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

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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.
This commit is contained in:
Jubilee 2021-10-07 20:26:09 -07:00 • committed by GitHub
commit 6c2d4bf3f7
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12 changed files with 120 additions and 9 deletions
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30
compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp
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@ -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)