electron/js2c_toolchain.gni

# Copyright (c) 2023 Microsoft, GmbH
# Use of this source code is governed by the MIT license that can be
# found in the LICENSE file.

declare_args() {
  electron_js2c_toolchain = ""
}

if (electron_js2c_toolchain == "") {
  if (current_os == host_os && current_cpu == host_cpu) {
    # This is not a cross-compile, so build the snapshot with the current
    # toolchain.
    electron_js2c_toolchain = current_toolchain
  } else if (current_os == host_os && current_cpu == "x86" &&
             host_cpu == "x64") {
    # This is an x64 -> x86 cross-compile, but x64 hosts can usually run x86
    # binaries built for the same OS, so build the snapshot with the current
    # toolchain here, too.
    electron_js2c_toolchain = current_toolchain
  } else if (current_os == host_os && host_cpu == "arm64" &&
             current_cpu == "arm") {
    # Trying to compile 32-bit arm on arm64. Good luck!
    electron_js2c_toolchain = current_toolchain
  } else if (host_cpu == current_cpu) {
    # Cross-build from same ISA on one OS to another. For example:
    # * targeting win/x64 on a linux/x64 host
    # * targeting win/arm64 on a mac/arm64 host
    electron_js2c_toolchain = host_toolchain
  } else if (host_cpu == "arm64" && current_cpu == "x64") {
    # Cross-build from arm64 to intel (likely on an Apple Silicon mac).
    electron_js2c_toolchain =
        "//build/toolchain/${host_os}:clang_arm64_v8_$current_cpu"
  } else if (host_cpu == "x64") {
    # This is a cross-compile from an x64 host to either a non-Intel target
    # cpu or to 32-bit x86 on a different target OS.

    assert(current_cpu != "x64", "handled by host_cpu == current_cpu branch")
    if (current_cpu == "x86") {
      _cpus = current_cpu
    } else if (current_cpu == "arm64") {
      if (is_win) {
        # set _cpus to blank for Windows ARM64 so host_toolchain could be
        # selected as snapshot toolchain later.
        _cpus = ""
      } else {
        _cpus = "x64_v8_${current_cpu}"
      }
    } else if (current_cpu == "arm") {
      _cpus = "x86_v8_${current_cpu}"
    } else {
      # This branch should not be reached; leave _cpus blank so the assert
      # below will fail.
      _cpus = ""
    }

    if (_cpus != "") {
      electron_js2c_toolchain = "//build/toolchain/${host_os}:clang_${_cpus}"
    } else if (is_win && current_cpu == "arm64") {
      # cross compile Windows arm64 with host toolchain.
      electron_js2c_toolchain = host_toolchain
    }
  } else if (host_cpu == "arm64" && current_cpu == "arm64" &&
             host_os == "mac") {
    # cross compile iOS arm64 with host_toolchain
    electron_js2c_toolchain = host_toolchain
  }
}

assert(electron_js2c_toolchain != "",
       "Do not know how to build js2c for $current_toolchain " +
           "on $host_os $host_cpu")