third_party/LLVM/lib/Target/Alpha/AlphaInstrInfo.cpp - SwiftShader - Git at Google

 //===- AlphaInstrInfo.cpp - Alpha Instruction Information -------*- C++ -*-===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file contains the Alpha implementation of the TargetInstrInfo class.
 //
 //===----------------------------------------------------------------------===//

 #include "Alpha.h"
 #include "AlphaInstrInfo.h"
 #include "AlphaMachineFunctionInfo.h"
 #include "llvm/CodeGen/MachineInstrBuilder.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/Support/ErrorHandling.h"

 #define GET_INSTRINFO_CTOR
 #include "AlphaGenInstrInfo.inc"
 using namespace llvm;

 AlphaInstrInfo::AlphaInstrInfo()
   : AlphaGenInstrInfo(Alpha::ADJUSTSTACKDOWN, Alpha::ADJUSTSTACKUP),
     RI(*this) {
 }


 unsigned
 AlphaInstrInfo::isLoadFromStackSlot(const MachineInstr *MI,
                                     int &FrameIndex) const {
   switch (MI->getOpcode()) {
   case Alpha::LDL:
   case Alpha::LDQ:
   case Alpha::LDBU:
   case Alpha::LDWU:
   case Alpha::LDS:
   case Alpha::LDT:
     if (MI->getOperand(1).isFI()) {
       FrameIndex = MI->getOperand(1).getIndex();
       return MI->getOperand(0).getReg();
     }
     break;
   }
   return 0;
 }

 unsigned
 AlphaInstrInfo::isStoreToStackSlot(const MachineInstr *MI,
                                    int &FrameIndex) const {
   switch (MI->getOpcode()) {
   case Alpha::STL:
   case Alpha::STQ:
   case Alpha::STB:
   case Alpha::STW:
   case Alpha::STS:
   case Alpha::STT:
     if (MI->getOperand(1).isFI()) {
       FrameIndex = MI->getOperand(1).getIndex();
       return MI->getOperand(0).getReg();
     }
     break;
   }
   return 0;
 }

 static bool isAlphaIntCondCode(unsigned Opcode) {
   switch (Opcode) {
   case Alpha::BEQ:
   case Alpha::BNE:
   case Alpha::BGE:
   case Alpha::BGT:
   case Alpha::BLE:
   case Alpha::BLT:
   case Alpha::BLBC:
   case Alpha::BLBS:
     return true;
   default:
     return false;
   }
 }

 unsigned AlphaInstrInfo::InsertBranch(MachineBasicBlock &MBB,
                                       MachineBasicBlock *TBB,
                                       MachineBasicBlock *FBB,
                                       const SmallVectorImpl<MachineOperand> &Cond,
                                       DebugLoc DL) const {
   assert(TBB && "InsertBranch must not be told to insert a fallthrough");
   assert((Cond.size() == 2 || Cond.size() == 0) &&
          "Alpha branch conditions have two components!");

   // One-way branch.
   if (FBB == 0) {
     if (Cond.empty())   // Unconditional branch
       BuildMI(&MBB, DL, get(Alpha::BR)).addMBB(TBB);
     else                // Conditional branch
       if (isAlphaIntCondCode(Cond[0].getImm()))
         BuildMI(&MBB, DL, get(Alpha::COND_BRANCH_I))
           .addImm(Cond[0].getImm()).addReg(Cond[1].getReg()).addMBB(TBB);
       else
         BuildMI(&MBB, DL, get(Alpha::COND_BRANCH_F))
           .addImm(Cond[0].getImm()).addReg(Cond[1].getReg()).addMBB(TBB);
     return 1;
   }

   // Two-way Conditional Branch.
   if (isAlphaIntCondCode(Cond[0].getImm()))
     BuildMI(&MBB, DL, get(Alpha::COND_BRANCH_I))
       .addImm(Cond[0].getImm()).addReg(Cond[1].getReg()).addMBB(TBB);
   else
     BuildMI(&MBB, DL, get(Alpha::COND_BRANCH_F))
       .addImm(Cond[0].getImm()).addReg(Cond[1].getReg()).addMBB(TBB);
   BuildMI(&MBB, DL, get(Alpha::BR)).addMBB(FBB);
   return 2;
 }

 void AlphaInstrInfo::copyPhysReg(MachineBasicBlock &MBB,
                                  MachineBasicBlock::iterator MI, DebugLoc DL,
                                  unsigned DestReg, unsigned SrcReg,
                                  bool KillSrc) const {
   if (Alpha::GPRCRegClass.contains(DestReg, SrcReg)) {
     BuildMI(MBB, MI, DL, get(Alpha::BISr), DestReg)
       .addReg(SrcReg)
       .addReg(SrcReg, getKillRegState(KillSrc));
   } else if (Alpha::F4RCRegClass.contains(DestReg, SrcReg)) {
     BuildMI(MBB, MI, DL, get(Alpha::CPYSS), DestReg)
       .addReg(SrcReg)
       .addReg(SrcReg, getKillRegState(KillSrc));
   } else if (Alpha::F8RCRegClass.contains(DestReg, SrcReg)) {
     BuildMI(MBB, MI, DL, get(Alpha::CPYST), DestReg)
       .addReg(SrcReg)
       .addReg(SrcReg, getKillRegState(KillSrc));
   } else {
     llvm_unreachable("Attempt to copy register that is not GPR or FPR");
   }
 }

 void
 AlphaInstrInfo::storeRegToStackSlot(MachineBasicBlock &MBB,
                                     MachineBasicBlock::iterator MI,
                                     unsigned SrcReg, bool isKill, int FrameIdx,
                                     const TargetRegisterClass *RC,
                                     const TargetRegisterInfo *TRI) const {
   //cerr << "Trying to store " << getPrettyName(SrcReg) << " to "
   //     << FrameIdx << "\n";
   //BuildMI(MBB, MI, Alpha::WTF, 0).addReg(SrcReg);

   DebugLoc DL;
   if (MI != MBB.end()) DL = MI->getDebugLoc();

   if (RC == Alpha::F4RCRegisterClass)
     BuildMI(MBB, MI, DL, get(Alpha::STS))
       .addReg(SrcReg, getKillRegState(isKill))
       .addFrameIndex(FrameIdx).addReg(Alpha::F31);
   else if (RC == Alpha::F8RCRegisterClass)
     BuildMI(MBB, MI, DL, get(Alpha::STT))
       .addReg(SrcReg, getKillRegState(isKill))
       .addFrameIndex(FrameIdx).addReg(Alpha::F31);
   else if (RC == Alpha::GPRCRegisterClass)
     BuildMI(MBB, MI, DL, get(Alpha::STQ))
       .addReg(SrcReg, getKillRegState(isKill))
       .addFrameIndex(FrameIdx).addReg(Alpha::F31);
   else
     llvm_unreachable("Unhandled register class");
 }

 void
 AlphaInstrInfo::loadRegFromStackSlot(MachineBasicBlock &MBB,
                                         MachineBasicBlock::iterator MI,
                                         unsigned DestReg, int FrameIdx,
                                      const TargetRegisterClass *RC,
                                      const TargetRegisterInfo *TRI) const {
   //cerr << "Trying to load " << getPrettyName(DestReg) << " to "
   //     << FrameIdx << "\n";
   DebugLoc DL;
   if (MI != MBB.end()) DL = MI->getDebugLoc();

   if (RC == Alpha::F4RCRegisterClass)
     BuildMI(MBB, MI, DL, get(Alpha::LDS), DestReg)
       .addFrameIndex(FrameIdx).addReg(Alpha::F31);
   else if (RC == Alpha::F8RCRegisterClass)
     BuildMI(MBB, MI, DL, get(Alpha::LDT), DestReg)
       .addFrameIndex(FrameIdx).addReg(Alpha::F31);
   else if (RC == Alpha::GPRCRegisterClass)
     BuildMI(MBB, MI, DL, get(Alpha::LDQ), DestReg)
       .addFrameIndex(FrameIdx).addReg(Alpha::F31);
   else
     llvm_unreachable("Unhandled register class");
 }

 static unsigned AlphaRevCondCode(unsigned Opcode) {
   switch (Opcode) {
   case Alpha::BEQ: return Alpha::BNE;
   case Alpha::BNE: return Alpha::BEQ;
   case Alpha::BGE: return Alpha::BLT;
   case Alpha::BGT: return Alpha::BLE;
   case Alpha::BLE: return Alpha::BGT;
   case Alpha::BLT: return Alpha::BGE;
   case Alpha::BLBC: return Alpha::BLBS;
   case Alpha::BLBS: return Alpha::BLBC;
   case Alpha::FBEQ: return Alpha::FBNE;
   case Alpha::FBNE: return Alpha::FBEQ;
   case Alpha::FBGE: return Alpha::FBLT;
   case Alpha::FBGT: return Alpha::FBLE;
   case Alpha::FBLE: return Alpha::FBGT;
   case Alpha::FBLT: return Alpha::FBGE;
   default:
     llvm_unreachable("Unknown opcode");
   }
   return 0; // Not reached
 }

 // Branch analysis.
 bool AlphaInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,MachineBasicBlock *&TBB,
                                    MachineBasicBlock *&FBB,
                                    SmallVectorImpl<MachineOperand> &Cond,
                                    bool AllowModify) const {
   // If the block has no terminators, it just falls into the block after it.
   MachineBasicBlock::iterator I = MBB.end();
   if (I == MBB.begin())
     return false;
   --I;
   while (I->isDebugValue()) {
     if (I == MBB.begin())
       return false;
     --I;
   }
   if (!isUnpredicatedTerminator(I))
     return false;

   // Get the last instruction in the block.
   MachineInstr *LastInst = I;

   // If there is only one terminator instruction, process it.
   if (I == MBB.begin() || !isUnpredicatedTerminator(--I)) {
     if (LastInst->getOpcode() == Alpha::BR) {
       TBB = LastInst->getOperand(0).getMBB();
       return false;
     } else if (LastInst->getOpcode() == Alpha::COND_BRANCH_I ||
                LastInst->getOpcode() == Alpha::COND_BRANCH_F) {
       // Block ends with fall-through condbranch.
       TBB = LastInst->getOperand(2).getMBB();
       Cond.push_back(LastInst->getOperand(0));
       Cond.push_back(LastInst->getOperand(1));
       return false;
     }
     // Otherwise, don't know what this is.
     return true;
   }

   // Get the instruction before it if it's a terminator.
   MachineInstr *SecondLastInst = I;

   // If there are three terminators, we don't know what sort of block this is.
   if (SecondLastInst && I != MBB.begin() &&
       isUnpredicatedTerminator(--I))
     return true;

   // If the block ends with Alpha::BR and Alpha::COND_BRANCH_*, handle it.
   if ((SecondLastInst->getOpcode() == Alpha::COND_BRANCH_I ||
       SecondLastInst->getOpcode() == Alpha::COND_BRANCH_F) &&
       LastInst->getOpcode() == Alpha::BR) {
     TBB =  SecondLastInst->getOperand(2).getMBB();
     Cond.push_back(SecondLastInst->getOperand(0));
     Cond.push_back(SecondLastInst->getOperand(1));
     FBB = LastInst->getOperand(0).getMBB();
     return false;
   }

   // If the block ends with two Alpha::BRs, handle it.  The second one is not
   // executed, so remove it.
   if (SecondLastInst->getOpcode() == Alpha::BR &&
       LastInst->getOpcode() == Alpha::BR) {
     TBB = SecondLastInst->getOperand(0).getMBB();
     I = LastInst;
     if (AllowModify)
       I->eraseFromParent();
     return false;
   }

   // Otherwise, can't handle this.
   return true;
 }

 unsigned AlphaInstrInfo::RemoveBranch(MachineBasicBlock &MBB) const {
   MachineBasicBlock::iterator I = MBB.end();
   if (I == MBB.begin()) return 0;
   --I;
   while (I->isDebugValue()) {
     if (I == MBB.begin())
       return 0;
     --I;
   }
   if (I->getOpcode() != Alpha::BR &&
       I->getOpcode() != Alpha::COND_BRANCH_I &&
       I->getOpcode() != Alpha::COND_BRANCH_F)
     return 0;

   // Remove the branch.
   I->eraseFromParent();

   I = MBB.end();

   if (I == MBB.begin()) return 1;
   --I;
   if (I->getOpcode() != Alpha::COND_BRANCH_I &&
       I->getOpcode() != Alpha::COND_BRANCH_F)
     return 1;

   // Remove the branch.
   I->eraseFromParent();
   return 2;
 }

 void AlphaInstrInfo::insertNoop(MachineBasicBlock &MBB,
                                 MachineBasicBlock::iterator MI) const {
   DebugLoc DL;
   BuildMI(MBB, MI, DL, get(Alpha::BISr), Alpha::R31)
     .addReg(Alpha::R31)
     .addReg(Alpha::R31);
 }

 bool AlphaInstrInfo::
 ReverseBranchCondition(SmallVectorImpl<MachineOperand> &Cond) const {
   assert(Cond.size() == 2 && "Invalid Alpha branch opcode!");
   Cond[0].setImm(AlphaRevCondCode(Cond[0].getImm()));
   return false;
 }

 /// getGlobalBaseReg - Return a virtual register initialized with the
 /// the global base register value. Output instructions required to
 /// initialize the register in the function entry block, if necessary.
 ///
 unsigned AlphaInstrInfo::getGlobalBaseReg(MachineFunction *MF) const {
   AlphaMachineFunctionInfo *AlphaFI = MF->getInfo<AlphaMachineFunctionInfo>();
   unsigned GlobalBaseReg = AlphaFI->getGlobalBaseReg();
   if (GlobalBaseReg != 0)
     return GlobalBaseReg;

   // Insert the set of GlobalBaseReg into the first MBB of the function
   MachineBasicBlock &FirstMBB = MF->front();
   MachineBasicBlock::iterator MBBI = FirstMBB.begin();
   MachineRegisterInfo &RegInfo = MF->getRegInfo();
   const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();

   GlobalBaseReg = RegInfo.createVirtualRegister(&Alpha::GPRCRegClass);
   BuildMI(FirstMBB, MBBI, DebugLoc(), TII->get(TargetOpcode::COPY),
           GlobalBaseReg).addReg(Alpha::R29);
   RegInfo.addLiveIn(Alpha::R29);

   AlphaFI->setGlobalBaseReg(GlobalBaseReg);
   return GlobalBaseReg;
 }

 /// getGlobalRetAddr - Return a virtual register initialized with the
 /// the global base register value. Output instructions required to
 /// initialize the register in the function entry block, if necessary.
 ///
 unsigned AlphaInstrInfo::getGlobalRetAddr(MachineFunction *MF) const {
   AlphaMachineFunctionInfo *AlphaFI = MF->getInfo<AlphaMachineFunctionInfo>();
   unsigned GlobalRetAddr = AlphaFI->getGlobalRetAddr();
   if (GlobalRetAddr != 0)
     return GlobalRetAddr;

   // Insert the set of GlobalRetAddr into the first MBB of the function
   MachineBasicBlock &FirstMBB = MF->front();
   MachineBasicBlock::iterator MBBI = FirstMBB.begin();
   MachineRegisterInfo &RegInfo = MF->getRegInfo();
   const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();

   GlobalRetAddr = RegInfo.createVirtualRegister(&Alpha::GPRCRegClass);
   BuildMI(FirstMBB, MBBI, DebugLoc(), TII->get(TargetOpcode::COPY),
           GlobalRetAddr).addReg(Alpha::R26);
   RegInfo.addLiveIn(Alpha::R26);

   AlphaFI->setGlobalRetAddr(GlobalRetAddr);
   return GlobalRetAddr;
 }
	//===- AlphaInstrInfo.cpp - Alpha Instruction Information -------- C++ --===//
	//
	// The LLVM Compiler Infrastructure
	//
	// This file is distributed under the University of Illinois Open Source
	// License. See LICENSE.TXT for details.
	//
	//===----------------------------------------------------------------------===//
	//
	// This file contains the Alpha implementation of the TargetInstrInfo class.
	//
	//===----------------------------------------------------------------------===//

	#include "Alpha.h"
	#include "AlphaInstrInfo.h"
	#include "AlphaMachineFunctionInfo.h"
	#include "llvm/CodeGen/MachineInstrBuilder.h"
	#include "llvm/CodeGen/MachineRegisterInfo.h"
	#include "llvm/ADT/STLExtras.h"
	#include "llvm/ADT/SmallVector.h"
	#include "llvm/Support/ErrorHandling.h"

	#define GET_INSTRINFO_CTOR
	#include "AlphaGenInstrInfo.inc"
	using namespace llvm;

	AlphaInstrInfo::AlphaInstrInfo()
	: AlphaGenInstrInfo(Alpha::ADJUSTSTACKDOWN, Alpha::ADJUSTSTACKUP),
	RI(*this) {
	}


	unsigned
	AlphaInstrInfo::isLoadFromStackSlot(const MachineInstr *MI,
	int &FrameIndex) const {
	switch (MI->getOpcode()) {
	case Alpha::LDL:
	case Alpha::LDQ:
	case Alpha::LDBU:
	case Alpha::LDWU:
	case Alpha::LDS:
	case Alpha::LDT:
	if (MI->getOperand(1).isFI()) {
	FrameIndex = MI->getOperand(1).getIndex();
	return MI->getOperand(0).getReg();
	}
	break;
	}
	return 0;
	}

	unsigned
	AlphaInstrInfo::isStoreToStackSlot(const MachineInstr *MI,
	int &FrameIndex) const {
	switch (MI->getOpcode()) {
	case Alpha::STL:
	case Alpha::STQ:
	case Alpha::STB:
	case Alpha::STW:
	case Alpha::STS:
	case Alpha::STT:
	if (MI->getOperand(1).isFI()) {
	FrameIndex = MI->getOperand(1).getIndex();
	return MI->getOperand(0).getReg();
	}
	break;
	}
	return 0;
	}

	static bool isAlphaIntCondCode(unsigned Opcode) {
	switch (Opcode) {
	case Alpha::BEQ:
	case Alpha::BNE:
	case Alpha::BGE:
	case Alpha::BGT:
	case Alpha::BLE:
	case Alpha::BLT:
	case Alpha::BLBC:
	case Alpha::BLBS:
	return true;
	default:
	return false;
	}
	}

	unsigned AlphaInstrInfo::InsertBranch(MachineBasicBlock &MBB,
	MachineBasicBlock *TBB,
	MachineBasicBlock *FBB,
	const SmallVectorImpl<MachineOperand> &Cond,
	DebugLoc DL) const {
	assert(TBB && "InsertBranch must not be told to insert a fallthrough");
	assert((Cond.size() == 2 \|\| Cond.size() == 0) &&
	"Alpha branch conditions have two components!");

	// One-way branch.
	if (FBB == 0) {
	if (Cond.empty()) // Unconditional branch
	BuildMI(&MBB, DL, get(Alpha::BR)).addMBB(TBB);
	else // Conditional branch
	if (isAlphaIntCondCode(Cond[0].getImm()))
	BuildMI(&MBB, DL, get(Alpha::COND_BRANCH_I))
	.addImm(Cond[0].getImm()).addReg(Cond[1].getReg()).addMBB(TBB);
	else
	BuildMI(&MBB, DL, get(Alpha::COND_BRANCH_F))
	.addImm(Cond[0].getImm()).addReg(Cond[1].getReg()).addMBB(TBB);
	return 1;
	}

	// Two-way Conditional Branch.
	if (isAlphaIntCondCode(Cond[0].getImm()))
	BuildMI(&MBB, DL, get(Alpha::COND_BRANCH_I))
	.addImm(Cond[0].getImm()).addReg(Cond[1].getReg()).addMBB(TBB);
	else
	BuildMI(&MBB, DL, get(Alpha::COND_BRANCH_F))
	.addImm(Cond[0].getImm()).addReg(Cond[1].getReg()).addMBB(TBB);
	BuildMI(&MBB, DL, get(Alpha::BR)).addMBB(FBB);
	return 2;
	}

	void AlphaInstrInfo::copyPhysReg(MachineBasicBlock &MBB,
	MachineBasicBlock::iterator MI, DebugLoc DL,
	unsigned DestReg, unsigned SrcReg,
	bool KillSrc) const {
	if (Alpha::GPRCRegClass.contains(DestReg, SrcReg)) {
	BuildMI(MBB, MI, DL, get(Alpha::BISr), DestReg)
	.addReg(SrcReg)
	.addReg(SrcReg, getKillRegState(KillSrc));
	} else if (Alpha::F4RCRegClass.contains(DestReg, SrcReg)) {
	BuildMI(MBB, MI, DL, get(Alpha::CPYSS), DestReg)
	.addReg(SrcReg)
	.addReg(SrcReg, getKillRegState(KillSrc));
	} else if (Alpha::F8RCRegClass.contains(DestReg, SrcReg)) {
	BuildMI(MBB, MI, DL, get(Alpha::CPYST), DestReg)
	.addReg(SrcReg)
	.addReg(SrcReg, getKillRegState(KillSrc));
	} else {
	llvm_unreachable("Attempt to copy register that is not GPR or FPR");
	}
	}

	void
	AlphaInstrInfo::storeRegToStackSlot(MachineBasicBlock &MBB,
	MachineBasicBlock::iterator MI,
	unsigned SrcReg, bool isKill, int FrameIdx,
	const TargetRegisterClass *RC,
	const TargetRegisterInfo *TRI) const {
	//cerr << "Trying to store " << getPrettyName(SrcReg) << " to "
	// << FrameIdx << "\n";
	//BuildMI(MBB, MI, Alpha::WTF, 0).addReg(SrcReg);

	DebugLoc DL;
	if (MI != MBB.end()) DL = MI->getDebugLoc();

	if (RC == Alpha::F4RCRegisterClass)
	BuildMI(MBB, MI, DL, get(Alpha::STS))
	.addReg(SrcReg, getKillRegState(isKill))
	.addFrameIndex(FrameIdx).addReg(Alpha::F31);
	else if (RC == Alpha::F8RCRegisterClass)
	BuildMI(MBB, MI, DL, get(Alpha::STT))
	.addReg(SrcReg, getKillRegState(isKill))
	.addFrameIndex(FrameIdx).addReg(Alpha::F31);
	else if (RC == Alpha::GPRCRegisterClass)
	BuildMI(MBB, MI, DL, get(Alpha::STQ))
	.addReg(SrcReg, getKillRegState(isKill))
	.addFrameIndex(FrameIdx).addReg(Alpha::F31);
	else
	llvm_unreachable("Unhandled register class");
	}

	void
	AlphaInstrInfo::loadRegFromStackSlot(MachineBasicBlock &MBB,
	MachineBasicBlock::iterator MI,
	unsigned DestReg, int FrameIdx,
	const TargetRegisterClass *RC,
	const TargetRegisterInfo *TRI) const {
	//cerr << "Trying to load " << getPrettyName(DestReg) << " to "
	// << FrameIdx << "\n";
	DebugLoc DL;
	if (MI != MBB.end()) DL = MI->getDebugLoc();

	if (RC == Alpha::F4RCRegisterClass)
	BuildMI(MBB, MI, DL, get(Alpha::LDS), DestReg)
	.addFrameIndex(FrameIdx).addReg(Alpha::F31);
	else if (RC == Alpha::F8RCRegisterClass)
	BuildMI(MBB, MI, DL, get(Alpha::LDT), DestReg)
	.addFrameIndex(FrameIdx).addReg(Alpha::F31);
	else if (RC == Alpha::GPRCRegisterClass)
	BuildMI(MBB, MI, DL, get(Alpha::LDQ), DestReg)
	.addFrameIndex(FrameIdx).addReg(Alpha::F31);
	else
	llvm_unreachable("Unhandled register class");
	}

	static unsigned AlphaRevCondCode(unsigned Opcode) {
	switch (Opcode) {
	case Alpha::BEQ: return Alpha::BNE;
	case Alpha::BNE: return Alpha::BEQ;
	case Alpha::BGE: return Alpha::BLT;
	case Alpha::BGT: return Alpha::BLE;
	case Alpha::BLE: return Alpha::BGT;
	case Alpha::BLT: return Alpha::BGE;
	case Alpha::BLBC: return Alpha::BLBS;
	case Alpha::BLBS: return Alpha::BLBC;
	case Alpha::FBEQ: return Alpha::FBNE;
	case Alpha::FBNE: return Alpha::FBEQ;
	case Alpha::FBGE: return Alpha::FBLT;
	case Alpha::FBGT: return Alpha::FBLE;
	case Alpha::FBLE: return Alpha::FBGT;
	case Alpha::FBLT: return Alpha::FBGE;
	default:
	llvm_unreachable("Unknown opcode");
	}
	return 0; // Not reached
	}

	// Branch analysis.
	bool AlphaInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,MachineBasicBlock *&TBB,
	MachineBasicBlock *&FBB,
	SmallVectorImpl<MachineOperand> &Cond,
	bool AllowModify) const {
	// If the block has no terminators, it just falls into the block after it.
	MachineBasicBlock::iterator I = MBB.end();
	if (I == MBB.begin())
	return false;
	--I;
	while (I->isDebugValue()) {
	if (I == MBB.begin())
	return false;
	--I;
	}
	if (!isUnpredicatedTerminator(I))
	return false;

	// Get the last instruction in the block.
	MachineInstr *LastInst = I;

	// If there is only one terminator instruction, process it.
	if (I == MBB.begin() \|\| !isUnpredicatedTerminator(--I)) {
	if (LastInst->getOpcode() == Alpha::BR) {
	TBB = LastInst->getOperand(0).getMBB();
	return false;
	} else if (LastInst->getOpcode() == Alpha::COND_BRANCH_I \|\|
	LastInst->getOpcode() == Alpha::COND_BRANCH_F) {
	// Block ends with fall-through condbranch.
	TBB = LastInst->getOperand(2).getMBB();
	Cond.push_back(LastInst->getOperand(0));
	Cond.push_back(LastInst->getOperand(1));
	return false;
	}
	// Otherwise, don't know what this is.
	return true;
	}

	// Get the instruction before it if it's a terminator.
	MachineInstr *SecondLastInst = I;

	// If there are three terminators, we don't know what sort of block this is.
	if (SecondLastInst && I != MBB.begin() &&
	isUnpredicatedTerminator(--I))
	return true;

	// If the block ends with Alpha::BR and Alpha::COND_BRANCH_*, handle it.
	if ((SecondLastInst->getOpcode() == Alpha::COND_BRANCH_I \|\|
	SecondLastInst->getOpcode() == Alpha::COND_BRANCH_F) &&
	LastInst->getOpcode() == Alpha::BR) {
	TBB = SecondLastInst->getOperand(2).getMBB();
	Cond.push_back(SecondLastInst->getOperand(0));
	Cond.push_back(SecondLastInst->getOperand(1));
	FBB = LastInst->getOperand(0).getMBB();
	return false;
	}

	// If the block ends with two Alpha::BRs, handle it. The second one is not
	// executed, so remove it.
	if (SecondLastInst->getOpcode() == Alpha::BR &&
	LastInst->getOpcode() == Alpha::BR) {
	TBB = SecondLastInst->getOperand(0).getMBB();
	I = LastInst;
	if (AllowModify)
	I->eraseFromParent();
	return false;
	}

	// Otherwise, can't handle this.
	return true;
	}

	unsigned AlphaInstrInfo::RemoveBranch(MachineBasicBlock &MBB) const {
	MachineBasicBlock::iterator I = MBB.end();
	if (I == MBB.begin()) return 0;
	--I;
	while (I->isDebugValue()) {
	if (I == MBB.begin())
	return 0;
	--I;
	}
	if (I->getOpcode() != Alpha::BR &&
	I->getOpcode() != Alpha::COND_BRANCH_I &&
	I->getOpcode() != Alpha::COND_BRANCH_F)
	return 0;

	// Remove the branch.
	I->eraseFromParent();

	I = MBB.end();

	if (I == MBB.begin()) return 1;
	--I;
	if (I->getOpcode() != Alpha::COND_BRANCH_I &&
	I->getOpcode() != Alpha::COND_BRANCH_F)
	return 1;

	// Remove the branch.
	I->eraseFromParent();
	return 2;
	}

	void AlphaInstrInfo::insertNoop(MachineBasicBlock &MBB,
	MachineBasicBlock::iterator MI) const {
	DebugLoc DL;
	BuildMI(MBB, MI, DL, get(Alpha::BISr), Alpha::R31)
	.addReg(Alpha::R31)
	.addReg(Alpha::R31);
	}

	bool AlphaInstrInfo::
	ReverseBranchCondition(SmallVectorImpl<MachineOperand> &Cond) const {
	assert(Cond.size() == 2 && "Invalid Alpha branch opcode!");
	Cond[0].setImm(AlphaRevCondCode(Cond[0].getImm()));
	return false;
	}

	/// getGlobalBaseReg - Return a virtual register initialized with the
	/// the global base register value. Output instructions required to
	/// initialize the register in the function entry block, if necessary.
	///
	unsigned AlphaInstrInfo::getGlobalBaseReg(MachineFunction *MF) const {
	AlphaMachineFunctionInfo *AlphaFI = MF->getInfo<AlphaMachineFunctionInfo>();
	unsigned GlobalBaseReg = AlphaFI->getGlobalBaseReg();
	if (GlobalBaseReg != 0)
	return GlobalBaseReg;

	// Insert the set of GlobalBaseReg into the first MBB of the function
	MachineBasicBlock &FirstMBB = MF->front();
	MachineBasicBlock::iterator MBBI = FirstMBB.begin();
	MachineRegisterInfo &RegInfo = MF->getRegInfo();
	const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();

	GlobalBaseReg = RegInfo.createVirtualRegister(&Alpha::GPRCRegClass);
	BuildMI(FirstMBB, MBBI, DebugLoc(), TII->get(TargetOpcode::COPY),
	GlobalBaseReg).addReg(Alpha::R29);
	RegInfo.addLiveIn(Alpha::R29);

	AlphaFI->setGlobalBaseReg(GlobalBaseReg);
	return GlobalBaseReg;
	}

	/// getGlobalRetAddr - Return a virtual register initialized with the
	/// the global base register value. Output instructions required to
	/// initialize the register in the function entry block, if necessary.
	///
	unsigned AlphaInstrInfo::getGlobalRetAddr(MachineFunction *MF) const {
	AlphaMachineFunctionInfo *AlphaFI = MF->getInfo<AlphaMachineFunctionInfo>();
	unsigned GlobalRetAddr = AlphaFI->getGlobalRetAddr();
	if (GlobalRetAddr != 0)
	return GlobalRetAddr;

	// Insert the set of GlobalRetAddr into the first MBB of the function
	MachineBasicBlock &FirstMBB = MF->front();
	MachineBasicBlock::iterator MBBI = FirstMBB.begin();
	MachineRegisterInfo &RegInfo = MF->getRegInfo();
	const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();

	GlobalRetAddr = RegInfo.createVirtualRegister(&Alpha::GPRCRegClass);
	BuildMI(FirstMBB, MBBI, DebugLoc(), TII->get(TargetOpcode::COPY),
	GlobalRetAddr).addReg(Alpha::R26);
	RegInfo.addLiveIn(Alpha::R26);

	AlphaFI->setGlobalRetAddr(GlobalRetAddr);
	return GlobalRetAddr;
	}