Beginning work on GN build

build/toolchain/gcc_toolchain.gni

+# 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.
+
+import("//build/config/nacl/config.gni")
+import("//build/config/sanitizers/sanitizers.gni")
+import("//build/toolchain/cc_wrapper.gni")
+import("//build/toolchain/goma.gni")
+import("//build/toolchain/toolchain.gni")
+
+# "concurrent_links" is a toolchain variable. By computing it here rather than
+# inside the toolchain, the exec_script will only get run once rather than
+# each time the toolchain template is invoked.
+if (allow_posix_link_time_opt || is_cfi) {
+  concurrent_links_ =
+      exec_script("get_concurrent_links.py", [ "--lto" ], "value")
+} else {
+  concurrent_links_ = exec_script("get_concurrent_links.py", [], "value")
+}
+
+# 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
+# and the following which is used in the toolchain_args
+#  - toolchain_cpu  (What "current_cpu" should be set to when invoking a
+#                    build using this toolchain.)
+#  - toolchain_os  (What "current_os" should be set to when invoking a
+#                   build using this toolchain.)
+#
+# 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/.
+#
+# Optional build argument contols.
+#
+#  - clear_sanitizers
+#      When set to true, is_asan, is_msan, etc.will all be set to false. Often
+#      secondary toolchains do not want to run with sanitizers.
+#  - is_clang
+#      Whether to use clang instead of gcc.
+#  - is_component_build
+#      Whether to forcibly enable or disable component builds for this
+#      toolchain; if not specified, the toolchain will inherit the
+#      default setting.
+#  - is_nacl_glibc
+#      Whether NaCl code is built using Glibc instead of Newlib.
+#  - cc_wrapper
+#      Override the global cc_wrapper setting. e.g. "ccache" or "icecc".
+#      useful to opt-out of cc_wrapper in a particular toolchain by setting
+#      cc_wrapper = "" in it.
+#  - use_debug_fission
+#      Override the global use_debug_fission setting, useful if the particular
+#      toolchain should not be generating split-dwarf code.
+#  - use_goma
+#      Override the global use_goma setting, useful to opt-out of goma in a
+#      particular toolchain by setting use_gome = false in it.
+#  - use_gold
+#      Override the global use_gold setting, useful if the particular
+#      toolchain has a custom link step that is not actually using Gold.
+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.toolchain_cpu),
+           "gcc_toolchain() must specify a \"toolchain_cpu\"")
+    assert(defined(invoker.toolchain_os),
+           "gcc_toolchain() must specify a \"toolchain_os\"")
+
+    concurrent_links = concurrent_links_
+
+    if (defined(invoker.cc_wrapper)) {
+      cc_wrapper = invoker.cc_wrapper
+    }
+    if (defined(invoker.use_goma)) {
+      use_goma = invoker.use_goma
+    }
+    if (use_goma) {
+      assert(cc_wrapper == "", "Goma and cc_wrapper can't be used together.")
+      compiler_prefix = "$goma_dir/gomacc "
+    } else if (cc_wrapper != "") {
+      compiler_prefix = cc_wrapper + " "
+    } else {
+      compiler_prefix = ""
+    }
+
+    # 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 = ""
+    }
+
+    cc = compiler_prefix + invoker.cc
+    cxx = compiler_prefix + invoker.cxx
+    ar = invoker.ar
+    ld = invoker.ld
+    if (defined(invoker.readelf)) {
+      readelf = invoker.readelf
+    } else {
+      readelf = "readelf"
+    }
+    if (defined(invoker.nm)) {
+      nm = invoker.nm
+    } else {
+      nm = "nm"
+    }
+
+    if (defined(invoker.shlib_extension)) {
+      default_shlib_extension = invoker.shlib_extension
+    } else {
+      default_shlib_extension = 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 = "$cc -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("//build/toolchain/gcc_ar_wrapper.py", root_build_dir)
+      command = "$python_path \"$ar_wrapper\" --output={{output}} --ar=\"$ar\" {{arflags}} rcsD @\"$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}}/$soname"  # Possibly including toolchain dir.
+      rspfile = sofile + ".rsp"
+
+      if (defined(invoker.strip)) {
+        unstripped_sofile = "{{root_out_dir}}/lib.unstripped/$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("//build/toolchain/gcc_solink_wrapper.py")
+      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 $sofile"
+
+      # Use this for {{output_extension}} expansions unless a target manually
+      # overrides it (in which case {{output_extension}} will be what the target
+      # specifies).
+      default_output_extension = default_shlib_extension
+
+      default_output_dir = "{{root_out_dir}}"
+      if (shlib_subdir != ".") {
+        default_output_dir += "/$shlib_subdir"
+      }
+
+      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}}/$soname"
+      rspfile = sofile + ".rsp"
+
+      if (defined(invoker.strip)) {
+        unstripped_sofile = "{{root_out_dir}}/lib.unstripped/$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 $sofile"
+
+      # Use this for {{output_extension}} expansions unless a target manually
+      # overrides it (in which case {{output_extension}} will be what the target
+      # specifies).
+      if (defined(invoker.loadable_module_extension)) {
+        default_output_extension = invoker.loadable_module_extension
+      } else {
+        default_output_extension = default_shlib_extension
+      }
+
+      default_output_dir = "{{root_out_dir}}"
+      if (shlib_subdir != ".") {
+        default_output_dir += "/$shlib_subdir"
+      }
+
+      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
+
+      # 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/$exename"
+      }
+
+      command = "$ld {{ldflags}}${extra_ldflags} -o \"$unstripped_outfile\" -Wl,--start-group @\"$rspfile\" {{solibs}} -Wl,--end-group $libs_section_prefix {{libs}} $libs_section_postfix"
+      if (defined(invoker.strip)) {
+        link_wrapper =
+            rebase_path("//build/toolchain/gcc_link_wrapper.py", root_build_dir)
+        command = "$python_path \"$link_wrapper\" --strip=\"${invoker.strip}\" --unstripped-file=\"$unstripped_outfile\" --output=\"$outfile\" -- $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_description
+    }
+    tool("copy") {
+      command = copy_command
+      description = copy_description
+    }
+
+    # 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() {
+      current_cpu = invoker.toolchain_cpu
+      current_os = invoker.toolchain_os
+
+      # These values need to be passed through unchanged.
+      host_toolchain = host_toolchain
+      target_os = target_os
+      target_cpu = target_cpu
+
+      if (defined(invoker.is_clang)) {
+        is_clang = invoker.is_clang
+      }
+      if (defined(invoker.is_component_build)) {
+        is_component_build = invoker.is_component_build
+      }
+      if (defined(invoker.is_nacl_glibc)) {
+        is_nacl_glibc = invoker.is_nacl_glibc
+      }
+      if (defined(invoker.symbol_level)) {
+        symbol_level = invoker.symbol_level
+      }
+      if (defined(invoker.use_allocator)) {
+        use_allocator = invoker.use_allocator
+      }
+      if (defined(invoker.use_debug_fission)) {
+        use_debug_fission = invoker.use_debug_fission
+      }
+      if (defined(invoker.use_gold)) {
+        use_gold = invoker.use_gold
+      }
+      if (defined(invoker.use_sysroot)) {
+        use_sysroot = invoker.use_sysroot
+      }
+
+      # Disable sanitizers for non-default toolchains.
+      is_asan = false
+      is_cfi = false
+      is_lsan = false
+      is_msan = false
+      is_syzyasan = false
+      is_tsan = false
+      is_ubsan = false
+      is_ubsan_vptr = false
+    }
+
+    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") {
+  assert(defined(invoker.toolchain_cpu),
+         "clang_toolchain() must specify a \"toolchain_cpu\"")
+  assert(defined(invoker.toolchain_os),
+         "clang_toolchain() must specify a \"toolchain_os\"")
+  if (defined(invoker.toolprefix)) {
+    toolprefix = invoker.toolprefix
+  } else {
+    toolprefix = ""
+  }
+
+  gcc_toolchain(target_name) {
+    prefix = rebase_path("//third_party/llvm-build/Release+Asserts/bin",
+                         root_build_dir)
+    cc = "$prefix/clang"
+    cxx = "$prefix/clang++"
+    ld = cxx
+    is_clang = true
+
+    readelf = "${toolprefix}readelf"
+    ar = "${toolprefix}ar"
+    nm = "${toolprefix}nm"
+
+    forward_variables_from(invoker,
+                           [
+                             "toolchain_cpu",
+                             "toolchain_os",
+                             "use_gold",
+                             "strip",
+                           ])
+
+    if (defined(invoker.use_debug_fission)) {
+      use_debug_fission = invoker.use_debug_fission
+    }
+  }
+}