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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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4
compiler/rustc_session/src/options.rs
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@ -1040,6 +1040,8 @@ options! {
"combine CGUs into a single one"),
crate_attr: Vec<String> = (Vec::new(), parse_string_push, [TRACKED],
"inject the given attribute in the crate"),
debug_info_for_profiling: bool = (false, parse_bool, [TRACKED],
"emit discriminators and other data necessary for AutoFDO"),
debug_macros: bool = (false, parse_bool, [TRACKED],
"emit line numbers debug info inside macros (default: no)"),
deduplicate_diagnostics: bool = (true, parse_bool, [UNTRACKED],
@ -1242,6 +1244,8 @@ options! {
(default based on relative source path)"),
profiler_runtime: String = (String::from("profiler_builtins"), parse_string, [TRACKED],
"name of the profiler runtime crate to automatically inject (default: `profiler_builtins`)"),
profile_sample_use: Option<PathBuf> = (None, parse_opt_pathbuf, [TRACKED],
"use the given `.prof` file for sampled profile-guided optimization (also known as AutoFDO)"),
query_dep_graph: bool = (false, parse_bool, [UNTRACKED],
"enable queries of the dependency graph for regression testing (default: no)"),
query_stats: bool = (false, parse_bool, [UNTRACKED],