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llvm-6502/lib/Target/ARM/ARMFrameInfo.cpp
Evan Cheng 3d2125c9db Enable sibling call optimization of libcalls which are expanded during 
legalization time. Since at legalization time there is no mapping from
SDNode back to the corresponding LLVM instruction and the return
SDNode is target specific, this requires a target hook to check for
eligibility. Only x86 and ARM support this form of sibcall optimization
right now.
rdar://8707777


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@120501 91177308-0d34-0410-b5e6-96231b3b80d8
2010-11-30 23:55:39 +00:00

945 lines
36 KiB
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//=======- ARMFrameInfo.cpp - ARM Frame 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 TargetFrameInfo class.
//
//===----------------------------------------------------------------------===//
#include "ARMFrameInfo.h"
#include "ARMBaseInstrInfo.h"
#include "ARMMachineFunctionInfo.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/RegisterScavenging.h"
#include "llvm/Target/TargetOptions.h"
using namespace llvm;
/// hasFP - Return true if the specified function should have a dedicated frame
/// pointer register. This is true if the function has variable sized allocas
/// or if frame pointer elimination is disabled.
///
bool ARMFrameInfo::hasFP(const MachineFunction &MF) const {
const TargetRegisterInfo *RegInfo = MF.getTarget().getRegisterInfo();
// Mac OS X requires FP not to be clobbered for backtracing purpose.
if (STI.isTargetDarwin())
return true;
const MachineFrameInfo *MFI = MF.getFrameInfo();
// Always eliminate non-leaf frame pointers.
return ((DisableFramePointerElim(MF) && MFI->hasCalls()) ||
RegInfo->needsStackRealignment(MF) ||
MFI->hasVarSizedObjects() ||
MFI->isFrameAddressTaken());
}
// hasReservedCallFrame - Under normal circumstances, when a frame pointer is
// not required, we reserve argument space for call sites in the function
// immediately on entry to the current function. This eliminates the need for
// add/sub sp brackets around call sites. Returns true if the call frame is
// included as part of the stack frame.
bool ARMFrameInfo::hasReservedCallFrame(const 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 << 12) - 1) / 2) // Half of imm12
return false;
return !MF.getFrameInfo()->hasVarSizedObjects();
}
// canSimplifyCallFramePseudos - If there is a reserved call frame, the
// call frame pseudos can be simplified. Unlike most targets, having a FP
// is not sufficient here since we still may reference some objects via SP
// even when FP is available in Thumb2 mode.
bool ARMFrameInfo::canSimplifyCallFramePseudos(const MachineFunction &MF)const {
return hasReservedCallFrame(MF) || MF.getFrameInfo()->hasVarSizedObjects();
}
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 ARMBaseInstrInfo &TII,
const unsigned *CSRegs) {
// Integer spill area is handled with "pop".
if (MI->getOpcode() == ARM::LDMIA_RET ||
MI->getOpcode() == ARM::t2LDMIA_RET ||
MI->getOpcode() == ARM::LDMIA_UPD ||
MI->getOpcode() == ARM::t2LDMIA_UPD ||
MI->getOpcode() == ARM::VLDMDIA_UPD) {
// The first two operands are predicates. The last two are
// imp-def and imp-use of SP. Check everything in between.
for (int i = 5, e = MI->getNumOperands(); i != e; ++i)
if (!isCalleeSavedRegister(MI->getOperand(i).getReg(), CSRegs))
return false;
return true;
}
return false;
}
static void
emitSPUpdate(bool isARM,
MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI,
DebugLoc dl, const ARMBaseInstrInfo &TII,
int NumBytes,
ARMCC::CondCodes Pred = ARMCC::AL, unsigned PredReg = 0) {
if (isARM)
emitARMRegPlusImmediate(MBB, MBBI, dl, ARM::SP, ARM::SP, NumBytes,
Pred, PredReg, TII);
else
emitT2RegPlusImmediate(MBB, MBBI, dl, ARM::SP, ARM::SP, NumBytes,
Pred, PredReg, TII);
}
void ARMFrameInfo::emitPrologue(MachineFunction &MF) const {
MachineBasicBlock &MBB = MF.front();
MachineBasicBlock::iterator MBBI = MBB.begin();
MachineFrameInfo *MFI = MF.getFrameInfo();
ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
const ARMBaseRegisterInfo *RegInfo =
static_cast<const ARMBaseRegisterInfo*>(MF.getTarget().getRegisterInfo());
const ARMBaseInstrInfo &TII =
*static_cast<const ARMBaseInstrInfo*>(MF.getTarget().getInstrInfo());
assert(!AFI->isThumb1OnlyFunction() &&
"This emitPrologue does not support Thumb1!");
bool isARM = !AFI->isThumbFunction();
unsigned VARegSaveSize = AFI->getVarArgsRegSaveSize();
unsigned NumBytes = MFI->getStackSize();
const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo();
DebugLoc dl = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
unsigned FramePtr = RegInfo->getFrameRegister(MF);
// 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;
// Allocate the vararg register save area. This is not counted in NumBytes.
if (VARegSaveSize)
emitSPUpdate(isARM, MBB, MBBI, dl, TII, -VARegSaveSize);
if (!AFI->hasStackFrame()) {
if (NumBytes != 0)
emitSPUpdate(isARM, MBB, MBBI, dl, TII, -NumBytes);
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;
}
}
// Move past area 1.
if (GPRCS1Size > 0) MBBI++;
// Set FP to point to the stack slot that contains the previous FP.
// For Darwin, FP is R7, which has now been stored in spill area 1.
// Otherwise, if this is not Darwin, all the callee-saved registers go
// into spill area 1, including the FP in R11. In either case, it is
// now safe to emit this assignment.
bool HasFP = hasFP(MF);
if (HasFP) {
unsigned ADDriOpc = !AFI->isThumbFunction() ? ARM::ADDri : ARM::t2ADDri;
MachineInstrBuilder MIB =
BuildMI(MBB, MBBI, dl, TII.get(ADDriOpc), FramePtr)
.addFrameIndex(FramePtrSpillFI).addImm(0);
AddDefaultCC(AddDefaultPred(MIB));
}
// Move past area 2.
if (GPRCS2Size > 0) MBBI++;
// Determine starting offsets of spill areas.
unsigned DPRCSOffset = NumBytes - (GPRCS1Size + GPRCS2Size + DPRCSSize);
unsigned GPRCS2Offset = DPRCSOffset + DPRCSSize;
unsigned GPRCS1Offset = GPRCS2Offset + GPRCS2Size;
if (HasFP)
AFI->setFramePtrSpillOffset(MFI->getObjectOffset(FramePtrSpillFI) +
NumBytes);
AFI->setGPRCalleeSavedArea1Offset(GPRCS1Offset);
AFI->setGPRCalleeSavedArea2Offset(GPRCS2Offset);
AFI->setDPRCalleeSavedAreaOffset(DPRCSOffset);
// Move past area 3.
if (DPRCSSize > 0) MBBI++;
NumBytes = DPRCSOffset;
if (NumBytes) {
// Adjust SP after all the callee-save spills.
emitSPUpdate(isARM, MBB, MBBI, dl, TII, -NumBytes);
if (HasFP && isARM)
// Restore from fp only in ARM mode: e.g. sub sp, r7, #24
// Note it's not safe to do this in Thumb2 mode because it would have
// taken two instructions:
// mov sp, r7
// sub sp, #24
// If an interrupt is taken between the two instructions, then sp is in
// an inconsistent state (pointing to the middle of callee-saved area).
// The interrupt handler can end up clobbering the registers.
AFI->setShouldRestoreSPFromFP(true);
}
if (STI.isTargetELF() && hasFP(MF))
MFI->setOffsetAdjustment(MFI->getOffsetAdjustment() -
AFI->getFramePtrSpillOffset());
AFI->setGPRCalleeSavedArea1Size(GPRCS1Size);
AFI->setGPRCalleeSavedArea2Size(GPRCS2Size);
AFI->setDPRCalleeSavedAreaSize(DPRCSSize);
// If we need dynamic stack realignment, do it here. Be paranoid and make
// sure if we also have VLAs, we have a base pointer for frame access.
if (RegInfo->needsStackRealignment(MF)) {
unsigned MaxAlign = MFI->getMaxAlignment();
assert (!AFI->isThumb1OnlyFunction());
if (!AFI->isThumbFunction()) {
// Emit bic sp, sp, MaxAlign
AddDefaultCC(AddDefaultPred(BuildMI(MBB, MBBI, dl,
TII.get(ARM::BICri), ARM::SP)
.addReg(ARM::SP, RegState::Kill)
.addImm(MaxAlign-1)));
} else {
// We cannot use sp as source/dest register here, thus we're emitting the
// following sequence:
// mov r4, sp
// bic r4, r4, MaxAlign
// mov sp, r4
// FIXME: It will be better just to find spare register here.
BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVgpr2tgpr), ARM::R4)
.addReg(ARM::SP, RegState::Kill);
AddDefaultCC(AddDefaultPred(BuildMI(MBB, MBBI, dl,
TII.get(ARM::t2BICri), ARM::R4)
.addReg(ARM::R4, RegState::Kill)
.addImm(MaxAlign-1)));
BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVtgpr2gpr), ARM::SP)
.addReg(ARM::R4, RegState::Kill);
}
AFI->setShouldRestoreSPFromFP(true);
}
// If we need a base pointer, set it up here. It's whatever the value
// of the stack pointer is at this point. Any variable size objects
// will be allocated after this, so we can still use the base pointer
// to reference locals.
if (RegInfo->hasBasePointer(MF)) {
if (isARM)
BuildMI(MBB, MBBI, dl,
TII.get(ARM::MOVr), RegInfo->getBaseRegister())
.addReg(ARM::SP)
.addImm((unsigned)ARMCC::AL).addReg(0).addReg(0);
else
BuildMI(MBB, MBBI, dl,
TII.get(ARM::tMOVgpr2gpr), RegInfo->getBaseRegister())
.addReg(ARM::SP);
}
// If the frame has variable sized objects then the epilogue must restore
// the sp from fp.
if (MFI->hasVarSizedObjects())
AFI->setShouldRestoreSPFromFP(true);
}
void ARMFrameInfo::emitEpilogue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
MachineBasicBlock::iterator MBBI = prior(MBB.end());
assert(MBBI->getDesc().isReturn() &&
"Can only insert epilog into returning blocks");
unsigned RetOpcode = MBBI->getOpcode();
DebugLoc dl = MBBI->getDebugLoc();
MachineFrameInfo *MFI = MF.getFrameInfo();
ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
const TargetRegisterInfo *RegInfo = MF.getTarget().getRegisterInfo();
const ARMBaseInstrInfo &TII =
*static_cast<const ARMBaseInstrInfo*>(MF.getTarget().getInstrInfo());
assert(!AFI->isThumb1OnlyFunction() &&
"This emitEpilogue does not support Thumb1!");
bool isARM = !AFI->isThumbFunction();
unsigned VARegSaveSize = AFI->getVarArgsRegSaveSize();
int NumBytes = (int)MFI->getStackSize();
unsigned FramePtr = RegInfo->getFrameRegister(MF);
if (!AFI->hasStackFrame()) {
if (NumBytes != 0)
emitSPUpdate(isARM, MBB, MBBI, dl, TII, NumBytes);
} else {
// Unwind MBBI to point to first LDR / VLDRD.
const unsigned *CSRegs = RegInfo->getCalleeSavedRegs();
if (MBBI != MBB.begin()) {
do
--MBBI;
while (MBBI != MBB.begin() && isCSRestore(MBBI, TII, CSRegs));
if (!isCSRestore(MBBI, TII, CSRegs))
++MBBI;
}
// Move SP to start of FP callee save spill area.
NumBytes -= (AFI->getGPRCalleeSavedArea1Size() +
AFI->getGPRCalleeSavedArea2Size() +
AFI->getDPRCalleeSavedAreaSize());
// 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 (AFI->shouldRestoreSPFromFP()) {
NumBytes = AFI->getFramePtrSpillOffset() - NumBytes;
if (NumBytes) {
if (isARM)
emitARMRegPlusImmediate(MBB, MBBI, dl, ARM::SP, FramePtr, -NumBytes,
ARMCC::AL, 0, TII);
else {
// It's not possible to restore SP from FP in a single instruction.
// For Darwin, this looks like:
// mov sp, r7
// sub sp, #24
// This is bad, if an interrupt is taken after the mov, sp is in an
// inconsistent state.
// Use the first callee-saved register as a scratch register.
assert(MF.getRegInfo().isPhysRegUsed(ARM::R4) &&
"No scratch register to restore SP from FP!");
emitT2RegPlusImmediate(MBB, MBBI, dl, ARM::R4, FramePtr, -NumBytes,
ARMCC::AL, 0, TII);
BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVgpr2gpr), ARM::SP)
.addReg(ARM::R4);
}
} else {
// Thumb2 or ARM.
if (isARM)
BuildMI(MBB, MBBI, dl, TII.get(ARM::MOVr), ARM::SP)
.addReg(FramePtr).addImm((unsigned)ARMCC::AL).addReg(0).addReg(0);
else
BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVgpr2gpr), ARM::SP)
.addReg(FramePtr);
}
} else if (NumBytes)
emitSPUpdate(isARM, MBB, MBBI, dl, TII, NumBytes);
// Increment past our save areas.
if (AFI->getDPRCalleeSavedAreaSize()) MBBI++;
if (AFI->getGPRCalleeSavedArea2Size()) MBBI++;
if (AFI->getGPRCalleeSavedArea1Size()) MBBI++;
}
if (RetOpcode == ARM::TCRETURNdi || RetOpcode == ARM::TCRETURNdiND ||
RetOpcode == ARM::TCRETURNri || RetOpcode == ARM::TCRETURNriND) {
// Tail call return: adjust the stack pointer and jump to callee.
MBBI = prior(MBB.end());
MachineOperand &JumpTarget = MBBI->getOperand(0);
// Jump to label or value in register.
if (RetOpcode == ARM::TCRETURNdi || RetOpcode == ARM::TCRETURNdiND) {
unsigned TCOpcode = (RetOpcode == ARM::TCRETURNdi)
? (STI.isThumb() ? ARM::TAILJMPdt : ARM::TAILJMPd)
: (STI.isThumb() ? ARM::TAILJMPdNDt : ARM::TAILJMPdND);
MachineInstrBuilder MIB = BuildMI(MBB, MBBI, dl, TII.get(TCOpcode));
if (JumpTarget.isGlobal())
MIB.addGlobalAddress(JumpTarget.getGlobal(), JumpTarget.getOffset(),
JumpTarget.getTargetFlags());
else {
assert(JumpTarget.isSymbol());
MIB.addExternalSymbol(JumpTarget.getSymbolName(),
JumpTarget.getTargetFlags());
}
} else if (RetOpcode == ARM::TCRETURNri) {
BuildMI(MBB, MBBI, dl, TII.get(ARM::TAILJMPr)).
addReg(JumpTarget.getReg(), RegState::Kill);
} else if (RetOpcode == ARM::TCRETURNriND) {
BuildMI(MBB, MBBI, dl, TII.get(ARM::TAILJMPrND)).
addReg(JumpTarget.getReg(), RegState::Kill);
}
MachineInstr *NewMI = prior(MBBI);
for (unsigned i = 1, e = MBBI->getNumOperands(); i != e; ++i)
NewMI->addOperand(MBBI->getOperand(i));
// Delete the pseudo instruction TCRETURN.
MBB.erase(MBBI);
}
if (VARegSaveSize)
emitSPUpdate(isARM, MBB, MBBI, dl, TII, VARegSaveSize);
}
// Provide a base+offset reference to an FI slot for debug info. It's the
// same as what we use for resolving the code-gen references for now.
// FIXME: This can go wrong when references are SP-relative and simple call
// frames aren't used.
int
ARMFrameInfo::getFrameIndexReference(const MachineFunction &MF, int FI,
unsigned &FrameReg) const {
return ResolveFrameIndexReference(MF, FI, FrameReg, 0);
}
int
ARMFrameInfo::ResolveFrameIndexReference(const MachineFunction &MF,
int FI,
unsigned &FrameReg,
int SPAdj) const {
const MachineFrameInfo *MFI = MF.getFrameInfo();
const ARMBaseRegisterInfo *RegInfo =
static_cast<const ARMBaseRegisterInfo*>(MF.getTarget().getRegisterInfo());
const ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
int Offset = MFI->getObjectOffset(FI) + MFI->getStackSize();
int FPOffset = Offset - AFI->getFramePtrSpillOffset();
bool isFixed = MFI->isFixedObjectIndex(FI);
FrameReg = ARM::SP;
Offset += SPAdj;
if (AFI->isGPRCalleeSavedArea1Frame(FI))
return Offset - AFI->getGPRCalleeSavedArea1Offset();
else if (AFI->isGPRCalleeSavedArea2Frame(FI))
return Offset - AFI->getGPRCalleeSavedArea2Offset();
else if (AFI->isDPRCalleeSavedAreaFrame(FI))
return Offset - AFI->getDPRCalleeSavedAreaOffset();
// When dynamically realigning the stack, use the frame pointer for
// parameters, and the stack/base pointer for locals.
if (RegInfo->needsStackRealignment(MF)) {
assert (hasFP(MF) && "dynamic stack realignment without a FP!");
if (isFixed) {
FrameReg = RegInfo->getFrameRegister(MF);
Offset = FPOffset;
} else if (MFI->hasVarSizedObjects()) {
assert(RegInfo->hasBasePointer(MF) &&
"VLAs and dynamic stack alignment, but missing base pointer!");
FrameReg = RegInfo->getBaseRegister();
}
return Offset;
}
// If there is a frame pointer, use it when we can.
if (hasFP(MF) && AFI->hasStackFrame()) {
// Use frame pointer to reference fixed objects. Use it for locals if
// there are VLAs (and thus the SP isn't reliable as a base).
if (isFixed || (MFI->hasVarSizedObjects() && !RegInfo->hasBasePointer(MF))) {
FrameReg = RegInfo->getFrameRegister(MF);
return FPOffset;
} else if (MFI->hasVarSizedObjects()) {
assert(RegInfo->hasBasePointer(MF) && "missing base pointer!");
// Try to use the frame pointer if we can, else use the base pointer
// since it's available. This is handy for the emergency spill slot, in
// particular.
if (AFI->isThumb2Function()) {
if (FPOffset >= -255 && FPOffset < 0) {
FrameReg = RegInfo->getFrameRegister(MF);
return FPOffset;
}
} else
FrameReg = RegInfo->getBaseRegister();
} else if (AFI->isThumb2Function()) {
// In Thumb2 mode, the negative offset is very limited. Try to avoid
// out of range references.
if (FPOffset >= -255 && FPOffset < 0) {
FrameReg = RegInfo->getFrameRegister(MF);
return FPOffset;
}
} else if (Offset > (FPOffset < 0 ? -FPOffset : FPOffset)) {
// Otherwise, use SP or FP, whichever is closer to the stack slot.
FrameReg = RegInfo->getFrameRegister(MF);
return FPOffset;
}
}
// Use the base pointer if we have one.
if (RegInfo->hasBasePointer(MF))
FrameReg = RegInfo->getBaseRegister();
return Offset;
}
int ARMFrameInfo::getFrameIndexOffset(const MachineFunction &MF, int FI) const {
unsigned FrameReg;
return getFrameIndexReference(MF, FI, FrameReg);
}
void ARMFrameInfo::emitPushInst(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
const std::vector<CalleeSavedInfo> &CSI,
unsigned Opc,
bool(*Func)(unsigned, bool)) const {
MachineFunction &MF = *MBB.getParent();
const TargetInstrInfo &TII = *MF.getTarget().getInstrInfo();
DebugLoc DL;
if (MI != MBB.end()) DL = MI->getDebugLoc();
MachineInstrBuilder MIB = BuildMI(MF, DL, TII.get(Opc));
MIB.addReg(ARM::SP, getDefRegState(true));
MIB.addReg(ARM::SP);
AddDefaultPred(MIB);
bool NumRegs = false;
for (unsigned i = CSI.size(); i != 0; --i) {
unsigned Reg = CSI[i-1].getReg();
if (!(Func)(Reg, STI.isTargetDarwin())) continue;
// Add the callee-saved register as live-in unless it's LR and
// @llvm.returnaddress is called. If LR is returned for @llvm.returnaddress
// then it's already added to the function and entry block live-in sets.
bool isKill = true;
if (Reg == ARM::LR) {
if (MF.getFrameInfo()->isReturnAddressTaken() &&
MF.getRegInfo().isLiveIn(Reg))
isKill = false;
}
if (isKill)
MBB.addLiveIn(Reg);
NumRegs = true;
MIB.addReg(Reg, getKillRegState(isKill));
}
// It's illegal to emit push instruction without operands.
if (NumRegs)
MBB.insert(MI, &*MIB);
else
MF.DeleteMachineInstr(MIB);
}
bool ARMFrameInfo::spillCalleeSavedRegisters(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
const std::vector<CalleeSavedInfo> &CSI,
const TargetRegisterInfo *TRI) const {
if (CSI.empty())
return false;
MachineFunction &MF = *MBB.getParent();
ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
DebugLoc DL = MI->getDebugLoc();
unsigned PushOpc = AFI->isThumbFunction() ? ARM::t2STMDB_UPD : ARM::STMDB_UPD;
unsigned FltOpc = ARM::VSTMDDB_UPD;
emitPushInst(MBB, MI, CSI, PushOpc, &isARMArea1Register);
emitPushInst(MBB, MI, CSI, PushOpc, &isARMArea2Register);
emitPushInst(MBB, MI, CSI, FltOpc, &isARMArea3Register);
return true;
}
void ARMFrameInfo::emitPopInst(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
const std::vector<CalleeSavedInfo> &CSI,
unsigned Opc, bool isVarArg,
bool(*Func)(unsigned, bool)) const {
MachineFunction &MF = *MBB.getParent();
const TargetInstrInfo &TII = *MF.getTarget().getInstrInfo();
ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
DebugLoc DL = MI->getDebugLoc();
MachineInstrBuilder MIB = BuildMI(MF, DL, TII.get(Opc));
MIB.addReg(ARM::SP, getDefRegState(true));
MIB.addReg(ARM::SP);
AddDefaultPred(MIB);
bool NumRegs = false;
for (unsigned i = CSI.size(); i != 0; --i) {
unsigned Reg = CSI[i-1].getReg();
if (!(Func)(Reg, STI.isTargetDarwin())) continue;
if (Reg == ARM::LR && !isVarArg) {
Reg = ARM::PC;
unsigned Opc = AFI->isThumbFunction() ? ARM::t2LDMIA_RET : ARM::LDMIA_RET;
(*MIB).setDesc(TII.get(Opc));
MI = MBB.erase(MI);
}
MIB.addReg(Reg, RegState::Define);
NumRegs = true;
}
// It's illegal to emit pop instruction without operands.
if (NumRegs)
MBB.insert(MI, &*MIB);
else
MF.DeleteMachineInstr(MIB);
}
bool ARMFrameInfo::restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
const std::vector<CalleeSavedInfo> &CSI,
const TargetRegisterInfo *TRI) const {
if (CSI.empty())
return false;
MachineFunction &MF = *MBB.getParent();
ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
bool isVarArg = AFI->getVarArgsRegSaveSize() > 0;
DebugLoc DL = MI->getDebugLoc();
unsigned PopOpc = AFI->isThumbFunction() ? ARM::t2LDMIA_UPD : ARM::LDMIA_UPD;
unsigned FltOpc = ARM::VLDMDIA_UPD;
emitPopInst(MBB, MI, CSI, FltOpc, isVarArg, &isARMArea3Register);
emitPopInst(MBB, MI, CSI, PopOpc, isVarArg, &isARMArea2Register);
emitPopInst(MBB, MI, CSI, PopOpc, isVarArg, &isARMArea1Register);
return true;
}
// FIXME: Make generic?
static unsigned GetFunctionSizeInBytes(const MachineFunction &MF,
const ARMBaseInstrInfo &TII) {
unsigned FnSize = 0;
for (MachineFunction::const_iterator MBBI = MF.begin(), E = MF.end();
MBBI != E; ++MBBI) {
const MachineBasicBlock &MBB = *MBBI;
for (MachineBasicBlock::const_iterator I = MBB.begin(),E = MBB.end();
I != E; ++I)
FnSize += TII.GetInstSizeInBytes(I);
}
return FnSize;
}
/// estimateStackSize - Estimate and return the size of the frame.
/// FIXME: Make generic?
static unsigned estimateStackSize(MachineFunction &MF) {
const MachineFrameInfo *FFI = MF.getFrameInfo();
int Offset = 0;
for (int i = FFI->getObjectIndexBegin(); i != 0; ++i) {
int FixedOff = -FFI->getObjectOffset(i);
if (FixedOff > Offset) Offset = FixedOff;
}
for (unsigned i = 0, e = FFI->getObjectIndexEnd(); i != e; ++i) {
if (FFI->isDeadObjectIndex(i))
continue;
Offset += FFI->getObjectSize(i);
unsigned Align = FFI->getObjectAlignment(i);
// Adjust to alignment boundary
Offset = (Offset+Align-1)/Align*Align;
}
return (unsigned)Offset;
}
/// estimateRSStackSizeLimit - Look at each instruction that references stack
/// frames and return the stack size limit beyond which some of these
/// instructions will require a scratch register during their expansion later.
// FIXME: Move to TII?
static unsigned estimateRSStackSizeLimit(MachineFunction &MF,
const TargetFrameInfo *TFI) {
const ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
unsigned Limit = (1 << 12) - 1;
for (MachineFunction::iterator BB = MF.begin(),E = MF.end(); BB != E; ++BB) {
for (MachineBasicBlock::iterator I = BB->begin(), E = BB->end();
I != E; ++I) {
for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
if (!I->getOperand(i).isFI()) continue;
// When using ADDri to get the address of a stack object, 255 is the
// largest offset guaranteed to fit in the immediate offset.
if (I->getOpcode() == ARM::ADDri) {
Limit = std::min(Limit, (1U << 8) - 1);
break;
}
// Otherwise check the addressing mode.
switch (I->getDesc().TSFlags & ARMII::AddrModeMask) {
case ARMII::AddrMode3:
case ARMII::AddrModeT2_i8:
Limit = std::min(Limit, (1U << 8) - 1);
break;
case ARMII::AddrMode5:
case ARMII::AddrModeT2_i8s4:
Limit = std::min(Limit, ((1U << 8) - 1) * 4);
break;
case ARMII::AddrModeT2_i12:
// i12 supports only positive offset so these will be converted to
// i8 opcodes. See llvm::rewriteT2FrameIndex.
if (TFI->hasFP(MF) && AFI->hasStackFrame())
Limit = std::min(Limit, (1U << 8) - 1);
break;
case ARMII::AddrMode4:
case ARMII::AddrMode6:
// Addressing modes 4 & 6 (load/store) instructions can't encode an
// immediate offset for stack references.
return 0;
default:
break;
}
break; // At most one FI per instruction
}
}
}
return Limit;
}
void
ARMFrameInfo::processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
RegScavenger *RS) const {
// This tells PEI to spill the FP as if it is any other callee-save register
// to take advantage the eliminateFrameIndex machinery. This also ensures it
// is spilled in the order specified by getCalleeSavedRegs() to make it easier
// to combine multiple loads / stores.
bool CanEliminateFrame = true;
bool CS1Spilled = false;
bool LRSpilled = false;
unsigned NumGPRSpills = 0;
SmallVector<unsigned, 4> UnspilledCS1GPRs;
SmallVector<unsigned, 4> UnspilledCS2GPRs;
const ARMBaseRegisterInfo *RegInfo =
static_cast<const ARMBaseRegisterInfo*>(MF.getTarget().getRegisterInfo());
const ARMBaseInstrInfo &TII =
*static_cast<const ARMBaseInstrInfo*>(MF.getTarget().getInstrInfo());
ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
MachineFrameInfo *MFI = MF.getFrameInfo();
unsigned FramePtr = RegInfo->getFrameRegister(MF);
// Spill R4 if Thumb2 function requires stack realignment - it will be used as
// scratch register. Also spill R4 if Thumb2 function has varsized objects,
// since it's always posible to restore sp from fp in a single instruction.
// FIXME: It will be better just to find spare register here.
if (AFI->isThumb2Function() &&
(MFI->hasVarSizedObjects() || RegInfo->needsStackRealignment(MF)))
MF.getRegInfo().setPhysRegUsed(ARM::R4);
// Spill LR if Thumb1 function uses variable length argument lists.
if (AFI->isThumb1OnlyFunction() && AFI->getVarArgsRegSaveSize() > 0)
MF.getRegInfo().setPhysRegUsed(ARM::LR);
// Spill the BasePtr if it's used.
if (RegInfo->hasBasePointer(MF))
MF.getRegInfo().setPhysRegUsed(RegInfo->getBaseRegister());
// Don't spill FP if the frame can be eliminated. This is determined
// by scanning the callee-save registers to see if any is used.
const unsigned *CSRegs = RegInfo->getCalleeSavedRegs();
for (unsigned i = 0; CSRegs[i]; ++i) {
unsigned Reg = CSRegs[i];
bool Spilled = false;
if (MF.getRegInfo().isPhysRegUsed(Reg)) {
AFI->setCSRegisterIsSpilled(Reg);
Spilled = true;
CanEliminateFrame = false;
} else {
// Check alias registers too.
for (const unsigned *Aliases =
RegInfo->getAliasSet(Reg); *Aliases; ++Aliases) {
if (MF.getRegInfo().isPhysRegUsed(*Aliases)) {
Spilled = true;
CanEliminateFrame = false;
}
}
}
if (!ARM::GPRRegisterClass->contains(Reg))
continue;
if (Spilled) {
NumGPRSpills++;
if (!STI.isTargetDarwin()) {
if (Reg == ARM::LR)
LRSpilled = true;
CS1Spilled = true;
continue;
}
// Keep track if LR and any of R4, R5, R6, and R7 is spilled.
switch (Reg) {
case ARM::LR:
LRSpilled = true;
// Fallthrough
case ARM::R4: case ARM::R5:
case ARM::R6: case ARM::R7:
CS1Spilled = true;
break;
default:
break;
}
} else {
if (!STI.isTargetDarwin()) {
UnspilledCS1GPRs.push_back(Reg);
continue;
}
switch (Reg) {
case ARM::R4: case ARM::R5:
case ARM::R6: case ARM::R7:
case ARM::LR:
UnspilledCS1GPRs.push_back(Reg);
break;
default:
UnspilledCS2GPRs.push_back(Reg);
break;
}
}
}
bool ForceLRSpill = false;
if (!LRSpilled && AFI->isThumb1OnlyFunction()) {
unsigned FnSize = GetFunctionSizeInBytes(MF, TII);
// Force LR to be spilled if the Thumb function size is > 2048. This enables
// use of BL to implement far jump. If it turns out that it's not needed
// then the branch fix up path will undo it.
if (FnSize >= (1 << 11)) {
CanEliminateFrame = false;
ForceLRSpill = true;
}
}
// If any of the stack slot references may be out of range of an immediate
// offset, make sure a register (or a spill slot) is available for the
// register scavenger. Note that if we're indexing off the frame pointer, the
// effective stack size is 4 bytes larger since the FP points to the stack
// slot of the previous FP. Also, if we have variable sized objects in the
// function, stack slot references will often be negative, and some of
// our instructions are positive-offset only, so conservatively consider
// that case to want a spill slot (or register) as well. Similarly, if
// the function adjusts the stack pointer during execution and the
// adjustments aren't already part of our stack size estimate, our offset
// calculations may be off, so be conservative.
// FIXME: We could add logic to be more precise about negative offsets
// and which instructions will need a scratch register for them. Is it
// worth the effort and added fragility?
bool BigStack =
(RS &&
(estimateStackSize(MF) + ((hasFP(MF) && AFI->hasStackFrame()) ? 4:0) >=
estimateRSStackSizeLimit(MF, this)))
|| MFI->hasVarSizedObjects()
|| (MFI->adjustsStack() && !canSimplifyCallFramePseudos(MF));
bool ExtraCSSpill = false;
if (BigStack || !CanEliminateFrame || RegInfo->cannotEliminateFrame(MF)) {
AFI->setHasStackFrame(true);
// If LR is not spilled, but at least one of R4, R5, R6, and R7 is spilled.
// Spill LR as well so we can fold BX_RET to the registers restore (LDM).
if (!LRSpilled && CS1Spilled) {
MF.getRegInfo().setPhysRegUsed(ARM::LR);
AFI->setCSRegisterIsSpilled(ARM::LR);
NumGPRSpills++;
UnspilledCS1GPRs.erase(std::find(UnspilledCS1GPRs.begin(),
UnspilledCS1GPRs.end(), (unsigned)ARM::LR));
ForceLRSpill = false;
ExtraCSSpill = true;
}
if (hasFP(MF)) {
MF.getRegInfo().setPhysRegUsed(FramePtr);
NumGPRSpills++;
}
// If stack and double are 8-byte aligned and we are spilling an odd number
// of GPRs, spill one extra callee save GPR so we won't have to pad between
// the integer and double callee save areas.
unsigned TargetAlign = MF.getTarget().getFrameInfo()->getStackAlignment();
if (TargetAlign == 8 && (NumGPRSpills & 1)) {
if (CS1Spilled && !UnspilledCS1GPRs.empty()) {
for (unsigned i = 0, e = UnspilledCS1GPRs.size(); i != e; ++i) {
unsigned Reg = UnspilledCS1GPRs[i];
// Don't spill high register if the function is thumb1
if (!AFI->isThumb1OnlyFunction() ||
isARMLowRegister(Reg) || Reg == ARM::LR) {
MF.getRegInfo().setPhysRegUsed(Reg);
AFI->setCSRegisterIsSpilled(Reg);
if (!RegInfo->isReservedReg(MF, Reg))
ExtraCSSpill = true;
break;
}
}
} else if (!UnspilledCS2GPRs.empty() && !AFI->isThumb1OnlyFunction()) {
unsigned Reg = UnspilledCS2GPRs.front();
MF.getRegInfo().setPhysRegUsed(Reg);
AFI->setCSRegisterIsSpilled(Reg);
if (!RegInfo->isReservedReg(MF, Reg))
ExtraCSSpill = true;
}
}
// Estimate if we might need to scavenge a register at some point in order
// to materialize a stack offset. If so, either spill one additional
// callee-saved register or reserve a special spill slot to facilitate
// register scavenging. Thumb1 needs a spill slot for stack pointer
// adjustments also, even when the frame itself is small.
if (BigStack && !ExtraCSSpill) {
// If any non-reserved CS register isn't spilled, just spill one or two
// extra. That should take care of it!
unsigned NumExtras = TargetAlign / 4;
SmallVector<unsigned, 2> Extras;
while (NumExtras && !UnspilledCS1GPRs.empty()) {
unsigned Reg = UnspilledCS1GPRs.back();
UnspilledCS1GPRs.pop_back();
if (!RegInfo->isReservedReg(MF, Reg) &&
(!AFI->isThumb1OnlyFunction() || isARMLowRegister(Reg) ||
Reg == ARM::LR)) {
Extras.push_back(Reg);
NumExtras--;
}
}
// For non-Thumb1 functions, also check for hi-reg CS registers
if (!AFI->isThumb1OnlyFunction()) {
while (NumExtras && !UnspilledCS2GPRs.empty()) {
unsigned Reg = UnspilledCS2GPRs.back();
UnspilledCS2GPRs.pop_back();
if (!RegInfo->isReservedReg(MF, Reg)) {
Extras.push_back(Reg);
NumExtras--;
}
}
}
if (Extras.size() && NumExtras == 0) {
for (unsigned i = 0, e = Extras.size(); i != e; ++i) {
MF.getRegInfo().setPhysRegUsed(Extras[i]);
AFI->setCSRegisterIsSpilled(Extras[i]);
}
} else if (!AFI->isThumb1OnlyFunction()) {
// note: Thumb1 functions spill to R12, not the stack. Reserve a slot
// closest to SP or frame pointer.
const TargetRegisterClass *RC = ARM::GPRRegisterClass;
RS->setScavengingFrameIndex(MFI->CreateStackObject(RC->getSize(),
RC->getAlignment(),
false));
}
}
}
if (ForceLRSpill) {
MF.getRegInfo().setPhysRegUsed(ARM::LR);
AFI->setCSRegisterIsSpilled(ARM::LR);
AFI->setLRIsSpilledForFarJump(true);
}
}
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