mirror of
https://github.com/carbon-language/carbon-lang.git
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Chandler Carruth
0546b48a7d
Add support to the driver for CLI flags that select which CPU to target, which CPU to tune performance for, and which CPU features to enable. - `--target-cpu` selects the architecture of CPU to target, similar to `-march` on x86. This combines `-march` with `armv*` strings and `-mcpu` on Arm for specific CPU names. Similarly for RISC-V (if/when we support and test it), etc. Notably, `--target-cpu=native` targets the current native CPU. - `--target-cpu-tune` maps to `-mtune`. This is expected to be rarely if ever desirable, and I'm open to removing it, but if folks are relying on this for performance I didn't want to hide the option. - `--target-cpu-features` allows a "standard" (for LLVM) comma-separated list of LLVM subtarget features, including `+feature` and `-feature` syntax. These flags, when provided, establish the default baseline for CPU targeting and control how on-demand runtimes are built. They can be changed or overridden by additional Clang flags when using `--clang-arg`. A critical part of this is building runtimes on demand using these features. For that, we need to do some amount of canonicalization (re-using Clang's canonicalization to ensure consistent behavior), and extend the runtimes cache features to recognize these customizations. Note that only the top-level Carbon flags impact runtimes, any particular Clang arguments are only used by the specific compiles that receive those arguments. There is some nascent RISC-V support here, but it is incomplete and only minimally tested. Still, it seemed better to record the parts we could test than remove them. Assisted-by: Antigravity with Gemini
42 lines
1.3 KiB
C++
42 lines
1.3 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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#ifndef CARBON_TOOLCHAIN_DRIVER_CODEGEN_OPTIONS_H_
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#define CARBON_TOOLCHAIN_DRIVER_CODEGEN_OPTIONS_H_
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#include <string>
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#include "common/command_line.h"
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#include "llvm/ADT/ArrayRef.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/ADT/StringRef.h"
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#include "llvm/TargetParser/Host.h"
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namespace Carbon {
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// Shared codegen-related options.
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//
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// See the implementation of `Build` for documentation on members.
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struct CodegenOptions {
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auto Build(CommandLine::CommandBuilder& b) -> void;
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// Appends the Clang driver flags corresponding to `target_cpu`,
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// `target_cpu_tune`, and `target_cpu_features`.
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auto AppendClangArgs(llvm::SmallVectorImpl<std::string>& args) const -> void;
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// Returns the Clang driver flags corresponding to `target_cpu`,
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// `target_cpu_tune`, and `target_cpu_features`.
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auto GetClangArgs() const -> llvm::SmallVector<std::string>;
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std::string host = llvm::sys::getDefaultTargetTriple();
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llvm::StringRef target;
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llvm::StringRef target_cpu;
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llvm::StringRef target_cpu_tune;
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llvm::StringRef target_cpu_features;
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};
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} // namespace Carbon
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#endif // CARBON_TOOLCHAIN_DRIVER_CODEGEN_OPTIONS_H_
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