[ios] Add support for building .swift files

Add compiler wrapper script at build/apple/swiftc.py, define
the necessary tool in the toolchain and pass the -target and
-sdk through the configuration.

Bug: none
Change-Id: I177b8a6acf169b5c1d2399b625bdc0a82083b6a5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2341135Reviewed-by: Mike Pinkerton <pinkerton@chromium.org>
Commit-Queue: Sylvain Defresne <sdefresne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#800939}

build/apple/swiftc.py

+#!/usr/bin/python3
+
+# Copyright 2020 The Chromium 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 argparse
+import collections
+import json
+import os
+import subprocess
+import sys
+import tempfile
+
+
+class OrderedSet(collections.OrderedDict):
+  def add(self, value):
+    self[value] = True
+
+
+def compile_module(module, sources, settings, extras, tmpdir):
+  output_file_map = {}
+  if settings.whole_module_optimization:
+    output_file_map[''] = {
+        'object': os.path.join(settings.object_dir, module + '.o'),
+        'dependencies': os.path.join(tmpdir, module + '.d'),
+    }
+  else:
+    for source in sources:
+      name, _ = os.path.splitext(os.path.basename(source))
+      output_file_map[source] = {
+          'object': os.path.join(settings.object_dir, name + '.o'),
+          'dependencies': os.path.join(tmpdir, name + '.d'),
+      }
+
+  for key in ('module_path', 'header_path', 'depfile'):
+    path = getattr(settings, key)
+    if os.path.exists(path):
+      os.unlink(path)
+    if key == 'module_path':
+      for ext in '.swiftdoc', '.swiftsourceinfo':
+        path = os.path.splitext(getattr(settings, key))[0] + ext
+        if os.path.exists(path):
+          os.unlink(path)
+    directory = os.path.dirname(path)
+    if not os.path.exists(directory):
+      os.makedirs(directory)
+
+  if not os.path.exists(settings.object_dir):
+    os.makedirs(settings.object_dir)
+
+  for key in output_file_map:
+    path = output_file_map[key]['object']
+    if os.path.exists(path):
+      os.unlink(path)
+
+  output_file_map_path = os.path.join(tmpdir, module + '.json')
+  with open(output_file_map_path, 'w') as output_file_map_file:
+    output_file_map_file.write(json.dumps(output_file_map))
+    output_file_map_file.flush()
+
+  extra_args = []
+  if settings.bridge_header:
+    extra_args.extend([
+        '-import-objc-header',
+        os.path.abspath(settings.bridge_header),
+    ])
+
+  if settings.whole_module_optimization:
+    extra_args.append('-whole-module-optimization')
+
+  if settings.target:
+    extra_args.extend([
+        '-target',
+        settings.target,
+    ])
+
+  if settings.sdk:
+    extra_args.extend([
+        '-sdk',
+        os.path.abspath(settings.sdk),
+    ])
+
+  if settings.swift_version:
+    extra_args.extend([
+        '-swift-version',
+        settings.swift_version,
+    ])
+
+  if settings.include_dirs:
+    for include_dir in settings.include_dirs:
+      extra_args.append('-I' + include_dir)
+
+  process = subprocess.Popen([
+      'swiftc',
+      '-parse-as-library',
+      '-module-name',
+      module,
+      '-emit-object',
+      '-emit-dependencies',
+      '-emit-module',
+      '-emit-module-path',
+      settings.module_path,
+      '-emit-objc-header',
+      '-emit-objc-header-path',
+      settings.header_path,
+      '-output-file-map',
+      output_file_map_path,
+  ] + extra_args + extras + sources,
+                             stdout=subprocess.PIPE,
+                             stderr=subprocess.PIPE,
+                             universal_newlines=True)
+
+  stdout, stderr = process.communicate()
+  if process.returncode:
+    sys.stdout.write(stdout)
+    sys.stderr.write(stderr)
+    sys.exit(process.returncode)
+
+  depfile_content = collections.OrderedDict()
+  for key in output_file_map:
+    for line in open(output_file_map[key]['dependencies']):
+      output, inputs = line.split(' : ', 2)
+      _, ext = os.path.splitext(output)
+      if ext == '.o':
+        key = output
+      else:
+        key = os.path.splitext(settings.module_path)[0] + ext
+      if key not in depfile_content:
+        depfile_content[key] = OrderedSet()
+      for path in inputs.split():
+        depfile_content[key].add(path)
+
+  with open(settings.depfile, 'w') as depfile:
+    for key in depfile_content:
+      if not settings.depfile_filter or key in settings.depfile_filter:
+        inputs = depfile_content[key]
+        depfile.write('%s : %s\n' % (key, ' '.join(inputs)))
+
+
+def main(args):
+  parser = argparse.ArgumentParser(add_help=False)
+  parser.add_argument('-module-name', help='name of the Swift module')
+  parser.add_argument('-include',
+                      '-I',
+                      action='append',
+                      dest='include_dirs',
+                      help='add directory to header search path')
+  parser.add_argument('sources', nargs='+', help='Swift source file to compile')
+  parser.add_argument('-whole-module-optimization',
+                      action='store_true',
+                      help='enable whole module optimization')
+  parser.add_argument('-object-dir',
+                      help='path to the generated object files directory')
+  parser.add_argument('-module-path', help='path to the generated module file')
+  parser.add_argument('-header-path', help='path to the generated header file')
+  parser.add_argument('-bridge-header',
+                      help='path to the Objective-C bridge header')
+  parser.add_argument('-depfile', help='path to the generated depfile')
+  parser.add_argument('-swift-version',
+                      help='version of Swift language to support')
+  parser.add_argument('-depfile-filter',
+                      action='append',
+                      help='limit depfile to those files')
+  parser.add_argument('-target',
+                      action='store',
+                      help='generate code for the given target <triple>')
+  parser.add_argument('-sdk', action='store', help='compile against sdk')
+
+  parsed, extras = parser.parse_known_args(args)
+  with tempfile.TemporaryDirectory() as tmpdir:
+    compile_module(parsed.module_name, parsed.sources, parsed, extras, tmpdir)
+
+
+if __name__ == '__main__':
+  sys.exit(main(sys.argv[1:]))

build/config/compiler/BUILD.gn

@@ -2313,6 +2313,10 @@ config("symbols") {
       ]
     }
 
+    if (is_apple) {
+      swiftflags = [ "-g" ]
+    }
+
     if (use_debug_fission && !is_nacl && !is_android) {
       # NOTE: Some Chrome OS builds globally set |use_debug_fission| to true,
       # but they also build some targets against Android toolchains which aren't

build/config/ios/BUILD.gn

@@ -36,23 +36,44 @@ config("compiler") {
       "-arch",
       "x86_64",
     ]
+    swiftflags = [
+      "-target",
+      "x86_64-apple-ios$ios_deployment_target-simulator",
+    ]
   } else if (current_cpu == "x86") {
     common_ios_flags += [
       "-arch",
       "i386",
     ]
+    swiftflags = [
+      "-target",
+      "i386-apple-ios$ios_deployment_target-simulator",
+    ]
   } else if (current_cpu == "armv7" || current_cpu == "arm") {
     common_ios_flags += [
       "-arch",
       "armv7",
     ]
+    swiftflags = [
+      "-target",
+      "armv7-apple-ios$ios_deployment_target",
+    ]
   } else if (current_cpu == "arm64") {
     common_ios_flags += [
       "-arch",
       "arm64",
     ]
+    swiftflags = [
+      "-target",
+      "arm64-apple-ios$ios_deployment_target",
+    ]
   }
 
+  swiftflags += [
+    "-swift-version",
+    "5",
+  ]
+
   # This is here so that all files get recompiled after an Xcode update.
   # (defines are passed via the command line, and build system rebuild things
   # when their commandline changes). Nothing should ever read this define.
@@ -78,11 +99,19 @@ config("runtime_library") {
       "-isysroot",
       rebase_path(sysroot, root_build_dir),
     ]
+    swiftflags = [
+      "-sdk",
+      rebase_path(sysroot, root_build_dir),
+    ]
   } else {
     common_flags = [
       "-isysroot",
       sysroot,
     ]
+    swiftflags = [
+      "-sdk",
+      sysroot,
+    ]
   }
 
   if (use_ios_simulator) {
@@ -113,6 +142,7 @@ config("ios_executable_flags") {
 
 config("ios_dynamic_flags") {
   ldflags = [ "-Wl,-ObjC" ]  # Always load Objective-C categories and class.
+  lib_dirs = [ "$sysroot/usr/lib/swift" ]
 }
 
 config("xctest_config") {

build/toolchain/mac/BUILD.gn

@@ -33,6 +33,17 @@ declare_args() {
   # https://reviews.llvm.org/rL368199 but that has not yet made it into a public
   # lldb release.
   mac_deterministic_build = false
+
+  # This controls whether whole module optimization is enabled when building
+  # Swift modules. If enabled, the compiler will compile the module as one
+  # unit, generating just one single object file. Otherwise, it will generate
+  # one object file per .swift file. If unspecified, will default to "true"
+  # for official builds, and "false" for all other builds.
+  swift_whole_module_optimization = -1
+}
+
+if (swift_whole_module_optimization == -1) {
+  swift_whole_module_optimization = is_official_build
 }
 
 if (current_toolchain == default_toolchain) {
@@ -95,6 +106,8 @@ template("mac_toolchain") {
     _cc = "${prefix}clang"
     _cxx = "${prefix}clang++"
 
+    swiftmodule_switch = "-Wl,-add_ast_path,"
+
     # When the invoker has explicitly overridden use_goma or cc_wrapper in the
     # toolchain args, use those values, otherwise default to the global one.
     # This works because the only reasonable override that toolchains might
@@ -304,7 +317,7 @@ template("mac_toolchain") {
         link_command += " -Wl,-install_name,@rpath/\"{{target_output_name}}{{output_extension}}\" "
       }
       link_command += dsym_switch
-      link_command += "{{ldflags}} -o \"$dylib\" -Wl,-filelist,\"$rspfile\" {{frameworks}} {{solibs}} {{libs}}"
+      link_command += "{{ldflags}} -o \"$dylib\" -Wl,-filelist,\"$rspfile\" {{frameworks}} {{swiftmodules}} {{solibs}} {{libs}}"
 
       replace_command = "if ! cmp -s \"$temporary_tocname\" \"$tocname\"; then mv \"$temporary_tocname\" \"$tocname\""
       extract_toc_command = "{ $otool -l \"$dylib\" | grep LC_ID_DYLIB -A 5; $nm -gPp \"$dylib\" | cut -f1-2 -d' ' | grep -v U\$\$; true; }"
@@ -356,7 +369,7 @@ template("mac_toolchain") {
         link_command += " -Wl,-install_name,@rpath/{{target_output_name}}{{output_extension}}"
       }
       link_command += dsym_switch
-      link_command += " {{frameworks}} {{solibs}} {{libs}}"
+      link_command += " {{frameworks}} {{swiftmodules}} {{solibs}} {{libs}}"
       command = link_command
 
       rspfile_content = "{{inputs_newline}}"
@@ -392,7 +405,7 @@ template("mac_toolchain") {
       # do for command-line arguments. Thus any source names with spaces, or
       # label names with spaces (which GN bases the output paths on) will be
       # corrupted by this process. Don't use spaces for source files or labels.
-      command = "$linker_driver $ld $dsym_switch {{ldflags}} -o \"$outfile\" -Wl,-filelist,\"$rspfile\" {{frameworks}} {{solibs}} {{libs}}"
+      command = "$linker_driver $ld $dsym_switch {{ldflags}} -o \"$outfile\" -Wl,-filelist,\"$rspfile\" {{frameworks}} {{swiftmodules}} {{solibs}} {{libs}}"
       description = "LINK $outfile"
       rspfile_content = "{{inputs_newline}}"
       outputs = [ outfile ]
@@ -436,6 +449,46 @@ template("mac_toolchain") {
       pool = ":bundle_pool($default_toolchain)"
     }
 
+    tool("swift") {
+      _tool = rebase_path("//build/apple/swiftc.py", root_build_dir)
+
+      depfile = "{{target_out_dir}}/{{module_name}}.d"
+      depsformat = "gcc"
+
+      outputs = [
+        # The module needs to be the first output listed. The blank line after
+        # the module is required to prevent `gn format` from changing the file
+        # order.
+        "{{target_gen_dir}}/{{module_name}}.swiftmodule",
+
+        "{{target_gen_dir}}/{{module_name}}.h",
+        "{{target_gen_dir}}/{{module_name}}.swiftdoc",
+        "{{target_gen_dir}}/{{module_name}}.swiftsourceinfo",
+      ]
+
+      if (swift_whole_module_optimization) {
+        _extra_flags = "-whole-module-optimization"
+        _objects_dir = "{{target_out_dir}}"
+
+        outputs += [ "$_objects_dir/{{module_name}}.o" ]
+      } else {
+        _extra_flags = ""
+        _objects_dir = "{{target_out_dir}}/{{label_name}}"
+
+        partial_outputs = [ "$_objects_dir/{{source_name_part}}.o" ]
+      }
+
+      command =
+          "$_tool -module-name {{module_name}} " +
+          "-object-dir $_objects_dir " +
+          "-module-path {{target_gen_dir}}/{{module_name}}.swiftmodule " +
+          "-header-path {{target_gen_dir}}/{{module_name}}.h " +
+          "-depfile {{target_out_dir}}/{{module_name}}.d " +
+          "-depfile-filter {{target_gen_dir}}/{{module_name}}.swiftmodule " +
+          "-bridge-header {{bridge_header}} $_extra_flags " +
+          "{{swiftflags}} {{include_dirs}} {{module_dirs}} {{inputs}}"
+    }
+
     # xcassets are only used on iOS, not macOS. We want to minimize the number
     # of Xcode-based tools used by the macOS toolchain, so we intentionally
     # disallow future uses of xcassets on macOS. https://crbug.com/965663.