diff options
Diffstat (limited to 'contrib/llvm/lib/Target/X86/X86FrameLowering.cpp')
| -rw-r--r-- | contrib/llvm/lib/Target/X86/X86FrameLowering.cpp | 986 |
1 files changed, 465 insertions, 521 deletions
diff --git a/contrib/llvm/lib/Target/X86/X86FrameLowering.cpp b/contrib/llvm/lib/Target/X86/X86FrameLowering.cpp index 66f54e9..85c5b64 100644 --- a/contrib/llvm/lib/Target/X86/X86FrameLowering.cpp +++ b/contrib/llvm/lib/Target/X86/X86FrameLowering.cpp @@ -37,6 +37,20 @@ using namespace llvm; // FIXME: completely move here. extern cl::opt<bool> ForceStackAlign; +X86FrameLowering::X86FrameLowering(const X86Subtarget &STI, + unsigned StackAlignOverride) + : TargetFrameLowering(StackGrowsDown, StackAlignOverride, + STI.is64Bit() ? -8 : -4), + STI(STI), TII(*STI.getInstrInfo()), TRI(STI.getRegisterInfo()) { + // Cache a bunch of frame-related predicates for this subtarget. + SlotSize = TRI->getSlotSize(); + Is64Bit = STI.is64Bit(); + IsLP64 = STI.isTarget64BitLP64(); + // standard x86_64 and NaCl use 64-bit frame/stack pointers, x32 - 32-bit. + Uses64BitFramePtr = STI.isTarget64BitLP64() || STI.isTargetNaCl64(); + StackPtr = TRI->getStackRegister(); +} + bool X86FrameLowering::hasReservedCallFrame(const MachineFunction &MF) const { return !MF.getFrameInfo()->hasVarSizedObjects() && !MF.getInfo<X86MachineFunctionInfo>()->getHasPushSequences(); @@ -48,11 +62,9 @@ bool X86FrameLowering::hasReservedCallFrame(const MachineFunction &MF) const { /// Use a more nuanced condition. bool X86FrameLowering::canSimplifyCallFramePseudos(const MachineFunction &MF) const { - const X86RegisterInfo *TRI = static_cast<const X86RegisterInfo *> - (MF.getSubtarget().getRegisterInfo()); return hasReservedCallFrame(MF) || - (hasFP(MF) && !TRI->needsStackRealignment(MF)) - || TRI->hasBasePointer(MF); + (hasFP(MF) && !TRI->needsStackRealignment(MF)) || + TRI->hasBasePointer(MF); } // needsFrameIndexResolution - Do we need to perform FI resolution for @@ -74,10 +86,9 @@ X86FrameLowering::needsFrameIndexResolution(const MachineFunction &MF) const { bool X86FrameLowering::hasFP(const MachineFunction &MF) const { const MachineFrameInfo *MFI = MF.getFrameInfo(); const MachineModuleInfo &MMI = MF.getMMI(); - const TargetRegisterInfo *RegInfo = MF.getSubtarget().getRegisterInfo(); return (MF.getTarget().Options.DisableFramePointerElim(MF) || - RegInfo->needsStackRealignment(MF) || + TRI->needsStackRealignment(MF) || MFI->hasVarSizedObjects() || MFI->isFrameAddressTaken() || MFI->hasInlineAsmWithSPAdjust() || MF.getInfo<X86MachineFunctionInfo>()->getForceFramePointer() || @@ -109,6 +120,14 @@ static unsigned getADDriOpcode(unsigned IsLP64, int64_t Imm) { } } +static unsigned getSUBrrOpcode(unsigned isLP64) { + return isLP64 ? X86::SUB64rr : X86::SUB32rr; +} + +static unsigned getADDrrOpcode(unsigned isLP64) { + return isLP64 ? X86::ADD64rr : X86::ADD32rr; +} + static unsigned getANDriOpcode(bool IsLP64, int64_t Imm) { if (IsLP64) { if (isInt<8>(Imm)) @@ -129,7 +148,7 @@ static unsigned getLEArOpcode(unsigned IsLP64) { /// to this register without worry about clobbering it. static unsigned findDeadCallerSavedReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI, - const TargetRegisterInfo &TRI, + const TargetRegisterInfo *TRI, bool Is64Bit) { const MachineFunction *MF = MBB.getParent(); const Function *F = MF->getFunction(); @@ -168,7 +187,7 @@ static unsigned findDeadCallerSavedReg(MachineBasicBlock &MBB, unsigned Reg = MO.getReg(); if (!Reg) continue; - for (MCRegAliasIterator AI(Reg, &TRI, true); AI.isValid(); ++AI) + for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI) Uses.insert(*AI); } @@ -182,38 +201,90 @@ static unsigned findDeadCallerSavedReg(MachineBasicBlock &MBB, return 0; } +static bool isEAXLiveIn(MachineFunction &MF) { + for (MachineRegisterInfo::livein_iterator II = MF.getRegInfo().livein_begin(), + EE = MF.getRegInfo().livein_end(); II != EE; ++II) { + unsigned Reg = II->first; + + if (Reg == X86::RAX || Reg == X86::EAX || Reg == X86::AX || + Reg == X86::AH || Reg == X86::AL) + return true; + } + + return false; +} + +/// Check whether or not the terminators of \p MBB needs to read EFLAGS. +static bool terminatorsNeedFlagsAsInput(const MachineBasicBlock &MBB) { + for (const MachineInstr &MI : MBB.terminators()) { + bool BreakNext = false; + for (const MachineOperand &MO : MI.operands()) { + if (!MO.isReg()) + continue; + unsigned Reg = MO.getReg(); + if (Reg != X86::EFLAGS) + continue; + + // This terminator needs an eflag that is not defined + // by a previous terminator. + if (!MO.isDef()) + return true; + BreakNext = true; + } + if (BreakNext) + break; + } + return false; +} /// emitSPUpdate - Emit a series of instructions to increment / decrement the /// stack pointer by a constant value. -static -void emitSPUpdate(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI, - unsigned StackPtr, int64_t NumBytes, - bool Is64BitTarget, bool Is64BitStackPtr, bool UseLEA, - const TargetInstrInfo &TII, const TargetRegisterInfo &TRI) { +void X86FrameLowering::emitSPUpdate(MachineBasicBlock &MBB, + MachineBasicBlock::iterator &MBBI, + int64_t NumBytes, bool InEpilogue) const { bool isSub = NumBytes < 0; uint64_t Offset = isSub ? -NumBytes : NumBytes; - unsigned Opc; - if (UseLEA) - Opc = getLEArOpcode(Is64BitStackPtr); - else - Opc = isSub - ? getSUBriOpcode(Is64BitStackPtr, Offset) - : getADDriOpcode(Is64BitStackPtr, Offset); uint64_t Chunk = (1LL << 31) - 1; DebugLoc DL = MBB.findDebugLoc(MBBI); while (Offset) { - uint64_t ThisVal = (Offset > Chunk) ? Chunk : Offset; - if (ThisVal == (Is64BitTarget ? 8 : 4)) { + if (Offset > Chunk) { + // Rather than emit a long series of instructions for large offsets, + // load the offset into a register and do one sub/add + unsigned Reg = 0; + + if (isSub && !isEAXLiveIn(*MBB.getParent())) + Reg = (unsigned)(Is64Bit ? X86::RAX : X86::EAX); + else + Reg = findDeadCallerSavedReg(MBB, MBBI, TRI, Is64Bit); + + if (Reg) { + unsigned Opc = Is64Bit ? X86::MOV64ri : X86::MOV32ri; + BuildMI(MBB, MBBI, DL, TII.get(Opc), Reg) + .addImm(Offset); + Opc = isSub + ? getSUBrrOpcode(Is64Bit) + : getADDrrOpcode(Is64Bit); + MachineInstr *MI = BuildMI(MBB, MBBI, DL, TII.get(Opc), StackPtr) + .addReg(StackPtr) + .addReg(Reg); + MI->getOperand(3).setIsDead(); // The EFLAGS implicit def is dead. + Offset = 0; + continue; + } + } + + uint64_t ThisVal = std::min(Offset, Chunk); + if (ThisVal == (Is64Bit ? 8 : 4)) { // Use push / pop instead. unsigned Reg = isSub - ? (unsigned)(Is64BitTarget ? X86::RAX : X86::EAX) - : findDeadCallerSavedReg(MBB, MBBI, TRI, Is64BitTarget); + ? (unsigned)(Is64Bit ? X86::RAX : X86::EAX) + : findDeadCallerSavedReg(MBB, MBBI, TRI, Is64Bit); if (Reg) { - Opc = isSub - ? (Is64BitTarget ? X86::PUSH64r : X86::PUSH32r) - : (Is64BitTarget ? X86::POP64r : X86::POP32r); + unsigned Opc = isSub + ? (Is64Bit ? X86::PUSH64r : X86::PUSH32r) + : (Is64Bit ? X86::POP64r : X86::POP32r); MachineInstr *MI = BuildMI(MBB, MBBI, DL, TII.get(Opc)) .addReg(Reg, getDefRegState(!isSub) | getUndefRegState(isSub)); if (isSub) @@ -223,25 +294,59 @@ void emitSPUpdate(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI, } } - MachineInstr *MI = nullptr; - - if (UseLEA) { - MI = addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(Opc), StackPtr), - StackPtr, false, isSub ? -ThisVal : ThisVal); - } else { - MI = BuildMI(MBB, MBBI, DL, TII.get(Opc), StackPtr) - .addReg(StackPtr) - .addImm(ThisVal); - MI->getOperand(3).setIsDead(); // The EFLAGS implicit def is dead. - } - + MachineInstrBuilder MI = BuildStackAdjustment( + MBB, MBBI, DL, isSub ? -ThisVal : ThisVal, InEpilogue); if (isSub) - MI->setFlag(MachineInstr::FrameSetup); + MI.setMIFlag(MachineInstr::FrameSetup); Offset -= ThisVal; } } +MachineInstrBuilder X86FrameLowering::BuildStackAdjustment( + MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI, DebugLoc DL, + int64_t Offset, bool InEpilogue) const { + assert(Offset != 0 && "zero offset stack adjustment requested"); + + // On Atom, using LEA to adjust SP is preferred, but using it in the epilogue + // is tricky. + bool UseLEA; + if (!InEpilogue) { + UseLEA = STI.useLeaForSP(); + } else { + // If we can use LEA for SP but we shouldn't, check that none + // of the terminators uses the eflags. Otherwise we will insert + // a ADD that will redefine the eflags and break the condition. + // Alternatively, we could move the ADD, but this may not be possible + // and is an optimization anyway. + UseLEA = canUseLEAForSPInEpilogue(*MBB.getParent()); + if (UseLEA && !STI.useLeaForSP()) + UseLEA = terminatorsNeedFlagsAsInput(MBB); + // If that assert breaks, that means we do not do the right thing + // in canUseAsEpilogue. + assert((UseLEA || !terminatorsNeedFlagsAsInput(MBB)) && + "We shouldn't have allowed this insertion point"); + } + + MachineInstrBuilder MI; + if (UseLEA) { + MI = addRegOffset(BuildMI(MBB, MBBI, DL, + TII.get(getLEArOpcode(Uses64BitFramePtr)), + StackPtr), + StackPtr, false, Offset); + } else { + bool IsSub = Offset < 0; + uint64_t AbsOffset = IsSub ? -Offset : Offset; + unsigned Opc = IsSub ? getSUBriOpcode(Uses64BitFramePtr, AbsOffset) + : getADDriOpcode(Uses64BitFramePtr, AbsOffset); + MI = BuildMI(MBB, MBBI, DL, TII.get(Opc), StackPtr) + .addReg(StackPtr) + .addImm(AbsOffset); + MI->getOperand(3).setIsDead(); // The EFLAGS implicit def is dead. + } + return MI; +} + /// mergeSPUpdatesUp - Merge two stack-manipulating instructions upper iterator. static void mergeSPUpdatesUp(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI, @@ -266,45 +371,9 @@ void mergeSPUpdatesUp(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI, } } -/// mergeSPUpdatesDown - Merge two stack-manipulating instructions lower -/// iterator. -static -void mergeSPUpdatesDown(MachineBasicBlock &MBB, - MachineBasicBlock::iterator &MBBI, - unsigned StackPtr, uint64_t *NumBytes = nullptr) { - // FIXME: THIS ISN'T RUN!!! - return; - - if (MBBI == MBB.end()) return; - - MachineBasicBlock::iterator NI = std::next(MBBI); - if (NI == MBB.end()) return; - - unsigned Opc = NI->getOpcode(); - if ((Opc == X86::ADD64ri32 || Opc == X86::ADD64ri8 || - Opc == X86::ADD32ri || Opc == X86::ADD32ri8) && - NI->getOperand(0).getReg() == StackPtr) { - if (NumBytes) - *NumBytes -= NI->getOperand(2).getImm(); - MBB.erase(NI); - MBBI = NI; - } else if ((Opc == X86::SUB64ri32 || Opc == X86::SUB64ri8 || - Opc == X86::SUB32ri || Opc == X86::SUB32ri8) && - NI->getOperand(0).getReg() == StackPtr) { - if (NumBytes) - *NumBytes += NI->getOperand(2).getImm(); - MBB.erase(NI); - MBBI = NI; - } -} - -/// mergeSPUpdates - Checks the instruction before/after the passed -/// instruction. If it is an ADD/SUB/LEA instruction it is deleted argument and -/// the stack adjustment is returned as a positive value for ADD/LEA and a -/// negative for SUB. -static int mergeSPUpdates(MachineBasicBlock &MBB, - MachineBasicBlock::iterator &MBBI, unsigned StackPtr, - bool doMergeWithPrevious) { +int X86FrameLowering::mergeSPUpdates(MachineBasicBlock &MBB, + MachineBasicBlock::iterator &MBBI, + bool doMergeWithPrevious) const { if ((doMergeWithPrevious && MBBI == MBB.begin()) || (!doMergeWithPrevious && MBBI == MBB.end())) return 0; @@ -333,17 +402,13 @@ static int mergeSPUpdates(MachineBasicBlock &MBB, return Offset; } -static bool isEAXLiveIn(MachineFunction &MF) { - for (MachineRegisterInfo::livein_iterator II = MF.getRegInfo().livein_begin(), - EE = MF.getRegInfo().livein_end(); II != EE; ++II) { - unsigned Reg = II->first; - - if (Reg == X86::EAX || Reg == X86::AX || - Reg == X86::AH || Reg == X86::AL) - return true; - } - - return false; +void X86FrameLowering::BuildCFI(MachineBasicBlock &MBB, + MachineBasicBlock::iterator MBBI, DebugLoc DL, + MCCFIInstruction CFIInst) const { + MachineFunction &MF = *MBB.getParent(); + unsigned CFIIndex = MF.getMMI().addFrameInst(CFIInst); + BuildMI(MBB, MBBI, DL, TII.get(TargetOpcode::CFI_INSTRUCTION)) + .addCFIIndex(CFIIndex); } void @@ -354,7 +419,6 @@ X86FrameLowering::emitCalleeSavedFrameMoves(MachineBasicBlock &MBB, MachineFrameInfo *MFI = MF.getFrameInfo(); MachineModuleInfo &MMI = MF.getMMI(); const MCRegisterInfo *MRI = MMI.getContext().getRegisterInfo(); - const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo(); // Add callee saved registers to move list. const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo(); @@ -367,11 +431,8 @@ X86FrameLowering::emitCalleeSavedFrameMoves(MachineBasicBlock &MBB, unsigned Reg = I->getReg(); unsigned DwarfReg = MRI->getDwarfRegNum(Reg, true); - unsigned CFIIndex = - MMI.addFrameInst(MCCFIInstruction::createOffset(nullptr, DwarfReg, - Offset)); - BuildMI(MBB, MBBI, DL, TII.get(TargetOpcode::CFI_INSTRUCTION)) - .addCFIIndex(CFIIndex); + BuildCFI(MBB, MBBI, DL, + MCCFIInstruction::createOffset(nullptr, DwarfReg, Offset)); } } @@ -395,13 +456,8 @@ static bool usesTheStack(const MachineFunction &MF) { void X86FrameLowering::emitStackProbeCall(MachineFunction &MF, MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI, - DebugLoc DL) { - const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo(); - const X86Subtarget &STI = MF.getTarget().getSubtarget<X86Subtarget>(); - bool Is64Bit = STI.is64Bit(); + DebugLoc DL) const { bool IsLargeCodeModel = MF.getTarget().getCodeModel() == CodeModel::Large; - const X86RegisterInfo *RegInfo = - static_cast<const X86RegisterInfo *>(MF.getSubtarget().getRegisterInfo()); unsigned CallOp; if (Is64Bit) @@ -453,6 +509,48 @@ void X86FrameLowering::emitStackProbeCall(MachineFunction &MF, } } +static unsigned calculateSetFPREG(uint64_t SPAdjust) { + // Win64 ABI has a less restrictive limitation of 240; 128 works equally well + // and might require smaller successive adjustments. + const uint64_t Win64MaxSEHOffset = 128; + uint64_t SEHFrameOffset = std::min(SPAdjust, Win64MaxSEHOffset); + // Win64 ABI requires 16-byte alignment for the UWOP_SET_FPREG opcode. + return SEHFrameOffset & -16; +} + +// If we're forcing a stack realignment we can't rely on just the frame +// info, we need to know the ABI stack alignment as well in case we +// have a call out. Otherwise just make sure we have some alignment - we'll +// go with the minimum SlotSize. +uint64_t X86FrameLowering::calculateMaxStackAlign(const MachineFunction &MF) const { + const MachineFrameInfo *MFI = MF.getFrameInfo(); + uint64_t MaxAlign = MFI->getMaxAlignment(); // Desired stack alignment. + unsigned StackAlign = getStackAlignment(); + if (ForceStackAlign) { + if (MFI->hasCalls()) + MaxAlign = (StackAlign > MaxAlign) ? StackAlign : MaxAlign; + else if (MaxAlign < SlotSize) + MaxAlign = SlotSize; + } + return MaxAlign; +} + +void X86FrameLowering::BuildStackAlignAND(MachineBasicBlock &MBB, + MachineBasicBlock::iterator MBBI, + DebugLoc DL, + uint64_t MaxAlign) const { + uint64_t Val = -MaxAlign; + MachineInstr *MI = + BuildMI(MBB, MBBI, DL, TII.get(getANDriOpcode(Uses64BitFramePtr, Val)), + StackPtr) + .addReg(StackPtr) + .addImm(Val) + .setMIFlag(MachineInstr::FrameSetup); + + // The EFLAGS implicit def is dead. + MI->getOperand(3).setIsDead(); +} + /// emitPrologue - Push callee-saved registers onto the stack, which /// automatically adjust the stack pointer. Adjust the stack pointer to allocate /// space for local variables. Also emit labels used by the exception handler to @@ -537,52 +635,36 @@ void X86FrameLowering::emitStackProbeCall(MachineFunction &MF, - for 32-bit code, substitute %e?? registers for %r?? */ -void X86FrameLowering::emitPrologue(MachineFunction &MF) const { - MachineBasicBlock &MBB = MF.front(); // Prologue goes in entry BB. +void X86FrameLowering::emitPrologue(MachineFunction &MF, + MachineBasicBlock &MBB) const { + assert(&STI == &MF.getSubtarget<X86Subtarget>() && + "MF used frame lowering for wrong subtarget"); MachineBasicBlock::iterator MBBI = MBB.begin(); MachineFrameInfo *MFI = MF.getFrameInfo(); const Function *Fn = MF.getFunction(); - const X86RegisterInfo *RegInfo = - static_cast<const X86RegisterInfo *>(MF.getSubtarget().getRegisterInfo()); - const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo(); MachineModuleInfo &MMI = MF.getMMI(); X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>(); - uint64_t MaxAlign = MFI->getMaxAlignment(); // Desired stack alignment. + uint64_t MaxAlign = calculateMaxStackAlign(MF); // Desired stack alignment. uint64_t StackSize = MFI->getStackSize(); // Number of bytes to allocate. bool HasFP = hasFP(MF); - const X86Subtarget &STI = MF.getTarget().getSubtarget<X86Subtarget>(); - bool Is64Bit = STI.is64Bit(); - // standard x86_64 and NaCl use 64-bit frame/stack pointers, x32 - 32-bit. - const bool Uses64BitFramePtr = STI.isTarget64BitLP64() || STI.isTargetNaCl64(); - bool IsWin64 = STI.isTargetWin64(); - // Not necessarily synonymous with IsWin64. - bool IsWinEH = MF.getTarget().getMCAsmInfo()->usesWindowsCFI(); - bool NeedsWinEH = IsWinEH && Fn->needsUnwindTableEntry(); + bool IsWin64CC = STI.isCallingConvWin64(Fn->getCallingConv()); + bool IsWin64Prologue = MF.getTarget().getMCAsmInfo()->usesWindowsCFI(); + bool NeedsWinCFI = IsWin64Prologue && Fn->needsUnwindTableEntry(); bool NeedsDwarfCFI = - !IsWinEH && (MMI.hasDebugInfo() || Fn->needsUnwindTableEntry()); - bool UseLEA = STI.useLeaForSP(); - unsigned StackAlign = getStackAlignment(); - unsigned SlotSize = RegInfo->getSlotSize(); - unsigned FramePtr = RegInfo->getFrameRegister(MF); - const unsigned MachineFramePtr = STI.isTarget64BitILP32() ? - getX86SubSuperRegister(FramePtr, MVT::i64, false) : FramePtr; - unsigned StackPtr = RegInfo->getStackRegister(); - unsigned BasePtr = RegInfo->getBaseRegister(); + !IsWin64Prologue && (MMI.hasDebugInfo() || Fn->needsUnwindTableEntry()); + unsigned FramePtr = TRI->getFrameRegister(MF); + const unsigned MachineFramePtr = + STI.isTarget64BitILP32() + ? getX86SubSuperRegister(FramePtr, MVT::i64, false) + : FramePtr; + unsigned BasePtr = TRI->getBaseRegister(); DebugLoc DL; - // If we're forcing a stack realignment we can't rely on just the frame - // info, we need to know the ABI stack alignment as well in case we - // have a call out. Otherwise just make sure we have some alignment - we'll - // go with the minimum SlotSize. - if (ForceStackAlign) { - if (MFI->hasCalls()) - MaxAlign = (StackAlign > MaxAlign) ? StackAlign : MaxAlign; - else if (MaxAlign < SlotSize) - MaxAlign = SlotSize; - } - // Add RETADDR move area to callee saved frame size. int TailCallReturnAddrDelta = X86FI->getTCReturnAddrDelta(); + if (TailCallReturnAddrDelta && IsWin64Prologue) + report_fatal_error("Can't handle guaranteed tail call under win64 yet"); + if (TailCallReturnAddrDelta < 0) X86FI->setCalleeSavedFrameSize( X86FI->getCalleeSavedFrameSize() - TailCallReturnAddrDelta); @@ -602,14 +684,13 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF) const { // pointer, calls, or dynamic alloca then we do not need to adjust the // stack pointer (we fit in the Red Zone). We also check that we don't // push and pop from the stack. - if (Is64Bit && !Fn->getAttributes().hasAttribute(AttributeSet::FunctionIndex, - Attribute::NoRedZone) && - !RegInfo->needsStackRealignment(MF) && - !MFI->hasVarSizedObjects() && // No dynamic alloca. - !MFI->adjustsStack() && // No calls. - !IsWin64 && // Win64 has no Red Zone - !usesTheStack(MF) && // Don't push and pop. - !MF.shouldSplitStack()) { // Regular stack + if (Is64Bit && !Fn->hasFnAttribute(Attribute::NoRedZone) && + !TRI->needsStackRealignment(MF) && + !MFI->hasVarSizedObjects() && // No dynamic alloca. + !MFI->adjustsStack() && // No calls. + !IsWin64CC && // Win64 has no Red Zone + !usesTheStack(MF) && // Don't push and pop. + !MF.shouldSplitStack()) { // Regular stack uint64_t MinSize = X86FI->getCalleeSavedFrameSize(); if (HasFP) MinSize += SlotSize; StackSize = std::max(MinSize, StackSize > 128 ? StackSize - 128 : 0); @@ -620,14 +701,9 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF) const { // applies to tail call optimized functions where the callee argument stack // size is bigger than the callers. if (TailCallReturnAddrDelta < 0) { - MachineInstr *MI = - BuildMI(MBB, MBBI, DL, - TII.get(getSUBriOpcode(Uses64BitFramePtr, -TailCallReturnAddrDelta)), - StackPtr) - .addReg(StackPtr) - .addImm(-TailCallReturnAddrDelta) + BuildStackAdjustment(MBB, MBBI, DL, TailCallReturnAddrDelta, + /*InEpilogue=*/false) .setMIFlag(MachineInstr::FrameSetup); - MI->getOperand(3).setIsDead(); // The EFLAGS implicit def is dead. } // Mapping for machine moves: @@ -653,14 +729,12 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF) const { // If required, include space for extra hidden slot for stashing base pointer. if (X86FI->getRestoreBasePointer()) FrameSize += SlotSize; - if (RegInfo->needsStackRealignment(MF)) { - // Callee-saved registers are pushed on stack before the stack - // is realigned. - FrameSize -= X86FI->getCalleeSavedFrameSize(); - NumBytes = (FrameSize + MaxAlign - 1) / MaxAlign * MaxAlign; - } else { - NumBytes = FrameSize - X86FI->getCalleeSavedFrameSize(); - } + + NumBytes = FrameSize - X86FI->getCalleeSavedFrameSize(); + + // Callee-saved registers are pushed on stack before the stack is realigned. + if (TRI->needsStackRealignment(MF) && !IsWin64Prologue) + NumBytes = RoundUpToAlignment(NumBytes, MaxAlign); // Get the offset of the stack slot for the EBP register, which is // guaranteed to be the last slot by processFunctionBeforeFrameFinalized. @@ -676,40 +750,36 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF) const { // Mark the place where EBP/RBP was saved. // Define the current CFA rule to use the provided offset. assert(StackSize); - unsigned CFIIndex = MMI.addFrameInst( - MCCFIInstruction::createDefCfaOffset(nullptr, 2 * stackGrowth)); - BuildMI(MBB, MBBI, DL, TII.get(TargetOpcode::CFI_INSTRUCTION)) - .addCFIIndex(CFIIndex); + BuildCFI(MBB, MBBI, DL, + MCCFIInstruction::createDefCfaOffset(nullptr, 2 * stackGrowth)); // Change the rule for the FramePtr to be an "offset" rule. - unsigned DwarfFramePtr = RegInfo->getDwarfRegNum(MachineFramePtr, true); - CFIIndex = MMI.addFrameInst( - MCCFIInstruction::createOffset(nullptr, - DwarfFramePtr, 2 * stackGrowth)); - BuildMI(MBB, MBBI, DL, TII.get(TargetOpcode::CFI_INSTRUCTION)) - .addCFIIndex(CFIIndex); + unsigned DwarfFramePtr = TRI->getDwarfRegNum(MachineFramePtr, true); + BuildCFI(MBB, MBBI, DL, MCCFIInstruction::createOffset( + nullptr, DwarfFramePtr, 2 * stackGrowth)); } - if (NeedsWinEH) { + if (NeedsWinCFI) { BuildMI(MBB, MBBI, DL, TII.get(X86::SEH_PushReg)) .addImm(FramePtr) .setMIFlag(MachineInstr::FrameSetup); } - // Update EBP with the new base value. - BuildMI(MBB, MBBI, DL, - TII.get(Uses64BitFramePtr ? X86::MOV64rr : X86::MOV32rr), FramePtr) - .addReg(StackPtr) - .setMIFlag(MachineInstr::FrameSetup); + if (!IsWin64Prologue) { + // Update EBP with the new base value. + BuildMI(MBB, MBBI, DL, + TII.get(Uses64BitFramePtr ? X86::MOV64rr : X86::MOV32rr), + FramePtr) + .addReg(StackPtr) + .setMIFlag(MachineInstr::FrameSetup); + } if (NeedsDwarfCFI) { // Mark effective beginning of when frame pointer becomes valid. // Define the current CFA to use the EBP/RBP register. - unsigned DwarfFramePtr = RegInfo->getDwarfRegNum(MachineFramePtr, true); - unsigned CFIIndex = MMI.addFrameInst( - MCCFIInstruction::createDefCfaRegister(nullptr, DwarfFramePtr)); - BuildMI(MBB, MBBI, DL, TII.get(TargetOpcode::CFI_INSTRUCTION)) - .addCFIIndex(CFIIndex); + unsigned DwarfFramePtr = TRI->getDwarfRegNum(MachineFramePtr, true); + BuildCFI(MBB, MBBI, DL, + MCCFIInstruction::createDefCfaRegister(nullptr, DwarfFramePtr)); } // Mark the FramePtr as live-in in every block. @@ -734,14 +804,12 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF) const { // Mark callee-saved push instruction. // Define the current CFA rule to use the provided offset. assert(StackSize); - unsigned CFIIndex = MMI.addFrameInst( - MCCFIInstruction::createDefCfaOffset(nullptr, StackOffset)); - BuildMI(MBB, MBBI, DL, TII.get(TargetOpcode::CFI_INSTRUCTION)) - .addCFIIndex(CFIIndex); + BuildCFI(MBB, MBBI, DL, + MCCFIInstruction::createDefCfaOffset(nullptr, StackOffset)); StackOffset += stackGrowth; } - if (NeedsWinEH) { + if (NeedsWinCFI) { BuildMI(MBB, MBBI, DL, TII.get(X86::SEH_PushReg)).addImm(Reg).setMIFlag( MachineInstr::FrameSetup); } @@ -749,28 +817,16 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF) const { // Realign stack after we pushed callee-saved registers (so that we'll be // able to calculate their offsets from the frame pointer). - if (RegInfo->needsStackRealignment(MF)) { + // Don't do this for Win64, it needs to realign the stack after the prologue. + if (!IsWin64Prologue && TRI->needsStackRealignment(MF)) { assert(HasFP && "There should be a frame pointer if stack is realigned."); - uint64_t Val = -MaxAlign; - MachineInstr *MI = - BuildMI(MBB, MBBI, DL, - TII.get(getANDriOpcode(Uses64BitFramePtr, Val)), StackPtr) - .addReg(StackPtr) - .addImm(Val) - .setMIFlag(MachineInstr::FrameSetup); - - // The EFLAGS implicit def is dead. - MI->getOperand(3).setIsDead(); + BuildStackAlignAND(MBB, MBBI, DL, MaxAlign); } // If there is an SUB32ri of ESP immediately before this instruction, merge // the two. This can be the case when tail call elimination is enabled and // the callee has more arguments then the caller. - NumBytes -= mergeSPUpdates(MBB, MBBI, StackPtr, true); - - // If there is an ADD32ri or SUB32ri of ESP immediately after this - // instruction, merge the two instructions. - mergeSPUpdatesDown(MBB, MBBI, StackPtr, &NumBytes); + NumBytes -= mergeSPUpdates(MBB, MBBI, true); // Adjust stack pointer: ESP -= numbytes. @@ -782,7 +838,10 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF) const { // responsible for adjusting the stack pointer. Touching the stack at 4K // increments is necessary to ensure that the guard pages used by the OS // virtual memory manager are allocated in correct sequence. - if (NumBytes >= StackProbeSize && UseStackProbe) { + uint64_t AlignedNumBytes = NumBytes; + if (IsWin64Prologue && TRI->needsStackRealignment(MF)) + AlignedNumBytes = RoundUpToAlignment(AlignedNumBytes, MaxAlign); + if (AlignedNumBytes >= StackProbeSize && UseStackProbe) { // Check whether EAX is livein for this function. bool isEAXAlive = isEAXLiveIn(MF); @@ -800,9 +859,19 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF) const { if (Is64Bit) { // Handle the 64-bit Windows ABI case where we need to call __chkstk. // Function prologue is responsible for adjusting the stack pointer. - BuildMI(MBB, MBBI, DL, TII.get(X86::MOV64ri), X86::RAX) - .addImm(NumBytes) - .setMIFlag(MachineInstr::FrameSetup); + if (isUInt<32>(NumBytes)) { + BuildMI(MBB, MBBI, DL, TII.get(X86::MOV32ri), X86::EAX) + .addImm(NumBytes) + .setMIFlag(MachineInstr::FrameSetup); + } else if (isInt<32>(NumBytes)) { + BuildMI(MBB, MBBI, DL, TII.get(X86::MOV64ri32), X86::RAX) + .addImm(NumBytes) + .setMIFlag(MachineInstr::FrameSetup); + } else { + BuildMI(MBB, MBBI, DL, TII.get(X86::MOV64ri), X86::RAX) + .addImm(NumBytes) + .setMIFlag(MachineInstr::FrameSetup); + } } else { // Allocate NumBytes-4 bytes on stack in case of isEAXAlive. // We'll also use 4 already allocated bytes for EAX. @@ -831,79 +900,67 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF) const { MBB.insert(MBBI, MI); } } else if (NumBytes) { - emitSPUpdate(MBB, MBBI, StackPtr, -(int64_t)NumBytes, Is64Bit, Uses64BitFramePtr, - UseLEA, TII, *RegInfo); + emitSPUpdate(MBB, MBBI, -(int64_t)NumBytes, /*InEpilogue=*/false); } + if (NeedsWinCFI && NumBytes) + BuildMI(MBB, MBBI, DL, TII.get(X86::SEH_StackAlloc)) + .addImm(NumBytes) + .setMIFlag(MachineInstr::FrameSetup); + int SEHFrameOffset = 0; - if (NeedsWinEH) { - if (HasFP) { - // We need to set frame base offset low enough such that all saved - // register offsets would be positive relative to it, but we can't - // just use NumBytes, because .seh_setframe offset must be <=240. - // So we pretend to have only allocated enough space to spill the - // non-volatile registers. - // We don't care about the rest of stack allocation, because unwinder - // will restore SP to (BP - SEHFrameOffset) - for (const CalleeSavedInfo &Info : MFI->getCalleeSavedInfo()) { - int offset = MFI->getObjectOffset(Info.getFrameIdx()); - SEHFrameOffset = std::max(SEHFrameOffset, std::abs(offset)); - } - SEHFrameOffset += SEHFrameOffset % 16; // ensure alignmant - - // This only needs to account for XMM spill slots, GPR slots - // are covered by the .seh_pushreg's emitted above. - unsigned Size = SEHFrameOffset - X86FI->getCalleeSavedFrameSize(); - if (Size) { - BuildMI(MBB, MBBI, DL, TII.get(X86::SEH_StackAlloc)) - .addImm(Size) - .setMIFlag(MachineInstr::FrameSetup); - } + if (IsWin64Prologue && HasFP) { + SEHFrameOffset = calculateSetFPREG(NumBytes); + if (SEHFrameOffset) + addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(X86::LEA64r), FramePtr), + StackPtr, false, SEHFrameOffset); + else + BuildMI(MBB, MBBI, DL, TII.get(X86::MOV64rr), FramePtr).addReg(StackPtr); + if (NeedsWinCFI) BuildMI(MBB, MBBI, DL, TII.get(X86::SEH_SetFrame)) .addImm(FramePtr) .addImm(SEHFrameOffset) .setMIFlag(MachineInstr::FrameSetup); - } else { - // SP will be the base register for restoring XMMs - if (NumBytes) { - BuildMI(MBB, MBBI, DL, TII.get(X86::SEH_StackAlloc)) - .addImm(NumBytes) - .setMIFlag(MachineInstr::FrameSetup); - } - } } - // Skip the rest of register spilling code - while (MBBI != MBB.end() && MBBI->getFlag(MachineInstr::FrameSetup)) + while (MBBI != MBB.end() && MBBI->getFlag(MachineInstr::FrameSetup)) { + const MachineInstr *FrameInstr = &*MBBI; ++MBBI; - // Emit SEH info for non-GPRs - if (NeedsWinEH) { - for (const CalleeSavedInfo &Info : MFI->getCalleeSavedInfo()) { - unsigned Reg = Info.getReg(); - if (X86::GR64RegClass.contains(Reg) || X86::GR32RegClass.contains(Reg)) - continue; - assert(X86::FR64RegClass.contains(Reg) && "Unexpected register class"); - - int Offset = getFrameIndexOffset(MF, Info.getFrameIdx()); - Offset += SEHFrameOffset; - - BuildMI(MBB, MBBI, DL, TII.get(X86::SEH_SaveXMM)) - .addImm(Reg) - .addImm(Offset) - .setMIFlag(MachineInstr::FrameSetup); + if (NeedsWinCFI) { + int FI; + if (unsigned Reg = TII.isStoreToStackSlot(FrameInstr, FI)) { + if (X86::FR64RegClass.contains(Reg)) { + int Offset = getFrameIndexOffset(MF, FI); + Offset += SEHFrameOffset; + + BuildMI(MBB, MBBI, DL, TII.get(X86::SEH_SaveXMM)) + .addImm(Reg) + .addImm(Offset) + .setMIFlag(MachineInstr::FrameSetup); + } + } } + } + if (NeedsWinCFI) BuildMI(MBB, MBBI, DL, TII.get(X86::SEH_EndPrologue)) .setMIFlag(MachineInstr::FrameSetup); + + // Realign stack after we spilled callee-saved registers (so that we'll be + // able to calculate their offsets from the frame pointer). + // Win64 requires aligning the stack after the prologue. + if (IsWin64Prologue && TRI->needsStackRealignment(MF)) { + assert(HasFP && "There should be a frame pointer if stack is realigned."); + BuildStackAlignAND(MBB, MBBI, DL, MaxAlign); } // 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 (TRI->hasBasePointer(MF)) { // Update the base pointer with the current stack pointer. unsigned Opc = Uses64BitFramePtr ? X86::MOV64rr : X86::MOV32rr; BuildMI(MBB, MBBI, DL, TII.get(Opc), BasePtr) @@ -924,12 +981,8 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF) const { if (!HasFP && NumBytes) { // Define the current CFA rule to use the provided offset. assert(StackSize); - unsigned CFIIndex = MMI.addFrameInst( - MCCFIInstruction::createDefCfaOffset(nullptr, - -StackSize + stackGrowth)); - - BuildMI(MBB, MBBI, DL, TII.get(TargetOpcode::CFI_INSTRUCTION)) - .addCFIIndex(CFIIndex); + BuildCFI(MBB, MBBI, DL, MCCFIInstruction::createDefCfaOffset( + nullptr, -StackSize + stackGrowth)); } // Emit DWARF info specifying the offsets of the callee-saved registers. @@ -938,79 +991,51 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF) const { } } +bool X86FrameLowering::canUseLEAForSPInEpilogue( + const MachineFunction &MF) const { + // We can't use LEA instructions for adjusting the stack pointer if this is a + // leaf function in the Win64 ABI. Only ADD instructions may be used to + // deallocate the stack. + // This means that we can use LEA for SP in two situations: + // 1. We *aren't* using the Win64 ABI which means we are free to use LEA. + // 2. We *have* a frame pointer which means we are permitted to use LEA. + return !MF.getTarget().getMCAsmInfo()->usesWindowsCFI() || hasFP(MF); +} + void X86FrameLowering::emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const { const MachineFrameInfo *MFI = MF.getFrameInfo(); X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>(); - const X86RegisterInfo *RegInfo = - static_cast<const X86RegisterInfo *>(MF.getSubtarget().getRegisterInfo()); - const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo(); - MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr(); - assert(MBBI != MBB.end() && "Returning block has no instructions"); - unsigned RetOpcode = MBBI->getOpcode(); - DebugLoc DL = MBBI->getDebugLoc(); - const X86Subtarget &STI = MF.getTarget().getSubtarget<X86Subtarget>(); - bool Is64Bit = STI.is64Bit(); + MachineBasicBlock::iterator MBBI = MBB.getFirstTerminator(); + DebugLoc DL; + if (MBBI != MBB.end()) + DL = MBBI->getDebugLoc(); // standard x86_64 and NaCl use 64-bit frame/stack pointers, x32 - 32-bit. - const bool Uses64BitFramePtr = STI.isTarget64BitLP64() || STI.isTargetNaCl64(); const bool Is64BitILP32 = STI.isTarget64BitILP32(); - bool UseLEA = STI.useLeaForSP(); - unsigned StackAlign = getStackAlignment(); - unsigned SlotSize = RegInfo->getSlotSize(); - unsigned FramePtr = RegInfo->getFrameRegister(MF); - unsigned MachineFramePtr = Is64BitILP32 ? - getX86SubSuperRegister(FramePtr, MVT::i64, false) : FramePtr; - unsigned StackPtr = RegInfo->getStackRegister(); - - bool IsWinEH = MF.getTarget().getMCAsmInfo()->usesWindowsCFI(); - bool NeedsWinEH = IsWinEH && MF.getFunction()->needsUnwindTableEntry(); - - switch (RetOpcode) { - default: - llvm_unreachable("Can only insert epilog into returning blocks"); - case X86::RETQ: - case X86::RETL: - case X86::RETIL: - case X86::RETIQ: - case X86::TCRETURNdi: - case X86::TCRETURNri: - case X86::TCRETURNmi: - case X86::TCRETURNdi64: - case X86::TCRETURNri64: - case X86::TCRETURNmi64: - case X86::EH_RETURN: - case X86::EH_RETURN64: - break; // These are ok - } + unsigned FramePtr = TRI->getFrameRegister(MF); + unsigned MachineFramePtr = + Is64BitILP32 ? getX86SubSuperRegister(FramePtr, MVT::i64, false) + : FramePtr; + + bool IsWin64Prologue = MF.getTarget().getMCAsmInfo()->usesWindowsCFI(); + bool NeedsWinCFI = + IsWin64Prologue && MF.getFunction()->needsUnwindTableEntry(); // Get the number of bytes to allocate from the FrameInfo. uint64_t StackSize = MFI->getStackSize(); - uint64_t MaxAlign = MFI->getMaxAlignment(); + uint64_t MaxAlign = calculateMaxStackAlign(MF); unsigned CSSize = X86FI->getCalleeSavedFrameSize(); uint64_t NumBytes = 0; - // If we're forcing a stack realignment we can't rely on just the frame - // info, we need to know the ABI stack alignment as well in case we - // have a call out. Otherwise just make sure we have some alignment - we'll - // go with the minimum. - if (ForceStackAlign) { - if (MFI->hasCalls()) - MaxAlign = (StackAlign > MaxAlign) ? StackAlign : MaxAlign; - else - MaxAlign = MaxAlign ? MaxAlign : 4; - } - if (hasFP(MF)) { // Calculate required stack adjustment. uint64_t FrameSize = StackSize - SlotSize; - if (RegInfo->needsStackRealignment(MF)) { - // Callee-saved registers were pushed on stack before the stack - // was realigned. - FrameSize -= CSSize; - NumBytes = (FrameSize + MaxAlign - 1) / MaxAlign * MaxAlign; - } else { - NumBytes = FrameSize - CSSize; - } + NumBytes = FrameSize - CSSize; + + // Callee-saved registers were pushed on stack before the stack was + // realigned. + if (TRI->needsStackRealignment(MF) && !IsWin64Prologue) + NumBytes = RoundUpToAlignment(FrameSize, MaxAlign); // Pop EBP. BuildMI(MBB, MBBI, DL, @@ -1018,6 +1043,7 @@ void X86FrameLowering::emitEpilogue(MachineFunction &MF, } else { NumBytes = StackSize - CSSize; } + uint64_t SEHStackAllocAmt = NumBytes; // Skip the callee-saved pop instructions. while (MBBI != MBB.begin()) { @@ -1032,7 +1058,8 @@ void X86FrameLowering::emitEpilogue(MachineFunction &MF, } MachineBasicBlock::iterator FirstCSPop = MBBI; - DL = MBBI->getDebugLoc(); + if (MBBI != MBB.end()) + DL = MBBI->getDebugLoc(); // If there is an ADD32ri or SUB32ri of ESP immediately before this // instruction, merge the two instructions. @@ -1042,13 +1069,24 @@ void X86FrameLowering::emitEpilogue(MachineFunction &MF, // If dynamic alloca is used, then reset esp to point to the last callee-saved // slot before popping them off! Same applies for the case, when stack was // realigned. - if (RegInfo->needsStackRealignment(MF) || MFI->hasVarSizedObjects()) { - if (RegInfo->needsStackRealignment(MF)) + if (TRI->needsStackRealignment(MF) || MFI->hasVarSizedObjects()) { + if (TRI->needsStackRealignment(MF)) MBBI = FirstCSPop; - if (CSSize != 0) { + unsigned SEHFrameOffset = calculateSetFPREG(SEHStackAllocAmt); + uint64_t LEAAmount = + IsWin64Prologue ? SEHStackAllocAmt - SEHFrameOffset : -CSSize; + + // There are only two legal forms of epilogue: + // - add SEHAllocationSize, %rsp + // - lea SEHAllocationSize(%FramePtr), %rsp + // + // 'mov %FramePtr, %rsp' will not be recognized as an epilogue sequence. + // However, we may use this sequence if we have a frame pointer because the + // effects of the prologue can safely be undone. + if (LEAAmount != 0) { unsigned Opc = getLEArOpcode(Uses64BitFramePtr); addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(Opc), StackPtr), - FramePtr, false, -CSSize); + FramePtr, false, LEAAmount); --MBBI; } else { unsigned Opc = (Uses64BitFramePtr ? X86::MOV64rr : X86::MOV32rr); @@ -1058,8 +1096,7 @@ void X86FrameLowering::emitEpilogue(MachineFunction &MF, } } else if (NumBytes) { // Adjust stack pointer back: ESP += numbytes. - emitSPUpdate(MBB, MBBI, StackPtr, NumBytes, Is64Bit, Uses64BitFramePtr, UseLEA, - TII, *RegInfo); + emitSPUpdate(MBB, MBBI, NumBytes, /*InEpilogue=*/true); --MBBI; } @@ -1069,147 +1106,105 @@ void X86FrameLowering::emitEpilogue(MachineFunction &MF, // into the epilogue. To cope with that, we insert an epilogue marker here, // then replace it with a 'nop' if it ends up immediately after a CALL in the // final emitted code. - if (NeedsWinEH) + if (NeedsWinCFI) BuildMI(MBB, MBBI, DL, TII.get(X86::SEH_Epilogue)); - // We're returning from function via eh_return. - if (RetOpcode == X86::EH_RETURN || RetOpcode == X86::EH_RETURN64) { - MBBI = MBB.getLastNonDebugInstr(); - MachineOperand &DestAddr = MBBI->getOperand(0); - assert(DestAddr.isReg() && "Offset should be in register!"); - BuildMI(MBB, MBBI, DL, - TII.get(Uses64BitFramePtr ? X86::MOV64rr : X86::MOV32rr), - StackPtr).addReg(DestAddr.getReg()); - } else if (RetOpcode == X86::TCRETURNri || RetOpcode == X86::TCRETURNdi || - RetOpcode == X86::TCRETURNmi || - RetOpcode == X86::TCRETURNri64 || RetOpcode == X86::TCRETURNdi64 || - RetOpcode == X86::TCRETURNmi64) { - bool isMem = RetOpcode == X86::TCRETURNmi || RetOpcode == X86::TCRETURNmi64; - // Tail call return: adjust the stack pointer and jump to callee. - MBBI = MBB.getLastNonDebugInstr(); - MachineOperand &JumpTarget = MBBI->getOperand(0); - MachineOperand &StackAdjust = MBBI->getOperand(isMem ? 5 : 1); - assert(StackAdjust.isImm() && "Expecting immediate value."); - - // Adjust stack pointer. - int StackAdj = StackAdjust.getImm(); - int MaxTCDelta = X86FI->getTCReturnAddrDelta(); - int Offset = 0; - assert(MaxTCDelta <= 0 && "MaxTCDelta should never be positive"); - - // Incoporate the retaddr area. - Offset = StackAdj-MaxTCDelta; - assert(Offset >= 0 && "Offset should never be negative"); - - if (Offset) { - // Check for possible merge with preceding ADD instruction. - Offset += mergeSPUpdates(MBB, MBBI, StackPtr, true); - emitSPUpdate(MBB, MBBI, StackPtr, Offset, Is64Bit, Uses64BitFramePtr, - UseLEA, TII, *RegInfo); - } - - // Jump to label or value in register. - if (RetOpcode == X86::TCRETURNdi || RetOpcode == X86::TCRETURNdi64) { - MachineInstrBuilder MIB = - BuildMI(MBB, MBBI, DL, TII.get((RetOpcode == X86::TCRETURNdi) - ? X86::TAILJMPd : X86::TAILJMPd64)); - if (JumpTarget.isGlobal()) - MIB.addGlobalAddress(JumpTarget.getGlobal(), JumpTarget.getOffset(), - JumpTarget.getTargetFlags()); - else { - assert(JumpTarget.isSymbol()); - MIB.addExternalSymbol(JumpTarget.getSymbolName(), - JumpTarget.getTargetFlags()); - } - } else if (RetOpcode == X86::TCRETURNmi || RetOpcode == X86::TCRETURNmi64) { - MachineInstrBuilder MIB = - BuildMI(MBB, MBBI, DL, TII.get((RetOpcode == X86::TCRETURNmi) - ? X86::TAILJMPm : X86::TAILJMPm64)); - for (unsigned i = 0; i != 5; ++i) - MIB.addOperand(MBBI->getOperand(i)); - } else if (RetOpcode == X86::TCRETURNri64) { - BuildMI(MBB, MBBI, DL, TII.get(X86::TAILJMPr64)). - addReg(JumpTarget.getReg(), RegState::Kill); - } else { - BuildMI(MBB, MBBI, DL, TII.get(X86::TAILJMPr)). - addReg(JumpTarget.getReg(), RegState::Kill); - } - - MachineInstr *NewMI = std::prev(MBBI); - NewMI->copyImplicitOps(MF, MBBI); - - // Delete the pseudo instruction TCRETURN. - MBB.erase(MBBI); - } else if ((RetOpcode == X86::RETQ || RetOpcode == X86::RETL || - RetOpcode == X86::RETIQ || RetOpcode == X86::RETIL) && - (X86FI->getTCReturnAddrDelta() < 0)) { - // Add the return addr area delta back since we are not tail calling. - int delta = -1*X86FI->getTCReturnAddrDelta(); - MBBI = MBB.getLastNonDebugInstr(); + // Add the return addr area delta back since we are not tail calling. + int Offset = -1 * X86FI->getTCReturnAddrDelta(); + assert(Offset >= 0 && "TCDelta should never be positive"); + if (Offset) { + MBBI = MBB.getFirstTerminator(); // Check for possible merge with preceding ADD instruction. - delta += mergeSPUpdates(MBB, MBBI, StackPtr, true); - emitSPUpdate(MBB, MBBI, StackPtr, delta, Is64Bit, Uses64BitFramePtr, UseLEA, TII, - *RegInfo); + Offset += mergeSPUpdates(MBB, MBBI, true); + emitSPUpdate(MBB, MBBI, Offset, /*InEpilogue=*/true); } } int X86FrameLowering::getFrameIndexOffset(const MachineFunction &MF, int FI) const { - const X86RegisterInfo *RegInfo = - static_cast<const X86RegisterInfo *>(MF.getSubtarget().getRegisterInfo()); const MachineFrameInfo *MFI = MF.getFrameInfo(); + // Offset will hold the offset from the stack pointer at function entry to the + // object. + // We need to factor in additional offsets applied during the prologue to the + // frame, base, and stack pointer depending on which is used. int Offset = MFI->getObjectOffset(FI) - getOffsetOfLocalArea(); + const X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>(); + unsigned CSSize = X86FI->getCalleeSavedFrameSize(); uint64_t StackSize = MFI->getStackSize(); + bool HasFP = hasFP(MF); + bool IsWin64Prologue = MF.getTarget().getMCAsmInfo()->usesWindowsCFI(); + int64_t FPDelta = 0; - if (RegInfo->hasBasePointer(MF)) { - assert (hasFP(MF) && "VLAs and dynamic stack realign, but no FP?!"); + if (IsWin64Prologue) { + assert(!MFI->hasCalls() || (StackSize % 16) == 8); + + // Calculate required stack adjustment. + uint64_t FrameSize = StackSize - SlotSize; + // If required, include space for extra hidden slot for stashing base pointer. + if (X86FI->getRestoreBasePointer()) + FrameSize += SlotSize; + uint64_t NumBytes = FrameSize - CSSize; + + uint64_t SEHFrameOffset = calculateSetFPREG(NumBytes); + if (FI && FI == X86FI->getFAIndex()) + return -SEHFrameOffset; + + // FPDelta is the offset from the "traditional" FP location of the old base + // pointer followed by return address and the location required by the + // restricted Win64 prologue. + // Add FPDelta to all offsets below that go through the frame pointer. + FPDelta = FrameSize - SEHFrameOffset; + assert((!MFI->hasCalls() || (FPDelta % 16) == 0) && + "FPDelta isn't aligned per the Win64 ABI!"); + } + + + if (TRI->hasBasePointer(MF)) { + assert(HasFP && "VLAs and dynamic stack realign, but no FP?!"); if (FI < 0) { // Skip the saved EBP. - return Offset + RegInfo->getSlotSize(); + return Offset + SlotSize + FPDelta; } else { assert((-(Offset + StackSize)) % MFI->getObjectAlignment(FI) == 0); return Offset + StackSize; } - } else if (RegInfo->needsStackRealignment(MF)) { + } else if (TRI->needsStackRealignment(MF)) { if (FI < 0) { // Skip the saved EBP. - return Offset + RegInfo->getSlotSize(); + return Offset + SlotSize + FPDelta; } else { assert((-(Offset + StackSize)) % MFI->getObjectAlignment(FI) == 0); return Offset + StackSize; } // FIXME: Support tail calls } else { - if (!hasFP(MF)) + if (!HasFP) return Offset + StackSize; // Skip the saved EBP. - Offset += RegInfo->getSlotSize(); + Offset += SlotSize; // Skip the RETADDR move area - const X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>(); int TailCallReturnAddrDelta = X86FI->getTCReturnAddrDelta(); if (TailCallReturnAddrDelta < 0) Offset -= TailCallReturnAddrDelta; } - return Offset; + return Offset + FPDelta; } int X86FrameLowering::getFrameIndexReference(const MachineFunction &MF, int FI, unsigned &FrameReg) const { - const X86RegisterInfo *RegInfo = - static_cast<const X86RegisterInfo *>(MF.getSubtarget().getRegisterInfo()); // We can't calculate offset from frame pointer if the stack is realigned, // so enforce usage of stack/base pointer. The base pointer is used when we // have dynamic allocas in addition to dynamic realignment. - if (RegInfo->hasBasePointer(MF)) - FrameReg = RegInfo->getBaseRegister(); - else if (RegInfo->needsStackRealignment(MF)) - FrameReg = RegInfo->getStackRegister(); + if (TRI->hasBasePointer(MF)) + FrameReg = TRI->getBaseRegister(); + else if (TRI->needsStackRealignment(MF)) + FrameReg = TRI->getStackRegister(); else - FrameReg = RegInfo->getFrameRegister(MF); + FrameReg = TRI->getFrameRegister(MF); return getFrameIndexOffset(MF, FI); } @@ -1220,8 +1215,6 @@ int X86FrameLowering::getFrameIndexOffsetFromSP(const MachineFunction &MF, int F const uint64_t StackSize = MFI->getStackSize(); { #ifndef NDEBUG - const X86RegisterInfo *RegInfo = - static_cast<const X86RegisterInfo*>(MF.getSubtarget().getRegisterInfo()); // Note: LLVM arranges the stack as: // Args > Saved RetPC (<--FP) > CSRs > dynamic alignment (<--BP) // > "Stack Slots" (<--SP) @@ -1233,7 +1226,7 @@ int X86FrameLowering::getFrameIndexOffsetFromSP(const MachineFunction &MF, int F // frame). As a result, THE RESULT OF THIS CALL IS MEANINGLESS FOR CSRs // AND FixedObjects IFF needsStackRealignment or hasVarSizedObject. - assert(!RegInfo->hasBasePointer(MF) && "we don't handle this case"); + assert(!TRI->hasBasePointer(MF) && "we don't handle this case"); // We don't handle tail calls, and shouldn't be seeing them // either. @@ -1275,14 +1268,12 @@ int X86FrameLowering::getFrameIndexOffsetFromSP(const MachineFunction &MF, int F return Offset + StackSize; } // Simplified from getFrameIndexReference keeping only StackPointer cases -int X86FrameLowering::getFrameIndexReferenceFromSP(const MachineFunction &MF, int FI, - unsigned &FrameReg) const { - const X86RegisterInfo *RegInfo = - static_cast<const X86RegisterInfo*>(MF.getSubtarget().getRegisterInfo()); - - assert(!RegInfo->hasBasePointer(MF) && "we don't handle this case"); +int X86FrameLowering::getFrameIndexReferenceFromSP(const MachineFunction &MF, + int FI, + unsigned &FrameReg) const { + assert(!TRI->hasBasePointer(MF) && "we don't handle this case"); - FrameReg = RegInfo->getStackRegister(); + FrameReg = TRI->getStackRegister(); return getFrameIndexOffsetFromSP(MF, FI); } @@ -1290,9 +1281,6 @@ bool X86FrameLowering::assignCalleeSavedSpillSlots( MachineFunction &MF, const TargetRegisterInfo *TRI, std::vector<CalleeSavedInfo> &CSI) const { MachineFrameInfo *MFI = MF.getFrameInfo(); - const X86RegisterInfo *RegInfo = - static_cast<const X86RegisterInfo *>(MF.getSubtarget().getRegisterInfo()); - unsigned SlotSize = RegInfo->getSlotSize(); X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>(); unsigned CalleeSavedFrameSize = 0; @@ -1306,7 +1294,7 @@ bool X86FrameLowering::assignCalleeSavedSpillSlots( // Since emitPrologue and emitEpilogue will handle spilling and restoring of // the frame register, we can delete it from CSI list and not have to worry // about avoiding it later. - unsigned FPReg = RegInfo->getFrameRegister(MF); + unsigned FPReg = TRI->getFrameRegister(MF); for (unsigned i = 0; i < CSI.size(); ++i) { if (TRI->regsOverlap(CSI[i].getReg(),FPReg)) { CSI.erase(CSI.begin() + i); @@ -1337,7 +1325,7 @@ bool X86FrameLowering::assignCalleeSavedSpillSlots( if (X86::GR64RegClass.contains(Reg) || X86::GR32RegClass.contains(Reg)) continue; - const TargetRegisterClass *RC = RegInfo->getMinimalPhysRegClass(Reg); + const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg); // ensure alignment SpillSlotOffset -= std::abs(SpillSlotOffset) % RC->getAlignment(); // spill into slot @@ -1357,10 +1345,6 @@ bool X86FrameLowering::spillCalleeSavedRegisters( const TargetRegisterInfo *TRI) const { DebugLoc DL = MBB.findDebugLoc(MI); - MachineFunction &MF = *MBB.getParent(); - const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo(); - const X86Subtarget &STI = MF.getTarget().getSubtarget<X86Subtarget>(); - // Push GPRs. It increases frame size. unsigned Opc = STI.is64Bit() ? X86::PUSH64r : X86::PUSH32r; for (unsigned i = CSI.size(); i != 0; --i) { @@ -1379,8 +1363,7 @@ bool X86FrameLowering::spillCalleeSavedRegisters( // It can be done by spilling XMMs to stack frame. for (unsigned i = CSI.size(); i != 0; --i) { unsigned Reg = CSI[i-1].getReg(); - if (X86::GR64RegClass.contains(Reg) || - X86::GR32RegClass.contains(Reg)) + if (X86::GR64RegClass.contains(Reg) || X86::GR32RegClass.contains(Reg)) continue; // Add the callee-saved register as live-in. It's killed at the spill. MBB.addLiveIn(Reg); @@ -1405,10 +1388,6 @@ bool X86FrameLowering::restoreCalleeSavedRegisters(MachineBasicBlock &MBB, DebugLoc DL = MBB.findDebugLoc(MI); - MachineFunction &MF = *MBB.getParent(); - const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo(); - const X86Subtarget &STI = MF.getTarget().getSubtarget<X86Subtarget>(); - // Reload XMMs from stack frame. for (unsigned i = 0, e = CSI.size(); i != e; ++i) { unsigned Reg = CSI[i].getReg(); @@ -1437,9 +1416,6 @@ void X86FrameLowering::processFunctionBeforeCalleeSavedScan(MachineFunction &MF, RegScavenger *RS) const { MachineFrameInfo *MFI = MF.getFrameInfo(); - const X86RegisterInfo *RegInfo = - static_cast<const X86RegisterInfo *>(MF.getSubtarget().getRegisterInfo()); - unsigned SlotSize = RegInfo->getSlotSize(); X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>(); int64_t TailCallReturnAddrDelta = X86FI->getTCReturnAddrDelta(); @@ -1459,8 +1435,8 @@ X86FrameLowering::processFunctionBeforeCalleeSavedScan(MachineFunction &MF, } // Spill the BasePtr if it's used. - if (RegInfo->hasBasePointer(MF)) - MF.getRegInfo().setPhysRegUsed(RegInfo->getBaseRegister()); + if (TRI->hasBasePointer(MF)) + MF.getRegInfo().setPhysRegUsed(TRI->getBaseRegister()); } static bool @@ -1515,15 +1491,10 @@ GetScratchRegister(bool Is64Bit, bool IsLP64, const MachineFunction &MF, bool Pr // limit. static const uint64_t kSplitStackAvailable = 256; -void -X86FrameLowering::adjustForSegmentedStacks(MachineFunction &MF) const { - MachineBasicBlock &prologueMBB = MF.front(); +void X86FrameLowering::adjustForSegmentedStacks( + MachineFunction &MF, MachineBasicBlock &PrologueMBB) const { MachineFrameInfo *MFI = MF.getFrameInfo(); - const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo(); uint64_t StackSize; - const X86Subtarget &STI = MF.getTarget().getSubtarget<X86Subtarget>(); - bool Is64Bit = STI.is64Bit(); - const bool IsLP64 = STI.isTarget64BitLP64(); unsigned TlsReg, TlsOffset; DebugLoc DL; @@ -1559,8 +1530,9 @@ X86FrameLowering::adjustForSegmentedStacks(MachineFunction &MF) const { // The MOV R10, RAX needs to be in a different block, since the RET we emit in // allocMBB needs to be last (terminating) instruction. - for (MachineBasicBlock::livein_iterator i = prologueMBB.livein_begin(), - e = prologueMBB.livein_end(); i != e; i++) { + for (MachineBasicBlock::livein_iterator i = PrologueMBB.livein_begin(), + e = PrologueMBB.livein_end(); + i != e; i++) { allocMBB->addLiveIn(*i); checkMBB->addLiveIn(*i); } @@ -1674,7 +1646,7 @@ X86FrameLowering::adjustForSegmentedStacks(MachineFunction &MF) const { // This jump is taken if SP >= (Stacklet Limit + Stack Space required). // It jumps to normal execution of the function body. - BuildMI(checkMBB, DL, TII.get(X86::JA_1)).addMBB(&prologueMBB); + BuildMI(checkMBB, DL, TII.get(X86::JA_1)).addMBB(&PrologueMBB); // On 32 bit we first push the arguments size and then the frame size. On 64 // bit, we pass the stack frame size in r10 and the argument size in r11. @@ -1741,10 +1713,10 @@ X86FrameLowering::adjustForSegmentedStacks(MachineFunction &MF) const { else BuildMI(allocMBB, DL, TII.get(X86::MORESTACK_RET)); - allocMBB->addSuccessor(&prologueMBB); + allocMBB->addSuccessor(&PrologueMBB); checkMBB->addSuccessor(allocMBB); - checkMBB->addSuccessor(&prologueMBB); + checkMBB->addSuccessor(&PrologueMBB); #ifdef XDEBUG MF.verify(); @@ -1766,15 +1738,9 @@ X86FrameLowering::adjustForSegmentedStacks(MachineFunction &MF) const { /// call inc_stack # doubles the stack space /// temp0 = sp - MaxStack /// if( temp0 < SP_LIMIT(P) ) goto IncStack else goto OldStart -void X86FrameLowering::adjustForHiPEPrologue(MachineFunction &MF) const { - const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo(); +void X86FrameLowering::adjustForHiPEPrologue( + MachineFunction &MF, MachineBasicBlock &PrologueMBB) const { MachineFrameInfo *MFI = MF.getFrameInfo(); - const unsigned SlotSize = - static_cast<const X86RegisterInfo *>(MF.getSubtarget().getRegisterInfo()) - ->getSlotSize(); - const X86Subtarget &STI = MF.getTarget().getSubtarget<X86Subtarget>(); - const bool Is64Bit = STI.is64Bit(); - const bool IsLP64 = STI.isTarget64BitLP64(); DebugLoc DL; // HiPE-specific values const unsigned HipeLeafWords = 24; @@ -1837,12 +1803,12 @@ void X86FrameLowering::adjustForHiPEPrologue(MachineFunction &MF) const { // If the stack frame needed is larger than the guaranteed then runtime checks // and calls to "inc_stack_0" BIF should be inserted in the assembly prologue. if (MaxStack > Guaranteed) { - MachineBasicBlock &prologueMBB = MF.front(); MachineBasicBlock *stackCheckMBB = MF.CreateMachineBasicBlock(); MachineBasicBlock *incStackMBB = MF.CreateMachineBasicBlock(); - for (MachineBasicBlock::livein_iterator I = prologueMBB.livein_begin(), - E = prologueMBB.livein_end(); I != E; I++) { + for (MachineBasicBlock::livein_iterator I = PrologueMBB.livein_begin(), + E = PrologueMBB.livein_end(); + I != E; I++) { stackCheckMBB->addLiveIn(*I); incStackMBB->addLiveIn(*I); } @@ -1878,7 +1844,7 @@ void X86FrameLowering::adjustForHiPEPrologue(MachineFunction &MF) const { // SPLimitOffset is in a fixed heap location (pointed by BP). addRegOffset(BuildMI(stackCheckMBB, DL, TII.get(CMPop)) .addReg(ScratchReg), PReg, false, SPLimitOffset); - BuildMI(stackCheckMBB, DL, TII.get(X86::JAE_1)).addMBB(&prologueMBB); + BuildMI(stackCheckMBB, DL, TII.get(X86::JAE_1)).addMBB(&PrologueMBB); // Create new MBB for IncStack: BuildMI(incStackMBB, DL, TII.get(CALLop)). @@ -1889,9 +1855,9 @@ void X86FrameLowering::adjustForHiPEPrologue(MachineFunction &MF) const { .addReg(ScratchReg), PReg, false, SPLimitOffset); BuildMI(incStackMBB, DL, TII.get(X86::JLE_1)).addMBB(incStackMBB); - stackCheckMBB->addSuccessor(&prologueMBB, 99); + stackCheckMBB->addSuccessor(&PrologueMBB, 99); stackCheckMBB->addSuccessor(incStackMBB, 1); - incStackMBB->addSuccessor(&prologueMBB, 99); + incStackMBB->addSuccessor(&PrologueMBB, 99); incStackMBB->addSuccessor(incStackMBB, 1); } #ifdef XDEBUG @@ -1902,15 +1868,9 @@ void X86FrameLowering::adjustForHiPEPrologue(MachineFunction &MF) const { void X86FrameLowering:: eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB, MachineBasicBlock::iterator I) const { - const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo(); - const X86RegisterInfo &RegInfo = *static_cast<const X86RegisterInfo *>( - MF.getSubtarget().getRegisterInfo()); - unsigned StackPtr = RegInfo.getStackRegister(); bool reserveCallFrame = hasReservedCallFrame(MF); - int Opcode = I->getOpcode(); + unsigned Opcode = I->getOpcode(); bool isDestroy = Opcode == TII.getCallFrameDestroyOpcode(); - const X86Subtarget &STI = MF.getTarget().getSubtarget<X86Subtarget>(); - bool IsLP64 = STI.isTarget64BitLP64(); DebugLoc DL = I->getDebugLoc(); uint64_t Amount = !reserveCallFrame ? I->getOperand(0).getImm() : 0; uint64_t InternalAmt = (isDestroy || Amount) ? I->getOperand(1).getImm() : 0; @@ -1926,60 +1886,44 @@ eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB, // 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 StackAlign = MF.getTarget() - .getSubtargetImpl() - ->getFrameLowering() - ->getStackAlignment(); - Amount = (Amount + StackAlign - 1) / StackAlign * StackAlign; - - MachineInstr *New = nullptr; + unsigned StackAlign = getStackAlignment(); + Amount = RoundUpToAlignment(Amount, StackAlign); // Factor out the amount that gets handled inside the sequence // (Pushes of argument for frame setup, callee pops for frame destroy) Amount -= InternalAmt; if (Amount) { - if (Opcode == TII.getCallFrameSetupOpcode()) { - New = BuildMI(MF, DL, TII.get(getSUBriOpcode(IsLP64, Amount)), StackPtr) - .addReg(StackPtr).addImm(Amount); - } else { - assert(Opcode == TII.getCallFrameDestroyOpcode()); - - unsigned Opc = getADDriOpcode(IsLP64, Amount); - New = BuildMI(MF, DL, TII.get(Opc), StackPtr) - .addReg(StackPtr).addImm(Amount); - } - } - - if (New) { - // The EFLAGS implicit def is dead. - New->getOperand(3).setIsDead(); - - // Replace the pseudo instruction with a new instruction. - MBB.insert(I, New); + // Add Amount to SP to destroy a frame, and subtract to setup. + int Offset = isDestroy ? Amount : -Amount; + BuildStackAdjustment(MBB, I, DL, Offset, /*InEpilogue=*/false); } - return; } - if (Opcode == TII.getCallFrameDestroyOpcode() && InternalAmt) { + if (isDestroy && InternalAmt) { // If we are performing frame pointer elimination and if the callee pops // something off the stack pointer, add it back. We do this until we have // more advanced stack pointer tracking ability. - unsigned Opc = getSUBriOpcode(IsLP64, InternalAmt); - MachineInstr *New = BuildMI(MF, DL, TII.get(Opc), StackPtr) - .addReg(StackPtr).addImm(InternalAmt); - - // The EFLAGS implicit def is dead. - New->getOperand(3).setIsDead(); - // We are not tracking the stack pointer adjustment by the callee, so make // sure we restore the stack pointer immediately after the call, there may // be spill code inserted between the CALL and ADJCALLSTACKUP instructions. MachineBasicBlock::iterator B = MBB.begin(); while (I != B && !std::prev(I)->isCall()) --I; - MBB.insert(I, New); + BuildStackAdjustment(MBB, I, DL, -InternalAmt, /*InEpilogue=*/false); } } +bool X86FrameLowering::canUseAsEpilogue(const MachineBasicBlock &MBB) const { + assert(MBB.getParent() && "Block is not attached to a function!"); + + if (canUseLEAForSPInEpilogue(*MBB.getParent())) + return true; + + // If we cannot use LEA to adjust SP, we may need to use ADD, which + // clobbers the EFLAGS. Check that none of the terminators reads the + // EFLAGS, and if one uses it, conservatively assume this is not + // safe to insert the epilogue here. + return !terminatorsNeedFlagsAsInput(MBB); +} |
