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//===- TailDuplication.cpp - Duplicate blocks into predecessors' tails ----===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
/// \file This pass duplicates basic blocks ending in unconditional branches
/// into the tails of their predecessors, using the TailDuplicator utility
/// class.
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/ProfileSummaryInfo.h"
#include "llvm/CodeGen/LazyMachineBlockFrequencyInfo.h"
#include "llvm/CodeGen/MachineBranchProbabilityInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/CodeGen/TailDuplicator.h"
#include "llvm/InitializePasses.h"
#include "llvm/Pass.h"
using namespace llvm;
#define DEBUG_TYPE "tailduplication"
namespace {
class TailDuplicateBase : public MachineFunctionPass {
TailDuplicator Duplicator;
std::unique_ptr<MBFIWrapper> MBFIW;
bool PreRegAlloc;
public:
TailDuplicateBase(char &PassID, bool PreRegAlloc)
: MachineFunctionPass(PassID), PreRegAlloc(PreRegAlloc) {}
bool runOnMachineFunction(MachineFunction &MF) override;
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.addRequired<MachineBranchProbabilityInfo>();
AU.addRequired<LazyMachineBlockFrequencyInfoPass>();
AU.addRequired<ProfileSummaryInfoWrapperPass>();
MachineFunctionPass::getAnalysisUsage(AU);
}
};
class TailDuplicate : public TailDuplicateBase {
public:
static char ID;
TailDuplicate() : TailDuplicateBase(ID, false) {
initializeTailDuplicatePass(*PassRegistry::getPassRegistry());
}
};
class EarlyTailDuplicate : public TailDuplicateBase {
public:
static char ID;
EarlyTailDuplicate() : TailDuplicateBase(ID, true) {
initializeEarlyTailDuplicatePass(*PassRegistry::getPassRegistry());
}
MachineFunctionProperties getClearedProperties() const override {
return MachineFunctionProperties()
.set(MachineFunctionProperties::Property::NoPHIs);
}
};
} // end anonymous namespace
char TailDuplicate::ID;
char EarlyTailDuplicate::ID;
char &llvm::TailDuplicateID = TailDuplicate::ID;
char &llvm::EarlyTailDuplicateID = EarlyTailDuplicate::ID;
INITIALIZE_PASS(TailDuplicate, DEBUG_TYPE, "Tail Duplication", false, false)
INITIALIZE_PASS(EarlyTailDuplicate, "early-tailduplication",
"Early Tail Duplication", false, false)
bool TailDuplicateBase::runOnMachineFunction(MachineFunction &MF) {
if (skipFunction(MF.getFunction()))
return false;
auto MBPI = &getAnalysis<MachineBranchProbabilityInfo>();
auto *PSI = &getAnalysis<ProfileSummaryInfoWrapperPass>().getPSI();
auto *MBFI = (PSI && PSI->hasProfileSummary()) ?
&getAnalysis<LazyMachineBlockFrequencyInfoPass>().getBFI() :
nullptr;
if (MBFI)
MBFIW = std::make_unique<MBFIWrapper>(*MBFI);
Duplicator.initMF(MF, PreRegAlloc, MBPI, MBFI ? MBFIW.get() : nullptr, PSI,
/*LayoutMode=*/false);
bool MadeChange = false;
while (Duplicator.tailDuplicateBlocks())
MadeChange = true;
return MadeChange;
}
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