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llvm-6502/lib/Target/ARM/ThumbRegisterInfo.cpp

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ARM refactoring. Step 2: split RegisterInfo git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@74384 91177308-0d34-0410-b5e6-96231b3b80d8
2009-06-27 12:16:40 +00:00
//===- ThumbRegisterInfo.cpp - Thumb Register 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 ARM implementation of the TargetRegisterInfo class.
//
//===----------------------------------------------------------------------===//
#include "ARM.h"
#include "ARMAddressingModes.h"
#include "ARMMachineFunctionInfo.h"
#include "ARMSubtarget.h"
#include "ThumbInstrInfo.h"
#include "ThumbRegisterInfo.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/CodeGen/MachineConstantPool.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineLocation.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/Target/TargetFrameInfo.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Support/CommandLine.h"
using namespace llvm;
static cl::opt<bool>
ThumbRegScavenging("enable-thumb-reg-scavenging",
cl::Hidden,
cl::desc("Enable register scavenging on Thumb"));
ThumbRegisterInfo::ThumbRegisterInfo(const TargetInstrInfo &tii,
const ARMSubtarget &sti)
: ARMBaseRegisterInfo(tii, sti) {
}
/// emitLoadConstPool - Emits a load from constpool to materialize the
/// specified immediate.
void ThumbRegisterInfo::emitLoadConstPool(MachineBasicBlock &MBB,
MachineBasicBlock::iterator &MBBI,
unsigned DestReg, int Val,
unsigned Pred, unsigned PredReg,
const TargetInstrInfo *TII,
DebugLoc dl) const {
MachineFunction &MF = *MBB.getParent();
MachineConstantPool *ConstantPool = MF.getConstantPool();
Constant *C = ConstantInt::get(Type::Int32Ty, Val);
unsigned Idx = ConstantPool->getConstantPoolIndex(C, 4);
BuildMI(MBB, MBBI, dl, TII->get(ARM::tLDRcp), DestReg)
.addConstantPoolIndex(Idx);
}
const TargetRegisterClass*
ThumbRegisterInfo::getPhysicalRegisterRegClass(unsigned Reg, MVT VT) const {
if (isLowRegister(Reg))
return ARM::tGPRRegisterClass;
switch (Reg) {
default:
break;
case ARM::R8: case ARM::R9: case ARM::R10: case ARM::R11:
case ARM::R12: case ARM::SP: case ARM::LR: case ARM::PC:
return ARM::GPRRegisterClass;
}
return TargetRegisterInfo::getPhysicalRegisterRegClass(Reg, VT);
}
bool
ThumbRegisterInfo::requiresRegisterScavenging(const MachineFunction &MF) const {
return ThumbRegScavenging;
}
bool ThumbRegisterInfo::hasReservedCallFrame(MachineFunction &MF) const {
const MachineFrameInfo *FFI = MF.getFrameInfo();
unsigned CFSize = FFI->getMaxCallFrameSize();
// It's not always a good idea to include the call frame as part of the
// stack frame. ARM (especially Thumb) has small immediate offset to
// address the stack frame. So a large call frame can cause poor codegen
// and may even makes it impossible to scavenge a register.
if (CFSize >= ((1 << 8) - 1) * 4 / 2) // Half of imm8 * 4
return false;
return !MF.getFrameInfo()->hasVarSizedObjects();
}
/// emitThumbRegPlusImmInReg - Emits a series of instructions to materialize
/// a destreg = basereg + immediate in Thumb code. Materialize the immediate
/// in a register using mov / mvn sequences or load the immediate from a
/// constpool entry.
static
void emitThumbRegPlusImmInReg(MachineBasicBlock &MBB,
MachineBasicBlock::iterator &MBBI,
unsigned DestReg, unsigned BaseReg,
int NumBytes, bool CanChangeCC,
const TargetInstrInfo &TII,
const ThumbRegisterInfo& MRI,
DebugLoc dl) {
bool isHigh = !MRI.isLowRegister(DestReg) ||
(BaseReg != 0 && !MRI.isLowRegister(BaseReg));
bool isSub = false;
// Subtract doesn't have high register version. Load the negative value
// if either base or dest register is a high register. Also, if do not
// issue sub as part of the sequence if condition register is to be
// preserved.
if (NumBytes < 0 && !isHigh && CanChangeCC) {
isSub = true;
NumBytes = -NumBytes;
}
unsigned LdReg = DestReg;
if (DestReg == ARM::SP) {
assert(BaseReg == ARM::SP && "Unexpected!");
LdReg = ARM::R3;
BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVlor2hir), ARM::R12)
.addReg(ARM::R3, RegState::Kill);
}
if (NumBytes <= 255 && NumBytes >= 0)
BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVi8), LdReg).addImm(NumBytes);
else if (NumBytes < 0 && NumBytes >= -255) {
BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVi8), LdReg).addImm(NumBytes);
BuildMI(MBB, MBBI, dl, TII.get(ARM::tNEG), LdReg)
.addReg(LdReg, RegState::Kill);
} else
MRI.emitLoadConstPool(MBB, MBBI, LdReg, NumBytes, ARMCC::AL, 0, &TII, dl);
// Emit add / sub.
int Opc = (isSub) ? ARM::tSUBrr : (isHigh ? ARM::tADDhirr : ARM::tADDrr);
const MachineInstrBuilder MIB = BuildMI(MBB, MBBI, dl,
TII.get(Opc), DestReg);
if (DestReg == ARM::SP || isSub)
MIB.addReg(BaseReg).addReg(LdReg, RegState::Kill);
else
MIB.addReg(LdReg).addReg(BaseReg, RegState::Kill);
if (DestReg == ARM::SP)
BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVhir2lor), ARM::R3)
.addReg(ARM::R12, RegState::Kill);
}
/// calcNumMI - Returns the number of instructions required to materialize
/// the specific add / sub r, c instruction.
static unsigned calcNumMI(int Opc, int ExtraOpc, unsigned Bytes,
unsigned NumBits, unsigned Scale) {
unsigned NumMIs = 0;
unsigned Chunk = ((1 << NumBits) - 1) * Scale;
if (Opc == ARM::tADDrSPi) {
unsigned ThisVal = (Bytes > Chunk) ? Chunk : Bytes;
Bytes -= ThisVal;
NumMIs++;
NumBits = 8;
Scale = 1; // Followed by a number of tADDi8.
Chunk = ((1 << NumBits) - 1) * Scale;
}
NumMIs += Bytes / Chunk;
if ((Bytes % Chunk) != 0)
NumMIs++;
if (ExtraOpc)
NumMIs++;
return NumMIs;
}
/// emitThumbRegPlusImmediate - Emits a series of instructions to materialize
/// a destreg = basereg + immediate in Thumb code.
static
void emitThumbRegPlusImmediate(MachineBasicBlock &MBB,
MachineBasicBlock::iterator &MBBI,
unsigned DestReg, unsigned BaseReg,
int NumBytes, const TargetInstrInfo &TII,
const ThumbRegisterInfo& MRI,
DebugLoc dl) {
bool isSub = NumBytes < 0;
unsigned Bytes = (unsigned)NumBytes;
if (isSub) Bytes = -NumBytes;
bool isMul4 = (Bytes & 3) == 0;
bool isTwoAddr = false;
bool DstNotEqBase = false;
unsigned NumBits = 1;
unsigned Scale = 1;
int Opc = 0;
int ExtraOpc = 0;
if (DestReg == BaseReg && BaseReg == ARM::SP) {
assert(isMul4 && "Thumb sp inc / dec size must be multiple of 4!");
NumBits = 7;
Scale = 4;
Opc = isSub ? ARM::tSUBspi : ARM::tADDspi;
isTwoAddr = true;
} else if (!isSub && BaseReg == ARM::SP) {
// r1 = add sp, 403
// =>
// r1 = add sp, 100 * 4
// r1 = add r1, 3
if (!isMul4) {
Bytes &= ~3;
ExtraOpc = ARM::tADDi3;
}
NumBits = 8;
Scale = 4;
Opc = ARM::tADDrSPi;
} else {
// sp = sub sp, c
// r1 = sub sp, c
// r8 = sub sp, c
if (DestReg != BaseReg)
DstNotEqBase = true;
NumBits = 8;
Opc = isSub ? ARM::tSUBi8 : ARM::tADDi8;
isTwoAddr = true;
}
unsigned NumMIs = calcNumMI(Opc, ExtraOpc, Bytes, NumBits, Scale);
unsigned Threshold = (DestReg == ARM::SP) ? 3 : 2;
if (NumMIs > Threshold) {
// This will expand into too many instructions. Load the immediate from a
// constpool entry.
emitThumbRegPlusImmInReg(MBB, MBBI, DestReg, BaseReg, NumBytes, true, TII,
MRI, dl);
return;
}
if (DstNotEqBase) {
if (MRI.isLowRegister(DestReg) && MRI.isLowRegister(BaseReg)) {
// If both are low registers, emit DestReg = add BaseReg, max(Imm, 7)
unsigned Chunk = (1 << 3) - 1;
unsigned ThisVal = (Bytes > Chunk) ? Chunk : Bytes;
Bytes -= ThisVal;
BuildMI(MBB, MBBI, dl,TII.get(isSub ? ARM::tSUBi3 : ARM::tADDi3), DestReg)
.addReg(BaseReg, RegState::Kill).addImm(ThisVal);
} else {
BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVr), DestReg)
.addReg(BaseReg, RegState::Kill);
}
BaseReg = DestReg;
}
unsigned Chunk = ((1 << NumBits) - 1) * Scale;
while (Bytes) {
unsigned ThisVal = (Bytes > Chunk) ? Chunk : Bytes;
Bytes -= ThisVal;
ThisVal /= Scale;
// Build the new tADD / tSUB.
if (isTwoAddr)
BuildMI(MBB, MBBI, dl, TII.get(Opc), DestReg)
.addReg(DestReg).addImm(ThisVal);
else {
bool isKill = BaseReg != ARM::SP;
BuildMI(MBB, MBBI, dl, TII.get(Opc), DestReg)
.addReg(BaseReg, getKillRegState(isKill)).addImm(ThisVal);
BaseReg = DestReg;
if (Opc == ARM::tADDrSPi) {
// r4 = add sp, imm
// r4 = add r4, imm
// ...
NumBits = 8;
Scale = 1;
Chunk = ((1 << NumBits) - 1) * Scale;
Opc = isSub ? ARM::tSUBi8 : ARM::tADDi8;
isTwoAddr = true;
}
}
}
if (ExtraOpc)
BuildMI(MBB, MBBI, dl, TII.get(ExtraOpc), DestReg)
.addReg(DestReg, RegState::Kill)
.addImm(((unsigned)NumBytes) & 3);
}
void ThumbRegisterInfo::
emitSPUpdate(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI,
int NumBytes, ARMCC::CondCodes Pred, unsigned PredReg,
const TargetInstrInfo &TII, DebugLoc dl) const {
emitThumbRegPlusImmediate(MBB, MBBI, ARM::SP, ARM::SP, NumBytes, TII,
*this, dl);
}
void ThumbRegisterInfo::
eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
MachineBasicBlock::iterator I) const {
if (!hasReservedCallFrame(MF)) {
// If we have alloca, convert as follows:
// ADJCALLSTACKDOWN -> sub, sp, sp, amount
// ADJCALLSTACKUP -> add, sp, sp, amount
MachineInstr *Old = I;
DebugLoc dl = Old->getDebugLoc();
unsigned Amount = Old->getOperand(0).getImm();
if (Amount != 0) {
// We need to keep the stack aligned properly. To do this, we round the
// amount of space needed for the outgoing arguments up to the next
// alignment boundary.
unsigned Align = MF.getTarget().getFrameInfo()->getStackAlignment();
Amount = (Amount+Align-1)/Align*Align;
// Replace the pseudo instruction with a new instruction...
unsigned Opc = Old->getOpcode();
if (Opc == ARM::ADJCALLSTACKDOWN || Opc == ARM::tADJCALLSTACKDOWN) {
// Note: PredReg is operand 2 for ADJCALLSTACKDOWN.
emitSPUpdate(MBB, I, -Amount, ARMCC::AL, 0, TII, dl);
} else {
// Note: PredReg is operand 3 for ADJCALLSTACKUP.
assert(Opc == ARM::ADJCALLSTACKUP || Opc == ARM::tADJCALLSTACKUP);
emitSPUpdate(MBB, I, Amount, ARMCC::AL, 0, TII, dl);
}
}
}
MBB.erase(I);
}
/// emitThumbConstant - Emit a series of instructions to materialize a
/// constant.
static void emitThumbConstant(MachineBasicBlock &MBB,
MachineBasicBlock::iterator &MBBI,
unsigned DestReg, int Imm,
const TargetInstrInfo &TII,
const ThumbRegisterInfo& MRI,
DebugLoc dl) {
bool isSub = Imm < 0;
if (isSub) Imm = -Imm;
int Chunk = (1 << 8) - 1;
int ThisVal = (Imm > Chunk) ? Chunk : Imm;
Imm -= ThisVal;
BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVi8), DestReg).addImm(ThisVal);
if (Imm > 0)
emitThumbRegPlusImmediate(MBB, MBBI, DestReg, DestReg, Imm, TII, MRI, dl);
if (isSub)
BuildMI(MBB, MBBI, dl, TII.get(ARM::tNEG), DestReg)
.addReg(DestReg, RegState::Kill);
}
void ThumbRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
int SPAdj, RegScavenger *RS) const{
unsigned i = 0;
MachineInstr &MI = *II;
MachineBasicBlock &MBB = *MI.getParent();
MachineFunction &MF = *MBB.getParent();
ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
DebugLoc dl = MI.getDebugLoc();
while (!MI.getOperand(i).isFI()) {
++i;
assert(i < MI.getNumOperands() && "Instr doesn't have FrameIndex operand!");
}
unsigned FrameReg = ARM::SP;
int FrameIndex = MI.getOperand(i).getIndex();
int Offset = MF.getFrameInfo()->getObjectOffset(FrameIndex) +
MF.getFrameInfo()->getStackSize() + SPAdj;
if (AFI->isGPRCalleeSavedArea1Frame(FrameIndex))
Offset -= AFI->getGPRCalleeSavedArea1Offset();
else if (AFI->isGPRCalleeSavedArea2Frame(FrameIndex))
Offset -= AFI->getGPRCalleeSavedArea2Offset();
else if (hasFP(MF)) {
assert(SPAdj == 0 && "Unexpected");
// There is alloca()'s in this function, must reference off the frame
// pointer instead.
FrameReg = getFrameRegister(MF);
Offset -= AFI->getFramePtrSpillOffset();
}
unsigned Opcode = MI.getOpcode();
const TargetInstrDesc &Desc = MI.getDesc();
unsigned AddrMode = (Desc.TSFlags & ARMII::AddrModeMask);
if (Opcode == ARM::tADDrSPi) {
Offset += MI.getOperand(i+1).getImm();
// Can't use tADDrSPi if it's based off the frame pointer.
unsigned NumBits = 0;
unsigned Scale = 1;
if (FrameReg != ARM::SP) {
Opcode = ARM::tADDi3;
MI.setDesc(TII.get(ARM::tADDi3));
NumBits = 3;
} else {
NumBits = 8;
Scale = 4;
assert((Offset & 3) == 0 &&
"Thumb add/sub sp, #imm immediate must be multiple of 4!");
}
if (Offset == 0) {
// Turn it into a move.
MI.setDesc(TII.get(ARM::tMOVhir2lor));
MI.getOperand(i).ChangeToRegister(FrameReg, false);
MI.RemoveOperand(i+1);
return;
}
// Common case: small offset, fits into instruction.
unsigned Mask = (1 << NumBits) - 1;
if (((Offset / Scale) & ~Mask) == 0) {
// Replace the FrameIndex with sp / fp
MI.getOperand(i).ChangeToRegister(FrameReg, false);
MI.getOperand(i+1).ChangeToImmediate(Offset / Scale);
return;
}
unsigned DestReg = MI.getOperand(0).getReg();
unsigned Bytes = (Offset > 0) ? Offset : -Offset;
unsigned NumMIs = calcNumMI(Opcode, 0, Bytes, NumBits, Scale);
// MI would expand into a large number of instructions. Don't try to
// simplify the immediate.
if (NumMIs > 2) {
emitThumbRegPlusImmediate(MBB, II, DestReg, FrameReg, Offset, TII,
*this, dl);
MBB.erase(II);
return;
}
if (Offset > 0) {
// Translate r0 = add sp, imm to
// r0 = add sp, 255*4
// r0 = add r0, (imm - 255*4)
MI.getOperand(i).ChangeToRegister(FrameReg, false);
MI.getOperand(i+1).ChangeToImmediate(Mask);
Offset = (Offset - Mask * Scale);
MachineBasicBlock::iterator NII = next(II);
emitThumbRegPlusImmediate(MBB, NII, DestReg, DestReg, Offset, TII,
*this, dl);
} else {
// Translate r0 = add sp, -imm to
// r0 = -imm (this is then translated into a series of instructons)
// r0 = add r0, sp
emitThumbConstant(MBB, II, DestReg, Offset, TII, *this, dl);
MI.setDesc(TII.get(ARM::tADDhirr));
MI.getOperand(i).ChangeToRegister(DestReg, false, false, true);
MI.getOperand(i+1).ChangeToRegister(FrameReg, false);
}
return;
} else {
unsigned ImmIdx = 0;
int InstrOffs = 0;
unsigned NumBits = 0;
unsigned Scale = 1;
switch (AddrMode) {
case ARMII::AddrModeTs: {
ImmIdx = i+1;
InstrOffs = MI.getOperand(ImmIdx).getImm();
NumBits = (FrameReg == ARM::SP) ? 8 : 5;
Scale = 4;
break;
}
default:
assert(0 && "Unsupported addressing mode!");
abort();
break;
}
Offset += InstrOffs * Scale;
assert((Offset & (Scale-1)) == 0 && "Can't encode this offset!");
// Common case: small offset, fits into instruction.
MachineOperand &ImmOp = MI.getOperand(ImmIdx);
int ImmedOffset = Offset / Scale;
unsigned Mask = (1 << NumBits) - 1;
if ((unsigned)Offset <= Mask * Scale) {
// Replace the FrameIndex with sp
MI.getOperand(i).ChangeToRegister(FrameReg, false);
ImmOp.ChangeToImmediate(ImmedOffset);
return;
}
bool isThumSpillRestore = Opcode == ARM::tRestore || Opcode == ARM::tSpill;
if (AddrMode == ARMII::AddrModeTs) {
// Thumb tLDRspi, tSTRspi. These will change to instructions that use
// a different base register.
NumBits = 5;
Mask = (1 << NumBits) - 1;
}
// If this is a thumb spill / restore, we will be using a constpool load to
// materialize the offset.
if (AddrMode == ARMII::AddrModeTs && isThumSpillRestore)
ImmOp.ChangeToImmediate(0);
else {
// Otherwise, it didn't fit. Pull in what we can to simplify the immed.
ImmedOffset = ImmedOffset & Mask;
ImmOp.ChangeToImmediate(ImmedOffset);
Offset &= ~(Mask*Scale);
}
}
// If we get here, the immediate doesn't fit into the instruction. We folded
// as much as possible above, handle the rest, providing a register that is
// SP+LargeImm.
assert(Offset && "This code isn't needed if offset already handled!");
if (Desc.mayLoad()) {
// Use the destination register to materialize sp + offset.
unsigned TmpReg = MI.getOperand(0).getReg();
bool UseRR = false;
if (Opcode == ARM::tRestore) {
if (FrameReg == ARM::SP)
emitThumbRegPlusImmInReg(MBB, II, TmpReg, FrameReg,
Offset, false, TII, *this, dl);
else {
emitLoadConstPool(MBB, II, TmpReg, Offset, ARMCC::AL, 0, &TII, dl);
UseRR = true;
}
} else
emitThumbRegPlusImmediate(MBB, II, TmpReg, FrameReg, Offset, TII,
*this, dl);
MI.setDesc(TII.get(ARM::tLDR));
MI.getOperand(i).ChangeToRegister(TmpReg, false, false, true);
if (UseRR)
// Use [reg, reg] addrmode.
MI.addOperand(MachineOperand::CreateReg(FrameReg, false));
else // tLDR has an extra register operand.
MI.addOperand(MachineOperand::CreateReg(0, false));
} else if (Desc.mayStore()) {
// FIXME! This is horrific!!! We need register scavenging.
// Our temporary workaround has marked r3 unavailable. Of course, r3 is
// also a ABI register so it's possible that is is the register that is
// being storing here. If that's the case, we do the following:
// r12 = r2
// Use r2 to materialize sp + offset
// str r3, r2
// r2 = r12
unsigned ValReg = MI.getOperand(0).getReg();
unsigned TmpReg = ARM::R3;
bool UseRR = false;
if (ValReg == ARM::R3) {
BuildMI(MBB, II, dl, TII.get(ARM::tMOVlor2hir), ARM::R12)
.addReg(ARM::R2, RegState::Kill);
TmpReg = ARM::R2;
}
if (TmpReg == ARM::R3 && AFI->isR3LiveIn())
BuildMI(MBB, II, dl, TII.get(ARM::tMOVlor2hir), ARM::R12)
.addReg(ARM::R3, RegState::Kill);
if (Opcode == ARM::tSpill) {
if (FrameReg == ARM::SP)
emitThumbRegPlusImmInReg(MBB, II, TmpReg, FrameReg,
Offset, false, TII, *this, dl);
else {
emitLoadConstPool(MBB, II, TmpReg, Offset, ARMCC::AL, 0, &TII, dl);
UseRR = true;
}
} else
emitThumbRegPlusImmediate(MBB, II, TmpReg, FrameReg, Offset, TII,
*this, dl);
MI.setDesc(TII.get(ARM::tSTR));
MI.getOperand(i).ChangeToRegister(TmpReg, false, false, true);
if (UseRR) // Use [reg, reg] addrmode.
MI.addOperand(MachineOperand::CreateReg(FrameReg, false));
else // tSTR has an extra register operand.
MI.addOperand(MachineOperand::CreateReg(0, false));
MachineBasicBlock::iterator NII = next(II);
if (ValReg == ARM::R3)
BuildMI(MBB, NII, dl, TII.get(ARM::tMOVhir2lor), ARM::R2)
.addReg(ARM::R12, RegState::Kill);
if (TmpReg == ARM::R3 && AFI->isR3LiveIn())
BuildMI(MBB, NII, dl, TII.get(ARM::tMOVhir2lor), ARM::R3)
.addReg(ARM::R12, RegState::Kill);
} else
assert(false && "Unexpected opcode!");
}
void ThumbRegisterInfo::emitPrologue(MachineFunction &MF) const {
MachineBasicBlock &MBB = MF.front();
MachineBasicBlock::iterator MBBI = MBB.begin();
MachineFrameInfo *MFI = MF.getFrameInfo();
ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
unsigned VARegSaveSize = AFI->getVarArgsRegSaveSize();
unsigned NumBytes = MFI->getStackSize();
const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo();
DebugLoc dl = (MBBI != MBB.end() ?
MBBI->getDebugLoc() : DebugLoc::getUnknownLoc());
// Check if R3 is live in. It might have to be used as a scratch register.
for (MachineRegisterInfo::livein_iterator I =MF.getRegInfo().livein_begin(),
E = MF.getRegInfo().livein_end(); I != E; ++I) {
if (I->first == ARM::R3) {
AFI->setR3IsLiveIn(true);
break;
}
}
// Thumb add/sub sp, imm8 instructions implicitly multiply the offset by 4.
NumBytes = (NumBytes + 3) & ~3;
MFI->setStackSize(NumBytes);
// Determine the sizes of each callee-save spill areas and record which frame
// belongs to which callee-save spill areas.
unsigned GPRCS1Size = 0, GPRCS2Size = 0, DPRCSSize = 0;
int FramePtrSpillFI = 0;
if (VARegSaveSize)
emitSPUpdate(MBB, MBBI, -VARegSaveSize, ARMCC::AL, 0, TII, dl);
if (!AFI->hasStackFrame()) {
if (NumBytes != 0)
emitSPUpdate(MBB, MBBI, -NumBytes, ARMCC::AL, 0, TII, dl);
return;
}
for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
unsigned Reg = CSI[i].getReg();
int FI = CSI[i].getFrameIdx();
switch (Reg) {
case ARM::R4:
case ARM::R5:
case ARM::R6:
case ARM::R7:
case ARM::LR:
if (Reg == FramePtr)
FramePtrSpillFI = FI;
AFI->addGPRCalleeSavedArea1Frame(FI);
GPRCS1Size += 4;
break;
case ARM::R8:
case ARM::R9:
case ARM::R10:
case ARM::R11:
if (Reg == FramePtr)
FramePtrSpillFI = FI;
if (STI.isTargetDarwin()) {
AFI->addGPRCalleeSavedArea2Frame(FI);
GPRCS2Size += 4;
} else {
AFI->addGPRCalleeSavedArea1Frame(FI);
GPRCS1Size += 4;
}
break;
default:
AFI->addDPRCalleeSavedAreaFrame(FI);
DPRCSSize += 8;
}
}
if (MBBI != MBB.end() && MBBI->getOpcode() == ARM::tPUSH) {
++MBBI;
if (MBBI != MBB.end())
dl = MBBI->getDebugLoc();
}
// Darwin ABI requires FP to point to the stack slot that contains the
// previous FP.
if (STI.isTargetDarwin() || hasFP(MF)) {
MachineInstrBuilder MIB =
BuildMI(MBB, MBBI, dl, TII.get(ARM::tADDrSPi), FramePtr)
.addFrameIndex(FramePtrSpillFI).addImm(0);
}
// Determine starting offsets of spill areas.
unsigned DPRCSOffset = NumBytes - (GPRCS1Size + GPRCS2Size + DPRCSSize);
unsigned GPRCS2Offset = DPRCSOffset + DPRCSSize;
unsigned GPRCS1Offset = GPRCS2Offset + GPRCS2Size;
AFI->setFramePtrSpillOffset(MFI->getObjectOffset(FramePtrSpillFI) + NumBytes);
AFI->setGPRCalleeSavedArea1Offset(GPRCS1Offset);
AFI->setGPRCalleeSavedArea2Offset(GPRCS2Offset);
AFI->setDPRCalleeSavedAreaOffset(DPRCSOffset);
NumBytes = DPRCSOffset;
if (NumBytes) {
// Insert it after all the callee-save spills.
emitSPUpdate(MBB, MBBI, -NumBytes, ARMCC::AL, 0, TII, dl);
}
if (STI.isTargetELF() && hasFP(MF)) {
MFI->setOffsetAdjustment(MFI->getOffsetAdjustment() -
AFI->getFramePtrSpillOffset());
}
AFI->setGPRCalleeSavedArea1Size(GPRCS1Size);
AFI->setGPRCalleeSavedArea2Size(GPRCS2Size);
AFI->setDPRCalleeSavedAreaSize(DPRCSSize);
}
static bool isCalleeSavedRegister(unsigned Reg, const unsigned *CSRegs) {
for (unsigned i = 0; CSRegs[i]; ++i)
if (Reg == CSRegs[i])
return true;
return false;
}
static bool isCSRestore(MachineInstr *MI, const unsigned *CSRegs) {
return (MI->getOpcode() == ARM::tRestore &&
MI->getOperand(1).isFI() &&
isCalleeSavedRegister(MI->getOperand(0).getReg(), CSRegs));
}
void ThumbRegisterInfo::emitEpilogue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
MachineBasicBlock::iterator MBBI = prior(MBB.end());
assert((MBBI->getOpcode() == ARM::tBX_RET ||
MBBI->getOpcode() == ARM::tPOP_RET) &&
"Can only insert epilog into returning blocks");
DebugLoc dl = MBBI->getDebugLoc();
MachineFrameInfo *MFI = MF.getFrameInfo();
ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
unsigned VARegSaveSize = AFI->getVarArgsRegSaveSize();
int NumBytes = (int)MFI->getStackSize();
if (!AFI->hasStackFrame()) {
if (NumBytes != 0)
emitSPUpdate(MBB, MBBI, NumBytes, ARMCC::AL, 0, TII, dl);
} else {
// Unwind MBBI to point to first LDR / FLDD.
const unsigned *CSRegs = getCalleeSavedRegs();
if (MBBI != MBB.begin()) {
do
--MBBI;
while (MBBI != MBB.begin() && isCSRestore(MBBI, CSRegs));
if (!isCSRestore(MBBI, CSRegs))
++MBBI;
}
// Move SP to start of FP callee save spill area.
NumBytes -= (AFI->getGPRCalleeSavedArea1Size() +
AFI->getGPRCalleeSavedArea2Size() +
AFI->getDPRCalleeSavedAreaSize());
if (hasFP(MF)) {
NumBytes = AFI->getFramePtrSpillOffset() - NumBytes;
// Reset SP based on frame pointer only if the stack frame extends beyond
// frame pointer stack slot or target is ELF and the function has FP.
if (NumBytes)
emitThumbRegPlusImmediate(MBB, MBBI, ARM::SP, FramePtr, -NumBytes,
TII, *this, dl);
else
BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVlor2hir), ARM::SP)
.addReg(FramePtr);
} else {
if (MBBI->getOpcode() == ARM::tBX_RET &&
&MBB.front() != MBBI &&
prior(MBBI)->getOpcode() == ARM::tPOP) {
MachineBasicBlock::iterator PMBBI = prior(MBBI);
emitSPUpdate(MBB, PMBBI, NumBytes, ARMCC::AL, 0, TII, dl);
} else
emitSPUpdate(MBB, MBBI, NumBytes, ARMCC::AL, 0, TII, dl);
}
}
if (VARegSaveSize) {
// Epilogue for vararg functions: pop LR to R3 and branch off it.
// FIXME: Verify this is still ok when R3 is no longer being reserved.
BuildMI(MBB, MBBI, dl, TII.get(ARM::tPOP)).addReg(ARM::R3);
emitSPUpdate(MBB, MBBI, VARegSaveSize, ARMCC::AL, 0, TII, dl);
BuildMI(MBB, MBBI, dl, TII.get(ARM::tBX_RET_vararg)).addReg(ARM::R3);
MBB.erase(MBBI);
}
}
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