1 //===- TailDuplication.cpp - Duplicate blocks into predecessors' tails ----===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 /// \file This pass duplicates basic blocks ending in unconditional branches
11 /// into the tails of their predecessors, using the TailDuplicator utility
12 /// class.
13 //
14 //===----------------------------------------------------------------------===//
15
16 #include "llvm/CodeGen/MachineBranchProbabilityInfo.h"
17 #include "llvm/CodeGen/MachineFunction.h"
18 #include "llvm/CodeGen/MachineFunctionPass.h"
19 #include "llvm/CodeGen/MachineRegisterInfo.h"
20 #include "llvm/CodeGen/Passes.h"
21 #include "llvm/CodeGen/TailDuplicator.h"
22 #include "llvm/Pass.h"
23
24 using namespace llvm;
25
26 #define DEBUG_TYPE "tailduplication"
27
28 namespace {
29
30 class TailDuplicateBase : public MachineFunctionPass {
31 TailDuplicator Duplicator;
32 bool PreRegAlloc;
33 public:
TailDuplicateBase(char & PassID,bool PreRegAlloc)34 TailDuplicateBase(char &PassID, bool PreRegAlloc)
35 : MachineFunctionPass(PassID), PreRegAlloc(PreRegAlloc) {}
36
37 bool runOnMachineFunction(MachineFunction &MF) override;
38
getAnalysisUsage(AnalysisUsage & AU) const39 void getAnalysisUsage(AnalysisUsage &AU) const override {
40 AU.addRequired<MachineBranchProbabilityInfo>();
41 MachineFunctionPass::getAnalysisUsage(AU);
42 }
43 };
44
45 class TailDuplicate : public TailDuplicateBase {
46 public:
47 static char ID;
TailDuplicate()48 TailDuplicate() : TailDuplicateBase(ID, false) {
49 initializeTailDuplicatePass(*PassRegistry::getPassRegistry());
50 }
51 };
52
53 class EarlyTailDuplicate : public TailDuplicateBase {
54 public:
55 static char ID;
EarlyTailDuplicate()56 EarlyTailDuplicate() : TailDuplicateBase(ID, true) {
57 initializeEarlyTailDuplicatePass(*PassRegistry::getPassRegistry());
58 }
59 };
60
61 } // end anonymous namespace
62
63 char TailDuplicate::ID;
64 char EarlyTailDuplicate::ID;
65
66 char &llvm::TailDuplicateID = TailDuplicate::ID;
67 char &llvm::EarlyTailDuplicateID = EarlyTailDuplicate::ID;
68
69 INITIALIZE_PASS(TailDuplicate, DEBUG_TYPE, "Tail Duplication", false, false)
70 INITIALIZE_PASS(EarlyTailDuplicate, "early-tailduplication",
71 "Early Tail Duplication", false, false)
72
runOnMachineFunction(MachineFunction & MF)73 bool TailDuplicateBase::runOnMachineFunction(MachineFunction &MF) {
74 if (skipFunction(MF.getFunction()))
75 return false;
76
77 auto MBPI = &getAnalysis<MachineBranchProbabilityInfo>();
78 Duplicator.initMF(MF, PreRegAlloc, MBPI, /*LayoutMode=*/false);
79
80 bool MadeChange = false;
81 while (Duplicator.tailDuplicateBlocks())
82 MadeChange = true;
83
84 return MadeChange;
85 }
86