lib/Target/Hexagon/HexagonFrameLowering.cpp - llvm - Git at Google

 //===-- HexagonFrameLowering.cpp - Define frame lowering ------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //
 //===----------------------------------------------------------------------===//

 #include "HexagonFrameLowering.h"
 #include "Hexagon.h"
 #include "HexagonInstrInfo.h"
 #include "HexagonRegisterInfo.h"
 #include "HexagonSubtarget.h"
 #include "HexagonTargetMachine.h"
 #include "HexagonMachineFunctionInfo.h"
 #include "llvm/Function.h"
 #include "llvm/Type.h"
 #include "llvm/ADT/BitVector.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/CodeGen/AsmPrinter.h"
 #include "llvm/CodeGen/MachineInstrBuilder.h"
 #include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
 #include "llvm/CodeGen/MachineFrameInfo.h"
 #include "llvm/CodeGen/MachineModuleInfo.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/CodeGen/RegisterScavenging.h"
 #include "llvm/MC/MachineLocation.h"
 #include "llvm/MC/MCAsmInfo.h"
 #include "llvm/Target/TargetInstrInfo.h"
 #include "llvm/Target/TargetMachine.h"
 #include "llvm/Target/TargetOptions.h"
 #include "llvm/Support/CommandLine.h"

 using namespace llvm;

 static cl::opt<bool> DisableDeallocRet(
                        "disable-hexagon-dealloc-ret",
                        cl::Hidden,
                        cl::desc("Disable Dealloc Return for Hexagon target"));

 /// determineFrameLayout - Determine the size of the frame and maximum call
 /// frame size.
 void HexagonFrameLowering::determineFrameLayout(MachineFunction &MF) const {
   MachineFrameInfo *MFI = MF.getFrameInfo();

   // Get the number of bytes to allocate from the FrameInfo.
   unsigned FrameSize = MFI->getStackSize();

   // Get the alignments provided by the target.
   unsigned TargetAlign = MF.getTarget().getFrameLowering()->getStackAlignment();
   // Get the maximum call frame size of all the calls.
   unsigned maxCallFrameSize = MFI->getMaxCallFrameSize();

   // If we have dynamic alloca then maxCallFrameSize needs to be aligned so
   // that allocations will be aligned.
   if (MFI->hasVarSizedObjects())
     maxCallFrameSize = RoundUpToAlignment(maxCallFrameSize, TargetAlign);

   // Update maximum call frame size.
   MFI->setMaxCallFrameSize(maxCallFrameSize);

   // Include call frame size in total.
   FrameSize += maxCallFrameSize;

   // Make sure the frame is aligned.
   FrameSize = RoundUpToAlignment(FrameSize, TargetAlign);

   // Update frame info.
   MFI->setStackSize(FrameSize);
 }


 void HexagonFrameLowering::emitPrologue(MachineFunction &MF) const {
   MachineBasicBlock &MBB = MF.front();
   MachineFrameInfo *MFI = MF.getFrameInfo();
   MachineModuleInfo &MMI = MF.getMMI();
   MachineBasicBlock::iterator MBBI = MBB.begin();
   const HexagonRegisterInfo *QRI =
     static_cast<const HexagonRegisterInfo *>(MF.getTarget().getRegisterInfo());
   DebugLoc dl = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
   determineFrameLayout(MF);

   // Check if frame moves are needed for EH.
   bool needsFrameMoves = MMI.hasDebugInfo() ||
     !MF.getFunction()->needsUnwindTableEntry();

   // Get the number of bytes to allocate from the FrameInfo.
   int NumBytes = (int) MFI->getStackSize();

   // LLVM expects allocframe not to be the first instruction in the
   // basic block.
   MachineBasicBlock::iterator InsertPt = MBB.begin();

   //
   // ALLOCA adjust regs.  Iterate over ADJDYNALLOC nodes and change the offset.
   //
   HexagonMachineFunctionInfo *FuncInfo =
     MF.getInfo<HexagonMachineFunctionInfo>();
   const std::vector<MachineInstr*>& AdjustRegs =
     FuncInfo->getAllocaAdjustInsts();
   for (std::vector<MachineInstr*>::const_iterator i = AdjustRegs.begin(),
          e = AdjustRegs.end();
        i != e; ++i) {
     MachineInstr* MI = *i;
     assert((MI->getOpcode() == Hexagon::ADJDYNALLOC) &&
            "Expected adjust alloca node");

     MachineOperand& MO = MI->getOperand(2);
     assert(MO.isImm() && "Expected immediate");
     MO.setImm(MFI->getMaxCallFrameSize());
   }

  std::vector<MachineMove> &Moves = MMI.getFrameMoves();

  if (needsFrameMoves) {
    // Advance CFA. DW_CFA_def_cfa
    unsigned FPReg = QRI->getFrameRegister();
    unsigned RAReg = QRI->getRARegister();

    MachineLocation Dst(MachineLocation::VirtualFP);
    MachineLocation Src(FPReg, -8);
    Moves.push_back(MachineMove(0, Dst, Src));

    // R31 = (R31 - #4)
    MachineLocation LRDst(RAReg, -4);
    MachineLocation LRSrc(RAReg);
    Moves.push_back(MachineMove(0, LRDst, LRSrc));

    // R30 = (R30 - #8)
    MachineLocation SPDst(FPReg, -8);
    MachineLocation SPSrc(FPReg);
    Moves.push_back(MachineMove(0, SPDst, SPSrc));
  }

   //
   // Only insert ALLOCFRAME if we need to.
   //
   if (hasFP(MF)) {
     // Check for overflow.
     // Hexagon_TODO: Ugh! hardcoding. Is there an API that can be used?
     const int ALLOCFRAME_MAX = 16384;
     const TargetInstrInfo &TII = *MF.getTarget().getInstrInfo();

     if (NumBytes >= ALLOCFRAME_MAX) {
       // Emit allocframe(#0).
       BuildMI(MBB, InsertPt, dl, TII.get(Hexagon::ALLOCFRAME)).addImm(0);

       // Subtract offset from frame pointer.
       BuildMI(MBB, InsertPt, dl, TII.get(Hexagon::CONST32_Int_Real),
                                       HEXAGON_RESERVED_REG_1).addImm(NumBytes);
       BuildMI(MBB, InsertPt, dl, TII.get(Hexagon::SUB_rr),
                                       QRI->getStackRegister()).
                                       addReg(QRI->getStackRegister()).
                                       addReg(HEXAGON_RESERVED_REG_1);
     } else {
       BuildMI(MBB, InsertPt, dl, TII.get(Hexagon::ALLOCFRAME)).addImm(NumBytes);
     }
   }
 }
 // Returns true if MBB has a machine instructions that indicates a tail call
 // in the block.
 bool HexagonFrameLowering::hasTailCall(MachineBasicBlock &MBB) const {
   MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
   unsigned RetOpcode = MBBI->getOpcode();

   return RetOpcode == Hexagon::TCRETURNtg || RetOpcode == Hexagon::TCRETURNtext;}

 void HexagonFrameLowering::emitEpilogue(MachineFunction &MF,
                                      MachineBasicBlock &MBB) const {
   MachineBasicBlock::iterator MBBI = prior(MBB.end());
   DebugLoc dl = MBBI->getDebugLoc();
   //
   // Only insert deallocframe if we need to.
   //
   if (hasFP(MF)) {
     MachineBasicBlock::iterator MBBI = prior(MBB.end());
     MachineBasicBlock::iterator MBBI_end = MBB.end();
     //
     // For Hexagon, we don't need the frame size.
     //
     MachineFrameInfo *MFI = MF.getFrameInfo();
     int NumBytes = (int) MFI->getStackSize();

     const TargetInstrInfo &TII = *MF.getTarget().getInstrInfo();

     // Replace 'jumpr r31' instruction with dealloc_return for V4 and higher
     // versions.
     if (STI.hasV4TOps() && MBBI->getOpcode() == Hexagon::JMPR
                         && !DisableDeallocRet) {
       // Remove jumpr node.
       MBB.erase(MBBI);
       // Add dealloc_return.
       BuildMI(MBB, MBBI_end, dl, TII.get(Hexagon::DEALLOC_RET_V4))
         .addImm(NumBytes);
     } else { // Add deallocframe for V2 and V3.
       BuildMI(MBB, MBBI, dl, TII.get(Hexagon::DEALLOCFRAME)).addImm(NumBytes);
     }
   }
 }

 bool HexagonFrameLowering::hasFP(const MachineFunction &MF) const {
   const MachineFrameInfo *MFI = MF.getFrameInfo();
   const HexagonMachineFunctionInfo *FuncInfo =
     MF.getInfo<HexagonMachineFunctionInfo>();
   return (MFI->hasCalls() || (MFI->getStackSize() > 0) ||
           FuncInfo->hasClobberLR() );
 }

 bool
 HexagonFrameLowering::spillCalleeSavedRegisters(
                                         MachineBasicBlock &MBB,
                                         MachineBasicBlock::iterator MI,
                                         const std::vector<CalleeSavedInfo> &CSI,
                                         const TargetRegisterInfo *TRI) const {
   MachineFunction *MF = MBB.getParent();
   const TargetInstrInfo &TII = *MF->getTarget().getInstrInfo();

   if (CSI.empty()) {
     return false;
   }

   // We can only schedule double loads if we spill contiguous callee-saved regs
   // For instance, we cannot scheduled double-word loads if we spill r24,
   // r26, and r27.
   // Hexagon_TODO: We can try to double-word align odd registers for -O2 and
   // above.
   bool ContiguousRegs = true;

   for (unsigned i = 0; i < CSI.size(); ++i) {
     unsigned Reg = CSI[i].getReg();

     //
     // Check if we can use a double-word store.
     //
     const uint16_t* SuperReg = TRI->getSuperRegisters(Reg);

     // Assume that there is exactly one superreg.
     assert(SuperReg[0] && !SuperReg[1] && "Expected exactly one superreg");
     bool CanUseDblStore = false;
     const TargetRegisterClass* SuperRegClass = 0;

     if (ContiguousRegs && (i < CSI.size()-1)) {
       const uint16_t* SuperRegNext = TRI->getSuperRegisters(CSI[i+1].getReg());
       assert(SuperRegNext[0] && !SuperRegNext[1] &&
              "Expected exactly one superreg");
       SuperRegClass = TRI->getMinimalPhysRegClass(SuperReg[0]);
       CanUseDblStore = (SuperRegNext[0] == SuperReg[0]);
     }


     if (CanUseDblStore) {
       TII.storeRegToStackSlot(MBB, MI, SuperReg[0], true,
                               CSI[i+1].getFrameIdx(), SuperRegClass, TRI);
       MBB.addLiveIn(SuperReg[0]);
       ++i;
     } else {
       // Cannot use a double-word store.
       ContiguousRegs = false;
       const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
       TII.storeRegToStackSlot(MBB, MI, Reg, true, CSI[i].getFrameIdx(), RC,
                               TRI);
       MBB.addLiveIn(Reg);
     }
   }
   return true;
 }


 bool HexagonFrameLowering::restoreCalleeSavedRegisters(
                                         MachineBasicBlock &MBB,
                                         MachineBasicBlock::iterator MI,
                                         const std::vector<CalleeSavedInfo> &CSI,
                                         const TargetRegisterInfo *TRI) const {

   MachineFunction *MF = MBB.getParent();
   const TargetInstrInfo &TII = *MF->getTarget().getInstrInfo();

   if (CSI.empty()) {
     return false;
   }

   // We can only schedule double loads if we spill contiguous callee-saved regs
   // For instance, we cannot scheduled double-word loads if we spill r24,
   // r26, and r27.
   // Hexagon_TODO: We can try to double-word align odd registers for -O2 and
   // above.
   bool ContiguousRegs = true;

   for (unsigned i = 0; i < CSI.size(); ++i) {
     unsigned Reg = CSI[i].getReg();

     //
     // Check if we can use a double-word load.
     //
     const uint16_t* SuperReg = TRI->getSuperRegisters(Reg);
     const TargetRegisterClass* SuperRegClass = 0;

     // Assume that there is exactly one superreg.
     assert(SuperReg[0] && !SuperReg[1] && "Expected exactly one superreg");
     bool CanUseDblLoad = false;
     if (ContiguousRegs && (i < CSI.size()-1)) {
       const uint16_t* SuperRegNext = TRI->getSuperRegisters(CSI[i+1].getReg());
       assert(SuperRegNext[0] && !SuperRegNext[1] &&
              "Expected exactly one superreg");
       SuperRegClass = TRI->getMinimalPhysRegClass(SuperReg[0]);
       CanUseDblLoad = (SuperRegNext[0] == SuperReg[0]);
     }


     if (CanUseDblLoad) {
       TII.loadRegFromStackSlot(MBB, MI, SuperReg[0], CSI[i+1].getFrameIdx(),
                                SuperRegClass, TRI);
       MBB.addLiveIn(SuperReg[0]);
       ++i;
     } else {
       // Cannot use a double-word load.
       ContiguousRegs = false;
       const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
       TII.loadRegFromStackSlot(MBB, MI, Reg, CSI[i].getFrameIdx(), RC, TRI);
       MBB.addLiveIn(Reg);
     }
   }
   return true;
 }

 int HexagonFrameLowering::getFrameIndexOffset(const MachineFunction &MF,
                                               int FI) const {
   return MF.getFrameInfo()->getObjectOffset(FI);
 }
	//===-- HexagonFrameLowering.cpp - Define frame lowering ------------------===//
	//
	// The LLVM Compiler Infrastructure
	//
	// This file is distributed under the University of Illinois Open Source
	// License. See LICENSE.TXT for details.
	//
	//
	//===----------------------------------------------------------------------===//

	#include "HexagonFrameLowering.h"
	#include "Hexagon.h"
	#include "HexagonInstrInfo.h"
	#include "HexagonRegisterInfo.h"
	#include "HexagonSubtarget.h"
	#include "HexagonTargetMachine.h"
	#include "HexagonMachineFunctionInfo.h"
	#include "llvm/Function.h"
	#include "llvm/Type.h"
	#include "llvm/ADT/BitVector.h"
	#include "llvm/ADT/STLExtras.h"
	#include "llvm/CodeGen/AsmPrinter.h"
	#include "llvm/CodeGen/MachineInstrBuilder.h"
	#include "llvm/CodeGen/MachineFunction.h"
	#include "llvm/CodeGen/MachineFunctionPass.h"
	#include "llvm/CodeGen/MachineFrameInfo.h"
	#include "llvm/CodeGen/MachineModuleInfo.h"
	#include "llvm/CodeGen/MachineRegisterInfo.h"
	#include "llvm/CodeGen/RegisterScavenging.h"
	#include "llvm/MC/MachineLocation.h"
	#include "llvm/MC/MCAsmInfo.h"
	#include "llvm/Target/TargetInstrInfo.h"
	#include "llvm/Target/TargetMachine.h"
	#include "llvm/Target/TargetOptions.h"
	#include "llvm/Support/CommandLine.h"

	using namespace llvm;

	static cl::opt<bool> DisableDeallocRet(
	"disable-hexagon-dealloc-ret",
	cl::Hidden,
	cl::desc("Disable Dealloc Return for Hexagon target"));

	/// determineFrameLayout - Determine the size of the frame and maximum call
	/// frame size.
	void HexagonFrameLowering::determineFrameLayout(MachineFunction &MF) const {
	MachineFrameInfo *MFI = MF.getFrameInfo();

	// Get the number of bytes to allocate from the FrameInfo.
	unsigned FrameSize = MFI->getStackSize();

	// Get the alignments provided by the target.
	unsigned TargetAlign = MF.getTarget().getFrameLowering()->getStackAlignment();
	// Get the maximum call frame size of all the calls.
	unsigned maxCallFrameSize = MFI->getMaxCallFrameSize();

	// If we have dynamic alloca then maxCallFrameSize needs to be aligned so
	// that allocations will be aligned.
	if (MFI->hasVarSizedObjects())
	maxCallFrameSize = RoundUpToAlignment(maxCallFrameSize, TargetAlign);

	// Update maximum call frame size.
	MFI->setMaxCallFrameSize(maxCallFrameSize);

	// Include call frame size in total.
	FrameSize += maxCallFrameSize;

	// Make sure the frame is aligned.
	FrameSize = RoundUpToAlignment(FrameSize, TargetAlign);

	// Update frame info.
	MFI->setStackSize(FrameSize);
	}


	void HexagonFrameLowering::emitPrologue(MachineFunction &MF) const {
	MachineBasicBlock &MBB = MF.front();
	MachineFrameInfo *MFI = MF.getFrameInfo();
	MachineModuleInfo &MMI = MF.getMMI();
	MachineBasicBlock::iterator MBBI = MBB.begin();
	const HexagonRegisterInfo *QRI =
	static_cast<const HexagonRegisterInfo *>(MF.getTarget().getRegisterInfo());
	DebugLoc dl = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
	determineFrameLayout(MF);

	// Check if frame moves are needed for EH.
	bool needsFrameMoves = MMI.hasDebugInfo() \|\|
	!MF.getFunction()->needsUnwindTableEntry();

	// Get the number of bytes to allocate from the FrameInfo.
	int NumBytes = (int) MFI->getStackSize();

	// LLVM expects allocframe not to be the first instruction in the
	// basic block.
	MachineBasicBlock::iterator InsertPt = MBB.begin();

	//
	// ALLOCA adjust regs. Iterate over ADJDYNALLOC nodes and change the offset.
	//
	HexagonMachineFunctionInfo *FuncInfo =
	MF.getInfo<HexagonMachineFunctionInfo>();
	const std::vector<MachineInstr*>& AdjustRegs =
	FuncInfo->getAllocaAdjustInsts();
	for (std::vector<MachineInstr*>::const_iterator i = AdjustRegs.begin(),
	e = AdjustRegs.end();
	i != e; ++i) {
	MachineInstr* MI = *i;
	assert((MI->getOpcode() == Hexagon::ADJDYNALLOC) &&
	"Expected adjust alloca node");

	MachineOperand& MO = MI->getOperand(2);
	assert(MO.isImm() && "Expected immediate");
	MO.setImm(MFI->getMaxCallFrameSize());
	}

	std::vector<MachineMove> &Moves = MMI.getFrameMoves();

	if (needsFrameMoves) {
	// Advance CFA. DW_CFA_def_cfa
	unsigned FPReg = QRI->getFrameRegister();
	unsigned RAReg = QRI->getRARegister();

	MachineLocation Dst(MachineLocation::VirtualFP);
	MachineLocation Src(FPReg, -8);
	Moves.push_back(MachineMove(0, Dst, Src));

	// R31 = (R31 - #4)
	MachineLocation LRDst(RAReg, -4);
	MachineLocation LRSrc(RAReg);
	Moves.push_back(MachineMove(0, LRDst, LRSrc));

	// R30 = (R30 - #8)
	MachineLocation SPDst(FPReg, -8);
	MachineLocation SPSrc(FPReg);
	Moves.push_back(MachineMove(0, SPDst, SPSrc));
	}

	//
	// Only insert ALLOCFRAME if we need to.
	//
	if (hasFP(MF)) {
	// Check for overflow.
	// Hexagon_TODO: Ugh! hardcoding. Is there an API that can be used?
	const int ALLOCFRAME_MAX = 16384;
	const TargetInstrInfo &TII = *MF.getTarget().getInstrInfo();

	if (NumBytes >= ALLOCFRAME_MAX) {
	// Emit allocframe(#0).
	BuildMI(MBB, InsertPt, dl, TII.get(Hexagon::ALLOCFRAME)).addImm(0);

	// Subtract offset from frame pointer.
	BuildMI(MBB, InsertPt, dl, TII.get(Hexagon::CONST32_Int_Real),
	HEXAGON_RESERVED_REG_1).addImm(NumBytes);
	BuildMI(MBB, InsertPt, dl, TII.get(Hexagon::SUB_rr),
	QRI->getStackRegister()).
	addReg(QRI->getStackRegister()).
	addReg(HEXAGON_RESERVED_REG_1);
	} else {
	BuildMI(MBB, InsertPt, dl, TII.get(Hexagon::ALLOCFRAME)).addImm(NumBytes);
	}
	}
	}
	// Returns true if MBB has a machine instructions that indicates a tail call
	// in the block.
	bool HexagonFrameLowering::hasTailCall(MachineBasicBlock &MBB) const {
	MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
	unsigned RetOpcode = MBBI->getOpcode();

	return RetOpcode == Hexagon::TCRETURNtg \|\| RetOpcode == Hexagon::TCRETURNtext;}

	void HexagonFrameLowering::emitEpilogue(MachineFunction &MF,
	MachineBasicBlock &MBB) const {
	MachineBasicBlock::iterator MBBI = prior(MBB.end());
	DebugLoc dl = MBBI->getDebugLoc();
	//
	// Only insert deallocframe if we need to.
	//
	if (hasFP(MF)) {
	MachineBasicBlock::iterator MBBI = prior(MBB.end());
	MachineBasicBlock::iterator MBBI_end = MBB.end();
	//
	// For Hexagon, we don't need the frame size.
	//
	MachineFrameInfo *MFI = MF.getFrameInfo();
	int NumBytes = (int) MFI->getStackSize();

	const TargetInstrInfo &TII = *MF.getTarget().getInstrInfo();

	// Replace 'jumpr r31' instruction with dealloc_return for V4 and higher
	// versions.
	if (STI.hasV4TOps() && MBBI->getOpcode() == Hexagon::JMPR
	&& !DisableDeallocRet) {
	// Remove jumpr node.
	MBB.erase(MBBI);
	// Add dealloc_return.
	BuildMI(MBB, MBBI_end, dl, TII.get(Hexagon::DEALLOC_RET_V4))
	.addImm(NumBytes);
	} else { // Add deallocframe for V2 and V3.
	BuildMI(MBB, MBBI, dl, TII.get(Hexagon::DEALLOCFRAME)).addImm(NumBytes);
	}
	}
	}

	bool HexagonFrameLowering::hasFP(const MachineFunction &MF) const {
	const MachineFrameInfo *MFI = MF.getFrameInfo();
	const HexagonMachineFunctionInfo *FuncInfo =
	MF.getInfo<HexagonMachineFunctionInfo>();
	return (MFI->hasCalls() \|\| (MFI->getStackSize() > 0) \|\|
	FuncInfo->hasClobberLR() );
	}

	bool
	HexagonFrameLowering::spillCalleeSavedRegisters(
	MachineBasicBlock &MBB,
	MachineBasicBlock::iterator MI,
	const std::vector<CalleeSavedInfo> &CSI,
	const TargetRegisterInfo *TRI) const {
	MachineFunction *MF = MBB.getParent();
	const TargetInstrInfo &TII = *MF->getTarget().getInstrInfo();

	if (CSI.empty()) {
	return false;
	}

	// We can only schedule double loads if we spill contiguous callee-saved regs
	// For instance, we cannot scheduled double-word loads if we spill r24,
	// r26, and r27.
	// Hexagon_TODO: We can try to double-word align odd registers for -O2 and
	// above.
	bool ContiguousRegs = true;

	for (unsigned i = 0; i < CSI.size(); ++i) {
	unsigned Reg = CSI[i].getReg();

	//
	// Check if we can use a double-word store.
	//
	const uint16_t* SuperReg = TRI->getSuperRegisters(Reg);

	// Assume that there is exactly one superreg.
	assert(SuperReg[0] && !SuperReg[1] && "Expected exactly one superreg");
	bool CanUseDblStore = false;
	const TargetRegisterClass* SuperRegClass = 0;

	if (ContiguousRegs && (i < CSI.size()-1)) {
	const uint16_t* SuperRegNext = TRI->getSuperRegisters(CSI[i+1].getReg());
	assert(SuperRegNext[0] && !SuperRegNext[1] &&
	"Expected exactly one superreg");
	SuperRegClass = TRI->getMinimalPhysRegClass(SuperReg[0]);
	CanUseDblStore = (SuperRegNext[0] == SuperReg[0]);
	}


	if (CanUseDblStore) {
	TII.storeRegToStackSlot(MBB, MI, SuperReg[0], true,
	CSI[i+1].getFrameIdx(), SuperRegClass, TRI);
	MBB.addLiveIn(SuperReg[0]);
	++i;
	} else {
	// Cannot use a double-word store.
	ContiguousRegs = false;
	const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
	TII.storeRegToStackSlot(MBB, MI, Reg, true, CSI[i].getFrameIdx(), RC,
	TRI);
	MBB.addLiveIn(Reg);
	}
	}
	return true;
	}


	bool HexagonFrameLowering::restoreCalleeSavedRegisters(
	MachineBasicBlock &MBB,
	MachineBasicBlock::iterator MI,
	const std::vector<CalleeSavedInfo> &CSI,
	const TargetRegisterInfo *TRI) const {

	MachineFunction *MF = MBB.getParent();
	const TargetInstrInfo &TII = *MF->getTarget().getInstrInfo();

	if (CSI.empty()) {
	return false;
	}

	// We can only schedule double loads if we spill contiguous callee-saved regs
	// For instance, we cannot scheduled double-word loads if we spill r24,
	// r26, and r27.
	// Hexagon_TODO: We can try to double-word align odd registers for -O2 and
	// above.
	bool ContiguousRegs = true;

	for (unsigned i = 0; i < CSI.size(); ++i) {
	unsigned Reg = CSI[i].getReg();

	//
	// Check if we can use a double-word load.
	//
	const uint16_t* SuperReg = TRI->getSuperRegisters(Reg);
	const TargetRegisterClass* SuperRegClass = 0;

	// Assume that there is exactly one superreg.
	assert(SuperReg[0] && !SuperReg[1] && "Expected exactly one superreg");
	bool CanUseDblLoad = false;
	if (ContiguousRegs && (i < CSI.size()-1)) {
	const uint16_t* SuperRegNext = TRI->getSuperRegisters(CSI[i+1].getReg());
	assert(SuperRegNext[0] && !SuperRegNext[1] &&
	"Expected exactly one superreg");
	SuperRegClass = TRI->getMinimalPhysRegClass(SuperReg[0]);
	CanUseDblLoad = (SuperRegNext[0] == SuperReg[0]);
	}


	if (CanUseDblLoad) {
	TII.loadRegFromStackSlot(MBB, MI, SuperReg[0], CSI[i+1].getFrameIdx(),
	SuperRegClass, TRI);
	MBB.addLiveIn(SuperReg[0]);
	++i;
	} else {
	// Cannot use a double-word load.
	ContiguousRegs = false;
	const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
	TII.loadRegFromStackSlot(MBB, MI, Reg, CSI[i].getFrameIdx(), RC, TRI);
	MBB.addLiveIn(Reg);
	}
	}
	return true;
	}

	int HexagonFrameLowering::getFrameIndexOffset(const MachineFunction &MF,
	int FI) const {
	return MF.getFrameInfo()->getObjectOffset(FI);
	}