src/starboard/build/toolchain/gcc_toolchain.gni - cobalt - Git at Google

 # Copyright (c) 2013 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.

 # Modifications Copyright 2017 The Cobalt Authors. All Rights Reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
 # You may obtain a copy of the License at
 #
 #     http://www.apache.org/licenses/LICENSE-2.0
 #
 # Unless required by applicable law or agreed to in writing, software
 # distributed under the License is distributed on an "AS IS" BASIS,
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.

 import("//starboard/build/toolchain/clang.gni")
 import("//starboard/build/toolchain/goma.gni")

 # This template defines a toolchain for something that works like gcc
 # (including clang).
 #
 # It requires the following variables specifying the executables to run:
 #  - ar
 #  - cc
 #  - cxx
 #  - ld
 #
 # Optional parameters that control the tools:
 #
 #  - extra_cflags
 #      Extra flags to be appended when compiling C files (but not C++ files).
 #  - extra_cppflags
 #      Extra flags to be appended when compiling both C and C++ files. "CPP"
 #      stands for "C PreProcessor" in this context, although it can be
 #      used for non-preprocessor flags as well. Not to be confused with
 #      "CXX" (which follows).
 #  - extra_cxxflags
 #      Extra flags to be appended when compiling C++ files (but not C files).
 #  - extra_ldflags
 #      Extra flags to be appended when linking
 #
 #  - libs_section_prefix
 #  - libs_section_postfix
 #      The contents of these strings, if specified, will be placed around
 #      the libs section of the linker line. It allows one to inject libraries
 #      at the beginning and end for all targets in a toolchain.
 #  - solink_libs_section_prefix
 #  - solink_libs_section_postfix
 #      Same as libs_section_{pre,post}fix except used for solink instead of link.
 #  - link_outputs
 #      The content of this array, if specified, will be added to the list of
 #      outputs from the link command. This can be useful in conjunction with
 #      the post_link parameter.
 #  - post_link
 #      The content of this string, if specified, will be run as a separate
 #      command following the the link command.
 #  - deps
 #      Just forwarded to the toolchain definition.
 #  - executable_extension
 #      If this string is specified it will be used for the file extension
 #      for an executable, rather than using no extension; targets will
 #      still be able to override the extension using the output_extension
 #      variable.
 #  - rebuild_define
 #      The contents of this string, if specified, will be passed as a #define
 #      to the toolchain. It can be used to force recompiles whenever a
 #      toolchain is updated.
 #  - shlib_extension
 #      If this string is specified it will be used for the file extension
 #      for a shared library, rather than default value specified in
 #      toolchain.gni
 #  - strip
 #      Location of the strip executable. When specified, strip will be run on
 #      all shared libraries and executables as they are built. The pre-stripped
 #      artifacts will be put in lib.unstripped/ and exe.unstripped/.
 template("gcc_toolchain") {
   toolchain(target_name) {
     assert(defined(invoker.ar), "gcc_toolchain() must specify a \"ar\" value")
     assert(defined(invoker.cc), "gcc_toolchain() must specify a \"cc\" value")
     assert(defined(invoker.cxx), "gcc_toolchain() must specify a \"cxx\" value")
     assert(defined(invoker.ld), "gcc_toolchain() must specify a \"ld\" value")
     assert(defined(invoker.shlib_extension),
            "gcc_toolchain() must specify a \"shlib_extension\" value")

     # This define changes when the toolchain changes, forcing a rebuild.
     # Nothing should ever use this define.
     if (defined(invoker.rebuild_define)) {
       rebuild_string = "-D" + invoker.rebuild_define + " "
     } else {
       rebuild_string = ""
     }

     # GN's syntax can't handle more than one scope dereference at once, like
     # "invoker.toolchain_args.foo", so make a temporary to hold the toolchain
     # args so we can do "invoker_toolchain_args.foo".
     assert(defined(invoker.toolchain_args),
            "Toolchains must specify toolchain_args")
     invoker_toolchain_args = invoker.toolchain_args
     assert(defined(invoker_toolchain_args.current_cpu),
            "toolchain_args must specify a current_cpu")
     assert(defined(invoker_toolchain_args.current_os),
            "toolchain_args must specify a current_os")

     # When invoking this toolchain not as the default one, these args will be
     # passed to the build. They are ignored when this is the default toolchain.
     toolchain_args = {
       # Populate toolchain args from the invoker.
       forward_variables_from(invoker_toolchain_args, "*")
     }

     # 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
     # supply for these values are to force-disable them.
     if (defined(toolchain_args.use_goma)) {
       toolchain_uses_goma = toolchain_args.use_goma
     } else {
       toolchain_uses_goma = use_goma
     }

     # When the invoker has explicitly overridden use_goma in the
     # toolchain args, use those values, otherwise default to the global one.
     # This works because the only reasonable override that toolchains might
     # supply for these values are to force-disable them.
     if (toolchain_uses_goma) {
       goma_path = "$goma_dir/gomacc"
       compiler_prefix = "${goma_path} "
     } else {
       compiler_prefix = ""
     }

     cc = compiler_prefix + invoker.cc
     cxx = compiler_prefix + invoker.cxx
     ar = invoker.ar
     ld = invoker.ld
     if (!defined(asm)) {
       asm = cc
     }
     if (defined(invoker.readelf)) {
       readelf = invoker.readelf
     } else {
       readelf = "readelf"
     }
     if (defined(invoker.nm)) {
       nm = invoker.nm
     } else {
       nm = "nm"
     }
     if (defined(invoker.stamp_command)) {
       stamp_command = invoker.stamp_command
     } else {
       stamp_command = "touch {{output}}"
     }
     if (defined(invoker.copy_command)) {
       copy_command = invoker.copy_command
     } else {
       copy_command = "ln -f {{source}} {{output}} 2>/dev/null || (rm -rf {{output}} && cp -af {{source}} {{output}})"
     }

     default_shlib_extension = invoker.shlib_extension

     if (defined(invoker.executable_extension)) {
       default_executable_extension = invoker.executable_extension
     } else {
       default_executable_extension = ""
     }

     # Bring these into our scope for string interpolation with default values.
     if (defined(invoker.libs_section_prefix)) {
       libs_section_prefix = invoker.libs_section_prefix
     } else {
       libs_section_prefix = ""
     }

     if (defined(invoker.libs_section_postfix)) {
       libs_section_postfix = invoker.libs_section_postfix
     } else {
       libs_section_postfix = ""
     }

     if (defined(invoker.solink_libs_section_prefix)) {
       solink_libs_section_prefix = invoker.solink_libs_section_prefix
     } else {
       solink_libs_section_prefix = ""
     }

     if (defined(invoker.solink_libs_section_postfix)) {
       solink_libs_section_postfix = invoker.solink_libs_section_postfix
     } else {
       solink_libs_section_postfix = ""
     }

     if (defined(invoker.extra_cflags) && invoker.extra_cflags != "") {
       extra_cflags = " " + invoker.extra_cflags
     } else {
       extra_cflags = ""
     }

     if (defined(invoker.extra_cppflags) && invoker.extra_cppflags != "") {
       extra_cppflags = " " + invoker.extra_cppflags
     } else {
       extra_cppflags = ""
     }

     if (defined(invoker.extra_cxxflags) && invoker.extra_cxxflags != "") {
       extra_cxxflags = " " + invoker.extra_cxxflags
     } else {
       extra_cxxflags = ""
     }

     if (defined(invoker.extra_ldflags) && invoker.extra_ldflags != "") {
       extra_ldflags = " " + invoker.extra_ldflags
     } else {
       extra_ldflags = ""
     }

     # These library switches can apply to all tools below.
     lib_switch = "-l"
     lib_dir_switch = "-L"

     # Object files go in this directory.
     object_subdir = "{{target_out_dir}}/{{label_name}}"

     tool("cc") {
       depfile = "{{output}}.d"
       command = "$cc -MMD -MF $depfile ${rebuild_string}{{defines}} {{include_dirs}} {{cflags}} {{cflags_c}}${extra_cppflags}${extra_cflags} -c {{source}} -o {{output}}"
       depsformat = "gcc"
       description = "CC {{output}}"
       outputs = [
         "$object_subdir/{{source_name_part}}.o",
       ]
     }

     tool("cxx") {
       depfile = "{{output}}.d"
       command = "$cxx -MMD -MF $depfile ${rebuild_string}{{defines}} {{include_dirs}} {{cflags}} {{cflags_cc}}${extra_cppflags}${extra_cxxflags} -c {{source}} -o {{output}}"
       depsformat = "gcc"
       description = "CXX {{output}}"
       outputs = [
         "$object_subdir/{{source_name_part}}.o",
       ]
     }

     tool("asm") {
       # For GCC we can just use the C compiler to compile assembly.
       depfile = "{{output}}.d"
       command = "$asm -MMD -MF $depfile ${rebuild_string}{{defines}} {{include_dirs}} {{asmflags}} -c {{source}} -o {{output}}"
       depsformat = "gcc"
       description = "ASM {{output}}"
       outputs = [
         "$object_subdir/{{source_name_part}}.o",
       ]
     }

     tool("alink") {
       rspfile = "{{output}}.rsp"

       # This needs a Python script to avoid using simple sh features in this
       # command, in case the host does not use a POSIX shell (e.g. compiling
       # POSIX-like toolchains such as NaCl on Windows).
       ar_wrapper = rebase_path("//starboard/build/toolchain/gcc_ar_wrapper.py",
                                root_build_dir)
       extra_arflags = "rcsD"
       command = "$python_path \"$ar_wrapper\" --output={{output}} --ar=\"$ar\" {{arflags}} $extra_arflags @\"$rspfile\""
       description = "AR {{output}}"
       rspfile_content = "{{inputs}}"
       outputs = [
         "{{output_dir}}/{{target_output_name}}{{output_extension}}",
       ]

       # Shared libraries go in the target out directory by default so we can
       # generate different targets with the same name and not have them collide.
       default_output_dir = "{{target_out_dir}}"
       default_output_extension = ".a"
       output_prefix = "lib"
     }

     tool("solink") {
       soname = "{{target_output_name}}{{output_extension}}"  # e.g. "libfoo.so".
       sofile = "{{output_dir}}/$soname"  # Possibly including toolchain dir.
       rspfile = sofile + ".rsp"
       pool = "//starboard/build/toolchain:link_pool($default_toolchain)"

       if (defined(invoker.strip)) {
         unstripped_sofile = "{{root_out_dir}}/lib.unstripped/$soname"
       } else {
         unstripped_sofile = sofile
       }

       # These variables are not built into GN but are helpers that
       # implement (1) linking to produce a .so, (2) extracting the symbols
       # from that file (3) if the extracted list differs from the existing
       # .TOC file, overwrite it, otherwise, don't change it.
       tocfile = sofile + ".TOC"

       link_command = "$ld -shared {{ldflags}}${extra_ldflags} -o \"$unstripped_sofile\" -Wl,-soname=\"$soname\" @\"$rspfile\""

       assert(defined(readelf), "to solink you must have a readelf")
       assert(defined(nm), "to solink you must have an nm")
       strip_switch = ""
       if (defined(invoker.strip)) {
         strip_switch = "--strip=${invoker.strip} "
       }

       # This needs a Python script to avoid using a complex shell command
       # requiring sh control structures, pipelines, and POSIX utilities.
       # The host might not have a POSIX shell and utilities (e.g. Windows).
       solink_wrapper =
           rebase_path("//starboard/build/toolchain/gcc_solink_wrapper.py",
                       root_build_dir)
       command = "$python_path \"$solink_wrapper\" --readelf=\"$readelf\" --nm=\"$nm\" $strip_switch--sofile=\"$unstripped_sofile\" --tocfile=\"$tocfile\" --output=\"$sofile\" -- $link_command"

       rspfile_content = "-Wl,--whole-archive {{inputs}} {{solibs}} -Wl,--no-whole-archive $solink_libs_section_prefix {{libs}} $solink_libs_section_postfix"

       description = "SOLINK $sofile"

       # Use this for {{output_extension}} expansions unless a target manually
       # overrides it (in which case {{output_extension}} will be what the target
       # specifies).
       default_output_extension = default_shlib_extension

       default_output_dir = "{{root_out_dir}}"

       output_prefix = "lib"

       # Since the above commands only updates the .TOC file when it changes, ask
       # Ninja to check if the timestamp actually changed to know if downstream
       # dependencies should be recompiled.
       restat = true

       # Tell GN about the output files. It will link to the sofile but use the
       # tocfile for dependency management.
       outputs = [
         sofile,
         tocfile,
       ]
       if (sofile != unstripped_sofile) {
         outputs += [ unstripped_sofile ]
       }
       link_output = sofile
       depend_output = tocfile
     }

     tool("solink_module") {
       soname = "{{target_output_name}}{{output_extension}}"  # e.g. "libfoo.so".
       sofile = "{{output_dir}}/$soname"
       rspfile = sofile + ".rsp"
       pool = "//starboard/build/toolchain:link_pool($default_toolchain)"

       if (defined(invoker.strip)) {
         unstripped_sofile = "{{root_out_dir}}/lib.unstripped/$soname"
       } else {
         unstripped_sofile = sofile
       }

       command = "$ld -shared {{ldflags}}${extra_ldflags} -o \"$unstripped_sofile\" -Wl,-soname=\"$soname\" @\"$rspfile\""

       if (defined(invoker.strip)) {
         strip_command = "${invoker.strip} --strip-unneeded -o \"$sofile\" \"$unstripped_sofile\""
         command += " && " + strip_command
       }
       rspfile_content = "-Wl,--whole-archive {{inputs}} {{solibs}} -Wl,--no-whole-archive $solink_libs_section_prefix {{libs}} $solink_libs_section_postfix"

       description = "SOLINK_MODULE $sofile"

       # Use this for {{output_extension}} expansions unless a target manually
       # overrides it (in which case {{output_extension}} will be what the target
       # specifies).
       if (defined(invoker.loadable_module_extension)) {
         default_output_extension = invoker.loadable_module_extension
       } else {
         default_output_extension = default_shlib_extension
       }

       default_output_dir = "{{root_out_dir}}"

       output_prefix = "lib"

       outputs = [
         sofile,
       ]
       if (sofile != unstripped_sofile) {
         outputs += [ unstripped_sofile ]
       }
     }

     tool("link") {
       exename = "{{target_output_name}}{{output_extension}}"
       outfile = "{{output_dir}}/$exename"
       rspfile = "$outfile.rsp"
       unstripped_outfile = outfile
       pool = "//starboard/build/toolchain:link_pool($default_toolchain)"

       # Use this for {{output_extension}} expansions unless a target manually
       # overrides it (in which case {{output_extension}} will be what the target
       # specifies).
       default_output_extension = default_executable_extension

       default_output_dir = "{{root_out_dir}}"

       if (defined(invoker.strip)) {
         unstripped_outfile = "{{root_out_dir}}/exe.unstripped/$exename"
       }

       start_group_flag = "-Wl,--start-group"
       end_group_flag = "-Wl,--end-group "
       link_command = "$ld {{ldflags}}${extra_ldflags} -o \"$unstripped_outfile\" $start_group_flag @\"$rspfile\" {{solibs}} $end_group_flag $libs_section_prefix {{libs}} $libs_section_postfix"

       strip_switch = ""

       if (defined(invoker.strip)) {
         strip_switch = " --strip=\"${invoker.strip}\" --unstripped-file=\"$unstripped_outfile\""
       }

       link_wrapper =
           rebase_path("//starboard/build/toolchain/gcc_link_wrapper.py",
                       root_build_dir)
       command = "$python_path \"$link_wrapper\" --output=\"$outfile\"$strip_switch -- $link_command"
       description = "LINK $outfile"
       rspfile_content = "{{inputs}}"
       outputs = [
         outfile,
       ]
       if (outfile != unstripped_outfile) {
         outputs += [ unstripped_outfile ]
       }
       if (defined(invoker.link_outputs)) {
         outputs += invoker.link_outputs
       }
     }

     # These two are really entirely generic, but have to be repeated in
     # each toolchain because GN doesn't allow a template to be used here.
     # See //build/toolchain/toolchain.gni for details.
     tool("stamp") {
       command = stamp_command
       description = "STAMP {{output}}"
     }
     tool("copy") {
       command = copy_command
       description = "COPY {{source}} {{output}}"
     }

     forward_variables_from(invoker, [ "deps" ])
   }
 }

 # This is a shorthand for gcc_toolchain instances based on the Chromium-built
 # version of Clang. Only the toolchain_cpu and toolchain_os variables need to
 # be specified by the invoker, and optionally toolprefix if it's a
 # cross-compile case. Note that for a cross-compile case this toolchain
 # requires a config to pass the appropriate -target option, or else it will
 # actually just be doing a native compile. The invoker can optionally override
 # use_gold too.
 template("clang_toolchain") {
   if (defined(invoker.toolprefix)) {
     toolprefix = invoker.toolprefix
   } else {
     toolprefix = ""
   }

   gcc_toolchain(target_name) {
     prefix = rebase_path("$clang_base_path/bin", root_build_dir)
     cc = "$prefix/clang"
     cxx = "$prefix/clang++"
     ld = cxx
     readelf = "${toolprefix}readelf"
     ar = "${prefix}/llvm-ar"
     nm = "${toolprefix}nm"

     forward_variables_from(invoker,
                            [
                              "strip",
                              "is_clang_analysis_supported",
                              "shlib_extension",
                            ])

     toolchain_args = {
       if (defined(invoker.toolchain_args)) {
         forward_variables_from(invoker.toolchain_args, "*")
       }
     }
   }
 }
	# Copyright (c) 2013 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.

	# Modifications Copyright 2017 The Cobalt Authors. All Rights Reserved.
	#
	# Licensed under the Apache License, Version 2.0 (the "License");
	# you may not use this file except in compliance with the License.
	# You may obtain a copy of the License at
	#
	# http://www.apache.org/licenses/LICENSE-2.0
	#
	# Unless required by applicable law or agreed to in writing, software
	# distributed under the License is distributed on an "AS IS" BASIS,
	# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	# See the License for the specific language governing permissions and
	# limitations under the License.

	import("//starboard/build/toolchain/clang.gni")
	import("//starboard/build/toolchain/goma.gni")

	# This template defines a toolchain for something that works like gcc
	# (including clang).
	#
	# It requires the following variables specifying the executables to run:
	# - ar
	# - cc
	# - cxx
	# - ld
	#
	# Optional parameters that control the tools:
	#
	# - extra_cflags
	# Extra flags to be appended when compiling C files (but not C++ files).
	# - extra_cppflags
	# Extra flags to be appended when compiling both C and C++ files. "CPP"
	# stands for "C PreProcessor" in this context, although it can be
	# used for non-preprocessor flags as well. Not to be confused with
	# "CXX" (which follows).
	# - extra_cxxflags
	# Extra flags to be appended when compiling C++ files (but not C files).
	# - extra_ldflags
	# Extra flags to be appended when linking
	#
	# - libs_section_prefix
	# - libs_section_postfix
	# The contents of these strings, if specified, will be placed around
	# the libs section of the linker line. It allows one to inject libraries
	# at the beginning and end for all targets in a toolchain.
	# - solink_libs_section_prefix
	# - solink_libs_section_postfix
	# Same as libs_section_{pre,post}fix except used for solink instead of link.
	# - link_outputs
	# The content of this array, if specified, will be added to the list of
	# outputs from the link command. This can be useful in conjunction with
	# the post_link parameter.
	# - post_link
	# The content of this string, if specified, will be run as a separate
	# command following the the link command.
	# - deps
	# Just forwarded to the toolchain definition.
	# - executable_extension
	# If this string is specified it will be used for the file extension
	# for an executable, rather than using no extension; targets will
	# still be able to override the extension using the output_extension
	# variable.
	# - rebuild_define
	# The contents of this string, if specified, will be passed as a #define
	# to the toolchain. It can be used to force recompiles whenever a
	# toolchain is updated.
	# - shlib_extension
	# If this string is specified it will be used for the file extension
	# for a shared library, rather than default value specified in
	# toolchain.gni
	# - strip
	# Location of the strip executable. When specified, strip will be run on
	# all shared libraries and executables as they are built. The pre-stripped
	# artifacts will be put in lib.unstripped/ and exe.unstripped/.
	template("gcc_toolchain") {
	toolchain(target_name) {
	assert(defined(invoker.ar), "gcc_toolchain() must specify a \"ar\" value")
	assert(defined(invoker.cc), "gcc_toolchain() must specify a \"cc\" value")
	assert(defined(invoker.cxx), "gcc_toolchain() must specify a \"cxx\" value")
	assert(defined(invoker.ld), "gcc_toolchain() must specify a \"ld\" value")
	assert(defined(invoker.shlib_extension),
	"gcc_toolchain() must specify a \"shlib_extension\" value")

	# This define changes when the toolchain changes, forcing a rebuild.
	# Nothing should ever use this define.
	if (defined(invoker.rebuild_define)) {
	rebuild_string = "-D" + invoker.rebuild_define + " "
	} else {
	rebuild_string = ""
	}

	# GN's syntax can't handle more than one scope dereference at once, like
	# "invoker.toolchain_args.foo", so make a temporary to hold the toolchain
	# args so we can do "invoker_toolchain_args.foo".
	assert(defined(invoker.toolchain_args),
	"Toolchains must specify toolchain_args")
	invoker_toolchain_args = invoker.toolchain_args
	assert(defined(invoker_toolchain_args.current_cpu),
	"toolchain_args must specify a current_cpu")
	assert(defined(invoker_toolchain_args.current_os),
	"toolchain_args must specify a current_os")

	# When invoking this toolchain not as the default one, these args will be
	# passed to the build. They are ignored when this is the default toolchain.
	toolchain_args = {
	# Populate toolchain args from the invoker.
	forward_variables_from(invoker_toolchain_args, "*")
	}

	# 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
	# supply for these values are to force-disable them.
	if (defined(toolchain_args.use_goma)) {
	toolchain_uses_goma = toolchain_args.use_goma
	} else {
	toolchain_uses_goma = use_goma
	}

	# When the invoker has explicitly overridden use_goma in the
	# toolchain args, use those values, otherwise default to the global one.
	# This works because the only reasonable override that toolchains might
	# supply for these values are to force-disable them.
	if (toolchain_uses_goma) {
	goma_path = "$goma_dir/gomacc"
	compiler_prefix = "${goma_path} "
	} else {
	compiler_prefix = ""
	}

	cc = compiler_prefix + invoker.cc
	cxx = compiler_prefix + invoker.cxx
	ar = invoker.ar
	ld = invoker.ld
	if (!defined(asm)) {
	asm = cc
	}
	if (defined(invoker.readelf)) {
	readelf = invoker.readelf
	} else {
	readelf = "readelf"
	}
	if (defined(invoker.nm)) {
	nm = invoker.nm
	} else {
	nm = "nm"
	}
	if (defined(invoker.stamp_command)) {
	stamp_command = invoker.stamp_command
	} else {
	stamp_command = "touch {{output}}"
	}
	if (defined(invoker.copy_command)) {
	copy_command = invoker.copy_command
	} else {
	copy_command = "ln -f {{source}} {{output}} 2>/dev/null \|\| (rm -rf {{output}} && cp -af {{source}} {{output}})"
	}

	default_shlib_extension = invoker.shlib_extension

	if (defined(invoker.executable_extension)) {
	default_executable_extension = invoker.executable_extension
	} else {
	default_executable_extension = ""
	}

	# Bring these into our scope for string interpolation with default values.
	if (defined(invoker.libs_section_prefix)) {
	libs_section_prefix = invoker.libs_section_prefix
	} else {
	libs_section_prefix = ""
	}

	if (defined(invoker.libs_section_postfix)) {
	libs_section_postfix = invoker.libs_section_postfix
	} else {
	libs_section_postfix = ""
	}

	if (defined(invoker.solink_libs_section_prefix)) {
	solink_libs_section_prefix = invoker.solink_libs_section_prefix
	} else {
	solink_libs_section_prefix = ""
	}

	if (defined(invoker.solink_libs_section_postfix)) {
	solink_libs_section_postfix = invoker.solink_libs_section_postfix
	} else {
	solink_libs_section_postfix = ""
	}

	if (defined(invoker.extra_cflags) && invoker.extra_cflags != "") {
	extra_cflags = " " + invoker.extra_cflags
	} else {
	extra_cflags = ""
	}

	if (defined(invoker.extra_cppflags) && invoker.extra_cppflags != "") {
	extra_cppflags = " " + invoker.extra_cppflags
	} else {
	extra_cppflags = ""
	}

	if (defined(invoker.extra_cxxflags) && invoker.extra_cxxflags != "") {
	extra_cxxflags = " " + invoker.extra_cxxflags
	} else {
	extra_cxxflags = ""
	}

	if (defined(invoker.extra_ldflags) && invoker.extra_ldflags != "") {
	extra_ldflags = " " + invoker.extra_ldflags
	} else {
	extra_ldflags = ""
	}

	# These library switches can apply to all tools below.
	lib_switch = "-l"
	lib_dir_switch = "-L"

	# Object files go in this directory.
	object_subdir = "{{target_out_dir}}/{{label_name}}"

	tool("cc") {
	depfile = "{{output}}.d"
	command = "$cc -MMD -MF $depfile ${rebuild_string}{{defines}} {{include_dirs}} {{cflags}} {{cflags_c}}${extra_cppflags}${extra_cflags} -c {{source}} -o {{output}}"
	depsformat = "gcc"
	description = "CC {{output}}"
	outputs = [
	"$object_subdir/{{source_name_part}}.o",
	]
	}

	tool("cxx") {
	depfile = "{{output}}.d"
	command = "$cxx -MMD -MF $depfile ${rebuild_string}{{defines}} {{include_dirs}} {{cflags}} {{cflags_cc}}${extra_cppflags}${extra_cxxflags} -c {{source}} -o {{output}}"
	depsformat = "gcc"
	description = "CXX {{output}}"
	outputs = [
	"$object_subdir/{{source_name_part}}.o",
	]
	}

	tool("asm") {
	# For GCC we can just use the C compiler to compile assembly.
	depfile = "{{output}}.d"
	command = "$asm -MMD -MF $depfile ${rebuild_string}{{defines}} {{include_dirs}} {{asmflags}} -c {{source}} -o {{output}}"
	depsformat = "gcc"
	description = "ASM {{output}}"
	outputs = [
	"$object_subdir/{{source_name_part}}.o",
	]
	}

	tool("alink") {
	rspfile = "{{output}}.rsp"

	# This needs a Python script to avoid using simple sh features in this
	# command, in case the host does not use a POSIX shell (e.g. compiling
	# POSIX-like toolchains such as NaCl on Windows).
	ar_wrapper = rebase_path("//starboard/build/toolchain/gcc_ar_wrapper.py",
	root_build_dir)
	extra_arflags = "rcsD"
	command = "$python_path \"$ar_wrapper\" --output={{output}} --ar=\"$ar\" {{arflags}} $extra_arflags @\"$rspfile\""
	description = "AR {{output}}"
	rspfile_content = "{{inputs}}"
	outputs = [
	"{{output_dir}}/{{target_output_name}}{{output_extension}}",
	]

	# Shared libraries go in the target out directory by default so we can
	# generate different targets with the same name and not have them collide.
	default_output_dir = "{{target_out_dir}}"
	default_output_extension = ".a"
	output_prefix = "lib"
	}

	tool("solink") {
	soname = "{{target_output_name}}{{output_extension}}" # e.g. "libfoo.so".
	sofile = "{{output_dir}}/$soname" # Possibly including toolchain dir.
	rspfile = sofile + ".rsp"
	pool = "//starboard/build/toolchain:link_pool($default_toolchain)"

	if (defined(invoker.strip)) {
	unstripped_sofile = "{{root_out_dir}}/lib.unstripped/$soname"
	} else {
	unstripped_sofile = sofile
	}

	# These variables are not built into GN but are helpers that
	# implement (1) linking to produce a .so, (2) extracting the symbols
	# from that file (3) if the extracted list differs from the existing
	# .TOC file, overwrite it, otherwise, don't change it.
	tocfile = sofile + ".TOC"

	link_command = "$ld -shared {{ldflags}}${extra_ldflags} -o \"$unstripped_sofile\" -Wl,-soname=\"$soname\" @\"$rspfile\""

	assert(defined(readelf), "to solink you must have a readelf")
	assert(defined(nm), "to solink you must have an nm")
	strip_switch = ""
	if (defined(invoker.strip)) {
	strip_switch = "--strip=${invoker.strip} "
	}

	# This needs a Python script to avoid using a complex shell command
	# requiring sh control structures, pipelines, and POSIX utilities.
	# The host might not have a POSIX shell and utilities (e.g. Windows).
	solink_wrapper =
	rebase_path("//starboard/build/toolchain/gcc_solink_wrapper.py",
	root_build_dir)
	command = "$python_path \"$solink_wrapper\" --readelf=\"$readelf\" --nm=\"$nm\" $strip_switch--sofile=\"$unstripped_sofile\" --tocfile=\"$tocfile\" --output=\"$sofile\" -- $link_command"

	rspfile_content = "-Wl,--whole-archive {{inputs}} {{solibs}} -Wl,--no-whole-archive $solink_libs_section_prefix {{libs}} $solink_libs_section_postfix"

	description = "SOLINK $sofile"

	# Use this for {{output_extension}} expansions unless a target manually
	# overrides it (in which case {{output_extension}} will be what the target
	# specifies).
	default_output_extension = default_shlib_extension

	default_output_dir = "{{root_out_dir}}"

	output_prefix = "lib"

	# Since the above commands only updates the .TOC file when it changes, ask
	# Ninja to check if the timestamp actually changed to know if downstream
	# dependencies should be recompiled.
	restat = true

	# Tell GN about the output files. It will link to the sofile but use the
	# tocfile for dependency management.
	outputs = [
	sofile,
	tocfile,
	]
	if (sofile != unstripped_sofile) {
	outputs += [ unstripped_sofile ]
	}
	link_output = sofile
	depend_output = tocfile
	}

	tool("solink_module") {
	soname = "{{target_output_name}}{{output_extension}}" # e.g. "libfoo.so".
	sofile = "{{output_dir}}/$soname"
	rspfile = sofile + ".rsp"
	pool = "//starboard/build/toolchain:link_pool($default_toolchain)"

	if (defined(invoker.strip)) {
	unstripped_sofile = "{{root_out_dir}}/lib.unstripped/$soname"
	} else {
	unstripped_sofile = sofile
	}

	command = "$ld -shared {{ldflags}}${extra_ldflags} -o \"$unstripped_sofile\" -Wl,-soname=\"$soname\" @\"$rspfile\""

	if (defined(invoker.strip)) {
	strip_command = "${invoker.strip} --strip-unneeded -o \"$sofile\" \"$unstripped_sofile\""
	command += " && " + strip_command
	}
	rspfile_content = "-Wl,--whole-archive {{inputs}} {{solibs}} -Wl,--no-whole-archive $solink_libs_section_prefix {{libs}} $solink_libs_section_postfix"

	description = "SOLINK_MODULE $sofile"

	# Use this for {{output_extension}} expansions unless a target manually
	# overrides it (in which case {{output_extension}} will be what the target
	# specifies).
	if (defined(invoker.loadable_module_extension)) {
	default_output_extension = invoker.loadable_module_extension
	} else {
	default_output_extension = default_shlib_extension
	}

	default_output_dir = "{{root_out_dir}}"

	output_prefix = "lib"

	outputs = [
	sofile,
	]
	if (sofile != unstripped_sofile) {
	outputs += [ unstripped_sofile ]
	}
	}

	tool("link") {
	exename = "{{target_output_name}}{{output_extension}}"
	outfile = "{{output_dir}}/$exename"
	rspfile = "$outfile.rsp"
	unstripped_outfile = outfile
	pool = "//starboard/build/toolchain:link_pool($default_toolchain)"

	# Use this for {{output_extension}} expansions unless a target manually
	# overrides it (in which case {{output_extension}} will be what the target
	# specifies).
	default_output_extension = default_executable_extension

	default_output_dir = "{{root_out_dir}}"

	if (defined(invoker.strip)) {
	unstripped_outfile = "{{root_out_dir}}/exe.unstripped/$exename"
	}

	start_group_flag = "-Wl,--start-group"
	end_group_flag = "-Wl,--end-group "
	link_command = "$ld {{ldflags}}${extra_ldflags} -o \"$unstripped_outfile\" $start_group_flag @\"$rspfile\" {{solibs}} $end_group_flag $libs_section_prefix {{libs}} $libs_section_postfix"

	strip_switch = ""

	if (defined(invoker.strip)) {
	strip_switch = " --strip=\"${invoker.strip}\" --unstripped-file=\"$unstripped_outfile\""
	}

	link_wrapper =
	rebase_path("//starboard/build/toolchain/gcc_link_wrapper.py",
	root_build_dir)
	command = "$python_path \"$link_wrapper\" --output=\"$outfile\"$strip_switch -- $link_command"
	description = "LINK $outfile"
	rspfile_content = "{{inputs}}"
	outputs = [
	outfile,
	]
	if (outfile != unstripped_outfile) {
	outputs += [ unstripped_outfile ]
	}
	if (defined(invoker.link_outputs)) {
	outputs += invoker.link_outputs
	}
	}

	# These two are really entirely generic, but have to be repeated in
	# each toolchain because GN doesn't allow a template to be used here.
	# See //build/toolchain/toolchain.gni for details.
	tool("stamp") {
	command = stamp_command
	description = "STAMP {{output}}"
	}
	tool("copy") {
	command = copy_command
	description = "COPY {{source}} {{output}}"
	}

	forward_variables_from(invoker, [ "deps" ])
	}
	}

	# This is a shorthand for gcc_toolchain instances based on the Chromium-built
	# version of Clang. Only the toolchain_cpu and toolchain_os variables need to
	# be specified by the invoker, and optionally toolprefix if it's a
	# cross-compile case. Note that for a cross-compile case this toolchain
	# requires a config to pass the appropriate -target option, or else it will
	# actually just be doing a native compile. The invoker can optionally override
	# use_gold too.
	template("clang_toolchain") {
	if (defined(invoker.toolprefix)) {
	toolprefix = invoker.toolprefix
	} else {
	toolprefix = ""
	}

	gcc_toolchain(target_name) {
	prefix = rebase_path("$clang_base_path/bin", root_build_dir)
	cc = "$prefix/clang"
	cxx = "$prefix/clang++"
	ld = cxx
	readelf = "${toolprefix}readelf"
	ar = "${prefix}/llvm-ar"
	nm = "${toolprefix}nm"

	forward_variables_from(invoker,
	[
	"strip",
	"is_clang_analysis_supported",
	"shlib_extension",
	])

	toolchain_args = {
	if (defined(invoker.toolchain_args)) {
	forward_variables_from(invoker.toolchain_args, "*")
	}
	}
	}
	}