1 //===- TailDuplication.cpp - Duplicate blocks into predecessors' tails ----===//
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //===----------------------------------------------------------------------===//
9 /// \file This pass duplicates basic blocks ending in unconditional branches
10 /// into the tails of their predecessors, using the TailDuplicator utility
13 //===----------------------------------------------------------------------===//
15 #include "llvm/Analysis/ProfileSummaryInfo.h"
16 #include "llvm/CodeGen/LazyMachineBlockFrequencyInfo.h"
17 #include "llvm/CodeGen/MachineBranchProbabilityInfo.h"
18 #include "llvm/CodeGen/MachineFunction.h"
19 #include "llvm/CodeGen/MachineFunctionPass.h"
20 #include "llvm/CodeGen/MachineRegisterInfo.h"
21 #include "llvm/CodeGen/Passes.h"
22 #include "llvm/CodeGen/TailDuplicator.h"
23 #include "llvm/InitializePasses.h"
24 #include "llvm/Pass.h"
28 #define DEBUG_TYPE "tailduplication"
32 class TailDuplicateBase : public MachineFunctionPass {
33 TailDuplicator Duplicator;
36 TailDuplicateBase(char &PassID, bool PreRegAlloc)
37 : MachineFunctionPass(PassID), PreRegAlloc(PreRegAlloc) {}
39 bool runOnMachineFunction(MachineFunction &MF) override;
41 void getAnalysisUsage(AnalysisUsage &AU) const override {
42 AU.addRequired<MachineBranchProbabilityInfo>();
43 AU.addRequired<LazyMachineBlockFrequencyInfoPass>();
44 AU.addRequired<ProfileSummaryInfoWrapperPass>();
45 MachineFunctionPass::getAnalysisUsage(AU);
49 class TailDuplicate : public TailDuplicateBase {
52 TailDuplicate() : TailDuplicateBase(ID, false) {
53 initializeTailDuplicatePass(*PassRegistry::getPassRegistry());
57 class EarlyTailDuplicate : public TailDuplicateBase {
60 EarlyTailDuplicate() : TailDuplicateBase(ID, true) {
61 initializeEarlyTailDuplicatePass(*PassRegistry::getPassRegistry());
64 MachineFunctionProperties getClearedProperties() const override {
65 return MachineFunctionProperties()
66 .set(MachineFunctionProperties::Property::NoPHIs);
70 } // end anonymous namespace
72 char TailDuplicate::ID;
73 char EarlyTailDuplicate::ID;
75 char &llvm::TailDuplicateID = TailDuplicate::ID;
76 char &llvm::EarlyTailDuplicateID = EarlyTailDuplicate::ID;
78 INITIALIZE_PASS(TailDuplicate, DEBUG_TYPE, "Tail Duplication", false, false)
79 INITIALIZE_PASS(EarlyTailDuplicate, "early-tailduplication",
80 "Early Tail Duplication", false, false)
82 bool TailDuplicateBase::runOnMachineFunction(MachineFunction &MF) {
83 if (skipFunction(MF.getFunction()))
86 auto MBPI = &getAnalysis<MachineBranchProbabilityInfo>();
87 auto *PSI = &getAnalysis<ProfileSummaryInfoWrapperPass>().getPSI();
88 auto *MBFI = (PSI && PSI->hasProfileSummary()) ?
89 &getAnalysis<LazyMachineBlockFrequencyInfoPass>().getBFI() :
91 Duplicator.initMF(MF, PreRegAlloc, MBPI, MBFI, PSI, /*LayoutMode=*/false);
93 bool MadeChange = false;
94 while (Duplicator.tailDuplicateBlocks())