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llvm-6502/lib/Target/ARM/ARMBaseInstrInfo.cpp
Jim Grosbach e45ab8a0a9 For aligned load/store instructions, it's only required to know whether a 
function can support dynamic stack realignment. That's a much easier question
to answer at instruction selection stage than whether the function actually
will have dynamic alignment prologue. This allows the removal of the
stack alignment heuristic pass, and improves code quality for cases where
the heuristic would result in dynamic alignment code being generated when
it was not strictly necessary.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@93885 91177308-0d34-0410-b5e6-96231b3b80d8
2010-01-19 18:31:11 +00:00

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//===- ARMBaseInstrInfo.cpp - ARM 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 Base ARM implementation of the TargetInstrInfo class.
//
//===----------------------------------------------------------------------===//
#include "ARMBaseInstrInfo.h"
#include "ARM.h"
#include "ARMAddressingModes.h"
#include "ARMConstantPoolValue.h"
#include "ARMGenInstrInfo.inc"
#include "ARMMachineFunctionInfo.h"
#include "ARMRegisterInfo.h"
#include "llvm/Constants.h"
#include "llvm/Function.h"
#include "llvm/GlobalValue.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/CodeGen/LiveVariables.h"
#include "llvm/CodeGen/MachineConstantPool.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineJumpTableInfo.h"
#include "llvm/CodeGen/MachineMemOperand.h"
#include "llvm/CodeGen/PseudoSourceValue.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
using namespace llvm;
static cl::opt<bool>
EnableARM3Addr("enable-arm-3-addr-conv", cl::Hidden,
cl::desc("Enable ARM 2-addr to 3-addr conv"));
ARMBaseInstrInfo::ARMBaseInstrInfo(const ARMSubtarget& STI)
: TargetInstrInfoImpl(ARMInsts, array_lengthof(ARMInsts)),
Subtarget(STI) {
}
MachineInstr *
ARMBaseInstrInfo::convertToThreeAddress(MachineFunction::iterator &MFI,
MachineBasicBlock::iterator &MBBI,
LiveVariables *LV) const {
// FIXME: Thumb2 support.
if (!EnableARM3Addr)
return NULL;
MachineInstr *MI = MBBI;
MachineFunction &MF = *MI->getParent()->getParent();
unsigned TSFlags = MI->getDesc().TSFlags;
bool isPre = false;
switch ((TSFlags & ARMII::IndexModeMask) >> ARMII::IndexModeShift) {
default: return NULL;
case ARMII::IndexModePre:
isPre = true;
break;
case ARMII::IndexModePost:
break;
}
// Try splitting an indexed load/store to an un-indexed one plus an add/sub
// operation.
unsigned MemOpc = getUnindexedOpcode(MI->getOpcode());
if (MemOpc == 0)
return NULL;
MachineInstr *UpdateMI = NULL;
MachineInstr *MemMI = NULL;
unsigned AddrMode = (TSFlags & ARMII::AddrModeMask);
const TargetInstrDesc &TID = MI->getDesc();
unsigned NumOps = TID.getNumOperands();
bool isLoad = !TID.mayStore();
const MachineOperand &WB = isLoad ? MI->getOperand(1) : MI->getOperand(0);
const MachineOperand &Base = MI->getOperand(2);
const MachineOperand &Offset = MI->getOperand(NumOps-3);
unsigned WBReg = WB.getReg();
unsigned BaseReg = Base.getReg();
unsigned OffReg = Offset.getReg();
unsigned OffImm = MI->getOperand(NumOps-2).getImm();
ARMCC::CondCodes Pred = (ARMCC::CondCodes)MI->getOperand(NumOps-1).getImm();
switch (AddrMode) {
default:
assert(false && "Unknown indexed op!");
return NULL;
case ARMII::AddrMode2: {
bool isSub = ARM_AM::getAM2Op(OffImm) == ARM_AM::sub;
unsigned Amt = ARM_AM::getAM2Offset(OffImm);
if (OffReg == 0) {
if (ARM_AM::getSOImmVal(Amt) == -1)
// Can't encode it in a so_imm operand. This transformation will
// add more than 1 instruction. Abandon!
return NULL;
UpdateMI = BuildMI(MF, MI->getDebugLoc(),
get(isSub ? ARM::SUBri : ARM::ADDri), WBReg)
.addReg(BaseReg).addImm(Amt)
.addImm(Pred).addReg(0).addReg(0);
} else if (Amt != 0) {
ARM_AM::ShiftOpc ShOpc = ARM_AM::getAM2ShiftOpc(OffImm);
unsigned SOOpc = ARM_AM::getSORegOpc(ShOpc, Amt);
UpdateMI = BuildMI(MF, MI->getDebugLoc(),
get(isSub ? ARM::SUBrs : ARM::ADDrs), WBReg)
.addReg(BaseReg).addReg(OffReg).addReg(0).addImm(SOOpc)
.addImm(Pred).addReg(0).addReg(0);
} else
UpdateMI = BuildMI(MF, MI->getDebugLoc(),
get(isSub ? ARM::SUBrr : ARM::ADDrr), WBReg)
.addReg(BaseReg).addReg(OffReg)
.addImm(Pred).addReg(0).addReg(0);
break;
}
case ARMII::AddrMode3 : {
bool isSub = ARM_AM::getAM3Op(OffImm) == ARM_AM::sub;
unsigned Amt = ARM_AM::getAM3Offset(OffImm);
if (OffReg == 0)
// Immediate is 8-bits. It's guaranteed to fit in a so_imm operand.
UpdateMI = BuildMI(MF, MI->getDebugLoc(),
get(isSub ? ARM::SUBri : ARM::ADDri), WBReg)
.addReg(BaseReg).addImm(Amt)
.addImm(Pred).addReg(0).addReg(0);
else
UpdateMI = BuildMI(MF, MI->getDebugLoc(),
get(isSub ? ARM::SUBrr : ARM::ADDrr), WBReg)
.addReg(BaseReg).addReg(OffReg)
.addImm(Pred).addReg(0).addReg(0);
break;
}
}
std::vector<MachineInstr*> NewMIs;
if (isPre) {
if (isLoad)
MemMI = BuildMI(MF, MI->getDebugLoc(),
get(MemOpc), MI->getOperand(0).getReg())
.addReg(WBReg).addReg(0).addImm(0).addImm(Pred);
else
MemMI = BuildMI(MF, MI->getDebugLoc(),
get(MemOpc)).addReg(MI->getOperand(1).getReg())
.addReg(WBReg).addReg(0).addImm(0).addImm(Pred);
NewMIs.push_back(MemMI);
NewMIs.push_back(UpdateMI);
} else {
if (isLoad)
MemMI = BuildMI(MF, MI->getDebugLoc(),
get(MemOpc), MI->getOperand(0).getReg())
.addReg(BaseReg).addReg(0).addImm(0).addImm(Pred);
else
MemMI = BuildMI(MF, MI->getDebugLoc(),
get(MemOpc)).addReg(MI->getOperand(1).getReg())
.addReg(BaseReg).addReg(0).addImm(0).addImm(Pred);
if (WB.isDead())
UpdateMI->getOperand(0).setIsDead();
NewMIs.push_back(UpdateMI);
NewMIs.push_back(MemMI);
}
// Transfer LiveVariables states, kill / dead info.
if (LV) {
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
MachineOperand &MO = MI->getOperand(i);
if (MO.isReg() && MO.getReg() &&
TargetRegisterInfo::isVirtualRegister(MO.getReg())) {
unsigned Reg = MO.getReg();
LiveVariables::VarInfo &VI = LV->getVarInfo(Reg);
if (MO.isDef()) {
MachineInstr *NewMI = (Reg == WBReg) ? UpdateMI : MemMI;
if (MO.isDead())
LV->addVirtualRegisterDead(Reg, NewMI);
}
if (MO.isUse() && MO.isKill()) {
for (unsigned j = 0; j < 2; ++j) {
// Look at the two new MI's in reverse order.
MachineInstr *NewMI = NewMIs[j];
if (!NewMI->readsRegister(Reg))
continue;
LV->addVirtualRegisterKilled(Reg, NewMI);
if (VI.removeKill(MI))
VI.Kills.push_back(NewMI);
break;
}
}
}
}
}
MFI->insert(MBBI, NewMIs[1]);
MFI->insert(MBBI, NewMIs[0]);
return NewMIs[0];
}
// Branch analysis.
bool
ARMBaseInstrInfo::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() || !isUnpredicatedTerminator(--I))
return false;
// Get the last instruction in the block.
MachineInstr *LastInst = I;
// If there is only one terminator instruction, process it.
unsigned LastOpc = LastInst->getOpcode();
if (I == MBB.begin() || !isUnpredicatedTerminator(--I)) {
if (isUncondBranchOpcode(LastOpc)) {
TBB = LastInst->getOperand(0).getMBB();
return false;
}
if (isCondBranchOpcode(LastOpc)) {
// Block ends with fall-through condbranch.
TBB = LastInst->getOperand(0).getMBB();
Cond.push_back(LastInst->getOperand(1));
Cond.push_back(LastInst->getOperand(2));
return false;
}
return true; // Can't handle indirect branch.
}
// Get the instruction before it if it is 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 a B and a Bcc, handle it.
unsigned SecondLastOpc = SecondLastInst->getOpcode();
if (isCondBranchOpcode(SecondLastOpc) && isUncondBranchOpcode(LastOpc)) {
TBB = SecondLastInst->getOperand(0).getMBB();
Cond.push_back(SecondLastInst->getOperand(1));
Cond.push_back(SecondLastInst->getOperand(2));
FBB = LastInst->getOperand(0).getMBB();
return false;
}
// If the block ends with two unconditional branches, handle it. The second
// one is not executed, so remove it.
if (isUncondBranchOpcode(SecondLastOpc) && isUncondBranchOpcode(LastOpc)) {
TBB = SecondLastInst->getOperand(0).getMBB();
I = LastInst;
if (AllowModify)
I->eraseFromParent();
return false;
}
// ...likewise if it ends with a branch table followed by an unconditional
// branch. The branch folder can create these, and we must get rid of them for
// correctness of Thumb constant islands.
if ((isJumpTableBranchOpcode(SecondLastOpc) ||
isIndirectBranchOpcode(SecondLastOpc)) &&
isUncondBranchOpcode(LastOpc)) {
I = LastInst;
if (AllowModify)
I->eraseFromParent();
return true;
}
// Otherwise, can't handle this.
return true;
}
unsigned ARMBaseInstrInfo::RemoveBranch(MachineBasicBlock &MBB) const {
MachineBasicBlock::iterator I = MBB.end();
if (I == MBB.begin()) return 0;
--I;
if (!isUncondBranchOpcode(I->getOpcode()) &&
!isCondBranchOpcode(I->getOpcode()))
return 0;
// Remove the branch.
I->eraseFromParent();
I = MBB.end();
if (I == MBB.begin()) return 1;
--I;
if (!isCondBranchOpcode(I->getOpcode()))
return 1;
// Remove the branch.
I->eraseFromParent();
return 2;
}
unsigned
ARMBaseInstrInfo::InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB,
MachineBasicBlock *FBB,
const SmallVectorImpl<MachineOperand> &Cond) const {
// FIXME this should probably have a DebugLoc argument
DebugLoc dl = DebugLoc::getUnknownLoc();
ARMFunctionInfo *AFI = MBB.getParent()->getInfo<ARMFunctionInfo>();
int BOpc = !AFI->isThumbFunction()
? ARM::B : (AFI->isThumb2Function() ? ARM::t2B : ARM::tB);
int BccOpc = !AFI->isThumbFunction()
? ARM::Bcc : (AFI->isThumb2Function() ? ARM::t2Bcc : ARM::tBcc);
// Shouldn't be a fall through.
assert(TBB && "InsertBranch must not be told to insert a fallthrough");
assert((Cond.size() == 2 || Cond.size() == 0) &&
"ARM branch conditions have two components!");
if (FBB == 0) {
if (Cond.empty()) // Unconditional branch?
BuildMI(&MBB, dl, get(BOpc)).addMBB(TBB);
else
BuildMI(&MBB, dl, get(BccOpc)).addMBB(TBB)
.addImm(Cond[0].getImm()).addReg(Cond[1].getReg());
return 1;
}
// Two-way conditional branch.
BuildMI(&MBB, dl, get(BccOpc)).addMBB(TBB)
.addImm(Cond[0].getImm()).addReg(Cond[1].getReg());
BuildMI(&MBB, dl, get(BOpc)).addMBB(FBB);
return 2;
}
bool ARMBaseInstrInfo::
ReverseBranchCondition(SmallVectorImpl<MachineOperand> &Cond) const {
ARMCC::CondCodes CC = (ARMCC::CondCodes)(int)Cond[0].getImm();
Cond[0].setImm(ARMCC::getOppositeCondition(CC));
return false;
}
bool ARMBaseInstrInfo::
PredicateInstruction(MachineInstr *MI,
const SmallVectorImpl<MachineOperand> &Pred) const {
unsigned Opc = MI->getOpcode();
if (isUncondBranchOpcode(Opc)) {
MI->setDesc(get(getMatchingCondBranchOpcode(Opc)));
MI->addOperand(MachineOperand::CreateImm(Pred[0].getImm()));
MI->addOperand(MachineOperand::CreateReg(Pred[1].getReg(), false));
return true;
}
int PIdx = MI->findFirstPredOperandIdx();
if (PIdx != -1) {
MachineOperand &PMO = MI->getOperand(PIdx);
PMO.setImm(Pred[0].getImm());
MI->getOperand(PIdx+1).setReg(Pred[1].getReg());
return true;
}
return false;
}
bool ARMBaseInstrInfo::
SubsumesPredicate(const SmallVectorImpl<MachineOperand> &Pred1,
const SmallVectorImpl<MachineOperand> &Pred2) const {
if (Pred1.size() > 2 || Pred2.size() > 2)
return false;
ARMCC::CondCodes CC1 = (ARMCC::CondCodes)Pred1[0].getImm();
ARMCC::CondCodes CC2 = (ARMCC::CondCodes)Pred2[0].getImm();
if (CC1 == CC2)
return true;
switch (CC1) {
default:
return false;
case ARMCC::AL:
return true;
case ARMCC::HS:
return CC2 == ARMCC::HI;
case ARMCC::LS:
return CC2 == ARMCC::LO || CC2 == ARMCC::EQ;
case ARMCC::GE:
return CC2 == ARMCC::GT;
case ARMCC::LE:
return CC2 == ARMCC::LT;
}
}
bool ARMBaseInstrInfo::DefinesPredicate(MachineInstr *MI,
std::vector<MachineOperand> &Pred) const {
// FIXME: This confuses implicit_def with optional CPSR def.
const TargetInstrDesc &TID = MI->getDesc();
if (!TID.getImplicitDefs() && !TID.hasOptionalDef())
return false;
bool Found = false;
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
const MachineOperand &MO = MI->getOperand(i);
if (MO.isReg() && MO.getReg() == ARM::CPSR) {
Pred.push_back(MO);
Found = true;
}
}
return Found;
}
/// isPredicable - Return true if the specified instruction can be predicated.
/// By default, this returns true for every instruction with a
/// PredicateOperand.
bool ARMBaseInstrInfo::isPredicable(MachineInstr *MI) const {
const TargetInstrDesc &TID = MI->getDesc();
if (!TID.isPredicable())
return false;
if ((TID.TSFlags & ARMII::DomainMask) == ARMII::DomainNEON) {
ARMFunctionInfo *AFI =
MI->getParent()->getParent()->getInfo<ARMFunctionInfo>();
return AFI->isThumb2Function();
}
return true;
}
/// FIXME: Works around a gcc miscompilation with -fstrict-aliasing.
DISABLE_INLINE
static unsigned getNumJTEntries(const std::vector<MachineJumpTableEntry> &JT,
unsigned JTI);
static unsigned getNumJTEntries(const std::vector<MachineJumpTableEntry> &JT,
unsigned JTI) {
assert(JTI < JT.size());
return JT[JTI].MBBs.size();
}
/// GetInstSize - Return the size of the specified MachineInstr.
///
unsigned ARMBaseInstrInfo::GetInstSizeInBytes(const MachineInstr *MI) const {
const MachineBasicBlock &MBB = *MI->getParent();
const MachineFunction *MF = MBB.getParent();
const MCAsmInfo *MAI = MF->getTarget().getMCAsmInfo();
// Basic size info comes from the TSFlags field.
const TargetInstrDesc &TID = MI->getDesc();
unsigned TSFlags = TID.TSFlags;
unsigned Opc = MI->getOpcode();
switch ((TSFlags & ARMII::SizeMask) >> ARMII::SizeShift) {
default: {
// If this machine instr is an inline asm, measure it.
if (MI->getOpcode() == ARM::INLINEASM)
return getInlineAsmLength(MI->getOperand(0).getSymbolName(), *MAI);
if (MI->isLabel())
return 0;
switch (Opc) {
default:
llvm_unreachable("Unknown or unset size field for instr!");
case TargetInstrInfo::IMPLICIT_DEF:
case TargetInstrInfo::KILL:
case TargetInstrInfo::DBG_LABEL:
case TargetInstrInfo::EH_LABEL:
return 0;
}
break;
}
case ARMII::Size8Bytes: return 8; // ARM instruction x 2.
case ARMII::Size4Bytes: return 4; // ARM / Thumb2 instruction.
case ARMII::Size2Bytes: return 2; // Thumb1 instruction.
case ARMII::SizeSpecial: {
switch (Opc) {
case ARM::CONSTPOOL_ENTRY:
// If this machine instr is a constant pool entry, its size is recorded as
// operand #2.
return MI->getOperand(2).getImm();
case ARM::Int_eh_sjlj_setjmp:
return 24;
case ARM::tInt_eh_sjlj_setjmp:
return 22;
case ARM::t2Int_eh_sjlj_setjmp:
return 22;
case ARM::BR_JTr:
case ARM::BR_JTm:
case ARM::BR_JTadd:
case ARM::tBR_JTr:
case ARM::t2BR_JT:
case ARM::t2TBB:
case ARM::t2TBH: {
// These are jumptable branches, i.e. a branch followed by an inlined
// jumptable. The size is 4 + 4 * number of entries. For TBB, each
// entry is one byte; TBH two byte each.
unsigned EntrySize = (Opc == ARM::t2TBB)
? 1 : ((Opc == ARM::t2TBH) ? 2 : 4);
unsigned NumOps = TID.getNumOperands();
MachineOperand JTOP =
MI->getOperand(NumOps - (TID.isPredicable() ? 3 : 2));
unsigned JTI = JTOP.getIndex();
const MachineJumpTableInfo *MJTI = MF->getJumpTableInfo();
const std::vector<MachineJumpTableEntry> &JT = MJTI->getJumpTables();
assert(JTI < JT.size());
// Thumb instructions are 2 byte aligned, but JT entries are 4 byte
// 4 aligned. The assembler / linker may add 2 byte padding just before
// the JT entries. The size does not include this padding; the
// constant islands pass does separate bookkeeping for it.
// FIXME: If we know the size of the function is less than (1 << 16) *2
// bytes, we can use 16-bit entries instead. Then there won't be an
// alignment issue.
unsigned InstSize = (Opc == ARM::tBR_JTr || Opc == ARM::t2BR_JT) ? 2 : 4;
unsigned NumEntries = getNumJTEntries(JT, JTI);
if (Opc == ARM::t2TBB && (NumEntries & 1))
// Make sure the instruction that follows TBB is 2-byte aligned.
// FIXME: Constant island pass should insert an "ALIGN" instruction
// instead.
++NumEntries;
return NumEntries * EntrySize + InstSize;
}
default:
// Otherwise, pseudo-instruction sizes are zero.
return 0;
}
}
}
return 0; // Not reached
}
/// Return true if the instruction is a register to register move and
/// leave the source and dest operands in the passed parameters.
///
bool
ARMBaseInstrInfo::isMoveInstr(const MachineInstr &MI,
unsigned &SrcReg, unsigned &DstReg,
unsigned& SrcSubIdx, unsigned& DstSubIdx) const {
SrcSubIdx = DstSubIdx = 0; // No sub-registers.
switch (MI.getOpcode()) {
default: break;
case ARM::VMOVS:
case ARM::VMOVD:
case ARM::VMOVDneon:
case ARM::VMOVQ: {
SrcReg = MI.getOperand(1).getReg();
DstReg = MI.getOperand(0).getReg();
return true;
}
case ARM::MOVr:
case ARM::tMOVr:
case ARM::tMOVgpr2tgpr:
case ARM::tMOVtgpr2gpr:
case ARM::tMOVgpr2gpr:
case ARM::t2MOVr: {
assert(MI.getDesc().getNumOperands() >= 2 &&
MI.getOperand(0).isReg() &&
MI.getOperand(1).isReg() &&
"Invalid ARM MOV instruction");
SrcReg = MI.getOperand(1).getReg();
DstReg = MI.getOperand(0).getReg();
return true;
}
}
return false;
}
unsigned
ARMBaseInstrInfo::isLoadFromStackSlot(const MachineInstr *MI,
int &FrameIndex) const {
switch (MI->getOpcode()) {
default: break;
case ARM::LDR:
case ARM::t2LDRs: // FIXME: don't use t2LDRs to access frame.
if (MI->getOperand(1).isFI() &&
MI->getOperand(2).isReg() &&
MI->getOperand(3).isImm() &&
MI->getOperand(2).getReg() == 0 &&
MI->getOperand(3).getImm() == 0) {
FrameIndex = MI->getOperand(1).getIndex();
return MI->getOperand(0).getReg();
}
break;
case ARM::t2LDRi12:
case ARM::tRestore:
if (MI->getOperand(1).isFI() &&
MI->getOperand(2).isImm() &&
MI->getOperand(2).getImm() == 0) {
FrameIndex = MI->getOperand(1).getIndex();
return MI->getOperand(0).getReg();
}
break;
case ARM::VLDRD:
case ARM::VLDRS:
if (MI->getOperand(1).isFI() &&
MI->getOperand(2).isImm() &&
MI->getOperand(2).getImm() == 0) {
FrameIndex = MI->getOperand(1).getIndex();
return MI->getOperand(0).getReg();
}
break;
}
return 0;
}
unsigned
ARMBaseInstrInfo::isStoreToStackSlot(const MachineInstr *MI,
int &FrameIndex) const {
switch (MI->getOpcode()) {
default: break;
case ARM::STR:
case ARM::t2STRs: // FIXME: don't use t2STRs to access frame.
if (MI->getOperand(1).isFI() &&
MI->getOperand(2).isReg() &&
MI->getOperand(3).isImm() &&
MI->getOperand(2).getReg() == 0 &&
MI->getOperand(3).getImm() == 0) {
FrameIndex = MI->getOperand(1).getIndex();
return MI->getOperand(0).getReg();
}
break;
case ARM::t2STRi12:
case ARM::tSpill:
if (MI->getOperand(1).isFI() &&
MI->getOperand(2).isImm() &&
MI->getOperand(2).getImm() == 0) {
FrameIndex = MI->getOperand(1).getIndex();
return MI->getOperand(0).getReg();
}
break;
case ARM::VSTRD:
case ARM::VSTRS:
if (MI->getOperand(1).isFI() &&
MI->getOperand(2).isImm() &&
MI->getOperand(2).getImm() == 0) {
FrameIndex = MI->getOperand(1).getIndex();
return MI->getOperand(0).getReg();
}
break;
}
return 0;
}
bool
ARMBaseInstrInfo::copyRegToReg(MachineBasicBlock &MBB,
MachineBasicBlock::iterator I,
unsigned DestReg, unsigned SrcReg,
const TargetRegisterClass *DestRC,
const TargetRegisterClass *SrcRC) const {
DebugLoc DL = DebugLoc::getUnknownLoc();
if (I != MBB.end()) DL = I->getDebugLoc();
if (DestRC != SrcRC) {
if (DestRC->getSize() != SrcRC->getSize())
return false;
// Allow DPR / DPR_VFP2 / DPR_8 cross-class copies.
// Allow QPR / QPR_VFP2 / QPR_8 cross-class copies.
if (DestRC->getSize() != 8 && DestRC->getSize() != 16)
return false;
}
if (DestRC == ARM::GPRRegisterClass) {
AddDefaultCC(AddDefaultPred(BuildMI(MBB, I, DL, get(ARM::MOVr),
DestReg).addReg(SrcReg)));
} else if (DestRC == ARM::SPRRegisterClass) {
AddDefaultPred(BuildMI(MBB, I, DL, get(ARM::VMOVS), DestReg)
.addReg(SrcReg));
} else if (DestRC == ARM::DPRRegisterClass) {
AddDefaultPred(BuildMI(MBB, I, DL, get(ARM::VMOVD), DestReg)
.addReg(SrcReg));
} else if (DestRC == ARM::DPR_VFP2RegisterClass ||
DestRC == ARM::DPR_8RegisterClass ||
SrcRC == ARM::DPR_VFP2RegisterClass ||
SrcRC == ARM::DPR_8RegisterClass) {
// Always use neon reg-reg move if source or dest is NEON-only regclass.
AddDefaultPred(BuildMI(MBB, I, DL, get(ARM::VMOVDneon),
DestReg).addReg(SrcReg));
} else if (DestRC == ARM::QPRRegisterClass ||
DestRC == ARM::QPR_VFP2RegisterClass ||
DestRC == ARM::QPR_8RegisterClass) {
AddDefaultPred(BuildMI(MBB, I, DL, get(ARM::VMOVQ),
DestReg).addReg(SrcReg));
} else {
return false;
}
return true;
}
void ARMBaseInstrInfo::
storeRegToStackSlot(MachineBasicBlock &MBB, MachineBasicBlock::iterator I,
unsigned SrcReg, bool isKill, int FI,
const TargetRegisterClass *RC) const {
DebugLoc DL = DebugLoc::getUnknownLoc();
if (I != MBB.end()) DL = I->getDebugLoc();
MachineFunction &MF = *MBB.getParent();
MachineFrameInfo &MFI = *MF.getFrameInfo();
unsigned Align = MFI.getObjectAlignment(FI);
MachineMemOperand *MMO =
MF.getMachineMemOperand(PseudoSourceValue::getFixedStack(FI),
MachineMemOperand::MOStore, 0,
MFI.getObjectSize(FI),
Align);
if (RC == ARM::GPRRegisterClass) {
AddDefaultPred(BuildMI(MBB, I, DL, get(ARM::STR))
.addReg(SrcReg, getKillRegState(isKill))
.addFrameIndex(FI).addReg(0).addImm(0).addMemOperand(MMO));
} else if (RC == ARM::DPRRegisterClass ||
RC == ARM::DPR_VFP2RegisterClass ||
RC == ARM::DPR_8RegisterClass) {
AddDefaultPred(BuildMI(MBB, I, DL, get(ARM::VSTRD))
.addReg(SrcReg, getKillRegState(isKill))
.addFrameIndex(FI).addImm(0).addMemOperand(MMO));
} else if (RC == ARM::SPRRegisterClass) {
AddDefaultPred(BuildMI(MBB, I, DL, get(ARM::VSTRS))
.addReg(SrcReg, getKillRegState(isKill))
.addFrameIndex(FI).addImm(0).addMemOperand(MMO));
} else {
assert((RC == ARM::QPRRegisterClass ||
RC == ARM::QPR_VFP2RegisterClass) && "Unknown regclass!");
// FIXME: Neon instructions should support predicates
if (Align >= 16
&& (getRegisterInfo().canRealignStack(MF))) {
AddDefaultPred(BuildMI(MBB, I, DL, get(ARM::VST1q64))
.addFrameIndex(FI).addImm(0).addImm(0).addImm(128)
.addMemOperand(MMO)
.addReg(SrcReg, getKillRegState(isKill)));
} else {
AddDefaultPred(BuildMI(MBB, I, DL, get(ARM::VSTRQ)).
addReg(SrcReg, getKillRegState(isKill))
.addFrameIndex(FI).addImm(0).addMemOperand(MMO));
}
}
}
void ARMBaseInstrInfo::
loadRegFromStackSlot(MachineBasicBlock &MBB, MachineBasicBlock::iterator I,
unsigned DestReg, int FI,
const TargetRegisterClass *RC) const {
DebugLoc DL = DebugLoc::getUnknownLoc();
if (I != MBB.end()) DL = I->getDebugLoc();
MachineFunction &MF = *MBB.getParent();
MachineFrameInfo &MFI = *MF.getFrameInfo();
unsigned Align = MFI.getObjectAlignment(FI);
MachineMemOperand *MMO =
MF.getMachineMemOperand(PseudoSourceValue::getFixedStack(FI),
MachineMemOperand::MOLoad, 0,
MFI.getObjectSize(FI),
Align);
if (RC == ARM::GPRRegisterClass) {
AddDefaultPred(BuildMI(MBB, I, DL, get(ARM::LDR), DestReg)
.addFrameIndex(FI).addReg(0).addImm(0).addMemOperand(MMO));
} else if (RC == ARM::DPRRegisterClass ||
RC == ARM::DPR_VFP2RegisterClass ||
RC == ARM::DPR_8RegisterClass) {
AddDefaultPred(BuildMI(MBB, I, DL, get(ARM::VLDRD), DestReg)
.addFrameIndex(FI).addImm(0).addMemOperand(MMO));
} else if (RC == ARM::SPRRegisterClass) {
AddDefaultPred(BuildMI(MBB, I, DL, get(ARM::VLDRS), DestReg)
.addFrameIndex(FI).addImm(0).addMemOperand(MMO));
} else {
assert((RC == ARM::QPRRegisterClass ||
RC == ARM::QPR_VFP2RegisterClass ||
RC == ARM::QPR_8RegisterClass) && "Unknown regclass!");
if (Align >= 16
&& (getRegisterInfo().canRealignStack(MF))) {
AddDefaultPred(BuildMI(MBB, I, DL, get(ARM::VLD1q64), DestReg)
.addFrameIndex(FI).addImm(0).addImm(0).addImm(128)
.addMemOperand(MMO));
} else {
AddDefaultPred(BuildMI(MBB, I, DL, get(ARM::VLDRQ), DestReg)
.addFrameIndex(FI).addImm(0).addMemOperand(MMO));
}
}
}
MachineInstr *ARMBaseInstrInfo::
foldMemoryOperandImpl(MachineFunction &MF, MachineInstr *MI,
const SmallVectorImpl<unsigned> &Ops, int FI) const {
if (Ops.size() != 1) return NULL;
unsigned OpNum = Ops[0];
unsigned Opc = MI->getOpcode();
MachineInstr *NewMI = NULL;
if (Opc == ARM::MOVr || Opc == ARM::t2MOVr) {
// If it is updating CPSR, then it cannot be folded.
if (MI->getOperand(4).getReg() == ARM::CPSR && !MI->getOperand(4).isDead())
return NULL;
unsigned Pred = MI->getOperand(2).getImm();
unsigned PredReg = MI->getOperand(3).getReg();
if (OpNum == 0) { // move -> store
unsigned SrcReg = MI->getOperand(1).getReg();
unsigned SrcSubReg = MI->getOperand(1).getSubReg();
bool isKill = MI->getOperand(1).isKill();
bool isUndef = MI->getOperand(1).isUndef();
if (Opc == ARM::MOVr)
NewMI = BuildMI(MF, MI->getDebugLoc(), get(ARM::STR))
.addReg(SrcReg,
getKillRegState(isKill) | getUndefRegState(isUndef),
SrcSubReg)
.addFrameIndex(FI).addReg(0).addImm(0).addImm(Pred).addReg(PredReg);
else // ARM::t2MOVr
NewMI = BuildMI(MF, MI->getDebugLoc(), get(ARM::t2STRi12))
.addReg(SrcReg,
getKillRegState(isKill) | getUndefRegState(isUndef),
SrcSubReg)
.addFrameIndex(FI).addImm(0).addImm(Pred).addReg(PredReg);
} else { // move -> load
unsigned DstReg = MI->getOperand(0).getReg();
unsigned DstSubReg = MI->getOperand(0).getSubReg();
bool isDead = MI->getOperand(0).isDead();
bool isUndef = MI->getOperand(0).isUndef();
if (Opc == ARM::MOVr)
NewMI = BuildMI(MF, MI->getDebugLoc(), get(ARM::LDR))
.addReg(DstReg,
RegState::Define |
getDeadRegState(isDead) |
getUndefRegState(isUndef), DstSubReg)
.addFrameIndex(FI).addReg(0).addImm(0).addImm(Pred).addReg(PredReg);
else // ARM::t2MOVr
NewMI = BuildMI(MF, MI->getDebugLoc(), get(ARM::t2LDRi12))
.addReg(DstReg,
RegState::Define |
getDeadRegState(isDead) |
getUndefRegState(isUndef), DstSubReg)
.addFrameIndex(FI).addImm(0).addImm(Pred).addReg(PredReg);
}
} else if (Opc == ARM::tMOVgpr2gpr ||
Opc == ARM::tMOVtgpr2gpr ||
Opc == ARM::tMOVgpr2tgpr) {
if (OpNum == 0) { // move -> store
unsigned SrcReg = MI->getOperand(1).getReg();
unsigned SrcSubReg = MI->getOperand(1).getSubReg();
bool isKill = MI->getOperand(1).isKill();
bool isUndef = MI->getOperand(1).isUndef();
NewMI = BuildMI(MF, MI->getDebugLoc(), get(ARM::t2STRi12))
.addReg(SrcReg,
getKillRegState(isKill) | getUndefRegState(isUndef),
SrcSubReg)
.addFrameIndex(FI).addImm(0).addImm(ARMCC::AL).addReg(0);
} else { // move -> load
unsigned DstReg = MI->getOperand(0).getReg();
unsigned DstSubReg = MI->getOperand(0).getSubReg();
bool isDead = MI->getOperand(0).isDead();
bool isUndef = MI->getOperand(0).isUndef();
NewMI = BuildMI(MF, MI->getDebugLoc(), get(ARM::t2LDRi12))
.addReg(DstReg,
RegState::Define |
getDeadRegState(isDead) |
getUndefRegState(isUndef),
DstSubReg)
.addFrameIndex(FI).addImm(0).addImm(ARMCC::AL).addReg(0);
}
} else if (Opc == ARM::VMOVS) {
unsigned Pred = MI->getOperand(2).getImm();
unsigned PredReg = MI->getOperand(3).getReg();
if (OpNum == 0) { // move -> store
unsigned SrcReg = MI->getOperand(1).getReg();
unsigned SrcSubReg = MI->getOperand(1).getSubReg();
bool isKill = MI->getOperand(1).isKill();
bool isUndef = MI->getOperand(1).isUndef();
NewMI = BuildMI(MF, MI->getDebugLoc(), get(ARM::VSTRS))
.addReg(SrcReg, getKillRegState(isKill) | getUndefRegState(isUndef),
SrcSubReg)
.addFrameIndex(FI)
.addImm(0).addImm(Pred).addReg(PredReg);
} else { // move -> load
unsigned DstReg = MI->getOperand(0).getReg();
unsigned DstSubReg = MI->getOperand(0).getSubReg();
bool isDead = MI->getOperand(0).isDead();
bool isUndef = MI->getOperand(0).isUndef();
NewMI = BuildMI(MF, MI->getDebugLoc(), get(ARM::VLDRS))
.addReg(DstReg,
RegState::Define |
getDeadRegState(isDead) |
getUndefRegState(isUndef),
DstSubReg)
.addFrameIndex(FI).addImm(0).addImm(Pred).addReg(PredReg);
}
}
else if (Opc == ARM::VMOVD) {
unsigned Pred = MI->getOperand(2).getImm();
unsigned PredReg = MI->getOperand(3).getReg();
if (OpNum == 0) { // move -> store
unsigned SrcReg = MI->getOperand(1).getReg();
unsigned SrcSubReg = MI->getOperand(1).getSubReg();
bool isKill = MI->getOperand(1).isKill();
bool isUndef = MI->getOperand(1).isUndef();
NewMI = BuildMI(MF, MI->getDebugLoc(), get(ARM::VSTRD))
.addReg(SrcReg,
getKillRegState(isKill) | getUndefRegState(isUndef),
SrcSubReg)
.addFrameIndex(FI).addImm(0).addImm(Pred).addReg(PredReg);
} else { // move -> load
unsigned DstReg = MI->getOperand(0).getReg();
unsigned DstSubReg = MI->getOperand(0).getSubReg();
bool isDead = MI->getOperand(0).isDead();
bool isUndef = MI->getOperand(0).isUndef();
NewMI = BuildMI(MF, MI->getDebugLoc(), get(ARM::VLDRD))
.addReg(DstReg,
RegState::Define |
getDeadRegState(isDead) |
getUndefRegState(isUndef),
DstSubReg)
.addFrameIndex(FI).addImm(0).addImm(Pred).addReg(PredReg);
}
}
return NewMI;
}
MachineInstr*
ARMBaseInstrInfo::foldMemoryOperandImpl(MachineFunction &MF,
MachineInstr* MI,
const SmallVectorImpl<unsigned> &Ops,
MachineInstr* LoadMI) const {
// FIXME
return 0;
}
bool
ARMBaseInstrInfo::canFoldMemoryOperand(const MachineInstr *MI,
const SmallVectorImpl<unsigned> &Ops) const {
if (Ops.size() != 1) return false;
unsigned Opc = MI->getOpcode();
if (Opc == ARM::MOVr || Opc == ARM::t2MOVr) {
// If it is updating CPSR, then it cannot be folded.
return MI->getOperand(4).getReg() != ARM::CPSR ||
MI->getOperand(4).isDead();
} else if (Opc == ARM::tMOVgpr2gpr ||
Opc == ARM::tMOVtgpr2gpr ||
Opc == ARM::tMOVgpr2tgpr) {
return true;
} else if (Opc == ARM::VMOVS || Opc == ARM::VMOVD) {
return true;
} else if (Opc == ARM::VMOVDneon || Opc == ARM::VMOVQ) {
return false; // FIXME
}
return false;
}
/// Create a copy of a const pool value. Update CPI to the new index and return
/// the label UID.
static unsigned duplicateCPV(MachineFunction &MF, unsigned &CPI) {
MachineConstantPool *MCP = MF.getConstantPool();
ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
const MachineConstantPoolEntry &MCPE = MCP->getConstants()[CPI];
assert(MCPE.isMachineConstantPoolEntry() &&
"Expecting a machine constantpool entry!");
ARMConstantPoolValue *ACPV =
static_cast<ARMConstantPoolValue*>(MCPE.Val.MachineCPVal);
unsigned PCLabelId = AFI->createConstPoolEntryUId();
ARMConstantPoolValue *NewCPV = 0;
if (ACPV->isGlobalValue())
NewCPV = new ARMConstantPoolValue(ACPV->getGV(), PCLabelId,
ARMCP::CPValue, 4);
else if (ACPV->isExtSymbol())
NewCPV = new ARMConstantPoolValue(MF.getFunction()->getContext(),
ACPV->getSymbol(), PCLabelId, 4);
else if (ACPV->isBlockAddress())
NewCPV = new ARMConstantPoolValue(ACPV->getBlockAddress(), PCLabelId,
ARMCP::CPBlockAddress, 4);
else
llvm_unreachable("Unexpected ARM constantpool value type!!");
CPI = MCP->getConstantPoolIndex(NewCPV, MCPE.getAlignment());
return PCLabelId;
}
void ARMBaseInstrInfo::
reMaterialize(MachineBasicBlock &MBB,
MachineBasicBlock::iterator I,
unsigned DestReg, unsigned SubIdx,
const MachineInstr *Orig,
const TargetRegisterInfo *TRI) const {
if (SubIdx && TargetRegisterInfo::isPhysicalRegister(DestReg)) {
DestReg = TRI->getSubReg(DestReg, SubIdx);
SubIdx = 0;
}
unsigned Opcode = Orig->getOpcode();
switch (Opcode) {
default: {
MachineInstr *MI = MBB.getParent()->CloneMachineInstr(Orig);
MI->getOperand(0).setReg(DestReg);
MBB.insert(I, MI);
break;
}
case ARM::tLDRpci_pic:
case ARM::t2LDRpci_pic: {
MachineFunction &MF = *MBB.getParent();
unsigned CPI = Orig->getOperand(1).getIndex();
unsigned PCLabelId = duplicateCPV(MF, CPI);
MachineInstrBuilder MIB = BuildMI(MBB, I, Orig->getDebugLoc(), get(Opcode),
DestReg)
.addConstantPoolIndex(CPI).addImm(PCLabelId);
(*MIB).setMemRefs(Orig->memoperands_begin(), Orig->memoperands_end());
break;
}
}
MachineInstr *NewMI = prior(I);
NewMI->getOperand(0).setSubReg(SubIdx);
}
MachineInstr *
ARMBaseInstrInfo::duplicate(MachineInstr *Orig, MachineFunction &MF) const {
MachineInstr *MI = TargetInstrInfoImpl::duplicate(Orig, MF);
switch(Orig->getOpcode()) {
case ARM::tLDRpci_pic:
case ARM::t2LDRpci_pic: {
unsigned CPI = Orig->getOperand(1).getIndex();
unsigned PCLabelId = duplicateCPV(MF, CPI);
Orig->getOperand(1).setIndex(CPI);
Orig->getOperand(2).setImm(PCLabelId);
break;
}
}
return MI;
}
bool ARMBaseInstrInfo::isIdentical(const MachineInstr *MI0,
const MachineInstr *MI1,
const MachineRegisterInfo *MRI) const {
int Opcode = MI0->getOpcode();
if (Opcode == ARM::t2LDRpci ||
Opcode == ARM::t2LDRpci_pic ||
Opcode == ARM::tLDRpci ||
Opcode == ARM::tLDRpci_pic) {
if (MI1->getOpcode() != Opcode)
return false;
if (MI0->getNumOperands() != MI1->getNumOperands())
return false;
const MachineOperand &MO0 = MI0->getOperand(1);
const MachineOperand &MO1 = MI1->getOperand(1);
if (MO0.getOffset() != MO1.getOffset())
return false;
const MachineFunction *MF = MI0->getParent()->getParent();
const MachineConstantPool *MCP = MF->getConstantPool();
int CPI0 = MO0.getIndex();
int CPI1 = MO1.getIndex();
const MachineConstantPoolEntry &MCPE0 = MCP->getConstants()[CPI0];
const MachineConstantPoolEntry &MCPE1 = MCP->getConstants()[CPI1];
ARMConstantPoolValue *ACPV0 =
static_cast<ARMConstantPoolValue*>(MCPE0.Val.MachineCPVal);
ARMConstantPoolValue *ACPV1 =
static_cast<ARMConstantPoolValue*>(MCPE1.Val.MachineCPVal);
return ACPV0->hasSameValue(ACPV1);
}
return TargetInstrInfoImpl::isIdentical(MI0, MI1, MRI);
}
/// getInstrPredicate - If instruction is predicated, returns its predicate
/// condition, otherwise returns AL. It also returns the condition code
/// register by reference.
ARMCC::CondCodes
llvm::getInstrPredicate(const MachineInstr *MI, unsigned &PredReg) {
int PIdx = MI->findFirstPredOperandIdx();
if (PIdx == -1) {
PredReg = 0;
return ARMCC::AL;
}
PredReg = MI->getOperand(PIdx+1).getReg();
return (ARMCC::CondCodes)MI->getOperand(PIdx).getImm();
}
int llvm::getMatchingCondBranchOpcode(int Opc) {
if (Opc == ARM::B)
return ARM::Bcc;
else if (Opc == ARM::tB)
return ARM::tBcc;
else if (Opc == ARM::t2B)
return ARM::t2Bcc;
llvm_unreachable("Unknown unconditional branch opcode!");
return 0;
}
void llvm::emitARMRegPlusImmediate(MachineBasicBlock &MBB,
MachineBasicBlock::iterator &MBBI, DebugLoc dl,
unsigned DestReg, unsigned BaseReg, int NumBytes,
ARMCC::CondCodes Pred, unsigned PredReg,
const ARMBaseInstrInfo &TII) {
bool isSub = NumBytes < 0;
if (isSub) NumBytes = -NumBytes;
while (NumBytes) {
unsigned RotAmt = ARM_AM::getSOImmValRotate(NumBytes);
unsigned ThisVal = NumBytes & ARM_AM::rotr32(0xFF, RotAmt);
assert(ThisVal && "Didn't extract field correctly");
// We will handle these bits from offset, clear them.
NumBytes &= ~ThisVal;
assert(ARM_AM::getSOImmVal(ThisVal) != -1 && "Bit extraction didn't work?");
// Build the new ADD / SUB.
unsigned Opc = isSub ? ARM::SUBri : ARM::ADDri;
BuildMI(MBB, MBBI, dl, TII.get(Opc), DestReg)
.addReg(BaseReg, RegState::Kill).addImm(ThisVal)
.addImm((unsigned)Pred).addReg(PredReg).addReg(0);
BaseReg = DestReg;
}
}
bool llvm::rewriteARMFrameIndex(MachineInstr &MI, unsigned FrameRegIdx,
unsigned FrameReg, int &Offset,
const ARMBaseInstrInfo &TII) {
unsigned Opcode = MI.getOpcode();
const TargetInstrDesc &Desc = MI.getDesc();
unsigned AddrMode = (Desc.TSFlags & ARMII::AddrModeMask);
bool isSub = false;
// Memory operands in inline assembly always use AddrMode2.
if (Opcode == ARM::INLINEASM)
AddrMode = ARMII::AddrMode2;
if (Opcode == ARM::ADDri) {
Offset += MI.getOperand(FrameRegIdx+1).getImm();
if (Offset == 0) {
// Turn it into a move.
MI.setDesc(TII.get(ARM::MOVr));
MI.getOperand(FrameRegIdx).ChangeToRegister(FrameReg, false);
MI.RemoveOperand(FrameRegIdx+1);
Offset = 0;
return true;
} else if (Offset < 0) {
Offset = -Offset;
isSub = true;
MI.setDesc(TII.get(ARM::SUBri));
}
// Common case: small offset, fits into instruction.
if (ARM_AM::getSOImmVal(Offset) != -1) {
// Replace the FrameIndex with sp / fp
MI.getOperand(FrameRegIdx).ChangeToRegister(FrameReg, false);
MI.getOperand(FrameRegIdx+1).ChangeToImmediate(Offset);
Offset = 0;
return true;
}
// Otherwise, pull as much of the immedidate into this ADDri/SUBri
// as possible.
unsigned RotAmt = ARM_AM::getSOImmValRotate(Offset);
unsigned ThisImmVal = Offset & ARM_AM::rotr32(0xFF, RotAmt);
// We will handle these bits from offset, clear them.
Offset &= ~ThisImmVal;
// Get the properly encoded SOImmVal field.
assert(ARM_AM::getSOImmVal(ThisImmVal) != -1 &&
"Bit extraction didn't work?");
MI.getOperand(FrameRegIdx+1).ChangeToImmediate(ThisImmVal);
} else {
unsigned ImmIdx = 0;
int InstrOffs = 0;
unsigned NumBits = 0;
unsigned Scale = 1;
switch (AddrMode) {
case ARMII::AddrMode2: {
ImmIdx = FrameRegIdx+2;
InstrOffs = ARM_AM::getAM2Offset(MI.getOperand(ImmIdx).getImm());
if (ARM_AM::getAM2Op(MI.getOperand(ImmIdx).getImm()) == ARM_AM::sub)
InstrOffs *= -1;
NumBits = 12;
break;
}
case ARMII::AddrMode3: {
ImmIdx = FrameRegIdx+2;
InstrOffs = ARM_AM::getAM3Offset(MI.getOperand(ImmIdx).getImm());
if (ARM_AM::getAM3Op(MI.getOperand(ImmIdx).getImm()) == ARM_AM::sub)
InstrOffs *= -1;
NumBits = 8;
break;
}
case ARMII::AddrMode4:
case ARMII::AddrMode6:
// Can't fold any offset even if it's zero.
return false;
case ARMII::AddrMode5: {
ImmIdx = FrameRegIdx+1;
InstrOffs = ARM_AM::getAM5Offset(MI.getOperand(ImmIdx).getImm());
if (ARM_AM::getAM5Op(MI.getOperand(ImmIdx).getImm()) == ARM_AM::sub)
InstrOffs *= -1;
NumBits = 8;
Scale = 4;
break;
}
default:
llvm_unreachable("Unsupported addressing mode!");
break;
}
Offset += InstrOffs * Scale;
assert((Offset & (Scale-1)) == 0 && "Can't encode this offset!");
if (Offset < 0) {
Offset = -Offset;
isSub = true;
}
// Attempt to fold address comp. if opcode has offset bits
if (NumBits > 0) {
// 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(FrameRegIdx).ChangeToRegister(FrameReg, false);
if (isSub)
ImmedOffset |= 1 << NumBits;
ImmOp.ChangeToImmediate(ImmedOffset);
Offset = 0;
return true;
}
// Otherwise, it didn't fit. Pull in what we can to simplify the immed.
ImmedOffset = ImmedOffset & Mask;
if (isSub)
ImmedOffset |= 1 << NumBits;
ImmOp.ChangeToImmediate(ImmedOffset);
Offset &= ~(Mask*Scale);
}
}
Offset = (isSub) ? -Offset : Offset;
return Offset == 0;
}
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