1 //===------- X86ExpandPseudo.cpp - Expand pseudo instructions -------------===//
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3 // The LLVM Compiler Infrastructure
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5 // This file is distributed under the University of Illinois Open Source
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6 // License. See LICENSE.TXT for details.
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8 //===----------------------------------------------------------------------===//
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10 // This file contains a pass that expands pseudo instructions into target
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11 // instructions to allow proper scheduling, if-conversion, other late
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12 // optimizations, or simply the encoding of the instructions.
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14 //===----------------------------------------------------------------------===//
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17 #include "X86FrameLowering.h"
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18 #include "X86InstrBuilder.h"
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19 #include "X86InstrInfo.h"
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20 #include "X86MachineFunctionInfo.h"
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21 #include "X86Subtarget.h"
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22 #include "llvm/Analysis/EHPersonalities.h"
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23 #include "llvm/CodeGen/MachineFunctionPass.h"
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24 #include "llvm/CodeGen/MachineInstrBuilder.h"
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25 #include "llvm/CodeGen/Passes.h" // For IDs of passes that are preserved.
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26 #include "llvm/IR/GlobalValue.h"
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27 using namespace llvm;
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29 #define DEBUG_TYPE "x86-pseudo"
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32 class X86ExpandPseudo : public MachineFunctionPass {
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35 X86ExpandPseudo() : MachineFunctionPass(ID) {}
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37 void getAnalysisUsage(AnalysisUsage &AU) const override {
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38 AU.setPreservesCFG();
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39 AU.addPreservedID(MachineLoopInfoID);
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40 AU.addPreservedID(MachineDominatorsID);
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41 MachineFunctionPass::getAnalysisUsage(AU);
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44 const X86Subtarget *STI;
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45 const X86InstrInfo *TII;
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46 const X86RegisterInfo *TRI;
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47 const X86FrameLowering *X86FL;
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49 bool runOnMachineFunction(MachineFunction &Fn) override;
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51 const char *getPassName() const override {
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52 return "X86 pseudo instruction expansion pass";
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56 bool ExpandMI(MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI);
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57 bool ExpandMBB(MachineBasicBlock &MBB);
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59 char X86ExpandPseudo::ID = 0;
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60 } // End anonymous namespace.
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62 /// If \p MBBI is a pseudo instruction, this method expands
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63 /// it to the corresponding (sequence of) actual instruction(s).
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64 /// \returns true if \p MBBI has been expanded.
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65 bool X86ExpandPseudo::ExpandMI(MachineBasicBlock &MBB,
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66 MachineBasicBlock::iterator MBBI) {
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67 MachineInstr &MI = *MBBI;
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68 unsigned Opcode = MI.getOpcode();
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69 DebugLoc DL = MBBI->getDebugLoc();
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73 case X86::TCRETURNdi:
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74 case X86::TCRETURNri:
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75 case X86::TCRETURNmi:
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76 case X86::TCRETURNdi64:
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77 case X86::TCRETURNri64:
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78 case X86::TCRETURNmi64: {
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79 bool isMem = Opcode == X86::TCRETURNmi || Opcode == X86::TCRETURNmi64;
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80 MachineOperand &JumpTarget = MBBI->getOperand(0);
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81 MachineOperand &StackAdjust = MBBI->getOperand(isMem ? 5 : 1);
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82 assert(StackAdjust.isImm() && "Expecting immediate value.");
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84 // Adjust stack pointer.
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85 int StackAdj = StackAdjust.getImm();
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88 // Check for possible merge with preceding ADD instruction.
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89 StackAdj += X86FL->mergeSPUpdates(MBB, MBBI, true);
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90 X86FL->emitSPUpdate(MBB, MBBI, StackAdj, /*InEpilogue=*/true);
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93 // Jump to label or value in register.
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94 bool IsWin64 = STI->isTargetWin64();
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95 if (Opcode == X86::TCRETURNdi || Opcode == X86::TCRETURNdi64) {
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96 unsigned Op = (Opcode == X86::TCRETURNdi)
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98 : (IsWin64 ? X86::TAILJMPd64_REX : X86::TAILJMPd64);
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99 MachineInstrBuilder MIB = BuildMI(MBB, MBBI, DL, TII->get(Op));
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100 if (JumpTarget.isGlobal())
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101 MIB.addGlobalAddress(JumpTarget.getGlobal(), JumpTarget.getOffset(),
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102 JumpTarget.getTargetFlags());
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104 assert(JumpTarget.isSymbol());
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105 MIB.addExternalSymbol(JumpTarget.getSymbolName(),
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106 JumpTarget.getTargetFlags());
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108 } else if (Opcode == X86::TCRETURNmi || Opcode == X86::TCRETURNmi64) {
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109 unsigned Op = (Opcode == X86::TCRETURNmi)
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111 : (IsWin64 ? X86::TAILJMPm64_REX : X86::TAILJMPm64);
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112 MachineInstrBuilder MIB = BuildMI(MBB, MBBI, DL, TII->get(Op));
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113 for (unsigned i = 0; i != 5; ++i)
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114 MIB.addOperand(MBBI->getOperand(i));
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115 } else if (Opcode == X86::TCRETURNri64) {
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116 BuildMI(MBB, MBBI, DL,
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117 TII->get(IsWin64 ? X86::TAILJMPr64_REX : X86::TAILJMPr64))
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118 .addReg(JumpTarget.getReg(), RegState::Kill);
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120 BuildMI(MBB, MBBI, DL, TII->get(X86::TAILJMPr))
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121 .addReg(JumpTarget.getReg(), RegState::Kill);
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124 MachineInstr *NewMI = std::prev(MBBI);
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125 NewMI->copyImplicitOps(*MBBI->getParent()->getParent(), MBBI);
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127 // Delete the pseudo instruction TCRETURN.
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132 case X86::EH_RETURN:
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133 case X86::EH_RETURN64: {
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134 MachineOperand &DestAddr = MBBI->getOperand(0);
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135 assert(DestAddr.isReg() && "Offset should be in register!");
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136 const bool Uses64BitFramePtr =
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137 STI->isTarget64BitLP64() || STI->isTargetNaCl64();
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138 unsigned StackPtr = TRI->getStackRegister();
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139 BuildMI(MBB, MBBI, DL,
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140 TII->get(Uses64BitFramePtr ? X86::MOV64rr : X86::MOV32rr), StackPtr)
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141 .addReg(DestAddr.getReg());
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142 // The EH_RETURN pseudo is really removed during the MC Lowering.
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146 // Adjust stack to erase error code
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147 int64_t StackAdj = MBBI->getOperand(0).getImm();
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148 X86FL->emitSPUpdate(MBB, MBBI, StackAdj, true);
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149 // Replace pseudo with machine iret
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150 BuildMI(MBB, MBBI, DL,
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151 TII->get(STI->is64Bit() ? X86::IRET64 : X86::IRET32));
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155 case X86::EH_RESTORE: {
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156 // Restore ESP and EBP, and optionally ESI if required.
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157 bool IsSEH = isAsynchronousEHPersonality(classifyEHPersonality(
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158 MBB.getParent()->getFunction()->getPersonalityFn()));
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159 X86FL->restoreWin32EHStackPointers(MBB, MBBI, DL, /*RestoreSP=*/IsSEH);
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160 MBBI->eraseFromParent();
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164 llvm_unreachable("Previous switch has a fallthrough?");
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167 /// Expand all pseudo instructions contained in \p MBB.
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168 /// \returns true if any expansion occurred for \p MBB.
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169 bool X86ExpandPseudo::ExpandMBB(MachineBasicBlock &MBB) {
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170 bool Modified = false;
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172 // MBBI may be invalidated by the expansion.
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173 MachineBasicBlock::iterator MBBI = MBB.begin(), E = MBB.end();
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174 while (MBBI != E) {
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175 MachineBasicBlock::iterator NMBBI = std::next(MBBI);
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176 Modified |= ExpandMI(MBB, MBBI);
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183 bool X86ExpandPseudo::runOnMachineFunction(MachineFunction &MF) {
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184 STI = &static_cast<const X86Subtarget &>(MF.getSubtarget());
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185 TII = STI->getInstrInfo();
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186 TRI = STI->getRegisterInfo();
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187 X86FL = STI->getFrameLowering();
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189 bool Modified = false;
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190 for (MachineBasicBlock &MBB : MF)
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191 Modified |= ExpandMBB(MBB);
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195 /// Returns an instance of the pseudo instruction expansion pass.
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196 FunctionPass *llvm::createX86ExpandPseudoPass() {
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197 return new X86ExpandPseudo();
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