bjoernager/rust
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Enable AutoFDO.

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This largely involves implementing the options debug-info-for-profiling
and profile-sample-use and forwarding them on to LLVM.

AutoFDO can be used on x86-64 Linux like this:
rustc -O -Cdebug-info-for-profiling main.rs -o main
perf record -b ./main
create_llvm_prof --binary=main --out=code.prof
rustc -O -Cprofile-sample-use=code.prof main.rs -o main2

Now `main2` will have feedback directed optimization applied to it.

The create_llvm_prof tool can be obtained from this github repository:
https://github.com/google/autofdo

Fixes #64892.
This commit is contained in:
Michael Benfield 2021-05-07 07:41:37 +00:00
parent d7539a6af0
commit a17193dbb9
12 changed files with 120 additions and 9 deletions
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3
compiler/rustc_codegen_ssa/src/back/linker.rs
View file

@ -286,6 +286,9 @@ impl<'a> GccLinker<'a> {
config::OptLevel::Aggressive => "O3",
};
if let Some(path) = &self.sess.opts.debugging_opts.profile_sample_use {
self.linker_arg(&format!("-plugin-opt=sample-profile={}", path.display()));
};
self.linker_arg(&format!("-plugin-opt={}", opt_level));
self.linker_arg(&format!("-plugin-opt=mcpu={}", self.target_cpu));
}

4
compiler/rustc_codegen_ssa/src/back/write.rs
View file

@ -83,6 +83,8 @@ pub struct ModuleConfig {
pub pgo_gen: SwitchWithOptPath,
pub pgo_use: Option<PathBuf>,
pub pgo_sample_use: Option<PathBuf>,
pub debug_info_for_profiling: bool,
pub instrument_coverage: bool,
pub instrument_gcov: bool,
@ -176,6 +178,8 @@ impl ModuleConfig {
SwitchWithOptPath::Disabled
),
pgo_use: if_regular!(sess.opts.cg.profile_use.clone(), None),
pgo_sample_use: if_regular!(sess.opts.debugging_opts.profile_sample_use.clone(), None),
debug_info_for_profiling: sess.opts.debugging_opts.debug_info_for_profiling,
instrument_coverage: if_regular!(sess.instrument_coverage(), false),
instrument_gcov: if_regular!(
// compiler_builtins overrides the codegen-units settings,