# The BUILDCONFIG file sets this config on targets by default, which means when
# building with ThinLTO, no optimization is performed in the link step.
config("thinlto_optimize_default") {
  if (!is_debug && use_thin_lto && is_a_target_toolchain) {
    lto_opt_level = 2

    if (is_win) {
      ldflags = [ "/opt:lldlto=" + lto_opt_level ]
    } else {
      ldflags = [ "-Wl,--lto-O" + lto_opt_level ]
    }
  }
}

# Use this to enable optimization in the ThinLTO link step for select targets
# when thin_lto_enable_optimizations is set by doing:
#
#   configs -= [ "//build/config/compiler:thinlto_optimize_default" ]
#   configs += [ "//build/config/compiler:thinlto_optimize_max" ]
#
# Since it makes linking significantly slower and more resource intensive, only
# use it on important targets such as the main browser executable or dll.
config("thinlto_optimize_max") {
  if (!is_debug && use_thin_lto && is_a_target_toolchain) {
    if (thin_lto_enable_optimizations) {
      lto_opt_level = 2
    } else {
      lto_opt_level = 2
    }

    if (is_win) {
      ldflags = [ "/opt:lldlto=" + lto_opt_level ]
    } else {
      ldflags = [ "-Wl,--lto-O" + lto_opt_level ]
    }
  }
}

----------------

# Default "optimization on" config.
config("optimize") {
  if (is_win) {
    if (chrome_pgo_phase != 2) {
      # Favor size over speed, /O1 must be before the common flags.
      # /O1 implies /Os and /GF.
      cflags = [ "/O1" ] + common_optimize_on_cflags + [ "/Oi" ]
    } else {
      # PGO requires all translation units to be compiled with /O2. The actual
      # optimization level will be decided based on the profiling data.
      cflags = [ "/O2" ] + common_optimize_on_cflags + [ "/Oi" ]
    }
  } else if (optimize_for_size) {
    # Favor size over speed.
    if (is_clang) {
      cflags = [ "-O2" ] + common_optimize_on_cflags
    } else {
      cflags = [ "-O2" ] + common_optimize_on_cflags
    }
  } else if (is_chromeos) {
    # TODO(gbiv): This is partially favoring size over speed. CrOS exclusively
    # uses clang, and -Os in clang is more of a size-conscious -O2 than "size at
    # any cost" (AKA -Oz). It'd be nice to:
    # - Make `optimize_for_size` apply to all platforms where we're optimizing
    #   for size by default (so, also Windows)
    # - Investigate -Oz here, maybe just for ARM?
    cflags = [ "-Os" ] + common_optimize_on_cflags
  } else {
    cflags = [ "-O2" ] + common_optimize_on_cflags
  }
  if (optimize_for_size) {
    rustflags = [ "-Copt-level=2" ]
  } else {
    rustflags = [ "-Copt-level=3" ]
  }
  ldflags = common_optimize_on_ldflags
}

# Turn off optimizations.
config("no_optimize") {
  if (is_win) {
    cflags = [
      "/Od",  # Disable optimization.
      "/Ob0",  # Disable all inlining (on by default).
      "/GF",  # Enable string pooling (off by default).
    ]

    if (target_cpu == "arm64") {
      # Disable omitting frame pointers for no_optimize build because stack
      # traces on Windows ARM64 rely on it.
      cflags += [ "/Oy-" ]
    }
  } else if (is_android && !android_full_debug) {
    # On Android we kind of optimize some things that don't affect debugging
    # much even when optimization is disabled to get the binary size down.
    if (is_clang) {
      cflags = [ "-Oz" ] + common_optimize_on_cflags
    } else {
      cflags = [ "-Os" ] + common_optimize_on_cflags
    }

    if (!is_component_build) {
      # Required for library partitions. Without this all symbols just end up
      # in the base partition.
      ldflags = [ "-Wl,--gc-sections" ]
    }
  } else if (is_fuchsia) {
    # On Fuchsia, we optimize for size here to reduce the size of debug build
    # packages so they can be run in a KVM. See crbug.com/910243 for details.
    cflags = [ "-Og" ]
  } else {
    cflags = [ "-O0" ]
    ldflags = []
  }
}

# Turns up the optimization level. On Windows, this implies whole program
# optimization and link-time code generation which is very expensive and should
# be used sparingly.
config("optimize_max") {
  if (is_nacl && is_nacl_irt) {
    # The NaCl IRT is a special case and always wants its own config.
    # Various components do:
    #   if (!is_debug) {
    #     configs -= [ "//build/config/compiler:default_optimization" ]
    #     configs += [ "//build/config/compiler:optimize_max" ]
    #   }
    # So this config has to have the selection logic just like
    # "default_optimization", below.
    configs = [ "//build/config/nacl:irt_optimize" ]
  } else {
    ldflags = common_optimize_on_ldflags
    if (is_win) {
      # Favor speed over size, /O2 must be before the common flags.
      # /O2 implies /Ot, /Oi, and /GF.
      cflags = [ "-Xclang", "-O3", ] + common_optimize_on_cflags
    } else if (optimize_for_fuzzing) {
      cflags = [ "-O1" ] + common_optimize_on_cflags
    } else {
      cflags = [ "-O3" ] + common_optimize_on_cflags
    }
    rustflags = [ "-Copt-level=3" ]
  }
}

# This config can be used to override the default settings for per-component
# and whole-program optimization, optimizing the particular target for speed
# instead of code size. This config is exactly the same as "optimize_max"
# except that we use -O3 instead of -O2 on non-win, non-IRT platforms.
#
# TODO(crbug.com/621335) - rework how all of these configs are related
# so that we don't need this disclaimer.
config("optimize_speed") {
  if (is_nacl && is_nacl_irt) {
    # The NaCl IRT is a special case and always wants its own config.
    # Various components do:
    #   if (!is_debug) {
    #     configs -= [ "//build/config/compiler:default_optimization" ]
    #     configs += [ "//build/config/compiler:optimize_max" ]
    #   }
    # So this config has to have the selection logic just like
    # "default_optimization", below.
    configs = [ "//build/config/nacl:irt_optimize" ]
  } else {
    ldflags = common_optimize_on_ldflags
    if (is_win) {
      # Favor speed over size, /O2 must be before the common flags.
      # /O2 implies /Ot, /Oi, and /GF.
      cflags = [ "-Xclang", "-O3", ] + common_optimize_on_cflags
    } else if (optimize_for_fuzzing) {
      cflags = [ "-O1" ] + common_optimize_on_cflags
    } else {
      cflags = [ "-O3" ] + common_optimize_on_cflags
    }
    rustflags = [ "-Copt-level=3" ]
  }
}