# 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")

# This value will be inherited in the toolchain below.
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:
#  - cc
#  - cxx
#  - ar
#  - 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:
#
#  - 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.
#  - post_solink
#      The content of this string, if specified, will be appended to the solink
#      command.
#  - deps
#      Just forwarded to the toolchain definition.
#
# Optional build argument contols.
#
#  - 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.
template("gcc_toolchain") {
  toolchain(target_name) {
    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.ar), "gcc_toolchain() must specify a \"ar\" 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\"")

    # 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 = ""
    }

    # We can't do string interpolation ($ in strings) on things with dots in
    # them. To allow us to use $cc below, for example, we create copies of
    # these values in our scope.
    cc = invoker.cc
    cxx = 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.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 = ""
    }

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

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

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

    tool("alink") {
      rspfile = "{{output}}.rsp"
      command = "rm -f {{output}} && $ar rcs {{output}} @$rspfile"
      description = "AR {{output}}"
      rspfile_content = "{{inputs}}"
      outputs = [
        "{{target_out_dir}}/{{target_output_name}}{{output_extension}}",
      ]
      default_output_extension = ".a"
      output_prefix = "lib"
    }

    tool("solink") {
      soname = "{{target_output_name}}{{output_extension}}"  # e.g. "libfoo.so".
      sofile = "{{root_out_dir}}/$soname"  # Possibly including toolchain dir.
      rspfile = sofile + ".rsp"

      # 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
      # to a temporary file, (3) if the temporary file has differences from the
      # existing .TOC file, overwrite it, otherwise, don't change it.
      tocfile = sofile + ".TOC"
      temporary_tocname = sofile + ".tmp"
      link_command =
          "$ld -shared {{ldflags}} -o $sofile -Wl,-soname=$soname @$rspfile"
      toc_command = "{ $readelf -d $sofile | grep SONAME ; $nm -gD -f p $sofile | cut -f1-2 -d' '; } > $temporary_tocname"
      replace_command = "if ! cmp -s $temporary_tocname $tocfile; then mv $temporary_tocname $tocfile; fi"

      command = "$link_command && $toc_command && $replace_command"
      if (defined(invoker.postsolink)) {
        command += " && " + invoker.postsolink
      }
      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 = ".so"

      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 (defined(invoker.solink_outputs)) {
        outputs += invoker.solink_outputs
      }
      link_output = sofile
      depend_output = tocfile
    }

    tool("link") {
      outfile = "{{root_out_dir}}/{{target_output_name}}{{output_extension}}"
      rspfile = "$outfile.rsp"
      command = "$ld {{ldflags}} -o $outfile -Wl,--start-group @$rspfile {{solibs}} -Wl,--end-group $libs_section_prefix {{libs}} $libs_section_postfix"

      default_output_extension = default_executable_extension

      if (defined(invoker.postlink)) {
        command += " && " + invoker.postlink
      }
      description = "LINK $outfile"
      rspfile_content = "{{inputs}}"
      outputs = [
        outfile,
      ]
      if (defined(invoker.link_outputs)) {
        outputs += invoker.link_outputs
      }
    }

    tool("stamp") {
      command = "touch {{output}}"
      description = "STAMP {{output}}"
    }

    tool("copy") {
      command = "ln -f {{source}} {{output}} 2>/dev/null || (rm -rf {{output}} && cp -af {{source}} {{output}})"
      description = "COPY {{source}} {{output}}"
    }

    # 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.
      target_os = target_os
      target_cpu = target_cpu

      forward_variables_from(invoker,
                             [
                               "is_clang",
                               "is_component_build",
                               "is_nacl_glibc",
                             ])
    }

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