mirror of
https://github.com/carbon-language/carbon-lang.git
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Jon Ross-Perkinsandjosh11b
c029931910
Note the purpose here is to make it simpler to add more subcommands, without adding a lot of things to Driver. This creates a copy of CodegenOptions, but it was double-registered at present which felt odd. It's also fairly small right now. If this becomes an issue, maybe we can look into using optional for delayed initialization, or just go back to straight sharing. --------- Co-authored-by: josh11b <15258583+josh11b@users.noreply.github.com>
120 lines
4.1 KiB
C++
120 lines
4.1 KiB
C++
// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
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// Exceptions. See /LICENSE for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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#include "toolchain/driver/link_subcommand.h"
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#include "llvm/TargetParser/Triple.h"
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#include "toolchain/driver/clang_runner.h"
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namespace Carbon {
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constexpr CommandLine::CommandInfo LinkOptions::Info = {
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.name = "link",
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.help = R"""(
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Link Carbon executables.
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This subcommand links Carbon executables by combining object files.
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TODO: Support linking binary libraries, both archives and shared libraries.
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TODO: Support linking against binary libraries.
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)""",
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};
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auto LinkOptions::Build(CommandLine::CommandBuilder& b) -> void {
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b.AddStringPositionalArg(
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{
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.name = "OBJECT_FILE",
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.help = R"""(
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The input object files.
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)""",
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},
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[&](auto& arg_b) {
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arg_b.Required(true);
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arg_b.Append(&object_filenames);
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});
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b.AddStringOption(
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{
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.name = "output",
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.value_name = "FILE",
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.help = R"""(
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The linked file name. The output is always a linked binary.
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)""",
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},
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[&](auto& arg_b) {
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arg_b.Required(true);
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arg_b.Set(&output_filename);
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});
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codegen_options.Build(b);
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}
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static void AddOSFlags(llvm::StringRef target,
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llvm::SmallVectorImpl<llvm::StringRef>& args) {
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llvm::Triple triple(target);
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switch (triple.getOS()) {
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case llvm::Triple::Darwin:
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case llvm::Triple::MacOSX:
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// On macOS we need to set the sysroot to a viable SDK. Currently, this
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// hard codes the path to be the unversioned symlink. The prefix is also
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// hard coded in Homebrew and so this seems likely to work reasonably
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// well. Homebrew and I suspect the Xcode Clang both have this hard coded
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// at build time, so this seems reasonably safe but we can revisit if/when
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// needed.
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args.push_back(
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"--sysroot=/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk");
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// We also need to insist on a modern linker, otherwise the driver tries
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// too old and deprecated flags. The specific number here comes from an
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// inspection of the Clang driver source code to understand where features
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// were enabled, and this appears to be the latest version to control
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// driver behavior.
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//
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// TODO: We should replace this with use of `lld` eventually.
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args.push_back("-mlinker-version=705");
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break;
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default:
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// By default, just let the Clang driver handle everything.
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break;
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}
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}
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auto LinkSubcommand::Run(DriverEnv& driver_env) -> DriverResult {
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// TODO: Currently we use the Clang driver to link. This works well on Unix
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// OSes but we likely need to directly build logic to invoke `link.exe` on
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// Windows where `cl.exe` doesn't typically cover that logic.
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// Use a reasonably large small vector here to minimize allocations. We expect
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// to link reasonably large numbers of object files.
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llvm::SmallVector<llvm::StringRef, 128> clang_args;
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// We link using a C++ mode of the driver.
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clang_args.push_back("--driver-mode=g++");
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// Use LLD, which we provide in our install directory, for linking.
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clang_args.push_back("-fuse-ld=lld");
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// Disable linking the C++ standard library until can build and ship it as
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// part of the Carbon toolchain. This clearly won't work once we get into
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// interop, but for now it avoids spurious failures and distraction. The plan
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// is to build and bundle libc++ at which point we can replace this with
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// pointing at our bundled library.
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// TODO: Replace this when ready.
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clang_args.push_back("-nostdlib++");
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// Add OS-specific flags based on the target.
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AddOSFlags(options_.codegen_options.target, clang_args);
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clang_args.push_back("-o");
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clang_args.push_back(options_.output_filename);
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clang_args.append(options_.object_filenames.begin(),
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options_.object_filenames.end());
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ClangRunner runner(driver_env.installation, options_.codegen_options.target,
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driver_env.vlog_stream);
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return {.success = runner.Run(clang_args)};
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}
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} // namespace Carbon
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