136 lines
4.6 KiB
Plaintext
136 lines
4.6 KiB
Plaintext
# Copyright 2019 The Dawn Authors
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import("../scripts/dawn_overrides_with_defaults.gni")
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###############################################################################
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# Template to wrap the Dawn code generator
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###############################################################################
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# Template to help with invocation of the Dawn code generator, looks like this:
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#
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# dawn_generator("my_target_gen") {
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# # Which generator target to output
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# target = "my_target"
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# # The list of expected outputs, generation fails if there's a mismatch
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# outputs = [
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# "MyTarget.cpp",
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# "MyTarget.h",
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# ]
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#
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# # Optional, use a custom generated file directory.
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# custom_gen_dir = "${target_gen_dir}/.."
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# }
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#
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# Using the generated files is done like so:
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#
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# shared_library("my_target") {
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# deps = [ ":my_target_gen "]
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# sources = get_target_outputs(":my_target_gen")
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# }
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#
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template("dawn_generator") {
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# The base arguments for the generator: from this dawn.json, generate this
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# target using templates in this directory.
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generator_args = [
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rebase_path("${dawn_root}/dawn.json", root_build_dir),
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"--wire-json",
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rebase_path("${dawn_root}/dawn_wire.json", root_build_dir),
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"--template-dir",
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rebase_path("${dawn_root}/generator/templates", root_build_dir),
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"--targets",
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invoker.target,
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]
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# Use the Jinja2 version pulled from the DEPS file. We do it so we don't
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# have version problems, and users don't have to install Jinja2.
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jinja2_python_path = rebase_path("${dawn_jinja2_dir}/..")
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generator_args += [
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"--extra-python-path",
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jinja2_python_path,
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]
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# Chooses either the default gen_dir or the custom one required by the
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# invoker. This allows moving the definition of code generators in different
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# BUILD.gn files without changing the location of generated file. Without
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# this generated headers could cause issues when old headers aren't removed.
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gen_dir = target_gen_dir
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if (defined(invoker.custom_gen_dir)) {
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gen_dir = invoker.custom_gen_dir
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}
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# For build parallelism GN wants to know the exact inputs and outputs of
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# action targets like we use for our code generator. We avoid asking the
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# generator about its inputs by using the "depfile" feature of GN/Ninja.
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#
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# A ninja limitation is that the depfile is a subset of Makefile that can
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# contain a single target, so we output a single "JSON-tarball" instead.
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json_tarball = "${gen_dir}/${target_name}.json_tarball"
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json_tarball_depfile = "${json_tarball}.d"
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generator_args += [
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"--output-json-tarball",
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rebase_path(json_tarball, root_build_dir),
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"--depfile",
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rebase_path(json_tarball_depfile, root_build_dir),
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]
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# After the JSON tarball is created we need an action target to extract it
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# with a list of its outputs. The invoker provided a list of expected
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# outputs. To make sure the list is in sync between the generator and the
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# build files, we write it to a file and ask the generator to assert it is
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# correct.
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expected_outputs_file = "${gen_dir}/${target_name}.expected_outputs"
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write_file(expected_outputs_file, invoker.outputs)
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generator_args += [
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"--expected-outputs-file",
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rebase_path(expected_outputs_file, root_build_dir),
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]
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# The code generator invocation that will write the JSON tarball, check the
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# outputs are what's expected and write a depfile for Ninja.
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action("${target_name}_json_tarball") {
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script = "${dawn_root}/generator/main.py"
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outputs = [
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json_tarball,
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]
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depfile = json_tarball_depfile
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args = generator_args
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}
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# Extract the JSON tarball into the gen_dir
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action("${target_name}") {
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script = "${dawn_root}/generator/extract_json.py"
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args = [
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rebase_path(json_tarball, root_build_dir),
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rebase_path(gen_dir, root_build_dir),
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]
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deps = [
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":${target_name}_json_tarball",
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]
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inputs = [
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json_tarball,
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]
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# The expected output list is relative to the gen_dir but action
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# target outputs are from the root dir so we need to rebase them.
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outputs = []
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foreach(source, invoker.outputs) {
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outputs += [ "${gen_dir}/${source}" ]
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}
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}
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}
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