lib/Target/MSP430/MSP430FrameLowering.cpp - llvm - Git at Google

 //===-- MSP430FrameLowering.cpp - MSP430 Frame Information ----------------===//
 //
 //                     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 MSP430 implementation of TargetFrameLowering class.
 //
 //===----------------------------------------------------------------------===//

 #include "MSP430FrameLowering.h"
 #include "MSP430InstrInfo.h"
 #include "MSP430MachineFunctionInfo.h"
 #include "llvm/Function.h"
 #include "llvm/CodeGen/MachineFrameInfo.h"
 #include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/CodeGen/MachineInstrBuilder.h"
 #include "llvm/CodeGen/MachineModuleInfo.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/Target/TargetData.h"
 #include "llvm/Target/TargetOptions.h"
 #include "llvm/Support/CommandLine.h"

 using namespace llvm;

 bool MSP430FrameLowering::hasFP(const MachineFunction &MF) const {
   const MachineFrameInfo *MFI = MF.getFrameInfo();

   return (MF.getTarget().Options.DisableFramePointerElim(MF) ||
           MF.getFrameInfo()->hasVarSizedObjects() ||
           MFI->isFrameAddressTaken());
 }

 bool MSP430FrameLowering::hasReservedCallFrame(const MachineFunction &MF) const {
   return !MF.getFrameInfo()->hasVarSizedObjects();
 }

 void MSP430FrameLowering::emitPrologue(MachineFunction &MF) const {
   MachineBasicBlock &MBB = MF.front();   // Prolog goes in entry BB
   MachineFrameInfo *MFI = MF.getFrameInfo();
   MSP430MachineFunctionInfo *MSP430FI = MF.getInfo<MSP430MachineFunctionInfo>();
   const MSP430InstrInfo &TII =
     *static_cast<const MSP430InstrInfo*>(MF.getTarget().getInstrInfo());

   MachineBasicBlock::iterator MBBI = MBB.begin();
   DebugLoc DL = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();

   // Get the number of bytes to allocate from the FrameInfo.
   uint64_t StackSize = MFI->getStackSize();

   uint64_t NumBytes = 0;
   if (hasFP(MF)) {
     // Calculate required stack adjustment
     uint64_t FrameSize = StackSize - 2;
     NumBytes = FrameSize - MSP430FI->getCalleeSavedFrameSize();

     // Get the offset of the stack slot for the EBP register... which is
     // guaranteed to be the last slot by processFunctionBeforeFrameFinalized.
     // Update the frame offset adjustment.
     MFI->setOffsetAdjustment(-NumBytes);

     // Save FPW into the appropriate stack slot...
     BuildMI(MBB, MBBI, DL, TII.get(MSP430::PUSH16r))
       .addReg(MSP430::FPW, RegState::Kill);

     // Update FPW with the new base value...
     BuildMI(MBB, MBBI, DL, TII.get(MSP430::MOV16rr), MSP430::FPW)
       .addReg(MSP430::SPW);

     // Mark the FramePtr as live-in in every block except the entry.
     for (MachineFunction::iterator I = llvm::next(MF.begin()), E = MF.end();
          I != E; ++I)
       I->addLiveIn(MSP430::FPW);

   } else
     NumBytes = StackSize - MSP430FI->getCalleeSavedFrameSize();

   // Skip the callee-saved push instructions.
   while (MBBI != MBB.end() && (MBBI->getOpcode() == MSP430::PUSH16r))
     ++MBBI;

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

   if (NumBytes) { // adjust stack pointer: SPW -= numbytes
     // If there is an SUB16ri of SPW immediately before this instruction, merge
     // the two.
     //NumBytes -= mergeSPUpdates(MBB, MBBI, true);
     // If there is an ADD16ri or SUB16ri of SPW immediately after this
     // instruction, merge the two instructions.
     // mergeSPUpdatesDown(MBB, MBBI, &NumBytes);

     if (NumBytes) {
       MachineInstr *MI =
         BuildMI(MBB, MBBI, DL, TII.get(MSP430::SUB16ri), MSP430::SPW)
         .addReg(MSP430::SPW).addImm(NumBytes);
       // The SRW implicit def is dead.
       MI->getOperand(3).setIsDead();
     }
   }
 }

 void MSP430FrameLowering::emitEpilogue(MachineFunction &MF,
                                        MachineBasicBlock &MBB) const {
   const MachineFrameInfo *MFI = MF.getFrameInfo();
   MSP430MachineFunctionInfo *MSP430FI = MF.getInfo<MSP430MachineFunctionInfo>();
   const MSP430InstrInfo &TII =
     *static_cast<const MSP430InstrInfo*>(MF.getTarget().getInstrInfo());

   MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
   unsigned RetOpcode = MBBI->getOpcode();
   DebugLoc DL = MBBI->getDebugLoc();

   switch (RetOpcode) {
   case MSP430::RET:
   case MSP430::RETI: break;  // These are ok
   default:
     llvm_unreachable("Can only insert epilog into returning blocks");
   }

   // Get the number of bytes to allocate from the FrameInfo
   uint64_t StackSize = MFI->getStackSize();
   unsigned CSSize = MSP430FI->getCalleeSavedFrameSize();
   uint64_t NumBytes = 0;

   if (hasFP(MF)) {
     // Calculate required stack adjustment
     uint64_t FrameSize = StackSize - 2;
     NumBytes = FrameSize - CSSize;

     // pop FPW.
     BuildMI(MBB, MBBI, DL, TII.get(MSP430::POP16r), MSP430::FPW);
   } else
     NumBytes = StackSize - CSSize;

   // Skip the callee-saved pop instructions.
   while (MBBI != MBB.begin()) {
     MachineBasicBlock::iterator PI = prior(MBBI);
     unsigned Opc = PI->getOpcode();
     if (Opc != MSP430::POP16r && !PI->isTerminator())
       break;
     --MBBI;
   }

   DL = MBBI->getDebugLoc();

   // If there is an ADD16ri or SUB16ri of SPW immediately before this
   // instruction, merge the two instructions.
   //if (NumBytes || MFI->hasVarSizedObjects())
   //  mergeSPUpdatesUp(MBB, MBBI, StackPtr, &NumBytes);

   if (MFI->hasVarSizedObjects()) {
     BuildMI(MBB, MBBI, DL,
             TII.get(MSP430::MOV16rr), MSP430::SPW).addReg(MSP430::FPW);
     if (CSSize) {
       MachineInstr *MI =
         BuildMI(MBB, MBBI, DL,
                 TII.get(MSP430::SUB16ri), MSP430::SPW)
         .addReg(MSP430::SPW).addImm(CSSize);
       // The SRW implicit def is dead.
       MI->getOperand(3).setIsDead();
     }
   } else {
     // adjust stack pointer back: SPW += numbytes
     if (NumBytes) {
       MachineInstr *MI =
         BuildMI(MBB, MBBI, DL, TII.get(MSP430::ADD16ri), MSP430::SPW)
         .addReg(MSP430::SPW).addImm(NumBytes);
       // The SRW implicit def is dead.
       MI->getOperand(3).setIsDead();
     }
   }
 }

 // FIXME: Can we eleminate these in favour of generic code?
 bool
 MSP430FrameLowering::spillCalleeSavedRegisters(MachineBasicBlock &MBB,
                                            MachineBasicBlock::iterator MI,
                                         const std::vector<CalleeSavedInfo> &CSI,
                                         const TargetRegisterInfo *TRI) const {
   if (CSI.empty())
     return false;

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

   MachineFunction &MF = *MBB.getParent();
   const TargetInstrInfo &TII = *MF.getTarget().getInstrInfo();
   MSP430MachineFunctionInfo *MFI = MF.getInfo<MSP430MachineFunctionInfo>();
   MFI->setCalleeSavedFrameSize(CSI.size() * 2);

   for (unsigned i = CSI.size(); i != 0; --i) {
     unsigned Reg = CSI[i-1].getReg();
     // Add the callee-saved register as live-in. It's killed at the spill.
     MBB.addLiveIn(Reg);
     BuildMI(MBB, MI, DL, TII.get(MSP430::PUSH16r))
       .addReg(Reg, RegState::Kill);
   }
   return true;
 }

 bool
 MSP430FrameLowering::restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
                                                  MachineBasicBlock::iterator MI,
                                         const std::vector<CalleeSavedInfo> &CSI,
                                         const TargetRegisterInfo *TRI) const {
   if (CSI.empty())
     return false;

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

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

   for (unsigned i = 0, e = CSI.size(); i != e; ++i)
     BuildMI(MBB, MI, DL, TII.get(MSP430::POP16r), CSI[i].getReg());

   return true;
 }
	//===-- MSP430FrameLowering.cpp - MSP430 Frame Information ----------------===//
	//
	// 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 MSP430 implementation of TargetFrameLowering class.
	//
	//===----------------------------------------------------------------------===//

	#include "MSP430FrameLowering.h"
	#include "MSP430InstrInfo.h"
	#include "MSP430MachineFunctionInfo.h"
	#include "llvm/Function.h"
	#include "llvm/CodeGen/MachineFrameInfo.h"
	#include "llvm/CodeGen/MachineFunction.h"
	#include "llvm/CodeGen/MachineInstrBuilder.h"
	#include "llvm/CodeGen/MachineModuleInfo.h"
	#include "llvm/CodeGen/MachineRegisterInfo.h"
	#include "llvm/Target/TargetData.h"
	#include "llvm/Target/TargetOptions.h"
	#include "llvm/Support/CommandLine.h"

	using namespace llvm;

	bool MSP430FrameLowering::hasFP(const MachineFunction &MF) const {
	const MachineFrameInfo *MFI = MF.getFrameInfo();

	return (MF.getTarget().Options.DisableFramePointerElim(MF) \|\|
	MF.getFrameInfo()->hasVarSizedObjects() \|\|
	MFI->isFrameAddressTaken());
	}

	bool MSP430FrameLowering::hasReservedCallFrame(const MachineFunction &MF) const {
	return !MF.getFrameInfo()->hasVarSizedObjects();
	}

	void MSP430FrameLowering::emitPrologue(MachineFunction &MF) const {
	MachineBasicBlock &MBB = MF.front(); // Prolog goes in entry BB
	MachineFrameInfo *MFI = MF.getFrameInfo();
	MSP430MachineFunctionInfo *MSP430FI = MF.getInfo<MSP430MachineFunctionInfo>();
	const MSP430InstrInfo &TII =
	static_cast<const MSP430InstrInfo>(MF.getTarget().getInstrInfo());

	MachineBasicBlock::iterator MBBI = MBB.begin();
	DebugLoc DL = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();

	// Get the number of bytes to allocate from the FrameInfo.
	uint64_t StackSize = MFI->getStackSize();

	uint64_t NumBytes = 0;
	if (hasFP(MF)) {
	// Calculate required stack adjustment
	uint64_t FrameSize = StackSize - 2;
	NumBytes = FrameSize - MSP430FI->getCalleeSavedFrameSize();

	// Get the offset of the stack slot for the EBP register... which is
	// guaranteed to be the last slot by processFunctionBeforeFrameFinalized.
	// Update the frame offset adjustment.
	MFI->setOffsetAdjustment(-NumBytes);

	// Save FPW into the appropriate stack slot...
	BuildMI(MBB, MBBI, DL, TII.get(MSP430::PUSH16r))
	.addReg(MSP430::FPW, RegState::Kill);

	// Update FPW with the new base value...
	BuildMI(MBB, MBBI, DL, TII.get(MSP430::MOV16rr), MSP430::FPW)
	.addReg(MSP430::SPW);

	// Mark the FramePtr as live-in in every block except the entry.
	for (MachineFunction::iterator I = llvm::next(MF.begin()), E = MF.end();
	I != E; ++I)
	I->addLiveIn(MSP430::FPW);

	} else
	NumBytes = StackSize - MSP430FI->getCalleeSavedFrameSize();

	// Skip the callee-saved push instructions.
	while (MBBI != MBB.end() && (MBBI->getOpcode() == MSP430::PUSH16r))
	++MBBI;

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

	if (NumBytes) { // adjust stack pointer: SPW -= numbytes
	// If there is an SUB16ri of SPW immediately before this instruction, merge
	// the two.
	//NumBytes -= mergeSPUpdates(MBB, MBBI, true);
	// If there is an ADD16ri or SUB16ri of SPW immediately after this
	// instruction, merge the two instructions.
	// mergeSPUpdatesDown(MBB, MBBI, &NumBytes);

	if (NumBytes) {
	MachineInstr *MI =
	BuildMI(MBB, MBBI, DL, TII.get(MSP430::SUB16ri), MSP430::SPW)
	.addReg(MSP430::SPW).addImm(NumBytes);
	// The SRW implicit def is dead.
	MI->getOperand(3).setIsDead();
	}
	}
	}

	void MSP430FrameLowering::emitEpilogue(MachineFunction &MF,
	MachineBasicBlock &MBB) const {
	const MachineFrameInfo *MFI = MF.getFrameInfo();
	MSP430MachineFunctionInfo *MSP430FI = MF.getInfo<MSP430MachineFunctionInfo>();
	const MSP430InstrInfo &TII =
	static_cast<const MSP430InstrInfo>(MF.getTarget().getInstrInfo());

	MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
	unsigned RetOpcode = MBBI->getOpcode();
	DebugLoc DL = MBBI->getDebugLoc();

	switch (RetOpcode) {
	case MSP430::RET:
	case MSP430::RETI: break; // These are ok
	default:
	llvm_unreachable("Can only insert epilog into returning blocks");
	}

	// Get the number of bytes to allocate from the FrameInfo
	uint64_t StackSize = MFI->getStackSize();
	unsigned CSSize = MSP430FI->getCalleeSavedFrameSize();
	uint64_t NumBytes = 0;

	if (hasFP(MF)) {
	// Calculate required stack adjustment
	uint64_t FrameSize = StackSize - 2;
	NumBytes = FrameSize - CSSize;

	// pop FPW.
	BuildMI(MBB, MBBI, DL, TII.get(MSP430::POP16r), MSP430::FPW);
	} else
	NumBytes = StackSize - CSSize;

	// Skip the callee-saved pop instructions.
	while (MBBI != MBB.begin()) {
	MachineBasicBlock::iterator PI = prior(MBBI);
	unsigned Opc = PI->getOpcode();
	if (Opc != MSP430::POP16r && !PI->isTerminator())
	break;
	--MBBI;
	}

	DL = MBBI->getDebugLoc();

	// If there is an ADD16ri or SUB16ri of SPW immediately before this
	// instruction, merge the two instructions.
	//if (NumBytes \|\| MFI->hasVarSizedObjects())
	// mergeSPUpdatesUp(MBB, MBBI, StackPtr, &NumBytes);

	if (MFI->hasVarSizedObjects()) {
	BuildMI(MBB, MBBI, DL,
	TII.get(MSP430::MOV16rr), MSP430::SPW).addReg(MSP430::FPW);
	if (CSSize) {
	MachineInstr *MI =
	BuildMI(MBB, MBBI, DL,
	TII.get(MSP430::SUB16ri), MSP430::SPW)
	.addReg(MSP430::SPW).addImm(CSSize);
	// The SRW implicit def is dead.
	MI->getOperand(3).setIsDead();
	}
	} else {
	// adjust stack pointer back: SPW += numbytes
	if (NumBytes) {
	MachineInstr *MI =
	BuildMI(MBB, MBBI, DL, TII.get(MSP430::ADD16ri), MSP430::SPW)
	.addReg(MSP430::SPW).addImm(NumBytes);
	// The SRW implicit def is dead.
	MI->getOperand(3).setIsDead();
	}
	}
	}

	// FIXME: Can we eleminate these in favour of generic code?
	bool
	MSP430FrameLowering::spillCalleeSavedRegisters(MachineBasicBlock &MBB,
	MachineBasicBlock::iterator MI,
	const std::vector<CalleeSavedInfo> &CSI,
	const TargetRegisterInfo *TRI) const {
	if (CSI.empty())
	return false;

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

	MachineFunction &MF = *MBB.getParent();
	const TargetInstrInfo &TII = *MF.getTarget().getInstrInfo();
	MSP430MachineFunctionInfo *MFI = MF.getInfo<MSP430MachineFunctionInfo>();
	MFI->setCalleeSavedFrameSize(CSI.size() * 2);

	for (unsigned i = CSI.size(); i != 0; --i) {
	unsigned Reg = CSI[i-1].getReg();
	// Add the callee-saved register as live-in. It's killed at the spill.
	MBB.addLiveIn(Reg);
	BuildMI(MBB, MI, DL, TII.get(MSP430::PUSH16r))
	.addReg(Reg, RegState::Kill);
	}
	return true;
	}

	bool
	MSP430FrameLowering::restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
	MachineBasicBlock::iterator MI,
	const std::vector<CalleeSavedInfo> &CSI,
	const TargetRegisterInfo *TRI) const {
	if (CSI.empty())
	return false;

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

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

	for (unsigned i = 0, e = CSI.size(); i != e; ++i)
	BuildMI(MBB, MI, DL, TII.get(MSP430::POP16r), CSI[i].getReg());

	return true;
	}