr_ptr = PTR_AT(msg, ofs, upb_array*);
+UPB_INLINE void *_upb_array_resize_accessor2(void *msg, size_t ofs, size_t size,
+                                             int elem_size_lg2,
+                                             upb_arena *arena) {
+  upb_array **arr_ptr = PTR_AT(msg, ofs, upb_array *);
   upb_array *arr = *arr_ptr;
   if (!arr || arr->size < size) {
-    return _upb_array_resize_fallback(arr_ptr, size, type, arena);
+    return _upb_array_resize_fallback(arr_ptr, size, elem_size_lg2, arena);
   }
   arr->len = size;
   return _upb_array_ptr(arr);
 }
 
-
-UPB_INLINE bool _upb_array_append_accessor(void *msg, size_t ofs,
-                                           size_t elem_size,
-                                           upb_fieldtype_t type,
-                                           const void *value,
-                                           upb_arena *arena) {
-  upb_array **arr_ptr = PTR_AT(msg, ofs, upb_array*);
+UPB_INLINE bool _upb_array_append_accessor2(void *msg, size_t ofs,
+                                            int elem_size_lg2,
+                                            const void *value,
+                                            upb_arena *arena) {
+  upb_array **arr_ptr = PTR_AT(msg, ofs, upb_array *);
+  size_t elem_size = 1 << elem_size_lg2;
   upb_array *arr = *arr_ptr;
-  void* ptr;
+  void *ptr;
   if (!arr || arr->len == arr->size) {
-    return _upb_array_append_fallback(arr_ptr, value, type, arena);
+    return _upb_array_append_fallback(arr_ptr, value, elem_size_lg2, arena);
   }
   ptr = _upb_array_ptr(arr);
   memcpy(PTR_AT(ptr, arr->len * elem_size, char), value, elem_size);
@@ -1189,6 +1239,42 @@
   return true;
 }
 
+/* Used by old generated code, remove once all code has been regenerated. */
+UPB_INLINE int _upb_sizelg2(upb_fieldtype_t type) {
+  switch (type) {
+    case UPB_TYPE_BOOL:
+      return 0;
+    case UPB_TYPE_FLOAT:
+    case UPB_TYPE_INT32:
+    case UPB_TYPE_UINT32:
+    case UPB_TYPE_ENUM:
+      return 2;
+    case UPB_TYPE_MESSAGE:
+      return UPB_SIZE(2, 3);
+    case UPB_TYPE_DOUBLE:
+    case UPB_TYPE_INT64:
+    case UPB_TYPE_UINT64:
+      return 3;
+    case UPB_TYPE_STRING:
+    case UPB_TYPE_BYTES:
+      return UPB_SIZE(3, 4);
+  }
+  UPB_UNREACHABLE();
+}
+UPB_INLINE void *_upb_array_resize_accessor(void *msg, size_t ofs, size_t size,
+                                             upb_fieldtype_t type,
+                                             upb_arena *arena) {
+  return _upb_array_resize_accessor2(msg, ofs, size, _upb_sizelg2(type), arena);
+}
+UPB_INLINE bool _upb_array_append_accessor(void *msg, size_t ofs,
+                                            size_t elem_size, upb_fieldtype_t type,
+                                            const void *value,
+                                            upb_arena *arena) {
+  (void)elem_size;
+  return _upb_array_append_accessor2(msg, ofs, _upb_sizelg2(type), value,
+                                     arena);
+}
+
 /** upb_map *******************************************************************/
 
 /* Right now we use strmaps for everything.  We'll likely want to use
@@ -1251,7 +1337,7 @@
   if (size == UPB_MAPTYPE_STRING) {
     upb_strview *strp = (upb_strview*)upb_arena_malloc(a, sizeof(*strp));
     *strp = *(upb_strview*)val;
-    memcpy(&ret, &strp, sizeof(strp));
+    ret = upb_value_ptr(strp);
   } else {
     memcpy(&ret, val, size);
   }
@@ -1382,7 +1468,7 @@
   /* This is like _upb_map_tovalue() except the entry already exists so we can
    * reuse the allocated upb_strview for string fields. */
   if (size == UPB_MAPTYPE_STRING) {
-    upb_strview *strp = (upb_strview*)ent->val.val;
+    upb_strview *strp = (upb_strview*)(uintptr_t)ent->val.val;
     memcpy(strp, val, sizeof(*strp));
   } else {
     memcpy(&ent->val.val, val, size);
@@ -1410,6 +1496,34 @@
 #endif
 
 #endif  /* UPB_DECODE_H_ */
+
+#ifndef UPB_INT_H_
+#define UPB_INT_H_
+
+
+struct mem_block;
+typedef struct mem_block mem_block;
+
+struct upb_arena {
+  _upb_arena_head head;
+  uint32_t *cleanups;
+
+  /* Allocator to allocate arena blocks.  We are responsible for freeing these
+   * when we are destroyed. */
+  upb_alloc *block_alloc;
+  uint32_t last_size;
+
+  /* When multiple arenas are fused together, each arena points to a parent
+   * arena (root points to itself). The root tracks how many live arenas
+   * reference it. */
+  uint32_t refcount;  /* Only used when a->parent == a */
+  struct upb_arena *parent;
+
+  /* Linked list of blocks to free/cleanup. */
+  mem_block *freelist, *freelist_tail;
+};
+
+#endif  /* UPB_INT_H_ */
 /*
 ** upb_encode: parsing into a upb_msg using a upb_msglayout.
 */
@@ -1602,12 +1716,12 @@
   return (google_protobuf_FileDescriptorProto**)_upb_array_mutable_accessor(msg, UPB_SIZE(0, 0), len);
 }
 UPB_INLINE google_protobuf_FileDescriptorProto** google_protobuf_FileDescriptorSet_resize_file(google_protobuf_FileDescriptorSet *msg, size_t len, upb_arena *arena) {
-  return (google_protobuf_FileDescriptorProto**)_upb_array_resize_accessor(msg, UPB_SIZE(0, 0), len, UPB_TYPE_MESSAGE, arena);
+  return (google_protobuf_FileDescriptorProto**)_upb_array_resize_accessor2(msg, UPB_SIZE(0, 0), len, UPB_SIZE(2, 3), arena);
 }
 UPB_INLINE struct google_protobuf_FileDescriptorProto* google_protobuf_FileDescriptorSet_add_file(google_protobuf_FileDescriptorSet *msg, upb_arena *arena) {
   struct google_protobuf_FileDescriptorProto* sub = (struct google_protobuf_FileDescriptorProto*)_upb_msg_new(&google_protobuf_FileDescriptorProto_msginit, arena);
-  bool ok = _upb_array_append_accessor(
-      msg, UPB_SIZE(0, 0), UPB_SIZE(4, 8), UPB_TYPE_MESSAGE, &sub, arena);
+  bool ok = _upb_array_append_accessor2(
+      msg, UPB_SIZE(0, 0), UPB_SIZE(2, 3), &sub, arena);
   if (!ok) return NULL;
   return sub;
 }
@@ -1660,22 +1774,22 @@
   return (upb_strview*)_upb_array_mutable_accessor(msg, UPB_SIZE(36, 72), len);
 }
 UPB_INLINE upb_strview* google_protobuf_FileDescriptorProto_resize_dependency(google_protobuf_FileDescriptorProto *msg, size_t len, upb_arena *arena) {
-  return (upb_strview*)_upb_array_resize_accessor(msg, UPB_SIZE(36, 72), len, UPB_TYPE_STRING, arena);
+  return (upb_strview*)_upb_array_resize_accessor2(msg, UPB_SIZE(36, 72), len, UPB_SIZE(3, 4), arena);
 }
 UPB_INLINE bool google_protobuf_FileDescriptorProto_add_dependency(google_protobuf_FileDescriptorProto *msg, upb_strview val, upb_arena *arena) {
-  return _upb_array_append_accessor(msg, UPB_SIZE(36, 72), UPB_SIZE(8, 16), UPB_TYPE_STRING, &val,
+  return _upb_array_append_accessor2(msg, UPB_SIZE(36, 72), UPB_SIZE(3, 4), &val,
       arena);
 }
 UPB_INLINE google_protobuf_DescriptorProto** google_protobuf_FileDescriptorProto_mutable_message_type(google_protobuf_FileDescriptorProto *msg, size_t *len) {
   return (google_protobuf_DescriptorProto**)_upb_array_mutable_accessor(msg, UPB_SIZE(40, 80), len);
 }
 UPB_INLINE google_protobuf_DescriptorProto** google_protobuf_FileDescriptorProto_resize_message_type(google_protobuf_FileDescriptorProto *msg, size_t len, upb_arena *arena) {
-  return (google_protobuf_DescriptorProto**)_upb_array_resize_accessor(msg, UPB_SIZE(40, 80), len, UPB_TYPE_MESSAGE, arena);
+  return (google_protobuf_DescriptorProto**)_upb_array_resize_accessor2(msg, UPB_SIZE(40, 80), len, UPB_SIZE(2, 3), arena);
 }
 UPB_INLINE struct google_protobuf_DescriptorProto* google_protobuf_FileDescriptorProto_add_message_type(google_protobuf_FileDescriptorProto *msg, upb_arena *arena) {
   struct google_protobuf_DescriptorProto* sub = (struct google_protobuf_DescriptorProto*)_upb_msg_new(&google_protobuf_DescriptorProto_msginit, arena);
-  bool ok = _upb_array_append_accessor(
-      msg, UPB_SIZE(40, 80), UPB_SIZE(4, 8), UPB_TYPE_MESSAGE, &sub, arena);
+  bool ok = _upb_array_append_accessor2(
+      msg, UPB_SIZE(40, 80), UPB_SIZE(2, 3), &sub, arena);
   if (!ok) return NULL;
   return sub;
 }
@@ -1683,12 +1797,12 @@
   return (google_protobuf_EnumDescriptorProto**)_upb_array_mutable_accessor(msg, UPB_SIZE(44, 88), len);
 }
 UPB_INLINE google_protobuf_EnumDescriptorProto** google_protobuf_FileDescriptorProto_resize_enum_type(google_protobuf_FileDescriptorProto *msg, size_t len, upb_arena *arena) {
-  return (google_protobuf_EnumDescriptorProto**)_upb_array_resize_accessor(msg, UPB_SIZE(44, 88), len, UPB_TYPE_MESSAGE, arena);
+  return (google_protobuf_EnumDescriptorProto**)_upb_array_resize_accessor2(msg, UPB_SIZE(44, 88), len, UPB_SIZE(2, 3), arena);
 }
 UPB_INLINE struct google_protobuf_EnumDescriptorProto* google_protobuf_FileDescriptorProto_add_enum_type(google_protobuf_FileDescriptorProto *msg, upb_arena *arena) {
   struct google_protobuf_EnumDescriptorProto* sub = (struct google_protobuf_EnumDescriptorProto*)_upb_msg_new(&google_protobuf_EnumDescriptorProto_msginit, arena);
-  bool ok = _upb_array_append_accessor(
-      msg, UPB_SIZE(44, 88), UPB_SIZE(4, 8), UPB_TYPE_MESSAGE, &sub, arena);
+  bool ok = _upb_array_append_accessor2(
+      msg, UPB_SIZE(44, 88), UPB_SIZE(2, 3), &sub, arena);
   if (!ok) return NULL;
   return sub;
 }
@@ -1696,12 +1810,12 @@
   return (google_protobuf_ServiceDescriptorProto**)_upb_array_mutable_accessor(msg, UPB_SIZE(48, 96), len);
 }
 UPB_INLINE google_protobuf_ServiceDescriptorProto** google_protobuf_FileDescriptorProto_resize_service(google_protobuf_FileDescriptorProto *msg, size_t len, upb_arena *arena) {
-  return (google_protobuf_ServiceDescriptorProto**)_upb_array_resize_accessor(msg, UPB_SIZE(48, 96), len, UPB_TYPE_MESSAGE, arena);
+  return (google_protobuf_ServiceDescriptorProto**)_upb_array_resize_accessor2(msg, UPB_SIZE(48, 96), len, UPB_SIZE(2, 3), arena);
 }
 UPB_INLINE struct google_protobuf_ServiceDescriptorProto* google_protobuf_FileDescriptorProto_add_service(google_protobuf_FileDescriptorProto *msg, upb_arena *arena) {
   struct google_protobuf_ServiceDescriptorProto* sub = (struct google_protobuf_ServiceDescriptorProto*)_upb_msg_new(&google_protobuf_ServiceDescriptorProto_msginit, arena);
-  bool ok = _upb_array_append_accessor(
-      msg, UPB_SIZE(48, 96), UPB_SIZE(4, 8), UPB_TYPE_MESSAGE, &sub, arena);
+  bool ok = _upb_array_append_accessor2(
+      msg, UPB_SIZE(48, 96), UPB_SIZE(2, 3), &sub, arena);
   if (!ok) return NULL;
   return sub;
 }
@@ -1709,12 +1823,12 @@
   return (google_protobuf_FieldDescriptorProto**)_upb_array_mutable_accessor(msg, UPB_SIZE(52, 104), len);
 }
 UPB_INLINE google_protobuf_FieldDescriptorProto** google_protobuf_FileDescriptorProto_resize_extension(google_protobuf_FileDescriptorProto *msg, size_t len, upb_arena *arena) {
-  return (google_protobuf_FieldDescriptorProto**)_upb_array_resize_accessor(msg, UPB_SIZE(52, 104), len, UPB_TYPE_MESSAGE, arena);
+  return (google_protobuf_FieldDescriptorProto**)_upb_array_resize_accessor2(msg, UPB_SIZE(52, 104), len, UPB_SIZE(2, 3), arena);
 }
 UPB_INLINE struct google_protobuf_FieldDescriptorProto* google_protobuf_FileDescriptorProto_add_extension(google_protobuf_FileDescriptorProto *msg, upb_arena *arena) {
   struct google_protobuf_FieldDescriptorProto* sub = (struct google_protobuf_FieldDescriptorProto*)_upb_msg_new(&google_protobuf_FieldDescriptorProto_msginit, arena);
-  bool ok = _upb_array_append_accessor(
-      msg, UPB_SIZE(52, 104), UPB_SIZE(4, 8), UPB_TYPE_MESSAGE, &sub, arena);
+  bool ok = _upb_array_append_accessor2(
+      msg, UPB_SIZE(52, 104), UPB_SIZE(2, 3), &sub, arena);
   if (!ok) return NULL;
   return sub;
 }
@@ -1748,20 +1862,20 @@
   return (int32_t*)_upb_array_mutable_accessor(msg, UPB_SIZE(56, 112), len);
 }
 UPB_INLINE int32_t* google_protobuf_FileDescriptorProto_resize_public_dependency(google_protobuf_FileDescriptorProto *msg, size_t len, upb_arena *arena) {
-  return (int32_t*)_upb_array_resize_accessor(msg, UPB_SIZE(56, 112), len, UPB_TYPE_INT32, arena);
+  return (int32_t*)_upb_array_resize_accessor2(msg, UPB_SIZE(56, 112), len, 2, arena);
 }
 UPB_INLINE bool google_protobuf_FileDescriptorProto_add_public_dependency(google_protobuf_FileDescriptorProto *msg, int32_t val, upb_arena *arena) {
-  return _upb_array_append_accessor(msg, UPB_SIZE(56, 112), UPB_SIZE(4, 4), UPB_TYPE_INT32, &val,
+  return _upb_array_append_accessor2(msg, UPB_SIZE(56, 112), 2, &val,
       arena);
 }
 UPB_INLINE int32_t* google_protobuf_FileDescriptorProto_mutable_weak_dependency(google_protobuf_FileDescriptorProto *msg, size_t *len) {
   return (int32_t*)_upb_array_mutable_accessor(msg, UPB_SIZE(60, 120), len);
 }
 UPB_INLINE int32_t* google_protobuf_FileDescriptorProto_resize_weak_dependency(google_protobuf_FileDescriptorProto *msg, size_t len, upb_arena *arena) {
-  return (int32_t*)_upb_array_resize_accessor(msg, UPB_SIZE(60, 120), len, UPB_TYPE_INT32, arena);
+  return (int32_t*)_upb_array_resize_accessor2(msg, UPB_SIZE(60, 120), len, 2, arena);
 }
 UPB_INLINE bool google_protobuf_FileDescriptorProto_add_weak_dependency(google_protobuf_FileDescriptorProto *msg, int32_t val, upb_arena *arena) {
-  return _upb_array_append_accessor(msg, UPB_SIZE(60, 120), UPB_SIZE(4, 4), UPB_TYPE_INT32, &val,
+  return _upb_array_append_accessor2(msg, UPB_SIZE(60, 120), 2, &val,
       arena);
 }
 UPB_INLINE void google_protobuf_FileDescriptorProto_set_syntax(google_protobuf_FileDescriptorProto *msg, upb_strview value) {
@@ -1811,12 +1925,12 @@
   return (google_protobuf_FieldDescriptorProto**)_upb_array_mutable_accessor(msg, UPB_SIZE(16, 32), len);
 }
 UPB_INLINE google_protobuf_FieldDescriptorProto** google_protobuf_DescriptorProto_resize_field(google_protobuf_DescriptorProto *msg, size_t len, upb_arena *arena) {
-  return (google_protobuf_FieldDescriptorProto**)_upb_array_resize_accessor(msg, UPB_SIZE(16, 32), len, UPB_TYPE_MESSAGE, arena);
+  return (google_protobuf_FieldDescriptorProto**)_upb_array_resize_accessor2(msg, UPB_SIZE(16, 32), len, UPB_SIZE(2, 3), arena);
 }
 UPB_INLINE struct google_protobuf_FieldDescriptorProto* google_protobuf_DescriptorProto_add_field(google_protobuf_DescriptorProto *msg, upb_arena *arena) {
   struct google_protobuf_FieldDescriptorProto* sub = (struct google_protobuf_FieldDescriptorProto*)_upb_msg_new(&google_protobuf_FieldDescriptorProto_msginit, arena);
-  bool ok = _upb_array_append_accessor(
-      msg, UPB_SIZE(16, 32), UPB_SIZE(4, 8), UPB_TYPE_MESSAGE, &sub, arena);
+  bool ok = _upb_array_append_accessor2(
+      msg, UPB_SIZE(16, 32), UPB_SIZE(2, 3), &sub, arena);
   if (!ok) return NULL;
   return sub;
 }
@@ -1824,12 +1938,12 @@
   return (google_protobuf_DescriptorProto**)_upb_array_mutable_accessor(msg, UPB_SIZE(20, 40), len);
 }
 UPB_INLINE google_protobuf_DescriptorProto** google_protobuf_DescriptorProto_resize_nested_type(google_protobuf_DescriptorProto *msg, size_t len, upb_arena *arena) {
-  return (google_protobuf_DescriptorProto**)_upb_array_resize_accessor(msg, UPB_SIZE(20, 40), len, UPB_TYPE_MESSAGE, arena);
+  return (google_protobuf_DescriptorProto**)_upb_array_resize_accessor2(msg, UPB_SIZE(20, 40), len, UPB_SIZE(2, 3), arena);
 }
 UPB_INLINE struct google_protobuf_DescriptorProto* google_protobuf_DescriptorProto_add_nested_type(google_protobuf_DescriptorProto *msg, upb_arena *arena) {
   struct google_protobuf_DescriptorProto* sub = (struct google_protobuf_DescriptorProto*)_upb_msg_new(&google_protobuf_DescriptorProto_msginit, arena);
-  bool ok = _upb_array_append_accessor(
-      msg, UPB_SIZE(20, 40), UPB_SIZE(4, 8), UPB_TYPE_MESSAGE, &sub, arena);
+  bool ok = _upb_array_append_accessor2(
+      msg, UPB_SIZE(20, 40), UPB_SIZE(2, 3), &sub, arena);
   if (!ok) return NULL;
   return sub;
 }
@@ -1837,12 +1951,12 @@
   return (google_protobuf_EnumDescriptorProto**)_upb_array_mutable_accessor(msg, UPB_SIZE(24, 48), len);
 }
 UPB_INLINE google_protobuf_EnumDescriptorProto** google_protobuf_DescriptorProto_resize_enum_type(google_protobuf_DescriptorProto *msg, size_t len, upb_arena *arena) {
-  return (google_protobuf_EnumDescriptorProto**)_upb_array_resize_accessor(msg, UPB_SIZE(24, 48), len, UPB_TYPE_MESSAGE, arena);
+  return (google_protobuf_EnumDescriptorProto**)_upb_array_resize_accessor2(msg, UPB_SIZE(24, 48), len, UPB_SIZE(2, 3), arena);
 }
 UPB_INLINE struct google_protobuf_EnumDescriptorProto* google_protobuf_DescriptorProto_add_enum_type(google_protobuf_DescriptorProto *msg, upb_arena *arena) {
   struct google_protobuf_EnumDescriptorProto* sub = (struct google_protobuf_EnumDescriptorProto*)_upb_msg_new(&google_protobuf_EnumDescriptorProto_msginit, arena);
-  bool ok = _upb_array_append_accessor(
-      msg, UPB_SIZE(24, 48), UPB_SIZE(4, 8), UPB_TYPE_MESSAGE, &sub, arena);
+  bool ok = _upb_array_append_accessor2(
+      msg, UPB_SIZE(24, 48), UPB_SIZE(2, 3), &sub, arena);
   if (!ok) return NULL;
   return sub;
 }
@@ -1850,12 +1964,12 @@
   return (google_protobuf_DescriptorProto_ExtensionRange**)_upb_array_mutable_accessor(msg, UPB_SIZE(28, 56), len);
 }
 UPB_INLINE google_protobuf_DescriptorProto_ExtensionRange** google_protobuf_DescriptorProto_resize_extension_range(google_protobuf_DescriptorProto *msg, size_t len, upb_arena *arena) {
-  return (google_protobuf_DescriptorProto_ExtensionRange**)_upb_array_resize_accessor(msg, UPB_SIZE(28, 56), len, UPB_TYPE_MESSAGE, arena);
+  return (google_protobuf_DescriptorProto_ExtensionRange**)_upb_array_resize_accessor2(msg, UPB_SIZE(28, 56), len, UPB_SIZE(2, 3), arena);
 }
 UPB_INLINE struct google_protobuf_DescriptorProto_ExtensionRange* google_protobuf_DescriptorProto_add_extension_range(google_protobuf_DescriptorProto *msg, upb_arena *arena) {
   struct google_protobuf_DescriptorProto_ExtensionRange* sub = (struct google_protobuf_DescriptorProto_ExtensionRange*)_upb_msg_new(&google_protobuf_DescriptorProto_ExtensionRange_msginit, arena);
-  bool ok = _upb_array_append_accessor(
-      msg, UPB_SIZE(28, 56), UPB_SIZE(4, 8), UPB_TYPE_MESSAGE, &sub, arena);
+  bool ok = _upb_array_append_accessor2(
+      msg, UPB_SIZE(28, 56), UPB_SIZE(2, 3), &sub, arena);
   if (!ok) return NULL;
   return sub;
 }
@@ -1863,12 +1977,12 @@
   return (google_protobuf_FieldDescriptorProto**)_upb_array_mutable_accessor(msg, UPB_SIZE(32, 64), len);
 }
 UPB_INLINE google_protobuf_FieldDescriptorProto** google_protobuf_DescriptorProto_resize_extension(google_protobuf_DescriptorProto *msg, size_t len, upb_arena *arena) {
-  return (google_protobuf_FieldDescriptorProto**)_upb_array_resize_accessor(msg, UPB_SIZE(32, 64), len, UPB_TYPE_MESSAGE, arena);
+  return (google_protobuf_FieldDescriptorProto**)_upb_array_resize_accessor2(msg, UPB_SIZE(32, 64), len, UPB_SIZE(2, 3), arena);
 }
 UPB_INLINE struct google_protobuf_FieldDescriptorProto* google_protobuf_DescriptorProto_add_extension(google_protobuf_DescriptorProto *msg, upb_arena *arena) {
   struct google_protobuf_FieldDescriptorProto* sub = (struct google_protobuf_FieldDescriptorProto*)_upb_msg_new(&google_protobuf_FieldDescriptorProto_msginit, arena);
-  bool ok = _upb_array_append_accessor(
-      msg, UPB_SIZE(32, 64), UPB_SIZE(4, 8), UPB_TYPE_MESSAGE, &sub, arena);
+  bool ok = _upb_array_append_accessor2(
+      msg, UPB_SIZE(32, 64), UPB_SIZE(2, 3), &sub, arena);
   if (!ok) return NULL;
   return sub;
 }
@@ -1889,12 +2003,12 @@
   return (google_protobuf_OneofDescriptorProto**)_upb_array_mutable_accessor(msg, UPB_SIZE(36, 72), len);
 }
 UPB_INLINE google_protobuf_OneofDescriptorProto** google_protobuf_DescriptorProto_resize_oneof_decl(google_protobuf_DescriptorProto *msg, size_t len, upb_arena *arena) {
-  return (google_protobuf_OneofDescriptorProto**)_upb_array_resize_accessor(msg, UPB_SIZE(36, 72), len, UPB_TYPE_MESSAGE, arena);
+  return (google_protobuf_OneofDescriptorProto**)_upb_array_resize_accessor2(msg, UPB_SIZE(36, 72), len, UPB_SIZE(2, 3), arena);
 }
 UPB_INLINE struct google_protobuf_OneofDescriptorProto* google_protobuf_DescriptorProto_add_oneof_decl(google_protobuf_DescriptorProto *msg, upb_arena *arena) {
   struct google_protobuf_OneofDescriptorProto* sub = (struct google_protobuf_OneofDescriptorProto*)_upb_msg_new(&google_protobuf_OneofDescriptorProto_msginit, arena);
-  bool ok = _upb_array_append_accessor(
-      msg, UPB_SIZE(36, 72), UPB_SIZE(4, 8), UPB_TYPE_MESSAGE, &sub, arena);
+  bool ok = _upb_array_append_accessor2(
+      msg, UPB_SIZE(36, 72), UPB_SIZE(2, 3), &sub, arena);
   if (!ok) return NULL;
   return sub;
 }
@@ -1902,12 +2016,12 @@
   return (google_protobuf_DescriptorProto_ReservedRange**)_upb_array_mutable_accessor(msg, UPB_SIZE(40, 80), len);
 }
 UPB_INLINE google_protobuf_DescriptorProto_ReservedRange** google_protobuf_DescriptorProto_resize_reserved_range(google_protobuf_DescriptorProto *msg, size_t len, upb_arena *arena) {
-  return (google_protobuf_DescriptorProto_ReservedRange**)_upb_array_resize_accessor(msg, UPB_SIZE(40, 80), len, UPB_TYPE_MESSAGE, arena);
+  return (google_protobuf_DescriptorProto_ReservedRange**)_upb_array_resize_accessor2(msg, UPB_SIZE(40, 80), len, UPB_SIZE(2, 3), arena);
 }
 UPB_INLINE struct google_protobuf_DescriptorProto_ReservedRange* google_protobuf_DescriptorProto_add_reserved_range(google_protobuf_DescriptorProto *msg, upb_arena *arena) {
   struct google_protobuf_DescriptorProto_ReservedRange* sub = (struct google_protobuf_DescriptorProto_ReservedRange*)_upb_msg_new(&google_protobuf_DescriptorProto_ReservedRange_msginit, arena);
-  bool ok = _upb_array_append_accessor(
-      msg, UPB_SIZE(40, 80), UPB_SIZE(4, 8), UPB_TYPE_MESSAGE, &sub, arena);
+  bool ok = _upb_array_append_accessor2(
+      msg, UPB_SIZE(40, 80), UPB_SIZE(2, 3), &sub, arena);
   if (!ok) return NULL;
   return sub;
 }
@@ -1915,10 +2029,10 @@
   return (upb_strview*)_upb_array_mutable_accessor(msg, UPB_SIZE(44, 88), len);
 }
 UPB_INLINE upb_strview* google_protobuf_DescriptorProto_resize_reserved_name(google_protobuf_DescriptorProto *msg, size_t len, upb_arena *arena) {
-  return (upb_strview*)_upb_array_resize_accessor(msg, UPB_SIZE(44, 88), len, UPB_TYPE_STRING, arena);
+  return (upb_strview*)_upb_array_resize_accessor2(msg, UPB_SIZE(44, 88), len, UPB_SIZE(3, 4), arena);
 }
 UPB_INLINE bool google_protobuf_DescriptorProto_add_reserved_name(google_protobuf_DescriptorProto *msg, upb_strview val, upb_arena *arena) {
-  return _upb_array_append_accessor(msg, UPB_SIZE(44, 88), UPB_SIZE(8, 16), UPB_TYPE_STRING, &val,
+  return _upb_array_append_accessor2(msg, UPB_SIZE(44, 88), UPB_SIZE(3, 4), &val,
       arena);
 }
 
@@ -2014,12 +2128,12 @@
   return (google_protobuf_UninterpretedOption**)_upb_array_mutable_accessor(msg, UPB_SIZE(0, 0), len);
 }
 UPB_INLINE google_protobuf_UninterpretedOption** google_protobuf_ExtensionRangeOptions_resize_uninterpreted_option(google_protobuf_ExtensionRangeOptions *msg, size_t len, upb_arena *arena) {
-  return (google_protobuf_UninterpretedOption**)_upb_array_resize_accessor(msg, UPB_SIZE(0, 0), len, UPB_TYPE_MESSAGE, arena);
+  return (google_protobuf_UninterpretedOption**)_upb_array_resize_accessor2(msg, UPB_SIZE(0, 0), len, UPB_SIZE(2, 3), arena);
 }
 UPB_INLINE struct google_protobuf_UninterpretedOption* google_protobuf_ExtensionRangeOptions_add_uninterpreted_option(google_protobuf_ExtensionRangeOptions *msg, upb_arena *arena) {
   struct google_protobuf_UninterpretedOption* sub = (struct google_protobuf_UninterpretedOption*)_upb_msg_new(&google_protobuf_UninterpretedOption_msginit, arena);
-  bool ok = _upb_array_append_accessor(
-      msg, UPB_SIZE(0, 0), UPB_SIZE(4, 8), UPB_TYPE_MESSAGE, &sub, arena);
+  bool ok = _upb_array_append_accessor2(
+      msg, UPB_SIZE(0, 0), UPB_SIZE(2, 3), &sub, arena);
   if (!ok) return NULL;
   return sub;
 }
@@ -2039,59 +2153,59 @@
 }
 
 UPB_INLINE bool google_protobuf_FieldDescriptorProto_has_name(const google_protobuf_FieldDescriptorProto *msg) { return _upb_hasbit(msg, 6); }
-UPB_INLINE upb_strview google_protobuf_FieldDescriptorProto_name(const google_protobuf_FieldDescriptorProto *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(36, 40), upb_strview); }
+UPB_INLINE upb_strview google_protobuf_FieldDescriptorProto_name(const google_protobuf_FieldDescriptorProto *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(24, 24), upb_strview); }
 UPB_INLINE bool google_protobuf_FieldDescriptorProto_has_extendee(const google_protobuf_FieldDescriptorProto *msg) { return _upb_hasbit(msg, 7); }
-UPB_INLINE upb_strview google_protobuf_FieldDescriptorProto_extendee(const google_protobuf_FieldDescriptorProto *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(44, 56), upb_strview); }
+UPB_INLINE upb_strview google_protobuf_FieldDescriptorProto_extendee(const google_protobuf_FieldDescriptorProto *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(32, 40), upb_strview); }
 UPB_INLINE bool google_protobuf_FieldDescriptorProto_has_number(const google_protobuf_FieldDescriptorProto *msg) { return _upb_hasbit(msg, 3); }
-UPB_INLINE int32_t google_protobuf_FieldDescriptorProto_number(const google_protobuf_FieldDescriptorProto *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(24, 24), int32_t); }
+UPB_INLINE int32_t google_protobuf_FieldDescriptorProto_number(const google_protobuf_FieldDescriptorProto *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(12, 12), int32_t); }
 UPB_INLINE bool google_protobuf_FieldDescriptorProto_has_label(const google_protobuf_FieldDescriptorProto *msg) { return _upb_hasbit(msg, 1); }
-UPB_INLINE int32_t google_protobuf_FieldDescriptorProto_label(const google_protobuf_FieldDescriptorProto *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(8, 8), int32_t); }
+UPB_INLINE int32_t google_protobuf_FieldDescriptorProto_label(const google_protobuf_FieldDescriptorProto *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(4, 4), int32_t); }
 UPB_INLINE bool google_protobuf_FieldDescriptorProto_has_type(const google_protobuf_FieldDescriptorProto *msg) { return _upb_hasbit(msg, 2); }
-UPB_INLINE int32_t google_protobuf_FieldDescriptorProto_type(const google_protobuf_FieldDescriptorProto *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(16, 16), int32_t); }
+UPB_INLINE int32_t google_protobuf_FieldDescriptorProto_type(const google_protobuf_FieldDescriptorProto *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(8, 8), int32_t); }
 UPB_INLINE bool google_protobuf_FieldDescriptorProto_has_type_name(const google_protobuf_FieldDescriptorProto *msg) { return _upb_hasbit(msg, 8); }
-UPB_INLINE upb_strview google_protobuf_FieldDescriptorProto_type_name(const google_protobuf_FieldDescriptorProto *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(52, 72), upb_strview); }
+UPB_INLINE upb_strview google_protobuf_FieldDescriptorProto_type_name(const google_protobuf_FieldDescriptorProto *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(40, 56), upb_strview); }
 UPB_INLINE bool google_protobuf_FieldDescriptorProto_has_default_value(const google_protobuf_FieldDescriptorProto *msg) { return _upb_hasbit(msg, 9); }
-UPB_INLINE upb_strview google_protobuf_FieldDescriptorProto_default_value(const google_protobuf_FieldDescriptorProto *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(60, 88), upb_strview); }
+UPB_INLINE upb_strview google_protobuf_FieldDescriptorProto_default_value(const google_protobuf_FieldDescriptorProto *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(48, 72), upb_strview); }
 UPB_INLINE bool google_protobuf_FieldDescriptorProto_has_options(const google_protobuf_FieldDescriptorProto *msg) { return _upb_hasbit(msg, 11); }
-UPB_INLINE const google_protobuf_FieldOptions* google_protobuf_FieldDescriptorProto_options(const google_protobuf_FieldDescriptorProto *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(76, 120), const google_protobuf_FieldOptions*); }
+UPB_INLINE const google_protobuf_FieldOptions* google_protobuf_FieldDescriptorProto_options(const google_protobuf_FieldDescriptorProto *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(64, 104), const google_protobuf_FieldOptions*); }
 UPB_INLINE bool google_protobuf_FieldDescriptorProto_has_oneof_index(const google_protobuf_FieldDescriptorProto *msg) { return _upb_hasbit(msg, 4); }
-UPB_INLINE int32_t google_protobuf_FieldDescriptorProto_oneof_index(const google_protobuf_FieldDescriptorProto *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(28, 28), int32_t); }
+UPB_INLINE int32_t google_protobuf_FieldDescriptorProto_oneof_index(const google_protobuf_FieldDescriptorProto *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(16, 16), int32_t); }
 UPB_INLINE bool google_protobuf_FieldDescriptorProto_has_json_name(const google_protobuf_FieldDescriptorProto *msg) { return _upb_hasbit(msg, 10); }
-UPB_INLINE upb_strview google_protobuf_FieldDescriptorProto_json_name(const google_protobuf_FieldDescriptorProto *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(68, 104), upb_strview); }
+UPB_INLINE upb_strview google_protobuf_FieldDescriptorProto_json_name(const google_protobuf_FieldDescriptorProto *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(56, 88), upb_strview); }
 UPB_INLINE bool google_protobuf_FieldDescriptorProto_has_proto3_optional(const google_protobuf_FieldDescriptorProto *msg) { return _upb_hasbit(msg, 5); }
-UPB_INLINE bool google_protobuf_FieldDescriptorProto_proto3_optional(const google_protobuf_FieldDescriptorProto *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(32, 32), bool); }
+UPB_INLINE bool google_protobuf_FieldDescriptorProto_proto3_optional(const google_protobuf_FieldDescriptorProto *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(20, 20), bool); }
 
 UPB_INLINE void google_protobuf_FieldDescriptorProto_set_name(google_protobuf_FieldDescriptorProto *msg, upb_strview value) {
   _upb_sethas(msg, 6);
-  *UPB_PTR_AT(msg, UPB_SIZE(36, 40), upb_strview) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(24, 24), upb_strview) = value;
 }
 UPB_INLINE void google_protobuf_FieldDescriptorProto_set_extendee(google_protobuf_FieldDescriptorProto *msg, upb_strview value) {
   _upb_sethas(msg, 7);
-  *UPB_PTR_AT(msg, UPB_SIZE(44, 56), upb_strview) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(32, 40), upb_strview) = value;
 }
 UPB_INLINE void google_protobuf_FieldDescriptorProto_set_number(google_protobuf_FieldDescriptorProto *msg, int32_t value) {
   _upb_sethas(msg, 3);
-  *UPB_PTR_AT(msg, UPB_SIZE(24, 24), int32_t) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(12, 12), int32_t) = value;
 }
 UPB_INLINE void google_protobuf_FieldDescriptorProto_set_label(google_protobuf_FieldDescriptorProto *msg, int32_t value) {
   _upb_sethas(msg, 1);
-  *UPB_PTR_AT(msg, UPB_SIZE(8, 8), int32_t) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(4, 4), int32_t) = value;
 }
 UPB_INLINE void google_protobuf_FieldDescriptorProto_set_type(google_protobuf_FieldDescriptorProto *msg, int32_t value) {
   _upb_sethas(msg, 2);
-  *UPB_PTR_AT(msg, UPB_SIZE(16, 16), int32_t) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(8, 8), int32_t) = value;
 }
 UPB_INLINE void google_protobuf_FieldDescriptorProto_set_type_name(google_protobuf_FieldDescriptorProto *msg, upb_strview value) {
   _upb_sethas(msg, 8);
-  *UPB_PTR_AT(msg, UPB_SIZE(52, 72), upb_strview) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(40, 56), upb_strview) = value;
 }
 UPB_INLINE void google_protobuf_FieldDescriptorProto_set_default_value(google_protobuf_FieldDescriptorProto *msg, upb_strview value) {
   _upb_sethas(msg, 9);
-  *UPB_PTR_AT(msg, UPB_SIZE(60, 88), upb_strview) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(48, 72), upb_strview) = value;
 }
 UPB_INLINE void google_protobuf_FieldDescriptorProto_set_options(google_protobuf_FieldDescriptorProto *msg, google_protobuf_FieldOptions* value) {
   _upb_sethas(msg, 11);
-  *UPB_PTR_AT(msg, UPB_SIZE(76, 120), google_protobuf_FieldOptions*) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(64, 104), google_protobuf_FieldOptions*) = value;
 }
 UPB_INLINE struct google_protobuf_FieldOptions* google_protobuf_FieldDescriptorProto_mutable_options(google_protobuf_FieldDescriptorProto *msg, upb_arena *arena) {
   struct google_protobuf_FieldOptions* sub = (struct google_protobuf_FieldOptions*)google_protobuf_FieldDescriptorProto_options(msg);
@@ -2104,15 +2218,15 @@
 }
 UPB_INLINE void google_protobuf_FieldDescriptorProto_set_oneof_index(google_protobuf_FieldDescriptorProto *msg, int32_t value) {
   _upb_sethas(msg, 4);
-  *UPB_PTR_AT(msg, UPB_SIZE(28, 28), int32_t) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(16, 16), int32_t) = value;
 }
 UPB_INLINE void google_protobuf_FieldDescriptorProto_set_json_name(google_protobuf_FieldDescriptorProto *msg, upb_strview value) {
   _upb_sethas(msg, 10);
-  *UPB_PTR_AT(msg, UPB_SIZE(68, 104), upb_strview) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(56, 88), upb_strview) = value;
 }
 UPB_INLINE void google_protobuf_FieldDescriptorProto_set_proto3_optional(google_protobuf_FieldDescriptorProto *msg, bool value) {
   _upb_sethas(msg, 5);
-  *UPB_PTR_AT(msg, UPB_SIZE(32, 32), bool) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(20, 20), bool) = value;
 }
 
 /* google.protobuf.OneofDescriptorProto */
@@ -2184,12 +2298,12 @@
   return (google_protobuf_EnumValueDescriptorProto**)_upb_array_mutable_accessor(msg, UPB_SIZE(16, 32), len);
 }
 UPB_INLINE google_protobuf_EnumValueDescriptorProto** google_protobuf_EnumDescriptorProto_resize_value(google_protobuf_EnumDescriptorProto *msg, size_t len, upb_arena *arena) {
-  return (google_protobuf_EnumValueDescriptorProto**)_upb_array_resize_accessor(msg, UPB_SIZE(16, 32), len, UPB_TYPE_MESSAGE, arena);
+  return (google_protobuf_EnumValueDescriptorProto**)_upb_array_resize_accessor2(msg, UPB_SIZE(16, 32), len, UPB_SIZE(2, 3), arena);
 }
 UPB_INLINE struct google_protobuf_EnumValueDescriptorProto* google_protobuf_EnumDescriptorProto_add_value(google_protobuf_EnumDescriptorProto *msg, upb_arena *arena) {
   struct google_protobuf_EnumValueDescriptorProto* sub = (struct google_protobuf_EnumValueDescriptorProto*)_upb_msg_new(&google_protobuf_EnumValueDescriptorProto_msginit, arena);
-  bool ok = _upb_array_append_accessor(
-      msg, UPB_SIZE(16, 32), UPB_SIZE(4, 8), UPB_TYPE_MESSAGE, &sub, arena);
+  bool ok = _upb_array_append_accessor2(
+      msg, UPB_SIZE(16, 32), UPB_SIZE(2, 3), &sub, arena);
   if (!ok) return NULL;
   return sub;
 }
@@ -2210,12 +2324,12 @@
   return (google_protobuf_EnumDescriptorProto_EnumReservedRange**)_upb_array_mutable_accessor(msg, UPB_SIZE(20, 40), len);
 }
 UPB_INLINE google_protobuf_EnumDescriptorProto_EnumReservedRange** google_protobuf_EnumDescriptorProto_resize_reserved_range(google_protobuf_EnumDescriptorProto *msg, size_t len, upb_arena *arena) {
-  return (google_protobuf_EnumDescriptorProto_EnumReservedRange**)_upb_array_resize_accessor(msg, UPB_SIZE(20, 40), len, UPB_TYPE_MESSAGE, arena);
+  return (google_protobuf_EnumDescriptorProto_EnumReservedRange**)_upb_array_resize_accessor2(msg, UPB_SIZE(20, 40), len, UPB_SIZE(2, 3), arena);
 }
 UPB_INLINE struct google_protobuf_EnumDescriptorProto_EnumReservedRange* google_protobuf_EnumDescriptorProto_add_reserved_range(google_protobuf_EnumDescriptorProto *msg, upb_arena *arena) {
   struct google_protobuf_EnumDescriptorProto_EnumReservedRange* sub = (struct google_protobuf_EnumDescriptorProto_EnumReservedRange*)_upb_msg_new(&google_protobuf_EnumDescriptorProto_EnumReservedRange_msginit, arena);
-  bool ok = _upb_array_append_accessor(
-      msg, UPB_SIZE(20, 40), UPB_SIZE(4, 8), UPB_TYPE_MESSAGE, &sub, arena);
+  bool ok = _upb_array_append_accessor2(
+      msg, UPB_SIZE(20, 40), UPB_SIZE(2, 3), &sub, arena);
   if (!ok) return NULL;
   return sub;
 }
@@ -2223,10 +2337,10 @@
   return (upb_strview*)_upb_array_mutable_accessor(msg, UPB_SIZE(24, 48), len);
 }
 UPB_INLINE upb_strview* google_protobuf_EnumDescriptorProto_resize_reserved_name(google_protobuf_EnumDescriptorProto *msg, size_t len, upb_arena *arena) {
-  return (upb_strview*)_upb_array_resize_accessor(msg, UPB_SIZE(24, 48), len, UPB_TYPE_STRING, arena);
+  return (upb_strview*)_upb_array_resize_accessor2(msg, UPB_SIZE(24, 48), len, UPB_SIZE(3, 4), arena);
 }
 UPB_INLINE bool google_protobuf_EnumDescriptorProto_add_reserved_name(google_protobuf_EnumDescriptorProto *msg, upb_strview val, upb_arena *arena) {
-  return _upb_array_append_accessor(msg, UPB_SIZE(24, 48), UPB_SIZE(8, 16), UPB_TYPE_STRING, &val,
+  return _upb_array_append_accessor2(msg, UPB_SIZE(24, 48), UPB_SIZE(3, 4), &val,
       arena);
 }
 
@@ -2330,12 +2444,12 @@
   return (google_protobuf_MethodDescriptorProto**)_upb_array_mutable_accessor(msg, UPB_SIZE(16, 32), len);
 }
 UPB_INLINE google_protobuf_MethodDescriptorProto** google_protobuf_ServiceDescriptorProto_resize_method(google_protobuf_ServiceDescriptorProto *msg, size_t len, upb_arena *arena) {
-  return (google_protobuf_MethodDescriptorProto**)_upb_array_resize_accessor(msg, UPB_SIZE(16, 32), len, UPB_TYPE_MESSAGE, arena);
+  return (google_protobuf_MethodDescriptorProto**)_upb_array_resize_accessor2(msg, UPB_SIZE(16, 32), len, UPB_SIZE(2, 3), arena);
 }
 UPB_INLINE struct google_protobuf_MethodDescriptorProto* google_protobuf_ServiceDescriptorProto_add_method(google_protobuf_ServiceDescriptorProto *msg, upb_arena *arena) {
   struct google_protobuf_MethodDescriptorProto* sub = (struct google_protobuf_MethodDescriptorProto*)_upb_msg_new(&google_protobuf_MethodDescriptorProto_msginit, arena);
-  bool ok = _upb_array_append_accessor(
-      msg, UPB_SIZE(16, 32), UPB_SIZE(4, 8), UPB_TYPE_MESSAGE, &sub, arena);
+  bool ok = _upb_array_append_accessor2(
+      msg, UPB_SIZE(16, 32), UPB_SIZE(2, 3), &sub, arena);
   if (!ok) return NULL;
   return sub;
 }
@@ -2429,138 +2543,138 @@
 }
 
 UPB_INLINE bool google_protobuf_FileOptions_has_java_package(const google_protobuf_FileOptions *msg) { return _upb_hasbit(msg, 11); }
-UPB_INLINE upb_strview google_protobuf_FileOptions_java_package(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(28, 32), upb_strview); }
+UPB_INLINE upb_strview google_protobuf_FileOptions_java_package(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(20, 24), upb_strview); }
 UPB_INLINE bool google_protobuf_FileOptions_has_java_outer_classname(const google_protobuf_FileOptions *msg) { return _upb_hasbit(msg, 12); }
-UPB_INLINE upb_strview google_protobuf_FileOptions_java_outer_classname(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(36, 48), upb_strview); }
+UPB_INLINE upb_strview google_protobuf_FileOptions_java_outer_classname(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(28, 40), upb_strview); }
 UPB_INLINE bool google_protobuf_FileOptions_has_optimize_for(const google_protobuf_FileOptions *msg) { return _upb_hasbit(msg, 1); }
-UPB_INLINE int32_t google_protobuf_FileOptions_optimize_for(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(8, 8), int32_t); }
+UPB_INLINE int32_t google_protobuf_FileOptions_optimize_for(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(4, 4), int32_t); }
 UPB_INLINE bool google_protobuf_FileOptions_has_java_multiple_files(const google_protobuf_FileOptions *msg) { return _upb_hasbit(msg, 2); }
-UPB_INLINE bool google_protobuf_FileOptions_java_multiple_files(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(16, 16), bool); }
+UPB_INLINE bool google_protobuf_FileOptions_java_multiple_files(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(8, 8), bool); }
 UPB_INLINE bool google_protobuf_FileOptions_has_go_package(const google_protobuf_FileOptions *msg) { return _upb_hasbit(msg, 13); }
-UPB_INLINE upb_strview google_protobuf_FileOptions_go_package(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(44, 64), upb_strview); }
+UPB_INLINE upb_strview google_protobuf_FileOptions_go_package(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(36, 56), upb_strview); }
 UPB_INLINE bool google_protobuf_FileOptions_has_cc_generic_services(const google_protobuf_FileOptions *msg) { return _upb_hasbit(msg, 3); }
-UPB_INLINE bool google_protobuf_FileOptions_cc_generic_services(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(17, 17), bool); }
+UPB_INLINE bool google_protobuf_FileOptions_cc_generic_services(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(9, 9), bool); }
 UPB_INLINE bool google_protobuf_FileOptions_has_java_generic_services(const google_protobuf_FileOptions *msg) { return _upb_hasbit(msg, 4); }
-UPB_INLINE bool google_protobuf_FileOptions_java_generic_services(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(18, 18), bool); }
+UPB_INLINE bool google_protobuf_FileOptions_java_generic_services(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(10, 10), bool); }
 UPB_INLINE bool google_protobuf_FileOptions_has_py_generic_services(const google_protobuf_FileOptions *msg) { return _upb_hasbit(msg, 5); }
-UPB_INLINE bool google_protobuf_FileOptions_py_generic_services(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(19, 19), bool); }
+UPB_INLINE bool google_protobuf_FileOptions_py_generic_services(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(11, 11), bool); }
 UPB_INLINE bool google_protobuf_FileOptions_has_java_generate_equals_and_hash(const google_protobuf_FileOptions *msg) { return _upb_hasbit(msg, 6); }
-UPB_INLINE bool google_protobuf_FileOptions_java_generate_equals_and_hash(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(20, 20), bool); }
+UPB_INLINE bool google_protobuf_FileOptions_java_generate_equals_and_hash(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(12, 12), bool); }
 UPB_INLINE bool google_protobuf_FileOptions_has_deprecated(const google_protobuf_FileOptions *msg) { return _upb_hasbit(msg, 7); }
-UPB_INLINE bool google_protobuf_FileOptions_deprecated(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(21, 21), bool); }
+UPB_INLINE bool google_protobuf_FileOptions_deprecated(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(13, 13), bool); }
 UPB_INLINE bool google_protobuf_FileOptions_has_java_string_check_utf8(const google_protobuf_FileOptions *msg) { return _upb_hasbit(msg, 8); }
-UPB_INLINE bool google_protobuf_FileOptions_java_string_check_utf8(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(22, 22), bool); }
+UPB_INLINE bool google_protobuf_FileOptions_java_string_check_utf8(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(14, 14), bool); }
 UPB_INLINE bool google_protobuf_FileOptions_has_cc_enable_arenas(const google_protobuf_FileOptions *msg) { return _upb_hasbit(msg, 9); }
-UPB_INLINE bool google_protobuf_FileOptions_cc_enable_arenas(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(23, 23), bool); }
+UPB_INLINE bool google_protobuf_FileOptions_cc_enable_arenas(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(15, 15), bool); }
 UPB_INLINE bool google_protobuf_FileOptions_has_objc_class_prefix(const google_protobuf_FileOptions *msg) { return _upb_hasbit(msg, 14); }
-UPB_INLINE upb_strview google_protobuf_FileOptions_objc_class_prefix(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(52, 80), upb_strview); }
+UPB_INLINE upb_strview google_protobuf_FileOptions_objc_class_prefix(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(44, 72), upb_strview); }
 UPB_INLINE bool google_protobuf_FileOptions_has_csharp_namespace(const google_protobuf_FileOptions *msg) { return _upb_hasbit(msg, 15); }
-UPB_INLINE upb_strview google_protobuf_FileOptions_csharp_namespace(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(60, 96), upb_strview); }
+UPB_INLINE upb_strview google_protobuf_FileOptions_csharp_namespace(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(52, 88), upb_strview); }
 UPB_INLINE bool google_protobuf_FileOptions_has_swift_prefix(const google_protobuf_FileOptions *msg) { return _upb_hasbit(msg, 16); }
-UPB_INLINE upb_strview google_protobuf_FileOptions_swift_prefix(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(68, 112), upb_strview); }
+UPB_INLINE upb_strview google_protobuf_FileOptions_swift_prefix(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(60, 104), upb_strview); }
 UPB_INLINE bool google_protobuf_FileOptions_has_php_class_prefix(const google_protobuf_FileOptions *msg) { return _upb_hasbit(msg, 17); }
-UPB_INLINE upb_strview google_protobuf_FileOptions_php_class_prefix(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(76, 128), upb_strview); }
+UPB_INLINE upb_strview google_protobuf_FileOptions_php_class_prefix(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(68, 120), upb_strview); }
 UPB_INLINE bool google_protobuf_FileOptions_has_php_namespace(const google_protobuf_FileOptions *msg) { return _upb_hasbit(msg, 18); }
-UPB_INLINE upb_strview google_protobuf_FileOptions_php_namespace(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(84, 144), upb_strview); }
+UPB_INLINE upb_strview google_protobuf_FileOptions_php_namespace(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(76, 136), upb_strview); }
 UPB_INLINE bool google_protobuf_FileOptions_has_php_generic_services(const google_protobuf_FileOptions *msg) { return _upb_hasbit(msg, 10); }
-UPB_INLINE bool google_protobuf_FileOptions_php_generic_services(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(24, 24), bool); }
+UPB_INLINE bool google_protobuf_FileOptions_php_generic_services(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(16, 16), bool); }
 UPB_INLINE bool google_protobuf_FileOptions_has_php_metadata_namespace(const google_protobuf_FileOptions *msg) { return _upb_hasbit(msg, 19); }
-UPB_INLINE upb_strview google_protobuf_FileOptions_php_metadata_namespace(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(92, 160), upb_strview); }
+UPB_INLINE upb_strview google_protobuf_FileOptions_php_metadata_namespace(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(84, 152), upb_strview); }
 UPB_INLINE bool google_protobuf_FileOptions_has_ruby_package(const google_protobuf_FileOptions *msg) { return _upb_hasbit(msg, 20); }
-UPB_INLINE upb_strview google_protobuf_FileOptions_ruby_package(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(100, 176), upb_strview); }
-UPB_INLINE bool google_protobuf_FileOptions_has_uninterpreted_option(const google_protobuf_FileOptions *msg) { return _upb_has_submsg_nohasbit(msg, UPB_SIZE(108, 192)); }
-UPB_INLINE const google_protobuf_UninterpretedOption* const* google_protobuf_FileOptions_uninterpreted_option(const google_protobuf_FileOptions *msg, size_t *len) { return (const google_protobuf_UninterpretedOption* const*)_upb_array_accessor(msg, UPB_SIZE(108, 192), len); }
+UPB_INLINE upb_strview google_protobuf_FileOptions_ruby_package(const google_protobuf_FileOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(92, 168), upb_strview); }
+UPB_INLINE bool google_protobuf_FileOptions_has_uninterpreted_option(const google_protobuf_FileOptions *msg) { return _upb_has_submsg_nohasbit(msg, UPB_SIZE(100, 184)); }
+UPB_INLINE const google_protobuf_UninterpretedOption* const* google_protobuf_FileOptions_uninterpreted_option(const google_protobuf_FileOptions *msg, size_t *len) { return (const google_protobuf_UninterpretedOption* const*)_upb_array_accessor(msg, UPB_SIZE(100, 184), len); }
 
 UPB_INLINE void google_protobuf_FileOptions_set_java_package(google_protobuf_FileOptions *msg, upb_strview value) {
   _upb_sethas(msg, 11);
-  *UPB_PTR_AT(msg, UPB_SIZE(28, 32), upb_strview) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(20, 24), upb_strview) = value;
 }
 UPB_INLINE void google_protobuf_FileOptions_set_java_outer_classname(google_protobuf_FileOptions *msg, upb_strview value) {
   _upb_sethas(msg, 12);
-  *UPB_PTR_AT(msg, UPB_SIZE(36, 48), upb_strview) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(28, 40), upb_strview) = value;
 }
 UPB_INLINE void google_protobuf_FileOptions_set_optimize_for(google_protobuf_FileOptions *msg, int32_t value) {
   _upb_sethas(msg, 1);
-  *UPB_PTR_AT(msg, UPB_SIZE(8, 8), int32_t) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(4, 4), int32_t) = value;
 }
 UPB_INLINE void google_protobuf_FileOptions_set_java_multiple_files(google_protobuf_FileOptions *msg, bool value) {
   _upb_sethas(msg, 2);
-  *UPB_PTR_AT(msg, UPB_SIZE(16, 16), bool) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(8, 8), bool) = value;
 }
 UPB_INLINE void google_protobuf_FileOptions_set_go_package(google_protobuf_FileOptions *msg, upb_strview value) {
   _upb_sethas(msg, 13);
-  *UPB_PTR_AT(msg, UPB_SIZE(44, 64), upb_strview) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(36, 56), upb_strview) = value;
 }
 UPB_INLINE void google_protobuf_FileOptions_set_cc_generic_services(google_protobuf_FileOptions *msg, bool value) {
   _upb_sethas(msg, 3);
-  *UPB_PTR_AT(msg, UPB_SIZE(17, 17), bool) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(9, 9), bool) = value;
 }
 UPB_INLINE void google_protobuf_FileOptions_set_java_generic_services(google_protobuf_FileOptions *msg, bool value) {
   _upb_sethas(msg, 4);
-  *UPB_PTR_AT(msg, UPB_SIZE(18, 18), bool) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(10, 10), bool) = value;
 }
 UPB_INLINE void google_protobuf_FileOptions_set_py_generic_services(google_protobuf_FileOptions *msg, bool value) {
   _upb_sethas(msg, 5);
-  *UPB_PTR_AT(msg, UPB_SIZE(19, 19), bool) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(11, 11), bool) = value;
 }
 UPB_INLINE void google_protobuf_FileOptions_set_java_generate_equals_and_hash(google_protobuf_FileOptions *msg, bool value) {
   _upb_sethas(msg, 6);
-  *UPB_PTR_AT(msg, UPB_SIZE(20, 20), bool) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(12, 12), bool) = value;
 }
 UPB_INLINE void google_protobuf_FileOptions_set_deprecated(google_protobuf_FileOptions *msg, bool value) {
   _upb_sethas(msg, 7);
-  *UPB_PTR_AT(msg, UPB_SIZE(21, 21), bool) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(13, 13), bool) = value;
 }
 UPB_INLINE void google_protobuf_FileOptions_set_java_string_check_utf8(google_protobuf_FileOptions *msg, bool value) {
   _upb_sethas(msg, 8);
-  *UPB_PTR_AT(msg, UPB_SIZE(22, 22), bool) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(14, 14), bool) = value;
 }
 UPB_INLINE void google_protobuf_FileOptions_set_cc_enable_arenas(google_protobuf_FileOptions *msg, bool value) {
   _upb_sethas(msg, 9);
-  *UPB_PTR_AT(msg, UPB_SIZE(23, 23), bool) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(15, 15), bool) = value;
 }
 UPB_INLINE void google_protobuf_FileOptions_set_objc_class_prefix(google_protobuf_FileOptions *msg, upb_strview value) {
   _upb_sethas(msg, 14);
-  *UPB_PTR_AT(msg, UPB_SIZE(52, 80), upb_strview) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(44, 72), upb_strview) = value;
 }
 UPB_INLINE void google_protobuf_FileOptions_set_csharp_namespace(google_protobuf_FileOptions *msg, upb_strview value) {
   _upb_sethas(msg, 15);
-  *UPB_PTR_AT(msg, UPB_SIZE(60, 96), upb_strview) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(52, 88), upb_strview) = value;
 }
 UPB_INLINE void google_protobuf_FileOptions_set_swift_prefix(google_protobuf_FileOptions *msg, upb_strview value) {
   _upb_sethas(msg, 16);
-  *UPB_PTR_AT(msg, UPB_SIZE(68, 112), upb_strview) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(60, 104), upb_strview) = value;
 }
 UPB_INLINE void google_protobuf_FileOptions_set_php_class_prefix(google_protobuf_FileOptions *msg, upb_strview value) {
   _upb_sethas(msg, 17);
-  *UPB_PTR_AT(msg, UPB_SIZE(76, 128), upb_strview) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(68, 120), upb_strview) = value;
 }
 UPB_INLINE void google_protobuf_FileOptions_set_php_namespace(google_protobuf_FileOptions *msg, upb_strview value) {
   _upb_sethas(msg, 18);
-  *UPB_PTR_AT(msg, UPB_SIZE(84, 144), upb_strview) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(76, 136), upb_strview) = value;
 }
 UPB_INLINE void google_protobuf_FileOptions_set_php_generic_services(google_protobuf_FileOptions *msg, bool value) {
   _upb_sethas(msg, 10);
-  *UPB_PTR_AT(msg, UPB_SIZE(24, 24), bool) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(16, 16), bool) = value;
 }
 UPB_INLINE void google_protobuf_FileOptions_set_php_metadata_namespace(google_protobuf_FileOptions *msg, upb_strview value) {
   _upb_sethas(msg, 19);
-  *UPB_PTR_AT(msg, UPB_SIZE(92, 160), upb_strview) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(84, 152), upb_strview) = value;
 }
 UPB_INLINE void google_protobuf_FileOptions_set_ruby_package(google_protobuf_FileOptions *msg, upb_strview value) {
   _upb_sethas(msg, 20);
-  *UPB_PTR_AT(msg, UPB_SIZE(100, 176), upb_strview) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(92, 168), upb_strview) = value;
 }
 UPB_INLINE google_protobuf_UninterpretedOption** google_protobuf_FileOptions_mutable_uninterpreted_option(google_protobuf_FileOptions *msg, size_t *len) {
-  return (google_protobuf_UninterpretedOption**)_upb_array_mutable_accessor(msg, UPB_SIZE(108, 192), len);
+  return (google_protobuf_UninterpretedOption**)_upb_array_mutable_accessor(msg, UPB_SIZE(100, 184), len);
 }
 UPB_INLINE google_protobuf_UninterpretedOption** google_protobuf_FileOptions_resize_uninterpreted_option(google_protobuf_FileOptions *msg, size_t len, upb_arena *arena) {
-  return (google_protobuf_UninterpretedOption**)_upb_array_resize_accessor(msg, UPB_SIZE(108, 192), len, UPB_TYPE_MESSAGE, arena);
+  return (google_protobuf_UninterpretedOption**)_upb_array_resize_accessor2(msg, UPB_SIZE(100, 184), len, UPB_SIZE(2, 3), arena);
 }
 UPB_INLINE struct google_protobuf_UninterpretedOption* google_protobuf_FileOptions_add_uninterpreted_option(google_protobuf_FileOptions *msg, upb_arena *arena) {
   struct google_protobuf_UninterpretedOption* sub = (struct google_protobuf_UninterpretedOption*)_upb_msg_new(&google_protobuf_UninterpretedOption_msginit, arena);
-  bool ok = _upb_array_append_accessor(
-      msg, UPB_SIZE(108, 192), UPB_SIZE(4, 8), UPB_TYPE_MESSAGE, &sub, arena);
+  bool ok = _upb_array_append_accessor2(
+      msg, UPB_SIZE(100, 184), UPB_SIZE(2, 3), &sub, arena);
   if (!ok) return NULL;
   return sub;
 }
@@ -2610,12 +2724,12 @@
   return (google_protobuf_UninterpretedOption**)_upb_array_mutable_accessor(msg, UPB_SIZE(8, 8), len);
 }
 UPB_INLINE google_protobuf_UninterpretedOption** google_protobuf_MessageOptions_resize_uninterpreted_option(google_protobuf_MessageOptions *msg, size_t len, upb_arena *arena) {
-  return (google_protobuf_UninterpretedOption**)_upb_array_resize_accessor(msg, UPB_SIZE(8, 8), len, UPB_TYPE_MESSAGE, arena);
+  return (google_protobuf_UninterpretedOption**)_upb_array_resize_accessor2(msg, UPB_SIZE(8, 8), len, UPB_SIZE(2, 3), arena);
 }
 UPB_INLINE struct google_protobuf_UninterpretedOption* google_protobuf_MessageOptions_add_uninterpreted_option(google_protobuf_MessageOptions *msg, upb_arena *arena) {
   struct google_protobuf_UninterpretedOption* sub = (struct google_protobuf_UninterpretedOption*)_upb_msg_new(&google_protobuf_UninterpretedOption_msginit, arena);
-  bool ok = _upb_array_append_accessor(
-      msg, UPB_SIZE(8, 8), UPB_SIZE(4, 8), UPB_TYPE_MESSAGE, &sub, arena);
+  bool ok = _upb_array_append_accessor2(
+      msg, UPB_SIZE(8, 8), UPB_SIZE(2, 3), &sub, arena);
   if (!ok) return NULL;
   return sub;
 }
@@ -2635,54 +2749,54 @@
 }
 
 UPB_INLINE bool google_protobuf_FieldOptions_has_ctype(const google_protobuf_FieldOptions *msg) { return _upb_hasbit(msg, 1); }
-UPB_INLINE int32_t google_protobuf_FieldOptions_ctype(const google_protobuf_FieldOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(8, 8), int32_t); }
+UPB_INLINE int32_t google_protobuf_FieldOptions_ctype(const google_protobuf_FieldOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(4, 4), int32_t); }
 UPB_INLINE bool google_protobuf_FieldOptions_has_packed(const google_protobuf_FieldOptions *msg) { return _upb_hasbit(msg, 3); }
-UPB_INLINE bool google_protobuf_FieldOptions_packed(const google_protobuf_FieldOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(24, 24), bool); }
+UPB_INLINE bool google_protobuf_FieldOptions_packed(const google_protobuf_FieldOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(12, 12), bool); }
 UPB_INLINE bool google_protobuf_FieldOptions_has_deprecated(const google_protobuf_FieldOptions *msg) { return _upb_hasbit(msg, 4); }
-UPB_INLINE bool google_protobuf_FieldOptions_deprecated(const google_protobuf_FieldOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(25, 25), bool); }
+UPB_INLINE bool google_protobuf_FieldOptions_deprecated(const google_protobuf_FieldOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(13, 13), bool); }
 UPB_INLINE bool google_protobuf_FieldOptions_has_lazy(const google_protobuf_FieldOptions *msg) { return _upb_hasbit(msg, 5); }
-UPB_INLINE bool google_protobuf_FieldOptions_lazy(const google_protobuf_FieldOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(26, 26), bool); }
+UPB_INLINE bool google_protobuf_FieldOptions_lazy(const google_protobuf_FieldOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(14, 14), bool); }
 UPB_INLINE bool google_protobuf_FieldOptions_has_jstype(const google_protobuf_FieldOptions *msg) { return _upb_hasbit(msg, 2); }
-UPB_INLINE int32_t google_protobuf_FieldOptions_jstype(const google_protobuf_FieldOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(16, 16), int32_t); }
+UPB_INLINE int32_t google_protobuf_FieldOptions_jstype(const google_protobuf_FieldOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(8, 8), int32_t); }
 UPB_INLINE bool google_protobuf_FieldOptions_has_weak(const google_protobuf_FieldOptions *msg) { return _upb_hasbit(msg, 6); }
-UPB_INLINE bool google_protobuf_FieldOptions_weak(const google_protobuf_FieldOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(27, 27), bool); }
-UPB_INLINE bool google_protobuf_FieldOptions_has_uninterpreted_option(const google_protobuf_FieldOptions *msg) { return _upb_has_submsg_nohasbit(msg, UPB_SIZE(28, 32)); }
-UPB_INLINE const google_protobuf_UninterpretedOption* const* google_protobuf_FieldOptions_uninterpreted_option(const google_protobuf_FieldOptions *msg, size_t *len) { return (const google_protobuf_UninterpretedOption* const*)_upb_array_accessor(msg, UPB_SIZE(28, 32), len); }
+UPB_INLINE bool google_protobuf_FieldOptions_weak(const google_protobuf_FieldOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(15, 15), bool); }
+UPB_INLINE bool google_protobuf_FieldOptions_has_uninterpreted_option(const google_protobuf_FieldOptions *msg) { return _upb_has_submsg_nohasbit(msg, UPB_SIZE(16, 16)); }
+UPB_INLINE const google_protobuf_UninterpretedOption* const* google_protobuf_FieldOptions_uninterpreted_option(const google_protobuf_FieldOptions *msg, size_t *len) { return (const google_protobuf_UninterpretedOption* const*)_upb_array_accessor(msg, UPB_SIZE(16, 16), len); }
 
 UPB_INLINE void google_protobuf_FieldOptions_set_ctype(google_protobuf_FieldOptions *msg, int32_t value) {
   _upb_sethas(msg, 1);
-  *UPB_PTR_AT(msg, UPB_SIZE(8, 8), int32_t) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(4, 4), int32_t) = value;
 }
 UPB_INLINE void google_protobuf_FieldOptions_set_packed(google_protobuf_FieldOptions *msg, bool value) {
   _upb_sethas(msg, 3);
-  *UPB_PTR_AT(msg, UPB_SIZE(24, 24), bool) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(12, 12), bool) = value;
 }
 UPB_INLINE void google_protobuf_FieldOptions_set_deprecated(google_protobuf_FieldOptions *msg, bool value) {
   _upb_sethas(msg, 4);
-  *UPB_PTR_AT(msg, UPB_SIZE(25, 25), bool) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(13, 13), bool) = value;
 }
 UPB_INLINE void google_protobuf_FieldOptions_set_lazy(google_protobuf_FieldOptions *msg, bool value) {
   _upb_sethas(msg, 5);
-  *UPB_PTR_AT(msg, UPB_SIZE(26, 26), bool) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(14, 14), bool) = value;
 }
 UPB_INLINE void google_protobuf_FieldOptions_set_jstype(google_protobuf_FieldOptions *msg, int32_t value) {
   _upb_sethas(msg, 2);
-  *UPB_PTR_AT(msg, UPB_SIZE(16, 16), int32_t) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(8, 8), int32_t) = value;
 }
 UPB_INLINE void google_protobuf_FieldOptions_set_weak(google_protobuf_FieldOptions *msg, bool value) {
   _upb_sethas(msg, 6);
-  *UPB_PTR_AT(msg, UPB_SIZE(27, 27), bool) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(15, 15), bool) = value;
 }
 UPB_INLINE google_protobuf_UninterpretedOption** google_protobuf_FieldOptions_mutable_uninterpreted_option(google_protobuf_FieldOptions *msg, size_t *len) {
-  return (google_protobuf_UninterpretedOption**)_upb_array_mutable_accessor(msg, UPB_SIZE(28, 32), len);
+  return (google_protobuf_UninterpretedOption**)_upb_array_mutable_accessor(msg, UPB_SIZE(16, 16), len);
 }
 UPB_INLINE google_protobuf_UninterpretedOption** google_protobuf_FieldOptions_resize_uninterpreted_option(google_protobuf_FieldOptions *msg, size_t len, upb_arena *arena) {
-  return (google_protobuf_UninterpretedOption**)_upb_array_resize_accessor(msg, UPB_SIZE(28, 32), len, UPB_TYPE_MESSAGE, arena);
+  return (google_protobuf_UninterpretedOption**)_upb_array_resize_accessor2(msg, UPB_SIZE(16, 16), len, UPB_SIZE(2, 3), arena);
 }
 UPB_INLINE struct google_protobuf_UninterpretedOption* google_protobuf_FieldOptions_add_uninterpreted_option(google_protobuf_FieldOptions *msg, upb_arena *arena) {
   struct google_protobuf_UninterpretedOption* sub = (struct google_protobuf_UninterpretedOption*)_upb_msg_new(&google_protobuf_UninterpretedOption_msginit, arena);
-  bool ok = _upb_array_append_accessor(
-      msg, UPB_SIZE(28, 32), UPB_SIZE(4, 8), UPB_TYPE_MESSAGE, &sub, arena);
+  bool ok = _upb_array_append_accessor2(
+      msg, UPB_SIZE(16, 16), UPB_SIZE(2, 3), &sub, arena);
   if (!ok) return NULL;
   return sub;
 }
@@ -2708,12 +2822,12 @@
   return (google_protobuf_UninterpretedOption**)_upb_array_mutable_accessor(msg, UPB_SIZE(0, 0), len);
 }
 UPB_INLINE google_protobuf_UninterpretedOption** google_protobuf_OneofOptions_resize_uninterpreted_option(google_protobuf_OneofOptions *msg, size_t len, upb_arena *arena) {
-  return (google_protobuf_UninterpretedOption**)_upb_array_resize_accessor(msg, UPB_SIZE(0, 0), len, UPB_TYPE_MESSAGE, arena);
+  return (google_protobuf_UninterpretedOption**)_upb_array_resize_accessor2(msg, UPB_SIZE(0, 0), len, UPB_SIZE(2, 3), arena);
 }
 UPB_INLINE struct google_protobuf_UninterpretedOption* google_protobuf_OneofOptions_add_uninterpreted_option(google_protobuf_OneofOptions *msg, upb_arena *arena) {
   struct google_protobuf_UninterpretedOption* sub = (struct google_protobuf_UninterpretedOption*)_upb_msg_new(&google_protobuf_UninterpretedOption_msginit, arena);
-  bool ok = _upb_array_append_accessor(
-      msg, UPB_SIZE(0, 0), UPB_SIZE(4, 8), UPB_TYPE_MESSAGE, &sub, arena);
+  bool ok = _upb_array_append_accessor2(
+      msg, UPB_SIZE(0, 0), UPB_SIZE(2, 3), &sub, arena);
   if (!ok) return NULL;
   return sub;
 }
@@ -2751,12 +2865,12 @@
   return (google_protobuf_UninterpretedOption**)_upb_array_mutable_accessor(msg, UPB_SIZE(4, 8), len);
 }
 UPB_INLINE google_protobuf_UninterpretedOption** google_protobuf_EnumOptions_resize_uninterpreted_option(google_protobuf_EnumOptions *msg, size_t len, upb_arena *arena) {
-  return (google_protobuf_UninterpretedOption**)_upb_array_resize_accessor(msg, UPB_SIZE(4, 8), len, UPB_TYPE_MESSAGE, arena);
+  return (google_protobuf_UninterpretedOption**)_upb_array_resize_accessor2(msg, UPB_SIZE(4, 8), len, UPB_SIZE(2, 3), arena);
 }
 UPB_INLINE struct google_protobuf_UninterpretedOption* google_protobuf_EnumOptions_add_uninterpreted_option(google_protobuf_EnumOptions *msg, upb_arena *arena) {
   struct google_protobuf_UninterpretedOption* sub = (struct google_protobuf_UninterpretedOption*)_upb_msg_new(&google_protobuf_UninterpretedOption_msginit, arena);
-  bool ok = _upb_array_append_accessor(
-      msg, UPB_SIZE(4, 8), UPB_SIZE(4, 8), UPB_TYPE_MESSAGE, &sub, arena);
+  bool ok = _upb_array_append_accessor2(
+      msg, UPB_SIZE(4, 8), UPB_SIZE(2, 3), &sub, arena);
   if (!ok) return NULL;
   return sub;
 }
@@ -2788,12 +2902,12 @@
   return (google_protobuf_UninterpretedOption**)_upb_array_mutable_accessor(msg, UPB_SIZE(4, 8), len);
 }
 UPB_INLINE google_protobuf_UninterpretedOption** google_protobuf_EnumValueOptions_resize_uninterpreted_option(google_protobuf_EnumValueOptions *msg, size_t len, upb_arena *arena) {
-  return (google_protobuf_UninterpretedOption**)_upb_array_resize_accessor(msg, UPB_SIZE(4, 8), len, UPB_TYPE_MESSAGE, arena);
+  return (google_protobuf_UninterpretedOption**)_upb_array_resize_accessor2(msg, UPB_SIZE(4, 8), len, UPB_SIZE(2, 3), arena);
 }
 UPB_INLINE struct google_protobuf_UninterpretedOption* google_protobuf_EnumValueOptions_add_uninterpreted_option(google_protobuf_EnumValueOptions *msg, upb_arena *arena) {
   struct google_protobuf_UninterpretedOption* sub = (struct google_protobuf_UninterpretedOption*)_upb_msg_new(&google_protobuf_UninterpretedOption_msginit, arena);
-  bool ok = _upb_array_append_accessor(
-      msg, UPB_SIZE(4, 8), UPB_SIZE(4, 8), UPB_TYPE_MESSAGE, &sub, arena);
+  bool ok = _upb_array_append_accessor2(
+      msg, UPB_SIZE(4, 8), UPB_SIZE(2, 3), &sub, arena);
   if (!ok) return NULL;
   return sub;
 }
@@ -2825,12 +2939,12 @@
   return (google_protobuf_UninterpretedOption**)_upb_array_mutable_accessor(msg, UPB_SIZE(4, 8), len);
 }
 UPB_INLINE google_protobuf_UninterpretedOption** google_protobuf_ServiceOptions_resize_uninterpreted_option(google_protobuf_ServiceOptions *msg, size_t len, upb_arena *arena) {
-  return (google_protobuf_UninterpretedOption**)_upb_array_resize_accessor(msg, UPB_SIZE(4, 8), len, UPB_TYPE_MESSAGE, arena);
+  return (google_protobuf_UninterpretedOption**)_upb_array_resize_accessor2(msg, UPB_SIZE(4, 8), len, UPB_SIZE(2, 3), arena);
 }
 UPB_INLINE struct google_protobuf_UninterpretedOption* google_protobuf_ServiceOptions_add_uninterpreted_option(google_protobuf_ServiceOptions *msg, upb_arena *arena) {
   struct google_protobuf_UninterpretedOption* sub = (struct google_protobuf_UninterpretedOption*)_upb_msg_new(&google_protobuf_UninterpretedOption_msginit, arena);
-  bool ok = _upb_array_append_accessor(
-      msg, UPB_SIZE(4, 8), UPB_SIZE(4, 8), UPB_TYPE_MESSAGE, &sub, arena);
+  bool ok = _upb_array_append_accessor2(
+      msg, UPB_SIZE(4, 8), UPB_SIZE(2, 3), &sub, arena);
   if (!ok) return NULL;
   return sub;
 }
@@ -2850,30 +2964,30 @@
 }
 
 UPB_INLINE bool google_protobuf_MethodOptions_has_deprecated(const google_protobuf_MethodOptions *msg) { return _upb_hasbit(msg, 2); }
-UPB_INLINE bool google_protobuf_MethodOptions_deprecated(const google_protobuf_MethodOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(16, 16), bool); }
+UPB_INLINE bool google_protobuf_MethodOptions_deprecated(const google_protobuf_MethodOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(8, 8), bool); }
 UPB_INLINE bool google_protobuf_MethodOptions_has_idempotency_level(const google_protobuf_MethodOptions *msg) { return _upb_hasbit(msg, 1); }
-UPB_INLINE int32_t google_protobuf_MethodOptions_idempotency_level(const google_protobuf_MethodOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(8, 8), int32_t); }
-UPB_INLINE bool google_protobuf_MethodOptions_has_uninterpreted_option(const google_protobuf_MethodOptions *msg) { return _upb_has_submsg_nohasbit(msg, UPB_SIZE(20, 24)); }
-UPB_INLINE const google_protobuf_UninterpretedOption* const* google_protobuf_MethodOptions_uninterpreted_option(const google_protobuf_MethodOptions *msg, size_t *len) { return (const google_protobuf_UninterpretedOption* const*)_upb_array_accessor(msg, UPB_SIZE(20, 24), len); }
+UPB_INLINE int32_t google_protobuf_MethodOptions_idempotency_level(const google_protobuf_MethodOptions *msg) { return *UPB_PTR_AT(msg, UPB_SIZE(4, 4), int32_t); }
+UPB_INLINE bool google_protobuf_MethodOptions_has_uninterpreted_option(const google_protobuf_MethodOptions *msg) { return _upb_has_submsg_nohasbit(msg, UPB_SIZE(12, 16)); }
+UPB_INLINE const google_protobuf_UninterpretedOption* const* google_protobuf_MethodOptions_uninterpreted_option(const google_protobuf_MethodOptions *msg, size_t *len) { return (const google_protobuf_UninterpretedOption* const*)_upb_array_accessor(msg, UPB_SIZE(12, 16), len); }
 
 UPB_INLINE void google_protobuf_MethodOptions_set_deprecated(google_protobuf_MethodOptions *msg, bool value) {
   _upb_sethas(msg, 2);
-  *UPB_PTR_AT(msg, UPB_SIZE(16, 16), bool) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(8, 8), bool) = value;
 }
 UPB_INLINE void google_protobuf_MethodOptions_set_idempotency_level(google_protobuf_MethodOptions *msg, int32_t value) {
   _upb_sethas(msg, 1);
-  *UPB_PTR_AT(msg, UPB_SIZE(8, 8), int32_t) = value;
+  *UPB_PTR_AT(msg, UPB_SIZE(4, 4), int32_t) = value;
 }
 UPB_INLINE google_protobuf_UninterpretedOption** google_protobuf_MethodOptions_mutable_uninterpreted_option(google_protobuf_MethodOptions *msg, size_t *len) {
-  return (google_protobuf_UninterpretedOption**)_upb_array_mutable_accessor(msg, UPB_SIZE(20, 24), len);
+  return (google_protobuf_UninterpretedOption**)_upb_array_mutable_accessor(msg, UPB_SIZE(12, 16), len);
 }
 UPB_INLINE google_protobuf_UninterpretedOption** google_protobuf_MethodOptions_resize_uninterpreted_option(google_protobuf_MethodOptions *msg, size_t len, upb_arena *arena) {
-  return (google_protobuf_UninterpretedOption**)_upb_array_resize_accessor(msg, UPB_SIZE(20, 24), len, UPB_TYPE_MESSAGE, arena);
+  return (google_protobuf_UninterpretedOption**)_upb_array_resize_accessor2(msg, UPB_SIZE(12, 16), len, UPB_SIZE(2, 3), arena);
 }
 UPB_INLINE struct google_protobuf_UninterpretedOption* google_protobuf_MethodOptions_add_uninterpreted_option(google_protobuf_MethodOptions *msg, upb_arena *arena) {
   struct google_protobuf_UninterpretedOption* sub = (struct google_protobuf_UninterpretedOption*)_upb_msg_new(&google_protobuf_UninterpretedOption_msginit, arena);
-  bool ok = _upb_array_append_accessor(
-      msg, UPB_SIZE(20, 24), UPB_SIZE(4, 8), UPB_TYPE_MESSAGE, &sub, arena);
+  bool ok = _upb_array_append_accessor2(
+      msg, UPB_SIZE(12, 16), UPB_SIZE(2, 3), &sub, arena);
   if (!ok) return NULL;
   return sub;
 }
@@ -2911,12 +3025,12 @@
   return (google_protobuf_UninterpretedOption_NamePart**)_upb_array_mutable_accessor(msg, UPB_SIZE(56, 80), len);
 }
 UPB_INLINE google_protobuf_UninterpretedOption_NamePart** google_protobuf_UninterpretedOption_resize_name(google_protobuf_UninterpretedOption *msg, size_t len, upb_arena *arena) {
-  return (google_protobuf_UninterpretedOption_NamePart**)_upb_array_resize_accessor(msg, UPB_SIZE(56, 80), len, UPB_TYPE_MESSAGE, arena);
+  return (google_protobuf_UninterpretedOption_NamePart**)_upb_array_resize_accessor2(msg, UPB_SIZE(56, 80), len, UPB_SIZE(2, 3), arena);
 }
 UPB_INLINE struct google_protobuf_UninterpretedOption_NamePart* google_protobuf_UninterpretedOption_add_name(google_protobuf_UninterpretedOption *msg, upb_arena *arena) {
   struct google_protobuf_UninterpretedOption_NamePart* sub = (struct google_protobuf_UninterpretedOption_NamePart*)_upb_msg_new(&google_protobuf_UninterpretedOption_NamePart_msginit, arena);
-  bool ok = _upb_array_append_accessor(
-      msg, UPB_SIZE(56, 80), UPB_SIZE(4, 8), UPB_TYPE_MESSAGE, &sub, arena);
+  bool ok = _upb_array_append_accessor2(
+      msg, UPB_SIZE(56, 80), UPB_SIZE(2, 3), &sub, arena);
   if (!ok) return NULL;
   return sub;
 }
@@ -2994,12 +3108,12 @@
   return (google_protobuf_SourceCodeInfo_Location**)_upb_array_mutable_accessor(msg, UPB_SIZE(0, 0), len);
 }
 UPB_INLINE google_protobuf_SourceCodeInfo_Location** google_protobuf_SourceCodeInfo_resize_location(google_protobuf_SourceCodeInfo *msg, size_t len, upb_arena *arena) {
-  return (google_protobuf_SourceCodeInfo_Location**)_upb_array_resize_accessor(msg, UPB_SIZE(0, 0), len, UPB_TYPE_MESSAGE, arena);
+  return (google_protobuf_SourceCodeInfo_Location**)_upb_array_resize_accessor2(msg, UPB_SIZE(0, 0), len, UPB_SIZE(2, 3), arena);
 }
 UPB_INLINE struct google_protobuf_SourceCodeInfo_Location* google_protobuf_SourceCodeInfo_add_location(google_protobuf_SourceCodeInfo *msg, upb_arena *arena) {
   struct google_protobuf_SourceCodeInfo_Location* sub = (struct google_protobuf_SourceCodeInfo_Location*)_upb_msg_new(&google_protobuf_SourceCodeInfo_Location_msginit, arena);
-  bool ok = _upb_array_append_accessor(
-      msg, UPB_SIZE(0, 0), UPB_SIZE(4, 8), UPB_TYPE_MESSAGE, &sub, arena);
+  bool ok = _upb_array_append_accessor2(
+      msg, UPB_SIZE(0, 0), UPB_SIZE(2, 3), &sub, arena);
   if (!ok) return NULL;
   return sub;
 }
@@ -3030,20 +3144,20 @@
   return (int32_t*)_upb_array_mutable_accessor(msg, UPB_SIZE(20, 40), len);
 }
 UPB_INLINE int32_t* google_protobuf_SourceCodeInfo_Location_resize_path(google_protobuf_SourceCodeInfo_Location *msg, size_t len, upb_arena *arena) {
-  return (int32_t*)_upb_array_resize_accessor(msg, UPB_SIZE(20, 40), len, UPB_TYPE_INT32, arena);
+  return (int32_t*)_upb_array_resize_accessor2(msg, UPB_SIZE(20, 40), len, 2, arena);
 }
 UPB_INLINE bool google_protobuf_SourceCodeInfo_Location_add_path(google_protobuf_SourceCodeInfo_Location *msg, int32_t val, upb_arena *arena) {
-  return _upb_array_append_accessor(msg, UPB_SIZE(20, 40), UPB_SIZE(4, 4), UPB_TYPE_INT32, &val,
+  return _upb_array_append_accessor2(msg, UPB_SIZE(20, 40), 2, &val,
       arena);
 }
 UPB_INLINE int32_t* google_protobuf_SourceCodeInfo_Location_mutable_span(google_protobuf_SourceCodeInfo_Location *msg, size_t *len) {
   return (int32_t*)_upb_array_mutable_accessor(msg, UPB_SIZE(24, 48), len);
 }
 UPB_INLINE int32_t* google_protobuf_SourceCodeInfo_Location_resize_span(google_protobuf_SourceCodeInfo_Location *msg, size_t len, upb_arena *arena) {
-  return (int32_t*)_upb_array_resize_accessor(msg, UPB_SIZE(24, 48), len, UPB_TYPE_INT32, arena);
+  return (int32_t*)_upb_array_resize_accessor2(msg, UPB_SIZE(24, 48), len, 2, arena);
 }
 UPB_INLINE bool google_protobuf_SourceCodeInfo_Location_add_span(google_protobuf_SourceCodeInfo_Location *msg, int32_t val, upb_arena *arena) {
-  return _upb_array_append_accessor(msg, UPB_SIZE(24, 48), UPB_SIZE(4, 4), UPB_TYPE_INT32, &val,
+  return _upb_array_append_accessor2(msg, UPB_SIZE(24, 48), 2, &val,
       arena);
 }
 UPB_INLINE void google_protobuf_SourceCodeInfo_Location_set_leading_comments(google_protobuf_SourceCodeInfo_Location *msg, upb_strview value) {
@@ -3058,10 +3172,10 @@
   return (upb_strview*)_upb_array_mutable_accessor(msg, UPB_SIZE(28, 56), len);
 }
 UPB_INLINE upb_strview* google_protobuf_SourceCodeInfo_Location_resize_leading_detached_comments(google_protobuf_SourceCodeInfo_Location *msg, size_t len, upb_arena *arena) {
-  return (upb_strview*)_upb_array_resize_accessor(msg, UPB_SIZE(28, 56), len, UPB_TYPE_STRING, arena);
+  return (upb_strview*)_upb_array_resize_accessor2(msg, UPB_SIZE(28, 56), len, UPB_SIZE(3, 4), arena);
 }
 UPB_INLINE bool google_protobuf_SourceCodeInfo_Location_add_leading_detached_comments(google_protobuf_SourceCodeInfo_Location *msg, upb_strview val, upb_arena *arena) {
-  return _upb_array_append_accessor(msg, UPB_SIZE(28, 56), UPB_SIZE(8, 16), UPB_TYPE_STRING, &val,
+  return _upb_array_append_accessor2(msg, UPB_SIZE(28, 56), UPB_SIZE(3, 4), &val,
       arena);
 }
 
@@ -3086,12 +3200,12 @@
   return (google_protobuf_GeneratedCodeInfo_Annotation**)_upb_array_mutable_accessor(msg, UPB_SIZE(0, 0), len);
 }
 UPB_INLINE google_protobuf_GeneratedCodeInfo_Annotation** google_protobuf_GeneratedCodeInfo_resize_annotation(google_protobuf_GeneratedCodeInfo *msg, size_t len, upb_arena *arena) {
-  return (google_protobuf_GeneratedCodeInfo_Annotation**)_upb_array_resize_accessor(msg, UPB_SIZE(0, 0), len, UPB_TYPE_MESSAGE, arena);
+  return (google_protobuf_GeneratedCodeInfo_Annotation**)_upb_array_resize_accessor2(msg, UPB_SIZE(0, 0), len, UPB_SIZE(2, 3), arena);
 }
 UPB_INLINE struct google_protobuf_GeneratedCodeInfo_Annotation* google_protobuf_GeneratedCodeInfo_add_annotation(google_protobuf_GeneratedCodeInfo *msg, upb_arena *arena) {
   struct google_protobuf_GeneratedCodeInfo_Annotation* sub = (struct google_protobuf_GeneratedCodeInfo_Annotation*)_upb_msg_new(&google_protobuf_GeneratedCodeInfo_Annotation_msginit, arena);
-  bool ok = _upb_array_append_accessor(
-      msg, UPB_SIZE(0, 0), UPB_SIZE(4, 8), UPB_TYPE_MESSAGE, &sub, arena);
+  bool ok = _upb_array_append_accessor2(
+      msg, UPB_SIZE(0, 0), UPB_SIZE(2, 3), &sub, arena);
   if (!ok) return NULL;
   return sub;
 }
@@ -3122,10 +3236,10 @@
   return (int32_t*)_upb_array_mutable_accessor(msg, UPB_SIZE(20, 32), len);
 }
 UPB_INLINE int32_t* google_protobuf_GeneratedCodeInfo_Annotation_resize_path(google_protobuf_GeneratedCodeInfo_Annotation *msg, size_t len, upb_arena *arena) {
-  return (int32_t*)_upb_array_resize_accessor(msg, UPB_SIZE(20, 32), len, UPB_TYPE_INT32, arena);
+  return (int32_t*)_upb_array_resize_accessor2(msg, UPB_SIZE(20, 32), len, 2, arena);
 }
 UPB_INLINE bool google_protobuf_GeneratedCodeInfo_Annotation_add_path(google_protobuf_GeneratedCodeInfo_Annotation *msg, int32_t val, upb_arena *arena) {
-  return _upb_array_append_accessor(msg, UPB_SIZE(20, 32), UPB_SIZE(4, 4), UPB_TYPE_INT32, &val,
+  return _upb_array_append_accessor2(msg, UPB_SIZE(20, 32), 2, &val,
       arena);
 }
 UPB_INLINE void google_protobuf_GeneratedCodeInfo_Annotation_set_source_file(google_protobuf_GeneratedCodeInfo_Annotation *msg, upb_strview value) {
@@ -3262,9 +3376,10 @@
 
 const char *upb_oneofdef_name(const upb_oneofdef *o);
 const upb_msgdef *upb_oneofdef_containingtype(const upb_oneofdef *o);
-int upb_oneofdef_numfields(const upb_oneofdef *o);
 uint32_t upb_oneofdef_index(const upb_oneofdef *o);
 bool upb_oneofdef_issynthetic(const upb_oneofdef *o);
+int upb_oneofdef_fieldcount(const upb_oneofdef *o);
+const upb_fielddef *upb_oneofdef_field(const upb_oneofdef *o, int i);
 
 /* Oneof lookups:
  * - ntof:  look up a field by name.
@@ -3278,11 +3393,8 @@
 }
 const upb_fielddef *upb_oneofdef_itof(const upb_oneofdef *o, uint32_t num);
 
-/*  upb_oneof_iter i;
- *  for(upb_oneof_begin(&i, e); !upb_oneof_done(&i); upb_oneof_next(&i)) {
- *    // ...
- *  }
- */
+/* DEPRECATED, slated for removal. */
+int upb_oneofdef_numfields(const upb_oneofdef *o);
 void upb_oneof_begin(upb_oneof_iter *iter, const upb_oneofdef *o);
 void upb_oneof_next(upb_oneof_iter *iter);
 bool upb_oneof_done(upb_oneof_iter *iter);
@@ -3290,6 +3402,7 @@
 void upb_oneof_iter_setdone(upb_oneof_iter *iter);
 bool upb_oneof_iter_isequal(const upb_oneof_iter *iter1,
                             const upb_oneof_iter *iter2);
+/* END DEPRECATED */
 
 /* upb_msgdef *****************************************************************/
 
@@ -3315,21 +3428,21 @@
 const char *upb_msgdef_fullname(const upb_msgdef *m);
 const upb_filedef *upb_msgdef_file(const upb_msgdef *m);
 const char *upb_msgdef_name(const upb_msgdef *m);
-int upb_msgdef_numfields(const upb_msgdef *m);
-int upb_msgdef_numoneofs(const upb_msgdef *m);
-int upb_msgdef_numrealoneofs(const upb_msgdef *m);
 upb_syntax_t upb_msgdef_syntax(const upb_msgdef *m);
 bool upb_msgdef_mapentry(const upb_msgdef *m);
 upb_wellknowntype_t upb_msgdef_wellknowntype(const upb_msgdef *m);
 bool upb_msgdef_iswrapper(const upb_msgdef *m);
 bool upb_msgdef_isnumberwrapper(const upb_msgdef *m);
+int upb_msgdef_fieldcount(const upb_msgdef *m);
+int upb_msgdef_oneofcount(const upb_msgdef *m);
+const upb_fielddef *upb_msgdef_field(const upb_msgdef *m, int i);
+const upb_oneofdef *upb_msgdef_oneof(const upb_msgdef *m, int i);
 const upb_fielddef *upb_msgdef_itof(const upb_msgdef *m, uint32_t i);
 const upb_fielddef *upb_msgdef_ntof(const upb_msgdef *m, const char *name,
                                     size_t len);
 const upb_oneofdef *upb_msgdef_ntoo(const upb_msgdef *m, const char *name,
                                     size_t len);
 const upb_msglayout *upb_msgdef_layout(const upb_msgdef *m);
-const upb_fielddef *_upb_msgdef_field(const upb_msgdef *m, int i);
 
 UPB_INLINE const upb_oneofdef *upb_msgdef_ntooz(const upb_msgdef *m,
                                                const char *name) {
@@ -3361,19 +3474,10 @@
 const upb_fielddef *upb_msgdef_lookupjsonname(const upb_msgdef *m,
                                               const char *name, size_t len);
 
-/* Iteration over fields and oneofs.  For example:
- *
- * upb_msg_field_iter i;
- * for(upb_msg_field_begin(&i, m);
- *     !upb_msg_field_done(&i);
- *     upb_msg_field_next(&i)) {
- *   upb_fielddef *f = upb_msg_iter_field(&i);
- *   // ...
- * }
- *
- * For C we don't have separate iterators for const and non-const.
- * It is the caller's responsibility to cast the upb_fielddef* to
- * const if the upb_msgdef* is const. */
+/* DEPRECATED, slated for removal */
+int upb_msgdef_numfields(const upb_msgdef *m);
+int upb_msgdef_numoneofs(const upb_msgdef *m);
+int upb_msgdef_numrealoneofs(const upb_msgdef *m);
 void upb_msg_field_begin(upb_msg_field_iter *iter, const upb_msgdef *m);
 void upb_msg_field_next(upb_msg_field_iter *iter);
 bool upb_msg_field_done(const upb_msg_field_iter *iter);
@@ -3381,9 +3485,6 @@
 void upb_msg_field_iter_setdone(upb_msg_field_iter *iter);
 bool upb_msg_field_iter_isequal(const upb_msg_field_iter * iter1,
                                 const upb_msg_field_iter * iter2);
-
-/* Similar to above, we also support iterating through the oneofs in a
- * msgdef. */
 void upb_msg_oneof_begin(upb_msg_oneof_iter * iter, const upb_msgdef *m);
 void upb_msg_oneof_next(upb_msg_oneof_iter * iter);
 bool upb_msg_oneof_done(const upb_msg_oneof_iter *iter);
@@ -3391,6 +3492,7 @@
 void upb_msg_oneof_iter_setdone(upb_msg_oneof_iter * iter);
 bool upb_msg_oneof_iter_isequal(const upb_msg_oneof_iter *iter1,
                                 const upb_msg_oneof_iter *iter2);
+/* END DEPRECATED */
 
 /* upb_enumdef ****************************************************************/
 
@@ -3415,11 +3517,6 @@
 }
 const char *upb_enumdef_iton(const upb_enumdef *e, int32_t num);
 
-/*  upb_enum_iter i;
- *  for(upb_enum_begin(&i, e); !upb_enum_done(&i); upb_enum_next(&i)) {
- *    // ...
- *  }
- */
 void upb_enum_begin(upb_enum_iter *iter, const upb_enumdef *e);
 void upb_enum_next(upb_enum_iter *iter);
 bool upb_enum_done(upb_enum_iter *iter);
@@ -3455,6 +3552,7 @@
 const upb_filedef *upb_symtab_addfile(
     upb_symtab *s, const google_protobuf_FileDescriptorProto *file,
     upb_status *status);
+size_t _upb_symtab_bytesloaded(const upb_symtab *s);
 
 /* For generated code only: loads a generated descriptor. */
 typedef struct upb_def_init {
@@ -3827,7 +3925,7 @@
 #endif
 
 enum {
-  /* When set, emits 0/default values.  TODO(haberman): proto3 only? */
+  /* When set, emits 0/default values.  TOOD(haberman): proto3 only? */
   UPB_JSONENC_EMITDEFAULTS = 1,
 
   /* When set, use normal (snake_caes) field names instead of JSON (camelCase)
@@ -3872,11 +3970,7 @@
 #undef UPB_UNUSED
 #undef UPB_ASSUME
 #undef UPB_ASSERT
-#undef UPB_ASSERT_DEBUGVAR
 #undef UPB_UNREACHABLE
-#undef UPB_INFINITY
-#undef UPB_NAN
-#undef UPB_MSVC_VSNPRINTF
-#undef _upb_snprintf
-#undef _upb_vsnprintf
-#undef _upb_va_copy
+#undef UPB_POISON_MEMORY_REGION
+#undef UPB_UNPOISON_MEMORY_REGION
+#undef UPB_ASAN
diff --git a/php/prepare_c_extension.sh b/php/prepare_c_extension.sh
new file mode 100755
index 0000000..84cd1aa
--- /dev/null
+++ b/php/prepare_c_extension.sh
@@ -0,0 +1,6 @@
+
+# wyhash has to live in the base third_party directory.
+# We copy it into the ext/google/protobuf directory for the build
+# (and for the release to PECL).
+mkdir -p ../ext/google/protobuf/third_party/wyhash
+cp ../../third_party/wyhash/* ../ext/google/protobuf/third_party/wyhash
diff --git a/php/tests/compile_extension.sh b/php/tests/compile_extension.sh
index 01ec79f..85c73c6 100755
--- a/php/tests/compile_extension.sh
+++ b/php/tests/compile_extension.sh
@@ -4,6 +4,7 @@
 
 cd $(dirname $0)
 
+../prepare_c_extension.sh
 pushd  ../ext/google/protobuf
 phpize --clean
 rm -f configure.in configure.ac
diff --git a/third_party/wyhash/LICENSE b/third_party/wyhash/LICENSE
new file mode 100644
index 0000000..471f09f
--- /dev/null
+++ b/third_party/wyhash/LICENSE
@@ -0,0 +1,25 @@
+This is free and unencumbered software released into the public domain.
+
+Anyone is free to copy, modify, publish, use, compile, sell, or
+distribute this software, either in source code form or as a compiled
+binary, for any purpose, commercial or non-commercial, and by any
+means.
+
+In jurisdictions that recognize copyright laws, the author or authors
+of this software dedicate any and all copyright interest in the
+software to the public domain. We make this dedication for the benefit
+of the public at large and to the detriment of our heirs and
+successors. We intend this dedication to be an overt act of
+relinquishment in perpetuity of all present and future rights to this
+software under copyright law.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+OTHER DEALINGS IN THE SOFTWARE.
+
+For more information, please refer to <http://unlicense.org/>
+
diff --git a/third_party/wyhash/wyhash.h b/third_party/wyhash/wyhash.h
new file mode 100644
index 0000000..1265169
--- /dev/null
+++ b/third_party/wyhash/wyhash.h
@@ -0,0 +1,142 @@
+//Author: Wang Yi <godspeed_china@yeah.net>
+#ifndef wyhash_final_version
+#define wyhash_final_version
+//defines that change behavior
+#ifndef WYHASH_CONDOM
+#define WYHASH_CONDOM 1 //0: read 8 bytes before and after boudaries, dangerous but fastest. 1: normal valid behavior 2: extra protection against entropy loss (probability=2^-63), aka. "blind multiplication"
+#endif
+#define WYHASH_32BIT_MUM 0	//faster on 32 bit system
+//includes
+#include <stdint.h>
+#include <string.h>
+#if defined(_MSC_VER) && defined(_M_X64)
+  #include <intrin.h>
+  #pragma intrinsic(_umul128)
+#endif
+#if defined(__GNUC__) || defined(__INTEL_COMPILER) || defined(__clang__)
+  #define _likely_(x)	__builtin_expect(x,1)
+  #define _unlikely_(x)	__builtin_expect(x,0)
+#else
+  #define _likely_(x) (x)
+  #define _unlikely_(x) (x)
+#endif
+//mum function
+static inline uint64_t _wyrot(uint64_t x) { return (x>>32)|(x<<32); }
+static inline void _wymum(uint64_t *A, uint64_t *B){
+#if(WYHASH_32BIT_MUM)
+  uint64_t hh=(*A>>32)*(*B>>32), hl=(*A>>32)*(unsigned)*B, lh=(unsigned)*A*(*B>>32), ll=(uint64_t)(unsigned)*A*(unsigned)*B;
+  #if(WYHASH_CONDOM>1)
+  *A^=_wyrot(hl)^hh; *B^=_wyrot(lh)^ll;
+  #else
+  *A=_wyrot(hl)^hh; *B=_wyrot(lh)^ll;
+  #endif
+#elif defined(__SIZEOF_INT128__)
+  __uint128_t r=*A; r*=*B; 
+  #if(WYHASH_CONDOM>1)
+  *A^=(uint64_t)r; *B^=(uint64_t)(r>>64);
+  #else
+  *A=(uint64_t)r; *B=(uint64_t)(r>>64);
+  #endif
+#elif defined(_MSC_VER) && defined(_M_X64)
+  #if(WYHASH_CONDOM>1)
+  uint64_t  a,  b;
+  a=_umul128(*A,*B,&b);
+  *A^=a;  *B^=b;
+  #else
+  *A=_umul128(*A,*B,B);
+  #endif
+#else
+  uint64_t ha=*A>>32, hb=*B>>32, la=(uint32_t)*A, lb=(uint32_t)*B, hi, lo;
+  uint64_t rh=ha*hb, rm0=ha*lb, rm1=hb*la, rl=la*lb, t=rl+(rm0<<32), c=t<rl;
+  lo=t+(rm1<<32); c+=lo<t; hi=rh+(rm0>>32)+(rm1>>32)+c;
+  #if(WYHASH_CONDOM>1)
+  *A^=lo;  *B^=hi;
+  #else
+  *A=lo;  *B=hi;
+  #endif
+#endif
+}
+static inline uint64_t _wymix(uint64_t A, uint64_t B){ _wymum(&A,&B); return A^B; }
+//read functions
+#ifndef WYHASH_LITTLE_ENDIAN
+  #if defined(_WIN32) || defined(__LITTLE_ENDIAN__) || (defined(__BYTE_ORDER__) && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__)
+    #define WYHASH_LITTLE_ENDIAN 1
+  #elif defined(__BIG_ENDIAN__) || (defined(__BYTE_ORDER__) && __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)
+    #define WYHASH_LITTLE_ENDIAN 0
+  #endif
+#endif
+#if (WYHASH_LITTLE_ENDIAN)
+static inline uint64_t _wyr8(const uint8_t *p) { uint64_t v; memcpy(&v, p, 8); return v;}
+static inline uint64_t _wyr4(const uint8_t *p) { unsigned v; memcpy(&v, p, 4); return v;}
+#elif defined(__GNUC__) || defined(__INTEL_COMPILER) || defined(__clang__)
+static inline uint64_t _wyr8(const uint8_t *p) { uint64_t v; memcpy(&v, p, 8); return __builtin_bswap64(v);}
+static inline uint64_t _wyr4(const uint8_t *p) { unsigned v; memcpy(&v, p, 4); return __builtin_bswap32(v);}
+#elif defined(_MSC_VER)
+static inline uint64_t _wyr8(const uint8_t *p) { uint64_t v; memcpy(&v, p, 8); return _byteswap_uint64(v);}
+static inline uint64_t _wyr4(const uint8_t *p) { unsigned v; memcpy(&v, p, 4); return _byteswap_ulong(v);}
+#endif
+static inline uint64_t _wyr3(const uint8_t *p, unsigned k) { return (((uint64_t)p[0])<<16)|(((uint64_t)p[k>>1])<<8)|p[k-1];}
+//wyhash function
+static inline uint64_t _wyfinish16(const uint8_t *p, uint64_t len, uint64_t seed, const uint64_t *secret, uint64_t i){
+#if(WYHASH_CONDOM>0)
+  uint64_t a, b;
+  if(_likely_(i<=8)){
+    if(_likely_(i>=4)){ a=_wyr4(p); b=_wyr4(p+i-4); }
+    else if (_likely_(i)){ a=_wyr3(p,i); b=0; }
+    else a=b=0;
+  } 
+  else{ a=_wyr8(p); b=_wyr8(p+i-8); }
+  return _wymix(secret[1]^len,_wymix(a^secret[1], b^seed));
+#else
+  #define oneshot_shift ((i<8)*((8-i)<<3))
+  return _wymix(secret[1]^len,_wymix((_wyr8(p)<<oneshot_shift)^secret[1],(_wyr8(p+i-8)>>oneshot_shift)^seed));
+#endif
+}
+
+static inline uint64_t _wyfinish(const uint8_t *p, uint64_t len, uint64_t seed, const uint64_t *secret, uint64_t i){
+  if(_likely_(i<=16)) return _wyfinish16(p,len,seed,secret,i);
+  return _wyfinish(p+16,len,_wymix(_wyr8(p)^secret[1],_wyr8(p+8)^seed),secret,i-16);
+}
+
+static inline uint64_t wyhash(const void *key, uint64_t len, uint64_t seed, const uint64_t *secret){
+  const uint8_t *p=(const uint8_t *)key;
+  uint64_t i=len; seed^=*secret;
+  if(_unlikely_(i>64)){
+    uint64_t see1=seed;
+    do{
+      seed=_wymix(_wyr8(p)^secret[1],_wyr8(p+8)^seed)^_wymix(_wyr8(p+16)^secret[2],_wyr8(p+24)^seed);
+      see1=_wymix(_wyr8(p+32)^secret[3],_wyr8(p+40)^see1)^_wymix(_wyr8(p+48)^secret[4],_wyr8(p+56)^see1);
+      p+=64; i-=64;
+    }while(i>64);
+    seed^=see1;
+  }
+  return _wyfinish(p,len,seed,secret,i);
+}
+//utility functions
+const uint64_t _wyp[5] = {0xa0761d6478bd642full, 0xe7037ed1a0b428dbull, 0x8ebc6af09c88c6e3ull, 0x589965cc75374cc3ull, 0x1d8e4e27c47d124full};
+static inline uint64_t wyhash64(uint64_t A, uint64_t B){  A^=_wyp[0]; B^=_wyp[1];  _wymum(&A,&B);  return _wymix(A^_wyp[0],B^_wyp[1]);}
+static inline uint64_t wyrand(uint64_t *seed){  *seed+=_wyp[0]; return _wymix(*seed,*seed^_wyp[1]);}
+static inline double wy2u01(uint64_t r){ const double _wynorm=1.0/(1ull<<52); return (r>>12)*_wynorm;}
+static inline double wy2gau(uint64_t r){ const double _wynorm=1.0/(1ull<<20); return ((r&0x1fffff)+((r>>21)&0x1fffff)+((r>>42)&0x1fffff))*_wynorm-3.0;}
+static inline uint64_t wy2u0k(uint64_t r, uint64_t k){ _wymum(&r,&k); return k; }
+
+static inline void make_secret(uint64_t seed, uint64_t *secret){
+  uint8_t c[] = {15, 23, 27, 29, 30, 39, 43, 45, 46, 51, 53, 54, 57, 58, 60, 71, 75, 77, 78, 83, 85, 86, 89, 90, 92, 99, 101, 102, 105, 106, 108, 113, 114, 116, 120, 135, 139, 141, 142, 147, 149, 150, 153, 154, 156, 163, 165, 166, 169, 170, 172, 177, 178, 180, 184, 195, 197, 198, 201, 202, 204, 209, 210, 212, 216, 225, 226, 228, 232, 240 };
+  for(size_t i=0;i<5;i++){
+    uint8_t ok;
+    do{
+      ok=1; secret[i]=0;
+      for(size_t j=0;j<64;j+=8) secret[i]|=((uint64_t)c[wyrand(&seed)%sizeof(c)])<<j;
+      if(secret[i]%2==0){ ok=0; continue; }
+      for(size_t j=0;j<i;j++)
+#if defined(__GNUC__) || defined(__INTEL_COMPILER) || defined(__clang__)
+        if(__builtin_popcountll(secret[j]^secret[i])!=32){ ok=0; break; }
+#elif defined(_MSC_VER) && defined(_M_X64)
+        if(_mm_popcnt_u64(secret[j]^secret[i])!=32){ ok=0; break; }
+#endif
+       if(!ok)continue;
+       for(uint64_t j=3;j<0x100000000ull;j+=2) if(secret[i]%j==0){ ok=0; break; }
+    }while(!ok);
+  }
+}
+#endif