[libpng16] Protect symbol prefixing against CC/CPPFLAGS/CFLAGS useage.
Previous iOS/Xcode fixes for the ARM NEON optimizations moved the test
on __ARM_NEON__ from configure time to compile time. This breaks symbol
prefixing because the definition of the special png_init_filter_functions
call was hidden at configure time if the relevant compiler arguments are
passed in CFLAGS as opposed to CC. This change attempts to avoid all
the confusion that would result by declaring the init function even when
it is not used, so that it will always get prefixed.
diff --git a/ANNOUNCE b/ANNOUNCE
index 37a01a7..cc5019f 100644
--- a/ANNOUNCE
+++ b/ANNOUNCE
@@ -93,6 +93,14 @@
the optimizations ('check' vs 'api') are exposed in the public header files
except that the new setting PNG_ARM_NEON_OPT documents how libpng makes the
decision about whether or not to use the optimizations.
+ Protect symbol prefixing against CC/CPPFLAGS/CFLAGS useage.
+ Previous iOS/Xcode fixes for the ARM NEON optimizations moved the test
+ on __ARM_NEON__ from configure time to compile time. This breaks symbol
+ prefixing because the definition of the special png_init_filter_functions
+ call was hidden at configure time if the relevant compiler arguments are
+ passed in CFLAGS as opposed to CC. This change attempts to avoid all
+ the confusion that would result by declaring the init function even when
+ it is not used, so that it will always get prefixed.
Send comments/corrections/commendations to png-mng-implement at lists.sf.net
(subscription required; visit
diff --git a/CHANGES b/CHANGES
index 4615e2b..68ba609 100644
--- a/CHANGES
+++ b/CHANGES
@@ -4577,6 +4577,14 @@
the optimizations ('check' vs 'api') are exposed in the public header files
except that the new setting PNG_ARM_NEON_OPT documents how libpng makes the
decision about whether or not to use the optimizations.
+ Protect symbol prefixing against CC/CPPFLAGS/CFLAGS useage.
+ Previous iOS/Xcode fixes for the ARM NEON optimizations moved the test
+ on __ARM_NEON__ from configure time to compile time. This breaks symbol
+ prefixing because the definition of the special png_init_filter_functions
+ call was hidden at configure time if the relevant compiler arguments are
+ passed in CFLAGS as opposed to CC. This change attempts to avoid all
+ the confusion that would result by declaring the init function even when
+ it is not used, so that it will always get prefixed.
Send comments/corrections/commendations to png-mng-implement at lists.sf.net
(subscription required; visit
diff --git a/pngpriv.h b/pngpriv.h
index c42aed7..9729dac 100644
--- a/pngpriv.h
+++ b/pngpriv.h
@@ -96,8 +96,16 @@
* done and this interferes with the handling of the ARM NEON optimizations, and
* possibly other similiar optimizations. Put additional tests here; in general
* this is needed when the same option can be changed at both compile time and
- * run time depending on the target OS (i.e. iOS vs Android.) The changes have
- * to occur here to get the symbol prefixing to work consistently.
+ * run time depending on the target OS (i.e. iOS vs Android.)
+ *
+ * NOTE: symbol prefixing does not pass $(CFLAGS) to the preprocessor, because
+ * this is not possible with certain compilers (Oracle SUN OS CC), as a result
+ * it is necessary to ensure that all extern functions that *might* be used
+ * regardless of $(CFLAGS) get declared in this file. The test on __ARM_NEON__
+ * below is one example of this behavior because it is controlled by the
+ * presence or not of -mfpu=neon on the GCC command line, it is possible to do
+ * this in $(CC), e.g. "CC=gcc -mfpu=neon", but people who build libpng rarely
+ * do this.
*/
#ifndef PNG_ARM_NEON_OPT
/* ARM NEON optimizations are being controlled by the compiler settings,
@@ -115,7 +123,7 @@
#if PNG_ARM_NEON_OPT > 0
/* NEON optimizations are to be at least considered by libpng, enable the
- * callbacks to do this. (This is what matters for the symbol prefixing.)
+ * callbacks to do this.
*/
# define PNG_FILTER_OPTIMIZATIONS png_init_filter_functions_neon
#endif
@@ -1941,14 +1949,22 @@
#endif /* SIMPLIFIED READ/WRITE */
+/* These are initialization functions for hardware specific PNG filter
+ * optimizations; list these here then select the appropriate one at compile
+ * time using the macro PNG_FILTER_OPTIMIZATIONS. If the macro is not defined
+ * the generic code is used.
+ */
#ifdef PNG_FILTER_OPTIMIZATIONS
PNG_INTERNAL_FUNCTION(void, PNG_FILTER_OPTIMIZATIONS, (png_structp png_ptr,
- unsigned int bpp), PNG_EMPTY);
- /* This is the initialization function for hardware specific optimizations,
- * one implementation (for ARM NEON machines) is contained in
- * arm/filter_neon.c. It need not be defined - the generic code will be used
- * if not.
+ unsigned int bpp), PNG_EMPTY);
+ /* Just declare the optimization that will be used */
+#else
+ /* List *all* the possible optimizations here - this branch is required if
+ * the builder of libpng passes the definition of PNG_FILTER_OPTIMIZATIONS in
+ * CFLAGS in place of CPPFLAGS *and* uses symbol prefixing.
*/
+PNG_INTERNAL_FUNCTION(void, png_init_filter_functions_neon,
+ (png_structp png_ptr, unsigned int bpp), PNG_EMPTY);
#endif
/* Maintainer: Put new private prototypes here ^ */
diff --git a/scripts/pnglibconf.dfa b/scripts/pnglibconf.dfa
index ae9f323..4dea09c 100755
--- a/scripts/pnglibconf.dfa
+++ b/scripts/pnglibconf.dfa
@@ -119,7 +119,7 @@
#
# If you create a private DLL you need to define the following
# macros in the file 'pngusr.h' and set -DPNG_USER_CONFIG for
-# compilation (i.e. in CFLAGS.)
+# compilation (i.e. in CPPFLAGS.)
# #define PNG_USER_PRIVATEBUILD \
# <Describes by whom and why this version of the DLL was built>
# e.g. #define PNG_USER_PRIVATEBUILD "Build by MyCompany for xyz reasons."
@@ -204,11 +204,11 @@
#
# ARM_NEON_OPT: unset: check at compile time (__ARM_NEON__ must be defined by
# the compiler, typically as a result of specifying
-# -mfpu=neon on the command line.)
+# CC="gcc -mfpu=neon".)
# 0: disable (even if the CPU has a NEON FPU.)
# 1: check at run time (via ARM_NEON_{API,CHECK})
# 2: switch on unconditionally (inadvisable - instead pass
-# -mfpu=neon to GCC in CFLAGS)
+# -mfpu=neon to GCC in CC)
# When building libpng avoid using any setting other than '0'; '1' is
# set automatically when either 'API' or 'CHECK' are configured in,
# '2' should not be necessary as -mfpu=neon will achieve the same
