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llvm-6502/lib/Target/ARM/Thumb2InstrInfo.cpp
Tim Northover e53abc2072 ARM: remove unnecessary state-tracking during frame lowering. 
ResolveFrameIndex had what appeared to be a very nasty hack for when the
frame-index referred to a callee-saved register. In this case it "adjusted" the
offset so that the address was correct if (and only if) the MachineInstr
immediately followed the respective push.

This "worked" for all forms of GPR & DPR but was only ever used to set the
frame pointer itself, and once this was put in a more sensible location the
entire state-tracking machinery it relied on became redundant. So I stripped
it.

The only wrinkle is that "add r7, sp, #0" might theoretically be slower (need
an actual ALU slot) compared to "mov r7, sp" so I added a micro-optimisation
that also makes emitARMRegUpdate and emitT2RegUpdate also work when NumBytes ==
0.

No test changes since there shouldn't be any functionality change.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194025 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-04 23:04:15 +00:00

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//===-- Thumb2InstrInfo.cpp - Thumb-2 Instruction 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 Thumb-2 implementation of the TargetInstrInfo class.
//
//===----------------------------------------------------------------------===//
#include "Thumb2InstrInfo.h"
#include "ARM.h"
#include "ARMConstantPoolValue.h"
#include "ARMMachineFunctionInfo.h"
#include "MCTargetDesc/ARMAddressingModes.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineMemOperand.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/MC/MCInst.h"
#include "llvm/Support/CommandLine.h"
using namespace llvm;
static cl::opt<bool>
OldT2IfCvt("old-thumb2-ifcvt", cl::Hidden,
cl::desc("Use old-style Thumb2 if-conversion heuristics"),
cl::init(false));
Thumb2InstrInfo::Thumb2InstrInfo(const ARMSubtarget &STI)
: ARMBaseInstrInfo(STI), RI(STI) {
}
/// getNoopForMachoTarget - Return the noop instruction to use for a noop.
void Thumb2InstrInfo::getNoopForMachoTarget(MCInst &NopInst) const {
NopInst.setOpcode(ARM::tHINT);
NopInst.addOperand(MCOperand::CreateImm(0));
NopInst.addOperand(MCOperand::CreateImm(ARMCC::AL));
NopInst.addOperand(MCOperand::CreateReg(0));
}
unsigned Thumb2InstrInfo::getUnindexedOpcode(unsigned Opc) const {
// FIXME
return 0;
}
void
Thumb2InstrInfo::ReplaceTailWithBranchTo(MachineBasicBlock::iterator Tail,
MachineBasicBlock *NewDest) const {
MachineBasicBlock *MBB = Tail->getParent();
ARMFunctionInfo *AFI = MBB->getParent()->getInfo<ARMFunctionInfo>();
if (!AFI->hasITBlocks()) {
TargetInstrInfo::ReplaceTailWithBranchTo(Tail, NewDest);
return;
}
// If the first instruction of Tail is predicated, we may have to update
// the IT instruction.
unsigned PredReg = 0;
ARMCC::CondCodes CC = getInstrPredicate(Tail, PredReg);
MachineBasicBlock::iterator MBBI = Tail;
if (CC != ARMCC::AL)
// Expecting at least the t2IT instruction before it.
--MBBI;
// Actually replace the tail.
TargetInstrInfo::ReplaceTailWithBranchTo(Tail, NewDest);
// Fix up IT.
if (CC != ARMCC::AL) {
MachineBasicBlock::iterator E = MBB->begin();
unsigned Count = 4; // At most 4 instructions in an IT block.
while (Count && MBBI != E) {
if (MBBI->isDebugValue()) {
--MBBI;
continue;
}
if (MBBI->getOpcode() == ARM::t2IT) {
unsigned Mask = MBBI->getOperand(1).getImm();
if (Count == 4)
MBBI->eraseFromParent();
else {
unsigned MaskOn = 1 << Count;
unsigned MaskOff = ~(MaskOn - 1);
MBBI->getOperand(1).setImm((Mask & MaskOff) | MaskOn);
}
return;
}
--MBBI;
--Count;
}
// Ctrl flow can reach here if branch folding is run before IT block
// formation pass.
}
}
bool
Thumb2InstrInfo::isLegalToSplitMBBAt(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MBBI) const {
while (MBBI->isDebugValue()) {
++MBBI;
if (MBBI == MBB.end())
return false;
}
unsigned PredReg = 0;
return getITInstrPredicate(MBBI, PredReg) == ARMCC::AL;
}
void Thumb2InstrInfo::copyPhysReg(MachineBasicBlock &MBB,
MachineBasicBlock::iterator I, DebugLoc DL,
unsigned DestReg, unsigned SrcReg,
bool KillSrc) const {
// Handle SPR, DPR, and QPR copies.
if (!ARM::GPRRegClass.contains(DestReg, SrcReg))
return ARMBaseInstrInfo::copyPhysReg(MBB, I, DL, DestReg, SrcReg, KillSrc);
AddDefaultPred(BuildMI(MBB, I, DL, get(ARM::tMOVr), DestReg)
.addReg(SrcReg, getKillRegState(KillSrc)));
}
void Thumb2InstrInfo::
storeRegToStackSlot(MachineBasicBlock &MBB, MachineBasicBlock::iterator I,
unsigned SrcReg, bool isKill, int FI,
const TargetRegisterClass *RC,
const TargetRegisterInfo *TRI) const {
DebugLoc DL;
if (I != MBB.end()) DL = I->getDebugLoc();
MachineFunction &MF = *MBB.getParent();
MachineFrameInfo &MFI = *MF.getFrameInfo();
MachineMemOperand *MMO =
MF.getMachineMemOperand(MachinePointerInfo::getFixedStack(FI),
MachineMemOperand::MOStore,
MFI.getObjectSize(FI),
MFI.getObjectAlignment(FI));
if (RC == &ARM::GPRRegClass || RC == &ARM::tGPRRegClass ||
RC == &ARM::tcGPRRegClass || RC == &ARM::rGPRRegClass ||
RC == &ARM::GPRnopcRegClass) {
AddDefaultPred(BuildMI(MBB, I, DL, get(ARM::t2STRi12))
.addReg(SrcReg, getKillRegState(isKill))
.addFrameIndex(FI).addImm(0).addMemOperand(MMO));
return;
}
if (ARM::GPRPairRegClass.hasSubClassEq(RC)) {
// Thumb2 STRD expects its dest-registers to be in rGPR. Not a problem for
// gsub_0, but needs an extra constraint for gsub_1 (which could be sp
// otherwise).
MachineRegisterInfo *MRI = &MF.getRegInfo();
MRI->constrainRegClass(SrcReg, &ARM::GPRPair_with_gsub_1_in_rGPRRegClass);
MachineInstrBuilder MIB = BuildMI(MBB, I, DL, get(ARM::t2STRDi8));
AddDReg(MIB, SrcReg, ARM::gsub_0, getKillRegState(isKill), TRI);
AddDReg(MIB, SrcReg, ARM::gsub_1, 0, TRI);
MIB.addFrameIndex(FI).addImm(0).addMemOperand(MMO);
AddDefaultPred(MIB);
return;
}
ARMBaseInstrInfo::storeRegToStackSlot(MBB, I, SrcReg, isKill, FI, RC, TRI);
}
void Thumb2InstrInfo::
loadRegFromStackSlot(MachineBasicBlock &MBB, MachineBasicBlock::iterator I,
unsigned DestReg, int FI,
const TargetRegisterClass *RC,
const TargetRegisterInfo *TRI) const {
MachineFunction &MF = *MBB.getParent();
MachineFrameInfo &MFI = *MF.getFrameInfo();
MachineMemOperand *MMO =
MF.getMachineMemOperand(MachinePointerInfo::getFixedStack(FI),
MachineMemOperand::MOLoad,
MFI.getObjectSize(FI),
MFI.getObjectAlignment(FI));
DebugLoc DL;
if (I != MBB.end()) DL = I->getDebugLoc();
if (RC == &ARM::GPRRegClass || RC == &ARM::tGPRRegClass ||
RC == &ARM::tcGPRRegClass || RC == &ARM::rGPRRegClass ||
RC == &ARM::GPRnopcRegClass) {
AddDefaultPred(BuildMI(MBB, I, DL, get(ARM::t2LDRi12), DestReg)
.addFrameIndex(FI).addImm(0).addMemOperand(MMO));
return;
}
if (ARM::GPRPairRegClass.hasSubClassEq(RC)) {
// Thumb2 LDRD expects its dest-registers to be in rGPR. Not a problem for
// gsub_0, but needs an extra constraint for gsub_1 (which could be sp
// otherwise).
MachineRegisterInfo *MRI = &MF.getRegInfo();
MRI->constrainRegClass(DestReg, &ARM::GPRPair_with_gsub_1_in_rGPRRegClass);
MachineInstrBuilder MIB = BuildMI(MBB, I, DL, get(ARM::t2LDRDi8));
AddDReg(MIB, DestReg, ARM::gsub_0, RegState::DefineNoRead, TRI);
AddDReg(MIB, DestReg, ARM::gsub_1, RegState::DefineNoRead, TRI);
MIB.addFrameIndex(FI).addImm(0).addMemOperand(MMO);
AddDefaultPred(MIB);
if (TargetRegisterInfo::isPhysicalRegister(DestReg))
MIB.addReg(DestReg, RegState::ImplicitDefine);
return;
}
ARMBaseInstrInfo::loadRegFromStackSlot(MBB, I, DestReg, FI, RC, TRI);
}
void llvm::emitT2RegPlusImmediate(MachineBasicBlock &MBB,
MachineBasicBlock::iterator &MBBI, DebugLoc dl,
unsigned DestReg, unsigned BaseReg, int NumBytes,
ARMCC::CondCodes Pred, unsigned PredReg,
const ARMBaseInstrInfo &TII, unsigned MIFlags) {
if (NumBytes == 0 && DestReg != BaseReg) {
BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVr), DestReg)
.addReg(BaseReg, RegState::Kill)
.addImm((unsigned)Pred).addReg(PredReg).setMIFlags(MIFlags);
return;
}
bool isSub = NumBytes < 0;
if (isSub) NumBytes = -NumBytes;
// If profitable, use a movw or movt to materialize the offset.
// FIXME: Use the scavenger to grab a scratch register.
if (DestReg != ARM::SP && DestReg != BaseReg &&
NumBytes >= 4096 &&
ARM_AM::getT2SOImmVal(NumBytes) == -1) {
bool Fits = false;
if (NumBytes < 65536) {
// Use a movw to materialize the 16-bit constant.
BuildMI(MBB, MBBI, dl, TII.get(ARM::t2MOVi16), DestReg)
.addImm(NumBytes)
.addImm((unsigned)Pred).addReg(PredReg).setMIFlags(MIFlags);
Fits = true;
} else if ((NumBytes & 0xffff) == 0) {
// Use a movt to materialize the 32-bit constant.
BuildMI(MBB, MBBI, dl, TII.get(ARM::t2MOVTi16), DestReg)
.addReg(DestReg)
.addImm(NumBytes >> 16)
.addImm((unsigned)Pred).addReg(PredReg).setMIFlags(MIFlags);
Fits = true;
}
if (Fits) {
if (isSub) {
BuildMI(MBB, MBBI, dl, TII.get(ARM::t2SUBrr), DestReg)
.addReg(BaseReg, RegState::Kill)
.addReg(DestReg, RegState::Kill)
.addImm((unsigned)Pred).addReg(PredReg).addReg(0)
.setMIFlags(MIFlags);
} else {
BuildMI(MBB, MBBI, dl, TII.get(ARM::t2ADDrr), DestReg)
.addReg(DestReg, RegState::Kill)
.addReg(BaseReg, RegState::Kill)
.addImm((unsigned)Pred).addReg(PredReg).addReg(0)
.setMIFlags(MIFlags);
}
return;
}
}
while (NumBytes) {
unsigned ThisVal = NumBytes;
unsigned Opc = 0;
if (DestReg == ARM::SP && BaseReg != ARM::SP) {
// mov sp, rn. Note t2MOVr cannot be used.
AddDefaultPred(BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVr),DestReg)
.addReg(BaseReg).setMIFlags(MIFlags));
BaseReg = ARM::SP;
continue;
}
bool HasCCOut = true;
if (BaseReg == ARM::SP) {
// sub sp, sp, #imm7
if (DestReg == ARM::SP && (ThisVal < ((1 << 7)-1) * 4)) {
assert((ThisVal & 3) == 0 && "Stack update is not multiple of 4?");
Opc = isSub ? ARM::tSUBspi : ARM::tADDspi;
AddDefaultPred(BuildMI(MBB, MBBI, dl, TII.get(Opc), DestReg)
.addReg(BaseReg).addImm(ThisVal/4).setMIFlags(MIFlags));
NumBytes = 0;
continue;
}
// sub rd, sp, so_imm
Opc = isSub ? ARM::t2SUBri : ARM::t2ADDri;
if (ARM_AM::getT2SOImmVal(NumBytes) != -1) {
NumBytes = 0;
} else {
// FIXME: Move this to ARMAddressingModes.h?
unsigned RotAmt = countLeadingZeros(ThisVal);
ThisVal = ThisVal & ARM_AM::rotr32(0xff000000U, RotAmt);
NumBytes &= ~ThisVal;
assert(ARM_AM::getT2SOImmVal(ThisVal) != -1 &&
"Bit extraction didn't work?");
}
} else {
assert(DestReg != ARM::SP && BaseReg != ARM::SP);
Opc = isSub ? ARM::t2SUBri : ARM::t2ADDri;
if (ARM_AM::getT2SOImmVal(NumBytes) != -1) {
NumBytes = 0;
} else if (ThisVal < 4096) {
Opc = isSub ? ARM::t2SUBri12 : ARM::t2ADDri12;
HasCCOut = false;
NumBytes = 0;
} else {
// FIXME: Move this to ARMAddressingModes.h?
unsigned RotAmt = countLeadingZeros(ThisVal);
ThisVal = ThisVal & ARM_AM::rotr32(0xff000000U, RotAmt);
NumBytes &= ~ThisVal;
assert(ARM_AM::getT2SOImmVal(ThisVal) != -1 &&
"Bit extraction didn't work?");
}
}
// Build the new ADD / SUB.
MachineInstrBuilder MIB =
AddDefaultPred(BuildMI(MBB, MBBI, dl, TII.get(Opc), DestReg)
.addReg(BaseReg, RegState::Kill)
.addImm(ThisVal)).setMIFlags(MIFlags);
if (HasCCOut)
AddDefaultCC(MIB);
BaseReg = DestReg;
}
}
static unsigned
negativeOffsetOpcode(unsigned opcode)
{
switch (opcode) {
case ARM::t2LDRi12: return ARM::t2LDRi8;
case ARM::t2LDRHi12: return ARM::t2LDRHi8;
case ARM::t2LDRBi12: return ARM::t2LDRBi8;
case ARM::t2LDRSHi12: return ARM::t2LDRSHi8;
case ARM::t2LDRSBi12: return ARM::t2LDRSBi8;
case ARM::t2STRi12: return ARM::t2STRi8;
case ARM::t2STRBi12: return ARM::t2STRBi8;
case ARM::t2STRHi12: return ARM::t2STRHi8;
case ARM::t2PLDi12: return ARM::t2PLDi8;
case ARM::t2LDRi8:
case ARM::t2LDRHi8:
case ARM::t2LDRBi8:
case ARM::t2LDRSHi8:
case ARM::t2LDRSBi8:
case ARM::t2STRi8:
case ARM::t2STRBi8:
case ARM::t2STRHi8:
case ARM::t2PLDi8:
return opcode;
default:
break;
}
return 0;
}
static unsigned
positiveOffsetOpcode(unsigned opcode)
{
switch (opcode) {
case ARM::t2LDRi8: return ARM::t2LDRi12;
case ARM::t2LDRHi8: return ARM::t2LDRHi12;
case ARM::t2LDRBi8: return ARM::t2LDRBi12;
case ARM::t2LDRSHi8: return ARM::t2LDRSHi12;
case ARM::t2LDRSBi8: return ARM::t2LDRSBi12;
case ARM::t2STRi8: return ARM::t2STRi12;
case ARM::t2STRBi8: return ARM::t2STRBi12;
case ARM::t2STRHi8: return ARM::t2STRHi12;
case ARM::t2PLDi8: return ARM::t2PLDi12;
case ARM::t2LDRi12:
case ARM::t2LDRHi12:
case ARM::t2LDRBi12:
case ARM::t2LDRSHi12:
case ARM::t2LDRSBi12:
case ARM::t2STRi12:
case ARM::t2STRBi12:
case ARM::t2STRHi12:
case ARM::t2PLDi12:
return opcode;
default:
break;
}
return 0;
}
static unsigned
immediateOffsetOpcode(unsigned opcode)
{
switch (opcode) {
case ARM::t2LDRs: return ARM::t2LDRi12;
case ARM::t2LDRHs: return ARM::t2LDRHi12;
case ARM::t2LDRBs: return ARM::t2LDRBi12;
case ARM::t2LDRSHs: return ARM::t2LDRSHi12;
case ARM::t2LDRSBs: return ARM::t2LDRSBi12;
case ARM::t2STRs: return ARM::t2STRi12;
case ARM::t2STRBs: return ARM::t2STRBi12;
case ARM::t2STRHs: return ARM::t2STRHi12;
case ARM::t2PLDs: return ARM::t2PLDi12;
case ARM::t2LDRi12:
case ARM::t2LDRHi12:
case ARM::t2LDRBi12:
case ARM::t2LDRSHi12:
case ARM::t2LDRSBi12:
case ARM::t2STRi12:
case ARM::t2STRBi12:
case ARM::t2STRHi12:
case ARM::t2PLDi12:
case ARM::t2LDRi8:
case ARM::t2LDRHi8:
case ARM::t2LDRBi8:
case ARM::t2LDRSHi8:
case ARM::t2LDRSBi8:
case ARM::t2STRi8:
case ARM::t2STRBi8:
case ARM::t2STRHi8:
case ARM::t2PLDi8:
return opcode;
default:
break;
}
return 0;
}
bool llvm::rewriteT2FrameIndex(MachineInstr &MI, unsigned FrameRegIdx,
unsigned FrameReg, int &Offset,
const ARMBaseInstrInfo &TII) {
unsigned Opcode = MI.getOpcode();
const MCInstrDesc &Desc = MI.getDesc();
unsigned AddrMode = (Desc.TSFlags & ARMII::AddrModeMask);
bool isSub = false;
// Memory operands in inline assembly always use AddrModeT2_i12.
if (Opcode == ARM::INLINEASM)
AddrMode = ARMII::AddrModeT2_i12; // FIXME. mode for thumb2?
if (Opcode == ARM::t2ADDri || Opcode == ARM::t2ADDri12) {
Offset += MI.getOperand(FrameRegIdx+1).getImm();
unsigned PredReg;
if (Offset == 0 && getInstrPredicate(&MI, PredReg) == ARMCC::AL) {
// Turn it into a move.
MI.setDesc(TII.get(ARM::tMOVr));
MI.getOperand(FrameRegIdx).ChangeToRegister(FrameReg, false);
// Remove offset and remaining explicit predicate operands.
do MI.RemoveOperand(FrameRegIdx+1);
while (MI.getNumOperands() > FrameRegIdx+1);
MachineInstrBuilder MIB(*MI.getParent()->getParent(), &MI);
AddDefaultPred(MIB);
return true;
}
bool HasCCOut = Opcode != ARM::t2ADDri12;
if (Offset < 0) {
Offset = -Offset;
isSub = true;
MI.setDesc(TII.get(ARM::t2SUBri));
} else {
MI.setDesc(TII.get(ARM::t2ADDri));
}
// Common case: small offset, fits into instruction.
if (ARM_AM::getT2SOImmVal(Offset) != -1) {
MI.getOperand(FrameRegIdx).ChangeToRegister(FrameReg, false);
MI.getOperand(FrameRegIdx+1).ChangeToImmediate(Offset);
// Add cc_out operand if the original instruction did not have one.
if (!HasCCOut)
MI.addOperand(MachineOperand::CreateReg(0, false));
Offset = 0;
return true;
}
// Another common case: imm12.
if (Offset < 4096 &&
(!HasCCOut || MI.getOperand(MI.getNumOperands()-1).getReg() == 0)) {
unsigned NewOpc = isSub ? ARM::t2SUBri12 : ARM::t2ADDri12;
MI.setDesc(TII.get(NewOpc));
MI.getOperand(FrameRegIdx).ChangeToRegister(FrameReg, false);
MI.getOperand(FrameRegIdx+1).ChangeToImmediate(Offset);
// Remove the cc_out operand.
if (HasCCOut)
MI.RemoveOperand(MI.getNumOperands()-1);
Offset = 0;
return true;
}
// Otherwise, extract 8 adjacent bits from the immediate into this
// t2ADDri/t2SUBri.
unsigned RotAmt = countLeadingZeros<unsigned>(Offset);
unsigned ThisImmVal = Offset & ARM_AM::rotr32(0xff000000U, RotAmt);
// We will handle these bits from offset, clear them.
Offset &= ~ThisImmVal;
assert(ARM_AM::getT2SOImmVal(ThisImmVal) != -1 &&
"Bit extraction didn't work?");
MI.getOperand(FrameRegIdx+1).ChangeToImmediate(ThisImmVal);
// Add cc_out operand if the original instruction did not have one.
if (!HasCCOut)
MI.addOperand(MachineOperand::CreateReg(0, false));
} else {
// AddrMode4 and AddrMode6 cannot handle any offset.
if (AddrMode == ARMII::AddrMode4 || AddrMode == ARMII::AddrMode6)
return false;
// AddrModeT2_so cannot handle any offset. If there is no offset
// register then we change to an immediate version.
unsigned NewOpc = Opcode;
if (AddrMode == ARMII::AddrModeT2_so) {
unsigned OffsetReg = MI.getOperand(FrameRegIdx+1).getReg();
if (OffsetReg != 0) {
MI.getOperand(FrameRegIdx).ChangeToRegister(FrameReg, false);
return Offset == 0;
}
MI.RemoveOperand(FrameRegIdx+1);
MI.getOperand(FrameRegIdx+1).ChangeToImmediate(0);
NewOpc = immediateOffsetOpcode(Opcode);
AddrMode = ARMII::AddrModeT2_i12;
}
unsigned NumBits = 0;
unsigned Scale = 1;
if (AddrMode == ARMII::AddrModeT2_i8 || AddrMode == ARMII::AddrModeT2_i12) {
// i8 supports only negative, and i12 supports only positive, so
// based on Offset sign convert Opcode to the appropriate
// instruction
Offset += MI.getOperand(FrameRegIdx+1).getImm();
if (Offset < 0) {
NewOpc = negativeOffsetOpcode(Opcode);
NumBits = 8;
isSub = true;
Offset = -Offset;
} else {
NewOpc = positiveOffsetOpcode(Opcode);
NumBits = 12;
}
} else if (AddrMode == ARMII::AddrMode5) {
// VFP address mode.
const MachineOperand &OffOp = MI.getOperand(FrameRegIdx+1);
int InstrOffs = ARM_AM::getAM5Offset(OffOp.getImm());
if (ARM_AM::getAM5Op(OffOp.getImm()) == ARM_AM::sub)
InstrOffs *= -1;
NumBits = 8;
Scale = 4;
Offset += InstrOffs * 4;
assert((Offset & (Scale-1)) == 0 && "Can't encode this offset!");
if (Offset < 0) {
Offset = -Offset;
isSub = true;
}
} else if (AddrMode == ARMII::AddrModeT2_i8s4) {
Offset += MI.getOperand(FrameRegIdx + 1).getImm() * 4;
NumBits = 8;
// MCInst operand has already scaled value.
Scale = 1;
if (Offset < 0) {
isSub = true;
Offset = -Offset;
}
} else {
llvm_unreachable("Unsupported addressing mode!");
}
if (NewOpc != Opcode)
MI.setDesc(TII.get(NewOpc));
MachineOperand &ImmOp = MI.getOperand(FrameRegIdx+1);
// Attempt to fold address computation
// Common case: small offset, fits into instruction.
int ImmedOffset = Offset / Scale;
unsigned Mask = (1 << NumBits) - 1;
if ((unsigned)Offset <= Mask * Scale) {
// Replace the FrameIndex with fp/sp
MI.getOperand(FrameRegIdx).ChangeToRegister(FrameReg, false);
if (isSub) {
if (AddrMode == ARMII::AddrMode5)
// FIXME: Not consistent.
ImmedOffset |= 1 << NumBits;
else
ImmedOffset = -ImmedOffset;
}
ImmOp.ChangeToImmediate(ImmedOffset);
Offset = 0;
return true;
}
// Otherwise, offset doesn't fit. Pull in what we can to simplify
ImmedOffset = ImmedOffset & Mask;
if (isSub) {
if (AddrMode == ARMII::AddrMode5)
// FIXME: Not consistent.
ImmedOffset |= 1 << NumBits;
else {
ImmedOffset = -ImmedOffset;
if (ImmedOffset == 0)
// Change the opcode back if the encoded offset is zero.
MI.setDesc(TII.get(positiveOffsetOpcode(NewOpc)));
}
}
ImmOp.ChangeToImmediate(ImmedOffset);
Offset &= ~(Mask*Scale);
}
Offset = (isSub) ? -Offset : Offset;
return Offset == 0;
}
ARMCC::CondCodes
llvm::getITInstrPredicate(const MachineInstr *MI, unsigned &PredReg) {
unsigned Opc = MI->getOpcode();
if (Opc == ARM::tBcc || Opc == ARM::t2Bcc)
return ARMCC::AL;
return getInstrPredicate(MI, PredReg);
}
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