impeller/tools/build_metal_library.py

# Copyright 2013 The Flutter Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

import sys

import argparse
import errno
import os
import subprocess

def MakeDirectories(path):
    try:
        os.makedirs(path)
    except OSError as exc:
        if exc.errno == errno.EEXIST and os.path.isdir(path):
            pass
        else:
            raise

def Main():
  parser = argparse.ArgumentParser()
  parser.add_argument("--output",
                    type=str, required=True,
                    help="The location to generate the Metal library to.")
  parser.add_argument("--depfile",
                    type=str, required=True,
                    help="The location of the depfile.")
  parser.add_argument("--source",
                    type=str, action="append", required=True,
                    help="The source file to compile. Can be specified multiple times.")
  parser.add_argument("--optimize", action="store_true", default=False,
                    help="If available optimizations must be applied to the compiled Metal sources.")
  parser.add_argument("--platform", required=True, choices=["mac", "ios", "ios-simulator"],
                    help="Select the platform.")

  args = parser.parse_args()

  MakeDirectories(os.path.dirname(args.depfile))

  command = [
    "xcrun",
  ]

  if args.platform == "mac":
    command += [
      "-sdk",
      "macosx",
    ]
  elif args.platform == "ios":
    command += [
      "-sdk",
      "iphoneos",
    ]
  elif args.platform == "ios-simulator":
    command += [
      "-sdk",
      "iphonesimulator",
    ]

  command += [
    "metal",
    # These warnings are from generated code and would make no sense to the GLSL
    # author.
    "-Wno-unused-variable",
    # Both user and system header will be tracked.
    "-MMD",
    "-MF",
    args.depfile,
    "-o",
    args.output,
  ]

  # The Metal standard must match the specification in impellerc.
  if args.platform == "mac":
    command += [
      "--std=macos-metal1.2",
    ]
  elif args.platform == "ios":
    command += [
      "--std=ios-metal1.2",
      "-mios-version-min=10.0",
    ]

  if args.optimize:
    command += [
      # Like -Os (and thus -O2), but reduces code size further.
      "-Oz",
      # Allow aggressive, lossy floating-point optimizations.
      "-ffast-math",
    ]
  else:
    command += [
      # Embeds both sources and driver options in the output. This aids in
      # debugging but should be removed from release builds.
      # TODO(chinmaygarde): Use -frecord-sources when CI upgrades to
      # Xcode 13.
      "-MO",
      # Assist the sampling profiler.
      "-gline-tables-only",
      "-g",
      # Optimize for debuggability.
      "-Og",
    ]

  command += args.source

  subprocess.check_call(command)

if __name__ == '__main__':
  if sys.platform != 'darwin':
    raise Exception("This script only runs on Mac")
  Main()