Enable AutoFDO.

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.

1 files changed, 2 insertions, 0 deletions

diff --git a/compiler/rustc_interface/src/tests.rs b/compiler/rustc_interface/src/tests.rs
index cfe13b1fd4e..844e5ab56a4 100644
--- a/compiler/rustc_interface/src/tests.rs
+++ b/compiler/rustc_interface/src/tests.rs
@@ -715,6 +715,7 @@ fn test_debugging_options_tracking_hash() {
     tracked!(chalk, true);
     tracked!(codegen_backend, Some("abc".to_string()));
     tracked!(crate_attr, vec!["abc".to_string()]);
+    tracked!(debug_info_for_profiling, true);
     tracked!(debug_macros, true);
     tracked!(dep_info_omit_d_target, true);
     tracked!(dual_proc_macros, true);
@@ -752,6 +753,7 @@ fn test_debugging_options_tracking_hash() {
     tracked!(profile, true);
     tracked!(profile_emit, Some(PathBuf::from("abc")));
     tracked!(profiler_runtime, "abc".to_string());
+    tracked!(profile_sample_use, Some(PathBuf::from("abc")));
     tracked!(relax_elf_relocations, Some(true));
     tracked!(relro_level, Some(RelroLevel::Full));
     tracked!(remap_cwd_prefix, Some(PathBuf::from("abc")));