lib/Target/X86/X86ExpandPseudo.cpp - llvm - Git at Google

 //===------- X86ExpandPseudo.cpp - Expand pseudo instructions -------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file contains a pass that expands pseudo instructions into target
 // instructions to allow proper scheduling, if-conversion, other late
 // optimizations, or simply the encoding of the instructions.
 //
 //===----------------------------------------------------------------------===//

 #include "X86.h"
 #include "X86FrameLowering.h"
 #include "X86InstrBuilder.h"
 #include "X86InstrInfo.h"
 #include "X86MachineFunctionInfo.h"
 #include "X86Subtarget.h"
 #include "llvm/Analysis/EHPersonalities.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
 #include "llvm/CodeGen/MachineInstrBuilder.h"
 #include "llvm/CodeGen/Passes.h" // For IDs of passes that are preserved.
 #include "llvm/IR/GlobalValue.h"
 using namespace llvm;

 #define DEBUG_TYPE "x86-pseudo"

 namespace {
 class X86ExpandPseudo : public MachineFunctionPass {
 public:
   static char ID;
   X86ExpandPseudo() : MachineFunctionPass(ID) {}

   void getAnalysisUsage(AnalysisUsage &AU) const override {
     AU.setPreservesCFG();
     AU.addPreservedID(MachineLoopInfoID);
     AU.addPreservedID(MachineDominatorsID);
     MachineFunctionPass::getAnalysisUsage(AU);
   }

   const X86Subtarget *STI;
   const X86InstrInfo *TII;
   const X86RegisterInfo *TRI;
   const X86MachineFunctionInfo *X86FI;
   const X86FrameLowering *X86FL;

   bool runOnMachineFunction(MachineFunction &Fn) override;

   MachineFunctionProperties getRequiredProperties() const override {
     return MachineFunctionProperties().set(
         MachineFunctionProperties::Property::NoVRegs);
   }

   StringRef getPassName() const override {
     return "X86 pseudo instruction expansion pass";
   }

 private:
   void ExpandICallBranchFunnel(MachineBasicBlock *MBB,
                                MachineBasicBlock::iterator MBBI);

   bool ExpandMI(MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI);
   bool ExpandMBB(MachineBasicBlock &MBB);
 };
 char X86ExpandPseudo::ID = 0;
 } // End anonymous namespace.

 void X86ExpandPseudo::ExpandICallBranchFunnel(
     MachineBasicBlock *MBB, MachineBasicBlock::iterator MBBI) {
   MachineBasicBlock *JTMBB = MBB;
   MachineInstr *JTInst = &*MBBI;
   MachineFunction *MF = MBB->getParent();
   const BasicBlock *BB = MBB->getBasicBlock();
   auto InsPt = MachineFunction::iterator(MBB);
   ++InsPt;

   std::vector<std::pair<MachineBasicBlock *, unsigned>> TargetMBBs;
   DebugLoc DL = JTInst->getDebugLoc();
   MachineOperand Selector = JTInst->getOperand(0);
   const GlobalValue *CombinedGlobal = JTInst->getOperand(1).getGlobal();

   auto CmpTarget = [&](unsigned Target) {
     BuildMI(*MBB, MBBI, DL, TII->get(X86::LEA64r), X86::R11)
         .addReg(X86::RIP)
         .addImm(1)
         .addReg(0)
         .addGlobalAddress(CombinedGlobal,
                           JTInst->getOperand(2 + 2 * Target).getImm())
         .addReg(0);
     BuildMI(*MBB, MBBI, DL, TII->get(X86::CMP64rr))
         .add(Selector)
         .addReg(X86::R11);
   };

   auto CreateMBB = [&]() {
     auto *NewMBB = MF->CreateMachineBasicBlock(BB);
     MBB->addSuccessor(NewMBB);
     return NewMBB;
   };

   auto EmitCondJump = [&](unsigned Opcode, MachineBasicBlock *ThenMBB) {
     BuildMI(*MBB, MBBI, DL, TII->get(Opcode)).addMBB(ThenMBB);

     auto *ElseMBB = CreateMBB();
     MF->insert(InsPt, ElseMBB);
     MBB = ElseMBB;
     MBBI = MBB->end();
   };

   auto EmitCondJumpTarget = [&](unsigned Opcode, unsigned Target) {
     auto *ThenMBB = CreateMBB();
     TargetMBBs.push_back({ThenMBB, Target});
     EmitCondJump(Opcode, ThenMBB);
   };

   auto EmitTailCall = [&](unsigned Target) {
     BuildMI(*MBB, MBBI, DL, TII->get(X86::TAILJMPd64))
         .add(JTInst->getOperand(3 + 2 * Target));
   };

   std::function<void(unsigned, unsigned)> EmitBranchFunnel =
       [&](unsigned FirstTarget, unsigned NumTargets) {
     if (NumTargets == 1) {
       EmitTailCall(FirstTarget);
       return;
     }

     if (NumTargets == 2) {
       CmpTarget(FirstTarget + 1);
       EmitCondJumpTarget(X86::JB_1, FirstTarget);
       EmitTailCall(FirstTarget + 1);
       return;
     }

     if (NumTargets < 6) {
       CmpTarget(FirstTarget + 1);
       EmitCondJumpTarget(X86::JB_1, FirstTarget);
       EmitCondJumpTarget(X86::JE_1, FirstTarget + 1);
       EmitBranchFunnel(FirstTarget + 2, NumTargets - 2);
       return;
     }

     auto *ThenMBB = CreateMBB();
     CmpTarget(FirstTarget + (NumTargets / 2));
     EmitCondJump(X86::JB_1, ThenMBB);
     EmitCondJumpTarget(X86::JE_1, FirstTarget + (NumTargets / 2));
     EmitBranchFunnel(FirstTarget + (NumTargets / 2) + 1,
                   NumTargets - (NumTargets / 2) - 1);

     MF->insert(InsPt, ThenMBB);
     MBB = ThenMBB;
     MBBI = MBB->end();
     EmitBranchFunnel(FirstTarget, NumTargets / 2);
   };

   EmitBranchFunnel(0, (JTInst->getNumOperands() - 2) / 2);
   for (auto P : TargetMBBs) {
     MF->insert(InsPt, P.first);
     BuildMI(P.first, DL, TII->get(X86::TAILJMPd64))
         .add(JTInst->getOperand(3 + 2 * P.second));
   }
   JTMBB->erase(JTInst);
 }

 /// If \p MBBI is a pseudo instruction, this method expands
 /// it to the corresponding (sequence of) actual instruction(s).
 /// \returns true if \p MBBI has been expanded.
 bool X86ExpandPseudo::ExpandMI(MachineBasicBlock &MBB,
                                MachineBasicBlock::iterator MBBI) {
   MachineInstr &MI = *MBBI;
   unsigned Opcode = MI.getOpcode();
   DebugLoc DL = MBBI->getDebugLoc();
   switch (Opcode) {
   default:
     return false;
   case X86::TCRETURNdi:
   case X86::TCRETURNdicc:
   case X86::TCRETURNri:
   case X86::TCRETURNmi:
   case X86::TCRETURNdi64:
   case X86::TCRETURNdi64cc:
   case X86::TCRETURNri64:
   case X86::TCRETURNmi64: {
     bool isMem = Opcode == X86::TCRETURNmi || Opcode == X86::TCRETURNmi64;
     MachineOperand &JumpTarget = MBBI->getOperand(0);
     MachineOperand &StackAdjust = MBBI->getOperand(isMem ? 5 : 1);
     assert(StackAdjust.isImm() && "Expecting immediate value.");

     // Adjust stack pointer.
     int StackAdj = StackAdjust.getImm();
     int MaxTCDelta = X86FI->getTCReturnAddrDelta();
     int Offset = 0;
     assert(MaxTCDelta <= 0 && "MaxTCDelta should never be positive");

     // Incoporate the retaddr area.
     Offset = StackAdj - MaxTCDelta;
     assert(Offset >= 0 && "Offset should never be negative");

     if (Opcode == X86::TCRETURNdicc || Opcode == X86::TCRETURNdi64cc) {
       assert(Offset == 0 && "Conditional tail call cannot adjust the stack.");
     }

     if (Offset) {
       // Check for possible merge with preceding ADD instruction.
       Offset += X86FL->mergeSPUpdates(MBB, MBBI, true);
       X86FL->emitSPUpdate(MBB, MBBI, DL, Offset, /*InEpilogue=*/true);
     }

     // Jump to label or value in register.
     bool IsWin64 = STI->isTargetWin64();
     if (Opcode == X86::TCRETURNdi || Opcode == X86::TCRETURNdicc ||
         Opcode == X86::TCRETURNdi64 || Opcode == X86::TCRETURNdi64cc) {
       unsigned Op;
       switch (Opcode) {
       case X86::TCRETURNdi:
         Op = X86::TAILJMPd;
         break;
       case X86::TCRETURNdicc:
         Op = X86::TAILJMPd_CC;
         break;
       case X86::TCRETURNdi64cc:
         assert(!MBB.getParent()->hasWinCFI() &&
                "Conditional tail calls confuse "
                "the Win64 unwinder.");
         Op = X86::TAILJMPd64_CC;
         break;
       default:
         // Note: Win64 uses REX prefixes indirect jumps out of functions, but
         // not direct ones.
         Op = X86::TAILJMPd64;
         break;
       }
       MachineInstrBuilder MIB = BuildMI(MBB, MBBI, DL, TII->get(Op));
       if (JumpTarget.isGlobal()) {
         MIB.addGlobalAddress(JumpTarget.getGlobal(), JumpTarget.getOffset(),
                              JumpTarget.getTargetFlags());
       } else {
         assert(JumpTarget.isSymbol());
         MIB.addExternalSymbol(JumpTarget.getSymbolName(),
                               JumpTarget.getTargetFlags());
       }
       if (Op == X86::TAILJMPd_CC || Op == X86::TAILJMPd64_CC) {
         MIB.addImm(MBBI->getOperand(2).getImm());
       }

     } else if (Opcode == X86::TCRETURNmi || Opcode == X86::TCRETURNmi64) {
       unsigned Op = (Opcode == X86::TCRETURNmi)
                         ? X86::TAILJMPm
                         : (IsWin64 ? X86::TAILJMPm64_REX : X86::TAILJMPm64);
       MachineInstrBuilder MIB = BuildMI(MBB, MBBI, DL, TII->get(Op));
       for (unsigned i = 0; i != 5; ++i)
         MIB.add(MBBI->getOperand(i));
     } else if (Opcode == X86::TCRETURNri64) {
       BuildMI(MBB, MBBI, DL,
               TII->get(IsWin64 ? X86::TAILJMPr64_REX : X86::TAILJMPr64))
           .addReg(JumpTarget.getReg(), RegState::Kill);
     } else {
       BuildMI(MBB, MBBI, DL, TII->get(X86::TAILJMPr))
           .addReg(JumpTarget.getReg(), RegState::Kill);
     }

     MachineInstr &NewMI = *std::prev(MBBI);
     NewMI.copyImplicitOps(*MBBI->getParent()->getParent(), *MBBI);

     // Delete the pseudo instruction TCRETURN.
     MBB.erase(MBBI);

     return true;
   }
   case X86::EH_RETURN:
   case X86::EH_RETURN64: {
     MachineOperand &DestAddr = MBBI->getOperand(0);
     assert(DestAddr.isReg() && "Offset should be in register!");
     const bool Uses64BitFramePtr =
         STI->isTarget64BitLP64() || STI->isTargetNaCl64();
     unsigned StackPtr = TRI->getStackRegister();
     BuildMI(MBB, MBBI, DL,
             TII->get(Uses64BitFramePtr ? X86::MOV64rr : X86::MOV32rr), StackPtr)
         .addReg(DestAddr.getReg());
     // The EH_RETURN pseudo is really removed during the MC Lowering.
     return true;
   }
   case X86::IRET: {
     // Adjust stack to erase error code
     int64_t StackAdj = MBBI->getOperand(0).getImm();
     X86FL->emitSPUpdate(MBB, MBBI, DL, StackAdj, true);
     // Replace pseudo with machine iret
     BuildMI(MBB, MBBI, DL,
             TII->get(STI->is64Bit() ? X86::IRET64 : X86::IRET32));
     MBB.erase(MBBI);
     return true;
   }
   case X86::RET: {
     // Adjust stack to erase error code
     int64_t StackAdj = MBBI->getOperand(0).getImm();
     MachineInstrBuilder MIB;
     if (StackAdj == 0) {
       MIB = BuildMI(MBB, MBBI, DL,
                     TII->get(STI->is64Bit() ? X86::RETQ : X86::RETL));
     } else if (isUInt<16>(StackAdj)) {
       MIB = BuildMI(MBB, MBBI, DL,
                     TII->get(STI->is64Bit() ? X86::RETIQ : X86::RETIL))
                 .addImm(StackAdj);
     } else {
       assert(!STI->is64Bit() &&
              "shouldn't need to do this for x86_64 targets!");
       // A ret can only handle immediates as big as 2**16-1.  If we need to pop
       // off bytes before the return address, we must do it manually.
       BuildMI(MBB, MBBI, DL, TII->get(X86::POP32r)).addReg(X86::ECX, RegState::Define);
       X86FL->emitSPUpdate(MBB, MBBI, DL, StackAdj, /*InEpilogue=*/true);
       BuildMI(MBB, MBBI, DL, TII->get(X86::PUSH32r)).addReg(X86::ECX);
       MIB = BuildMI(MBB, MBBI, DL, TII->get(X86::RETL));
     }
     for (unsigned I = 1, E = MBBI->getNumOperands(); I != E; ++I)
       MIB.add(MBBI->getOperand(I));
     MBB.erase(MBBI);
     return true;
   }
   case X86::EH_RESTORE: {
     // Restore ESP and EBP, and optionally ESI if required.
     bool IsSEH = isAsynchronousEHPersonality(classifyEHPersonality(
         MBB.getParent()->getFunction().getPersonalityFn()));
     X86FL->restoreWin32EHStackPointers(MBB, MBBI, DL, /*RestoreSP=*/IsSEH);
     MBBI->eraseFromParent();
     return true;
   }
   case X86::LCMPXCHG8B_SAVE_EBX:
   case X86::LCMPXCHG16B_SAVE_RBX: {
     // Perform the following transformation.
     // SaveRbx = pseudocmpxchg Addr, <4 opds for the address>, InArg, SaveRbx
     // =>
     // [E|R]BX = InArg
     // actualcmpxchg Addr
     // [E|R]BX = SaveRbx
     const MachineOperand &InArg = MBBI->getOperand(6);
     unsigned SaveRbx = MBBI->getOperand(7).getReg();

     unsigned ActualInArg =
         Opcode == X86::LCMPXCHG8B_SAVE_EBX ? X86::EBX : X86::RBX;
     // Copy the input argument of the pseudo into the argument of the
     // actual instruction.
     TII->copyPhysReg(MBB, MBBI, DL, ActualInArg, InArg.getReg(),
                      InArg.isKill());
     // Create the actual instruction.
     unsigned ActualOpc =
         Opcode == X86::LCMPXCHG8B_SAVE_EBX ? X86::LCMPXCHG8B : X86::LCMPXCHG16B;
     MachineInstr *NewInstr = BuildMI(MBB, MBBI, DL, TII->get(ActualOpc));
     // Copy the operands related to the address.
     for (unsigned Idx = 1; Idx < 6; ++Idx)
       NewInstr->addOperand(MBBI->getOperand(Idx));
     // Finally, restore the value of RBX.
     TII->copyPhysReg(MBB, MBBI, DL, ActualInArg, SaveRbx,
                      /*SrcIsKill*/ true);

     // Delete the pseudo.
     MBBI->eraseFromParent();
     return true;
   }
   case TargetOpcode::ICALL_BRANCH_FUNNEL:
     ExpandICallBranchFunnel(&MBB, MBBI);
     return true;
   }
   llvm_unreachable("Previous switch has a fallthrough?");
 }

 /// Expand all pseudo instructions contained in \p MBB.
 /// \returns true if any expansion occurred for \p MBB.
 bool X86ExpandPseudo::ExpandMBB(MachineBasicBlock &MBB) {
   bool Modified = false;

   // MBBI may be invalidated by the expansion.
   MachineBasicBlock::iterator MBBI = MBB.begin(), E = MBB.end();
   while (MBBI != E) {
     MachineBasicBlock::iterator NMBBI = std::next(MBBI);
     Modified |= ExpandMI(MBB, MBBI);
     MBBI = NMBBI;
   }

   return Modified;
 }

 bool X86ExpandPseudo::runOnMachineFunction(MachineFunction &MF) {
   STI = &static_cast<const X86Subtarget &>(MF.getSubtarget());
   TII = STI->getInstrInfo();
   TRI = STI->getRegisterInfo();
   X86FI = MF.getInfo<X86MachineFunctionInfo>();
   X86FL = STI->getFrameLowering();

   bool Modified = false;
   for (MachineBasicBlock &MBB : MF)
     Modified |= ExpandMBB(MBB);
   return Modified;
 }

 /// Returns an instance of the pseudo instruction expansion pass.
 FunctionPass *llvm::createX86ExpandPseudoPass() {
   return new X86ExpandPseudo();
 }
	//===------- X86ExpandPseudo.cpp - Expand pseudo instructions -------------===//
	//
	// The LLVM Compiler Infrastructure
	//
	// This file is distributed under the University of Illinois Open Source
	// License. See LICENSE.TXT for details.
	//
	//===----------------------------------------------------------------------===//
	//
	// This file contains a pass that expands pseudo instructions into target
	// instructions to allow proper scheduling, if-conversion, other late
	// optimizations, or simply the encoding of the instructions.
	//
	//===----------------------------------------------------------------------===//

	#include "X86.h"
	#include "X86FrameLowering.h"
	#include "X86InstrBuilder.h"
	#include "X86InstrInfo.h"
	#include "X86MachineFunctionInfo.h"
	#include "X86Subtarget.h"
	#include "llvm/Analysis/EHPersonalities.h"
	#include "llvm/CodeGen/MachineFunctionPass.h"
	#include "llvm/CodeGen/MachineInstrBuilder.h"
	#include "llvm/CodeGen/Passes.h" // For IDs of passes that are preserved.
	#include "llvm/IR/GlobalValue.h"
	using namespace llvm;

	#define DEBUG_TYPE "x86-pseudo"

	namespace {
	class X86ExpandPseudo : public MachineFunctionPass {
	public:
	static char ID;
	X86ExpandPseudo() : MachineFunctionPass(ID) {}

	void getAnalysisUsage(AnalysisUsage &AU) const override {
	AU.setPreservesCFG();
	AU.addPreservedID(MachineLoopInfoID);
	AU.addPreservedID(MachineDominatorsID);
	MachineFunctionPass::getAnalysisUsage(AU);
	}

	const X86Subtarget *STI;
	const X86InstrInfo *TII;
	const X86RegisterInfo *TRI;
	const X86MachineFunctionInfo *X86FI;
	const X86FrameLowering *X86FL;

	bool runOnMachineFunction(MachineFunction &Fn) override;

	MachineFunctionProperties getRequiredProperties() const override {
	return MachineFunctionProperties().set(
	MachineFunctionProperties::Property::NoVRegs);
	}

	StringRef getPassName() const override {
	return "X86 pseudo instruction expansion pass";
	}

	private:
	void ExpandICallBranchFunnel(MachineBasicBlock *MBB,
	MachineBasicBlock::iterator MBBI);

	bool ExpandMI(MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI);
	bool ExpandMBB(MachineBasicBlock &MBB);
	};
	char X86ExpandPseudo::ID = 0;
	} // End anonymous namespace.

	void X86ExpandPseudo::ExpandICallBranchFunnel(
	MachineBasicBlock *MBB, MachineBasicBlock::iterator MBBI) {
	MachineBasicBlock *JTMBB = MBB;
	MachineInstr JTInst = &MBBI;
	MachineFunction *MF = MBB->getParent();
	const BasicBlock *BB = MBB->getBasicBlock();
	auto InsPt = MachineFunction::iterator(MBB);
	++InsPt;

	std::vector<std::pair<MachineBasicBlock *, unsigned>> TargetMBBs;
	DebugLoc DL = JTInst->getDebugLoc();
	MachineOperand Selector = JTInst->getOperand(0);
	const GlobalValue *CombinedGlobal = JTInst->getOperand(1).getGlobal();

	auto CmpTarget = [&](unsigned Target) {
	BuildMI(*MBB, MBBI, DL, TII->get(X86::LEA64r), X86::R11)
	.addReg(X86::RIP)
	.addImm(1)
	.addReg(0)
	.addGlobalAddress(CombinedGlobal,
	JTInst->getOperand(2 + 2 * Target).getImm())
	.addReg(0);
	BuildMI(*MBB, MBBI, DL, TII->get(X86::CMP64rr))
	.add(Selector)
	.addReg(X86::R11);
	};

	auto CreateMBB = [&]() {
	auto *NewMBB = MF->CreateMachineBasicBlock(BB);
	MBB->addSuccessor(NewMBB);
	return NewMBB;
	};

	auto EmitCondJump = [&](unsigned Opcode, MachineBasicBlock *ThenMBB) {
	BuildMI(*MBB, MBBI, DL, TII->get(Opcode)).addMBB(ThenMBB);

	auto *ElseMBB = CreateMBB();
	MF->insert(InsPt, ElseMBB);
	MBB = ElseMBB;
	MBBI = MBB->end();
	};

	auto EmitCondJumpTarget = [&](unsigned Opcode, unsigned Target) {
	auto *ThenMBB = CreateMBB();
	TargetMBBs.push_back({ThenMBB, Target});
	EmitCondJump(Opcode, ThenMBB);
	};

	auto EmitTailCall = [&](unsigned Target) {
	BuildMI(*MBB, MBBI, DL, TII->get(X86::TAILJMPd64))
	.add(JTInst->getOperand(3 + 2 * Target));
	};

	std::function<void(unsigned, unsigned)> EmitBranchFunnel =
	[&](unsigned FirstTarget, unsigned NumTargets) {
	if (NumTargets == 1) {
	EmitTailCall(FirstTarget);
	return;
	}

	if (NumTargets == 2) {
	CmpTarget(FirstTarget + 1);
	EmitCondJumpTarget(X86::JB_1, FirstTarget);
	EmitTailCall(FirstTarget + 1);
	return;
	}

	if (NumTargets < 6) {
	CmpTarget(FirstTarget + 1);
	EmitCondJumpTarget(X86::JB_1, FirstTarget);
	EmitCondJumpTarget(X86::JE_1, FirstTarget + 1);
	EmitBranchFunnel(FirstTarget + 2, NumTargets - 2);
	return;
	}

	auto *ThenMBB = CreateMBB();
	CmpTarget(FirstTarget + (NumTargets / 2));
	EmitCondJump(X86::JB_1, ThenMBB);
	EmitCondJumpTarget(X86::JE_1, FirstTarget + (NumTargets / 2));
	EmitBranchFunnel(FirstTarget + (NumTargets / 2) + 1,
	NumTargets - (NumTargets / 2) - 1);

	MF->insert(InsPt, ThenMBB);
	MBB = ThenMBB;
	MBBI = MBB->end();
	EmitBranchFunnel(FirstTarget, NumTargets / 2);
	};

	EmitBranchFunnel(0, (JTInst->getNumOperands() - 2) / 2);
	for (auto P : TargetMBBs) {
	MF->insert(InsPt, P.first);
	BuildMI(P.first, DL, TII->get(X86::TAILJMPd64))
	.add(JTInst->getOperand(3 + 2 * P.second));
	}
	JTMBB->erase(JTInst);
	}

	/// If \p MBBI is a pseudo instruction, this method expands
	/// it to the corresponding (sequence of) actual instruction(s).
	/// \returns true if \p MBBI has been expanded.
	bool X86ExpandPseudo::ExpandMI(MachineBasicBlock &MBB,
	MachineBasicBlock::iterator MBBI) {
	MachineInstr &MI = *MBBI;
	unsigned Opcode = MI.getOpcode();
	DebugLoc DL = MBBI->getDebugLoc();
	switch (Opcode) {
	default:
	return false;
	case X86::TCRETURNdi:
	case X86::TCRETURNdicc:
	case X86::TCRETURNri:
	case X86::TCRETURNmi:
	case X86::TCRETURNdi64:
	case X86::TCRETURNdi64cc:
	case X86::TCRETURNri64:
	case X86::TCRETURNmi64: {
	bool isMem = Opcode == X86::TCRETURNmi \|\| Opcode == X86::TCRETURNmi64;
	MachineOperand &JumpTarget = MBBI->getOperand(0);
	MachineOperand &StackAdjust = MBBI->getOperand(isMem ? 5 : 1);
	assert(StackAdjust.isImm() && "Expecting immediate value.");

	// Adjust stack pointer.
	int StackAdj = StackAdjust.getImm();
	int MaxTCDelta = X86FI->getTCReturnAddrDelta();
	int Offset = 0;
	assert(MaxTCDelta <= 0 && "MaxTCDelta should never be positive");

	// Incoporate the retaddr area.
	Offset = StackAdj - MaxTCDelta;
	assert(Offset >= 0 && "Offset should never be negative");

	if (Opcode == X86::TCRETURNdicc \|\| Opcode == X86::TCRETURNdi64cc) {
	assert(Offset == 0 && "Conditional tail call cannot adjust the stack.");
	}

	if (Offset) {
	// Check for possible merge with preceding ADD instruction.
	Offset += X86FL->mergeSPUpdates(MBB, MBBI, true);
	X86FL->emitSPUpdate(MBB, MBBI, DL, Offset, /InEpilogue=/true);
	}

	// Jump to label or value in register.
	bool IsWin64 = STI->isTargetWin64();
	if (Opcode == X86::TCRETURNdi \|\| Opcode == X86::TCRETURNdicc \|\|
	Opcode == X86::TCRETURNdi64 \|\| Opcode == X86::TCRETURNdi64cc) {
	unsigned Op;
	switch (Opcode) {
	case X86::TCRETURNdi:
	Op = X86::TAILJMPd;
	break;
	case X86::TCRETURNdicc:
	Op = X86::TAILJMPd_CC;
	break;
	case X86::TCRETURNdi64cc:
	assert(!MBB.getParent()->hasWinCFI() &&
	"Conditional tail calls confuse "
	"the Win64 unwinder.");
	Op = X86::TAILJMPd64_CC;
	break;
	default:
	// Note: Win64 uses REX prefixes indirect jumps out of functions, but
	// not direct ones.
	Op = X86::TAILJMPd64;
	break;
	}
	MachineInstrBuilder MIB = BuildMI(MBB, MBBI, DL, TII->get(Op));
	if (JumpTarget.isGlobal()) {
	MIB.addGlobalAddress(JumpTarget.getGlobal(), JumpTarget.getOffset(),
	JumpTarget.getTargetFlags());
	} else {
	assert(JumpTarget.isSymbol());
	MIB.addExternalSymbol(JumpTarget.getSymbolName(),
	JumpTarget.getTargetFlags());
	}
	if (Op == X86::TAILJMPd_CC \|\| Op == X86::TAILJMPd64_CC) {
	MIB.addImm(MBBI->getOperand(2).getImm());
	}

	} else if (Opcode == X86::TCRETURNmi \|\| Opcode == X86::TCRETURNmi64) {
	unsigned Op = (Opcode == X86::TCRETURNmi)
	? X86::TAILJMPm
	: (IsWin64 ? X86::TAILJMPm64_REX : X86::TAILJMPm64);
	MachineInstrBuilder MIB = BuildMI(MBB, MBBI, DL, TII->get(Op));
	for (unsigned i = 0; i != 5; ++i)
	MIB.add(MBBI->getOperand(i));
	} else if (Opcode == X86::TCRETURNri64) {
	BuildMI(MBB, MBBI, DL,
	TII->get(IsWin64 ? X86::TAILJMPr64_REX : X86::TAILJMPr64))
	.addReg(JumpTarget.getReg(), RegState::Kill);
	} else {
	BuildMI(MBB, MBBI, DL, TII->get(X86::TAILJMPr))
	.addReg(JumpTarget.getReg(), RegState::Kill);
	}

	MachineInstr &NewMI = *std::prev(MBBI);
	NewMI.copyImplicitOps(MBBI->getParent()->getParent(), MBBI);

	// Delete the pseudo instruction TCRETURN.
	MBB.erase(MBBI);

	return true;
	}
	case X86::EH_RETURN:
	case X86::EH_RETURN64: {
	MachineOperand &DestAddr = MBBI->getOperand(0);
	assert(DestAddr.isReg() && "Offset should be in register!");
	const bool Uses64BitFramePtr =
	STI->isTarget64BitLP64() \|\| STI->isTargetNaCl64();
	unsigned StackPtr = TRI->getStackRegister();
	BuildMI(MBB, MBBI, DL,
	TII->get(Uses64BitFramePtr ? X86::MOV64rr : X86::MOV32rr), StackPtr)
	.addReg(DestAddr.getReg());
	// The EH_RETURN pseudo is really removed during the MC Lowering.
	return true;
	}
	case X86::IRET: {
	// Adjust stack to erase error code
	int64_t StackAdj = MBBI->getOperand(0).getImm();
	X86FL->emitSPUpdate(MBB, MBBI, DL, StackAdj, true);
	// Replace pseudo with machine iret
	BuildMI(MBB, MBBI, DL,
	TII->get(STI->is64Bit() ? X86::IRET64 : X86::IRET32));
	MBB.erase(MBBI);
	return true;
	}
	case X86::RET: {
	// Adjust stack to erase error code
	int64_t StackAdj = MBBI->getOperand(0).getImm();
	MachineInstrBuilder MIB;
	if (StackAdj == 0) {
	MIB = BuildMI(MBB, MBBI, DL,
	TII->get(STI->is64Bit() ? X86::RETQ : X86::RETL));
	} else if (isUInt<16>(StackAdj)) {
	MIB = BuildMI(MBB, MBBI, DL,
	TII->get(STI->is64Bit() ? X86::RETIQ : X86::RETIL))
	.addImm(StackAdj);
	} else {
	assert(!STI->is64Bit() &&
	"shouldn't need to do this for x86_64 targets!");
	// A ret can only handle immediates as big as 2**16-1. If we need to pop
	// off bytes before the return address, we must do it manually.
	BuildMI(MBB, MBBI, DL, TII->get(X86::POP32r)).addReg(X86::ECX, RegState::Define);
	X86FL->emitSPUpdate(MBB, MBBI, DL, StackAdj, /InEpilogue=/true);
	BuildMI(MBB, MBBI, DL, TII->get(X86::PUSH32r)).addReg(X86::ECX);
	MIB = BuildMI(MBB, MBBI, DL, TII->get(X86::RETL));
	}
	for (unsigned I = 1, E = MBBI->getNumOperands(); I != E; ++I)
	MIB.add(MBBI->getOperand(I));
	MBB.erase(MBBI);
	return true;
	}
	case X86::EH_RESTORE: {
	// Restore ESP and EBP, and optionally ESI if required.
	bool IsSEH = isAsynchronousEHPersonality(classifyEHPersonality(
	MBB.getParent()->getFunction().getPersonalityFn()));
	X86FL->restoreWin32EHStackPointers(MBB, MBBI, DL, /RestoreSP=/IsSEH);
	MBBI->eraseFromParent();
	return true;
	}
	case X86::LCMPXCHG8B_SAVE_EBX:
	case X86::LCMPXCHG16B_SAVE_RBX: {
	// Perform the following transformation.
	// SaveRbx = pseudocmpxchg Addr, <4 opds for the address>, InArg, SaveRbx
	// =>
	// [E\|R]BX = InArg
	// actualcmpxchg Addr
	// [E\|R]BX = SaveRbx
	const MachineOperand &InArg = MBBI->getOperand(6);
	unsigned SaveRbx = MBBI->getOperand(7).getReg();

	unsigned ActualInArg =
	Opcode == X86::LCMPXCHG8B_SAVE_EBX ? X86::EBX : X86::RBX;
	// Copy the input argument of the pseudo into the argument of the
	// actual instruction.
	TII->copyPhysReg(MBB, MBBI, DL, ActualInArg, InArg.getReg(),
	InArg.isKill());
	// Create the actual instruction.
	unsigned ActualOpc =
	Opcode == X86::LCMPXCHG8B_SAVE_EBX ? X86::LCMPXCHG8B : X86::LCMPXCHG16B;
	MachineInstr *NewInstr = BuildMI(MBB, MBBI, DL, TII->get(ActualOpc));
	// Copy the operands related to the address.
	for (unsigned Idx = 1; Idx < 6; ++Idx)
	NewInstr->addOperand(MBBI->getOperand(Idx));
	// Finally, restore the value of RBX.
	TII->copyPhysReg(MBB, MBBI, DL, ActualInArg, SaveRbx,
	/SrcIsKill/ true);

	// Delete the pseudo.
	MBBI->eraseFromParent();
	return true;
	}
	case TargetOpcode::ICALL_BRANCH_FUNNEL:
	ExpandICallBranchFunnel(&MBB, MBBI);
	return true;
	}
	llvm_unreachable("Previous switch has a fallthrough?");
	}

	/// Expand all pseudo instructions contained in \p MBB.
	/// \returns true if any expansion occurred for \p MBB.
	bool X86ExpandPseudo::ExpandMBB(MachineBasicBlock &MBB) {
	bool Modified = false;

	// MBBI may be invalidated by the expansion.
	MachineBasicBlock::iterator MBBI = MBB.begin(), E = MBB.end();
	while (MBBI != E) {
	MachineBasicBlock::iterator NMBBI = std::next(MBBI);
	Modified \|= ExpandMI(MBB, MBBI);
	MBBI = NMBBI;
	}

	return Modified;
	}

	bool X86ExpandPseudo::runOnMachineFunction(MachineFunction &MF) {
	STI = &static_cast<const X86Subtarget &>(MF.getSubtarget());
	TII = STI->getInstrInfo();
	TRI = STI->getRegisterInfo();
	X86FI = MF.getInfo<X86MachineFunctionInfo>();
	X86FL = STI->getFrameLowering();

	bool Modified = false;
	for (MachineBasicBlock &MBB : MF)
	Modified \|= ExpandMBB(MBB);
	return Modified;
	}

	/// Returns an instance of the pseudo instruction expansion pass.
	FunctionPass *llvm::createX86ExpandPseudoPass() {
	return new X86ExpandPseudo();
	}