Add PGO support

Author: nikic

src/librustc_codegen_llvm/back/write.rs

@@ -346,6 +346,24 @@ pub(crate) unsafe fn optimize(
                 || cgcx.lto == Lto::ThinLocal
                 || (cgcx.lto != Lto::Fat && cgcx.opts.cg.linker_plugin_lto.enabled());
             let using_thin_buffers = prepare_for_thin_lto || config.bitcode_needed();
+
+            let pgo_gen_path = match config.pgo_gen {
+                SwitchWithOptPath::Enabled(ref opt_dir_path) => {
+                    let path = if let Some(dir_path) = opt_dir_path {
+                        dir_path.join("default_%m.profraw")
+                    } else {
+                        PathBuf::from("default_%m.profraw")
+                    };
+
+                    Some(CString::new(format!("{}", path.display())).unwrap())
+                }
+                SwitchWithOptPath::Disabled => None,
+            };
+            let pgo_use_path = config
+                .pgo_use
+                .as_ref()
+                .map(|path_buf| CString::new(path_buf.to_string_lossy().as_bytes()).unwrap());
+
             // FIXME: NewPM doesn't seem to have a facility to provide custom InlineParams.
             // FIXME: Extra passes.
             llvm::LLVMRustOptimizeWithNewPassManager(
@@ -367,6 +385,8 @@ pub(crate) unsafe fn optimize(
                 Some(Sanitizer::Address) == config.sanitizer,
                 config.sanitizer.as_ref().map_or(false, |s| config.sanitizer_recover.contains(s)),
                 config.sanitizer_memory_track_origins as c_int,
+                pgo_gen_path.as_ref().map_or(std::ptr::null(), |s| s.as_ptr()),
+                pgo_use_path.as_ref().map_or(std::ptr::null(), |s| s.as_ptr()),
             );
             return Ok(());
         }

src/librustc_codegen_llvm/llvm/ffi.rs

@@ -1924,6 +1924,8 @@ extern "C" {
         SanitizeAddress: bool,
         SanitizeRecover: bool,
         SanitizeMemoryTrackOrigins: c_int,
+        PGOGenPath: *const c_char,
+        PGOUsePath: *const c_char,
     );
     pub fn LLVMRustPrintModule(
         M: &'a Module,

src/rustllvm/PassWrapper.cpp

@@ -613,7 +613,8 @@ LLVMRustOptimizeWithNewPassManager(
     bool MergeFunctions, bool UnrollLoops, bool SLPVectorize, bool LoopVectorize,
     bool DisableSimplifyLibCalls,
     bool SanitizeMemory, bool SanitizeThread, bool SanitizeAddress,
-    bool SanitizeRecover, int SanitizeMemoryTrackOrigins) {
+    bool SanitizeRecover, int SanitizeMemoryTrackOrigins,
+    const char *PGOGenPath, const char *PGOUsePath) {
   Module *TheModule = unwrap(ModuleRef);
   TargetMachine *TM = unwrap(TMRef);
   PassBuilder::OptimizationLevel OptLevel = fromRust(OptLevelRust);
@@ -634,6 +635,14 @@ LLVMRustOptimizeWithNewPassManager(
 
   // FIXME: PGOOpt
   Optional<PGOOptions> PGOOpt;
+  if (PGOGenPath) {
+    assert(!PGOUsePath);
+    PGOOpt = PGOOptions(PGOGenPath, "", "", PGOOptions::IRInstr);
+  } else if (PGOUsePath) {
+    assert(!PGOGenPath);
+    PGOOpt = PGOOptions(PGOUsePath, "", "", PGOOptions::IRUse);
+  }
+
   PassBuilder PB(TM, PTO, PGOOpt, &PIC);
 
   bool DebugPassManager = false;