Rollup merge of #87918 - mikebenfield:pr-afdo, r=nikic

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 -Clink-arg='Wl,--no-rosegment' -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

The option -Clink-arg='Wl,--no-rosegment' is necessary to avoid lld
putting an extra RO segment before the executable code, which would make
the binary silently incompatible with create_llvm_prof.

1 files changed, 21 insertions, 9 deletions

diff --git a/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp b/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp
index ddb5f7dcebf..87f423fb2d5 100644
--- a/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp
+++ b/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp
@@ -25,6 +25,7 @@
 #include "llvm/Transforms/IPO/PassManagerBuilder.h"
 #include "llvm/Transforms/IPO/AlwaysInliner.h"
 #include "llvm/Transforms/IPO/FunctionImport.h"
+#include "llvm/Transforms/Utils/AddDiscriminators.h"
 #include "llvm/Transforms/Utils/FunctionImportUtils.h"
 #include "llvm/LTO/LTO.h"
 #include "llvm-c/Transforms/PassManagerBuilder.h"
@@ -39,6 +40,7 @@
 #include "llvm/Transforms/Instrumentation/HWAddressSanitizer.h"
 #include "llvm/Transforms/Utils/CanonicalizeAliases.h"
 #include "llvm/Transforms/Utils/NameAnonGlobals.h"
+#include "llvm/Transforms/Utils.h"
 
 using namespace llvm;
 
@@ -523,7 +525,7 @@ extern "C" void LLVMRustDisposeTargetMachine(LLVMTargetMachineRef TM) {
 extern "C" void LLVMRustConfigurePassManagerBuilder(
     LLVMPassManagerBuilderRef PMBR, LLVMRustCodeGenOptLevel OptLevel,
     bool MergeFunctions, bool SLPVectorize, bool LoopVectorize, bool PrepareForThinLTO,
-    const char* PGOGenPath, const char* PGOUsePath) {
+    const char* PGOGenPath, const char* PGOUsePath, const char* PGOSampleUsePath) {
   unwrap(PMBR)->MergeFunctions = MergeFunctions;
   unwrap(PMBR)->SLPVectorize = SLPVectorize;
   unwrap(PMBR)->OptLevel = fromRust(OptLevel);
@@ -531,13 +533,14 @@ extern "C" void LLVMRustConfigurePassManagerBuilder(
   unwrap(PMBR)->PrepareForThinLTO = PrepareForThinLTO;
 
   if (PGOGenPath) {
-    assert(!PGOUsePath);
+    assert(!PGOUsePath && !PGOSampleUsePath);
     unwrap(PMBR)->EnablePGOInstrGen = true;
     unwrap(PMBR)->PGOInstrGen = PGOGenPath;
-  }
-  if (PGOUsePath) {
-    assert(!PGOGenPath);
+  } else if (PGOUsePath) {
+    assert(!PGOSampleUsePath);
     unwrap(PMBR)->PGOInstrUse = PGOUsePath;
+  } else if (PGOSampleUsePath) {
+    unwrap(PMBR)->PGOSampleUse = PGOSampleUsePath;
   }
 }
 
@@ -759,6 +762,7 @@ LLVMRustOptimizeWithNewPassManager(
     LLVMRustSanitizerOptions *SanitizerOptions,
     const char *PGOGenPath, const char *PGOUsePath,
     bool InstrumentCoverage, bool InstrumentGCOV,
+    const char *PGOSampleUsePath, bool DebugInfoForProfiling,
     void* LlvmSelfProfiler,
     LLVMRustSelfProfileBeforePassCallback BeforePassCallback,
     LLVMRustSelfProfileAfterPassCallback AfterPassCallback,
@@ -797,11 +801,19 @@ LLVMRustOptimizeWithNewPassManager(
 
   Optional<PGOOptions> PGOOpt;
   if (PGOGenPath) {
-    assert(!PGOUsePath);
-    PGOOpt = PGOOptions(PGOGenPath, "", "", PGOOptions::IRInstr);
+    assert(!PGOUsePath && !PGOSampleUsePath);
+    PGOOpt = PGOOptions(PGOGenPath, "", "", PGOOptions::IRInstr,
+                        PGOOptions::NoCSAction, DebugInfoForProfiling);
   } else if (PGOUsePath) {
-    assert(!PGOGenPath);
-    PGOOpt = PGOOptions(PGOUsePath, "", "", PGOOptions::IRUse);
+    assert(!PGOSampleUsePath);
+    PGOOpt = PGOOptions(PGOUsePath, "", "", PGOOptions::IRUse,
+                        PGOOptions::NoCSAction, DebugInfoForProfiling);
+  } else if (PGOSampleUsePath) {
+    PGOOpt = PGOOptions(PGOSampleUsePath, "", "", PGOOptions::SampleUse,
+                        PGOOptions::NoCSAction, DebugInfoForProfiling);
+  } else if (DebugInfoForProfiling) {
+    PGOOpt = PGOOptions("", "", "", PGOOptions::NoAction,
+                        PGOOptions::NoCSAction, DebugInfoForProfiling);
   }
 
 #if LLVM_VERSION_GE(12, 0) && !LLVM_VERSION_GE(13,0)