blob: 8418f34d4106265aeabeab35b0cb603e36f5c8af [file] [log] [blame]
# Copyright 2020 The Pigweed Authors
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may not
# use this file except in compliance with the License. You may obtain a copy of
# the License at
#
# https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations under
# the License.
import("//build_overrides/pigweed.gni")
import("$dir_pw_build/exec.gni")
import("$dir_pw_build/target_types.gni")
import("$dir_pw_toolchain/generate_toolchain.gni")
# Preprocess a linker script and turn it into a target.
#
# In lieu of direct GN support for linker scripts, this template makes it
# possible to run the C Preprocessor on a linker script file so defines can
# be properly evaluated before the linker script is passed to the dir_pw_build
#
# TODO(pwbug/53): This template serves as a stand-in until native GN support for
# linker scripts is added.
#
# Args:
# linker_script: The linker script to send through the C preprocessor.
#
# defines: Preprocessor defines to apply when running the C preprocessor.
#
# cflags: Flags to pass to the C compiler.
#
# includes: Include these files when running the C preprocessor.
#
# inputs: Files that, when changed, should trigger a re-build of the linker
# script. linker_script and includes are implicitly added to this by the
# template.
#
# Example:
#
# pw_linker_script("generic_linker_script") {
# defines = [
# "PW_HEAP_SIZE=1K",
# "PW_NOINIT_SIZE=512"
# ]
# linker_script = "basic_script.ld"
# }
#
template("pw_linker_script") {
assert(
defined(invoker.linker_script) && invoker.linker_script != "",
"$target_name did not set `linker_script` to refer to a valid linker " +
"script. This variable is required for linker script targets.")
_final_linker_script = "${target_gen_dir}/${target_name}_final.ld"
# This action invokes the C compiler provided by the target to preprocess the
# linker script.
pw_exec("${target_name}_preprocess") {
program = pw_toolchain_SCOPE.cxx
inputs = [ invoker.linker_script ]
args = [
# Run compiler in preprocessor-only mode.
"-E",
# Do not generate linemarkers in output.
"-P",
# Do not discard comments.
"-C",
# Treat the following file as a C file.
"-x",
"c",
rebase_path(invoker.linker_script, root_build_dir),
]
# Trigger a re-generation of the linker script when these inputs change.
if (defined(invoker.inputs)) {
inputs += invoker.inputs
}
# Include any explicitly listed C flags.
if (defined(invoker.cflags)) {
args += invoker.cflags
}
# Include files from the command line.
if (defined(invoker.includes)) {
inputs += invoker.includes
foreach(include_file, invoker.includes) {
args += [ "-include" + rebase_path(include_file, root_build_dir) ]
}
}
# Add defines.
if (defined(invoker.defines)) {
foreach(compiler_define, invoker.defines) {
args += [ "-D${compiler_define}" ]
}
}
# Set output file.
args += [
"-o",
rebase_path(_final_linker_script, root_build_dir),
]
outputs = [ _final_linker_script ]
}
# This config adds a the linker script produced by the preprocess action to
# the linker flags.
config("${target_name}_config") {
inputs = [ invoker.linker_script ]
if (!defined(invoker.ldflags)) {
ldflags = []
}
ldflags += [ "-T" + rebase_path(_final_linker_script, root_build_dir) ]
}
# The target that adds the linker script config to this library and everything
# that depends on it.
pw_source_set(target_name) {
inputs = [ _final_linker_script ]
all_dependent_configs = [ ":${target_name}_config" ]
deps = [ ":${target_name}_preprocess" ]
}
}