concurrent_links.gni

# Copyright 2016 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.

# This file should only be imported from files that define toolchains.
# There's no way to enforce this exactly, but all toolchains are processed
# in the context of the default_toolchain, so we can at least check for that.
assert(current_toolchain == default_toolchain)

import("//build/config/compiler/compiler.gni")
import("//build/config/mac/symbols.gni")
import("//build/config/sanitizers/sanitizers.gni")
import("//build/toolchain/toolchain.gni")

declare_args() {
  # Limit the number of concurrent links; we often want to run fewer
  # links at once than we do compiles, because linking is memory-intensive.
  # The default to use varies by platform and by the amount of memory
  # available, so we call out to a script to get the right value.
  concurrent_links = -1
}

if (concurrent_links == -1) {
  if (use_thin_lto) {
    _args = [ "--reserve_mem_gb=10" ]
    if (is_win) {
      # Based on measurements of linking chrome.dll and chrome_child.dll, plus
      # a little padding to account for future growth.
      _args += [ "--mem_per_link_gb=45" ]
    } else {
      _args += [ "--mem_per_link_gb=10" ]
    }
  } else if (use_sanitizer_coverage || use_fuzzing_engine) {
    # Sanitizer coverage instrumentation increases linker memory consumption
    # significantly.
    _args = [ "--mem_per_link_gb=16" ]
  } else if (is_win && symbol_level == 1 && !is_debug && is_component_build) {
    _args = [ "--mem_per_link_gb=3" ]
  } else if (is_win) {
    _args = [ "--mem_per_link_gb=5" ]
  } else if (is_mac) {
    if (enable_dsyms) {
      _args = [ "--mem_per_link_gb=12" ]
    } else {
      _args = [ "--mem_per_link_gb=4" ]
    }
  } else if (is_android && !is_component_build && symbol_level == 2) {
    # Full debug symbols require large memory for link.
    _args = [ "--mem_per_link_gb=25" ]
  } else if (is_android && !is_debug && !using_sanitizer && symbol_level < 2) {
    # Increase the number of concurrent links for release bots. Debug builds
    # make heavier use of ProGuard, and so should not be raised. Sanitizers also
    # increase the memory overhead.
    if (symbol_level == 1) {
      _args = [ "--mem_per_link_gb=6" ]
    } else {
      _args = [ "--mem_per_link_gb=4" ]
    }
  } else if (is_linux && !is_chromeos && symbol_level == 0) {
    # Memory consumption on link without debug symbols is low on linux.
    _args = [ "--mem_per_link_gb=3" ]
  } else {
    _args = []
  }

  # TODO(crbug.com/617429) Pass more build configuration info to the script
  # so that we can compute better values.
  concurrent_links = exec_script("get_concurrent_links.py", _args, "value")
}