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llvm-mirror/lib/Transforms/Instrumentation/Instrumentation.cpp
Hiroshi Yamauchi a56dc5d07f [PGO] Control Height Reduction
Summary:
Control height reduction merges conditional blocks of code and reduces the
number of conditional branches in the hot path based on profiles.

if (hot_cond1) { // Likely true.
  do_stg_hot1();
}
if (hot_cond2) { // Likely true.
  do_stg_hot2();
}

->

if (hot_cond1 && hot_cond2) { // Hot path.
  do_stg_hot1();
  do_stg_hot2();
} else { // Cold path.
  if (hot_cond1) {
    do_stg_hot1();
  }
  if (hot_cond2) {
    do_stg_hot2();
  }
}

This speeds up some internal benchmarks up to ~30%.

Reviewers: davidxl

Reviewed By: davidxl

Subscribers: xbolva00, dmgreen, mehdi_amini, llvm-commits, mgorny

Differential Revision: https://reviews.llvm.org/D50591

llvm-svn: 341386
2018-09-04 17:19:13 +00:00

82 lines
3.1 KiB
C++

//===-- Instrumentation.cpp - TransformUtils Infrastructure ---------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the common initialization infrastructure for the
// Instrumentation library.
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/Instrumentation.h"
#include "llvm-c/Initialization.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/InitializePasses.h"
#include "llvm/PassRegistry.h"
using namespace llvm;
/// Moves I before IP. Returns new insert point.
static BasicBlock::iterator moveBeforeInsertPoint(BasicBlock::iterator I, BasicBlock::iterator IP) {
// If I is IP, move the insert point down.
if (I == IP)
return ++IP;
// Otherwise, move I before IP and return IP.
I->moveBefore(&*IP);
return IP;
}
/// Instrumentation passes often insert conditional checks into entry blocks.
/// Call this function before splitting the entry block to move instructions
/// that must remain in the entry block up before the split point. Static
/// allocas and llvm.localescape calls, for example, must remain in the entry
/// block.
BasicBlock::iterator llvm::PrepareToSplitEntryBlock(BasicBlock &BB,
BasicBlock::iterator IP) {
assert(&BB.getParent()->getEntryBlock() == &BB);
for (auto I = IP, E = BB.end(); I != E; ++I) {
bool KeepInEntry = false;
if (auto *AI = dyn_cast<AllocaInst>(I)) {
if (AI->isStaticAlloca())
KeepInEntry = true;
} else if (auto *II = dyn_cast<IntrinsicInst>(I)) {
if (II->getIntrinsicID() == llvm::Intrinsic::localescape)
KeepInEntry = true;
}
if (KeepInEntry)
IP = moveBeforeInsertPoint(I, IP);
}
return IP;
}
/// initializeInstrumentation - Initialize all passes in the TransformUtils
/// library.
void llvm::initializeInstrumentation(PassRegistry &Registry) {
initializeAddressSanitizerPass(Registry);
initializeAddressSanitizerModulePass(Registry);
initializeBoundsCheckingLegacyPassPass(Registry);
initializeControlHeightReductionLegacyPassPass(Registry);
initializeGCOVProfilerLegacyPassPass(Registry);
initializePGOInstrumentationGenLegacyPassPass(Registry);
initializePGOInstrumentationUseLegacyPassPass(Registry);
initializePGOIndirectCallPromotionLegacyPassPass(Registry);
initializePGOMemOPSizeOptLegacyPassPass(Registry);
initializeInstrProfilingLegacyPassPass(Registry);
initializeMemorySanitizerPass(Registry);
initializeHWAddressSanitizerPass(Registry);
initializeThreadSanitizerPass(Registry);
initializeSanitizerCoverageModulePass(Registry);
initializeDataFlowSanitizerPass(Registry);
initializeEfficiencySanitizerPass(Registry);
}
/// LLVMInitializeInstrumentation - C binding for
/// initializeInstrumentation.
void LLVMInitializeInstrumentation(LLVMPassRegistryRef R) {
initializeInstrumentation(*unwrap(R));
}