X-Git-Url: http://plrg.eecs.uci.edu/git/?p=oota-llvm.git;a=blobdiff_plain;f=lib%2FTarget%2FX86%2FX86FrameLowering.cpp;h=f049635a5fee3a806ab056b28e0cd3303fc676ab;hp=f64e5d45dfb602c3fbbcf52d979854e5dbd18e5a;hb=d3c9c4b30394bda99d7ffd0210c70f2cb28d0349;hpb=4c757e0907cb279d3e61d572d852fea50f3bf90c diff --git a/lib/Target/X86/X86FrameLowering.cpp b/lib/Target/X86/X86FrameLowering.cpp index f64e5d45dfb..f049635a5fe 100644 --- a/lib/Target/X86/X86FrameLowering.cpp +++ b/lib/Target/X86/X86FrameLowering.cpp @@ -18,27 +18,64 @@ #include "X86Subtarget.h" #include "X86TargetMachine.h" #include "llvm/ADT/SmallSet.h" +#include "llvm/Analysis/EHPersonalities.h" #include "llvm/CodeGen/MachineFrameInfo.h" #include "llvm/CodeGen/MachineFunction.h" #include "llvm/CodeGen/MachineInstrBuilder.h" #include "llvm/CodeGen/MachineModuleInfo.h" #include "llvm/CodeGen/MachineRegisterInfo.h" +#include "llvm/CodeGen/WinEHFuncInfo.h" #include "llvm/IR/DataLayout.h" #include "llvm/IR/Function.h" #include "llvm/MC/MCAsmInfo.h" #include "llvm/MC/MCSymbol.h" -#include "llvm/Support/CommandLine.h" #include "llvm/Target/TargetOptions.h" #include "llvm/Support/Debug.h" #include using namespace llvm; -// FIXME: completely move here. -extern cl::opt 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(); + return !MF.getFrameInfo()->hasVarSizedObjects() && + !MF.getInfo()->getHasPushSequences(); +} + +/// canSimplifyCallFramePseudos - If there is a reserved call frame, the +/// call frame pseudos can be simplified. Having a FP, as in the default +/// implementation, is not sufficient here since we can't always use it. +/// Use a more nuanced condition. +bool +X86FrameLowering::canSimplifyCallFramePseudos(const MachineFunction &MF) const { + return hasReservedCallFrame(MF) || + (hasFP(MF) && !TRI->needsStackRealignment(MF)) || + TRI->hasBasePointer(MF); +} + +// needsFrameIndexResolution - Do we need to perform FI resolution for +// this function. Normally, this is required only when the function +// has any stack objects. However, FI resolution actually has another job, +// not apparent from the title - it resolves callframesetup/destroy +// that were not simplified earlier. +// So, this is required for x86 functions that have push sequences even +// when there are no stack objects. +bool +X86FrameLowering::needsFrameIndexResolution(const MachineFunction &MF) const { + return MF.getFrameInfo()->hasStackObjects() || + MF.getInfo()->getHasPushSequences(); } /// hasFP - Return true if the specified function should have a dedicated frame @@ -47,14 +84,13 @@ bool X86FrameLowering::hasReservedCallFrame(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() || + MFI->isFrameAddressTaken() || MFI->hasOpaqueSPAdjustment() || MF.getInfo()->getForceFramePointer() || - MMI.callsUnwindInit() || MMI.callsEHReturn() || + MMI.callsUnwindInit() || MMI.hasEHFunclets() || MMI.callsEHReturn() || MFI->hasStackMap() || MFI->hasPatchPoint()); } @@ -101,16 +137,6 @@ static unsigned getANDriOpcode(bool IsLP64, int64_t Imm) { return X86::AND32ri; } -static unsigned getPUSHiOpcode(bool IsLP64, MachineOperand MO) { - // We don't support LP64 for now. - assert(!IsLP64); - - if (MO.isImm() && isInt<8>(MO.getImm())) - return X86::PUSH32i8; - - return X86::PUSHi32;; -} - static unsigned getLEArOpcode(unsigned IsLP64) { return IsLP64 ? X86::LEA64r : X86::LEA32r; } @@ -120,21 +146,14 @@ 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 X86RegisterInfo *TRI, bool Is64Bit) { const MachineFunction *MF = MBB.getParent(); const Function *F = MF->getFunction(); if (!F || MF->getMMI().callsEHReturn()) return 0; - static const uint16_t CallerSavedRegs32Bit[] = { - X86::EAX, X86::EDX, X86::ECX, 0 - }; - - static const uint16_t CallerSavedRegs64Bit[] = { - X86::RAX, X86::RDX, X86::RCX, X86::RSI, X86::RDI, - X86::R8, X86::R9, X86::R10, X86::R11, 0 - }; + const TargetRegisterClass &AvailableRegs = *TRI->getGPRsForTailCall(*MF); unsigned Opc = MBBI->getOpcode(); switch (Opc) { @@ -159,14 +178,13 @@ 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); } - const uint16_t *CS = Is64Bit ? CallerSavedRegs64Bit : CallerSavedRegs32Bit; - for (; *CS; ++CS) - if (!Uses.count(*CS)) - return *CS; + for (auto CS : AvailableRegs) + if (!Uses.count(CS) && CS != X86::RIP) + return CS; } } @@ -186,22 +204,52 @@ static bool isEAXLiveIn(MachineFunction &MF) { return false; } +/// Check if the flags need to be preserved before the terminators. +/// This would be the case, if the eflags is live-in of the region +/// composed by the terminators or live-out of that region, without +/// being defined by a terminator. +static bool +flagsNeedToBePreservedBeforeTheTerminators(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 eflags that is not defined + // by a previous another terminator: + // EFLAGS is live-in of the region composed by the terminators. + if (!MO.isDef()) + return true; + // This terminator defines the eflags, i.e., we don't need to preserve it. + // However, we still need to check this specific terminator does not + // read a live-in value. + BreakNext = true; + } + // We found a definition of the eflags, no need to preserve them. + if (BreakNext) + return false; + } + + // None of the terminators use or define the eflags. + // Check if they are live-out, that would imply we need to preserve them. + for (const MachineBasicBlock *Succ : MBB.successors()) + if (Succ->isLiveIn(X86::EFLAGS)) + return true; + + 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); @@ -213,17 +261,17 @@ void emitSPUpdate(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI, unsigned Reg = 0; if (isSub && !isEAXLiveIn(*MBB.getParent())) - Reg = (unsigned)(Is64BitTarget ? X86::RAX : X86::EAX); + Reg = (unsigned)(Is64Bit ? X86::RAX : X86::EAX); else - Reg = findDeadCallerSavedReg(MBB, MBBI, TRI, Is64BitTarget); + Reg = findDeadCallerSavedReg(MBB, MBBI, TRI, Is64Bit); if (Reg) { - Opc = Is64BitTarget ? X86::MOV64ri : X86::MOV32ri; + unsigned Opc = Is64Bit ? X86::MOV64ri : X86::MOV32ri; BuildMI(MBB, MBBI, DL, TII.get(Opc), Reg) .addImm(Offset); Opc = isSub - ? getSUBrrOpcode(Is64BitTarget) - : getADDrrOpcode(Is64BitTarget); + ? getSUBrrOpcode(Is64Bit) + : getADDrrOpcode(Is64Bit); MachineInstr *MI = BuildMI(MBB, MBBI, DL, TII.get(Opc), StackPtr) .addReg(StackPtr) .addReg(Reg); @@ -233,107 +281,89 @@ void emitSPUpdate(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI, } } - uint64_t ThisVal = (Offset > Chunk) ? Chunk : Offset; - if (ThisVal == (Is64BitTarget ? 8 : 4)) { + 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) MI->setFlag(MachineInstr::FrameSetup); + else + MI->setFlag(MachineInstr::FrameDestroy); Offset -= ThisVal; continue; } } - 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); + else + MI.setMIFlag(MachineInstr::FrameDestroy); Offset -= ThisVal; } } -/// mergeSPUpdatesUp - Merge two stack-manipulating instructions upper iterator. -static -void mergeSPUpdatesUp(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI, - unsigned StackPtr, uint64_t *NumBytes = nullptr) { - if (MBBI == MBB.begin()) return; - - MachineBasicBlock::iterator PI = std::prev(MBBI); - unsigned Opc = PI->getOpcode(); - if ((Opc == X86::ADD64ri32 || Opc == X86::ADD64ri8 || - Opc == X86::ADD32ri || Opc == X86::ADD32ri8 || - Opc == X86::LEA32r || Opc == X86::LEA64_32r) && - PI->getOperand(0).getReg() == StackPtr) { - if (NumBytes) - *NumBytes += PI->getOperand(2).getImm(); - MBB.erase(PI); - } else if ((Opc == X86::SUB64ri32 || Opc == X86::SUB64ri8 || - Opc == X86::SUB32ri || Opc == X86::SUB32ri8) && - PI->getOperand(0).getReg() == StackPtr) { - if (NumBytes) - *NumBytes -= PI->getOperand(2).getImm(); - MBB.erase(PI); +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) { + // Check if inserting the prologue at the beginning + // of MBB would require to use LEA operations. + // We need to use LEA operations if EFLAGS is live in, because + // it means an instruction will read it before it gets defined. + UseLEA = STI.useLeaForSP() || MBB.isLiveIn(X86::EFLAGS); + } 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 = flagsNeedToBePreservedBeforeTheTerminators(MBB); + // If that assert breaks, that means we do not do the right thing + // in canUseAsEpilogue. + assert((UseLEA || !flagsNeedToBePreservedBeforeTheTerminators(MBB)) && + "We shouldn't have allowed this insertion point"); } -} - -/// 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; + 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; } -/// 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; @@ -362,6 +392,15 @@ static int mergeSPUpdates(MachineBasicBlock &MBB, return Offset; } +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 X86FrameLowering::emitCalleeSavedFrameMoves(MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI, @@ -370,7 +409,6 @@ 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 &CSI = MFI->getCalleeSavedInfo(); @@ -383,11 +421,8 @@ 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)); } } @@ -408,13 +443,265 @@ static bool usesTheStack(const MachineFunction &MF) { return false; } -void X86FrameLowering::emitStackProbeCall(MachineFunction &MF, - MachineBasicBlock &MBB, - MachineBasicBlock::iterator MBBI, - DebugLoc DL) { - const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo(); - const X86Subtarget &STI = MF.getTarget().getSubtarget(); - bool Is64Bit = STI.is64Bit(); +MachineInstr *X86FrameLowering::emitStackProbe(MachineFunction &MF, + MachineBasicBlock &MBB, + MachineBasicBlock::iterator MBBI, + DebugLoc DL, + bool InProlog) const { + const X86Subtarget &STI = MF.getSubtarget(); + if (STI.isTargetWindowsCoreCLR()) { + if (InProlog) { + return emitStackProbeInlineStub(MF, MBB, MBBI, DL, true); + } else { + return emitStackProbeInline(MF, MBB, MBBI, DL, false); + } + } else { + return emitStackProbeCall(MF, MBB, MBBI, DL, InProlog); + } +} + +void X86FrameLowering::inlineStackProbe(MachineFunction &MF, + MachineBasicBlock &PrologMBB) const { + const StringRef ChkStkStubSymbol = "__chkstk_stub"; + MachineInstr *ChkStkStub = nullptr; + + for (MachineInstr &MI : PrologMBB) { + if (MI.isCall() && MI.getOperand(0).isSymbol() && + ChkStkStubSymbol == MI.getOperand(0).getSymbolName()) { + ChkStkStub = &MI; + break; + } + } + + if (ChkStkStub != nullptr) { + MachineBasicBlock::iterator MBBI = std::next(ChkStkStub->getIterator()); + assert(std::prev(MBBI).operator==(ChkStkStub) && + "MBBI expected after __chkstk_stub."); + DebugLoc DL = PrologMBB.findDebugLoc(MBBI); + emitStackProbeInline(MF, PrologMBB, MBBI, DL, true); + ChkStkStub->eraseFromParent(); + } +} + +MachineInstr *X86FrameLowering::emitStackProbeInline( + MachineFunction &MF, MachineBasicBlock &MBB, + MachineBasicBlock::iterator MBBI, DebugLoc DL, bool InProlog) const { + const X86Subtarget &STI = MF.getSubtarget(); + assert(STI.is64Bit() && "different expansion needed for 32 bit"); + assert(STI.isTargetWindowsCoreCLR() && "custom expansion expects CoreCLR"); + const TargetInstrInfo &TII = *STI.getInstrInfo(); + const BasicBlock *LLVM_BB = MBB.getBasicBlock(); + + // RAX contains the number of bytes of desired stack adjustment. + // The handling here assumes this value has already been updated so as to + // maintain stack alignment. + // + // We need to exit with RSP modified by this amount and execute suitable + // page touches to notify the OS that we're growing the stack responsibly. + // All stack probing must be done without modifying RSP. + // + // MBB: + // SizeReg = RAX; + // ZeroReg = 0 + // CopyReg = RSP + // Flags, TestReg = CopyReg - SizeReg + // FinalReg = !Flags.Ovf ? TestReg : ZeroReg + // LimitReg = gs magic thread env access + // if FinalReg >= LimitReg goto ContinueMBB + // RoundBB: + // RoundReg = page address of FinalReg + // LoopMBB: + // LoopReg = PHI(LimitReg,ProbeReg) + // ProbeReg = LoopReg - PageSize + // [ProbeReg] = 0 + // if (ProbeReg > RoundReg) goto LoopMBB + // ContinueMBB: + // RSP = RSP - RAX + // [rest of original MBB] + + // Set up the new basic blocks + MachineBasicBlock *RoundMBB = MF.CreateMachineBasicBlock(LLVM_BB); + MachineBasicBlock *LoopMBB = MF.CreateMachineBasicBlock(LLVM_BB); + MachineBasicBlock *ContinueMBB = MF.CreateMachineBasicBlock(LLVM_BB); + + MachineFunction::iterator MBBIter = std::next(MBB.getIterator()); + MF.insert(MBBIter, RoundMBB); + MF.insert(MBBIter, LoopMBB); + MF.insert(MBBIter, ContinueMBB); + + // Split MBB and move the tail portion down to ContinueMBB. + MachineBasicBlock::iterator BeforeMBBI = std::prev(MBBI); + ContinueMBB->splice(ContinueMBB->begin(), &MBB, MBBI, MBB.end()); + ContinueMBB->transferSuccessorsAndUpdatePHIs(&MBB); + + // Some useful constants + const int64_t ThreadEnvironmentStackLimit = 0x10; + const int64_t PageSize = 0x1000; + const int64_t PageMask = ~(PageSize - 1); + + // Registers we need. For the normal case we use virtual + // registers. For the prolog expansion we use RAX, RCX and RDX. + MachineRegisterInfo &MRI = MF.getRegInfo(); + const TargetRegisterClass *RegClass = &X86::GR64RegClass; + const unsigned SizeReg = InProlog ? (unsigned)X86::RAX + : MRI.createVirtualRegister(RegClass), + ZeroReg = InProlog ? (unsigned)X86::RCX + : MRI.createVirtualRegister(RegClass), + CopyReg = InProlog ? (unsigned)X86::RDX + : MRI.createVirtualRegister(RegClass), + TestReg = InProlog ? (unsigned)X86::RDX + : MRI.createVirtualRegister(RegClass), + FinalReg = InProlog ? (unsigned)X86::RDX + : MRI.createVirtualRegister(RegClass), + RoundedReg = InProlog ? (unsigned)X86::RDX + : MRI.createVirtualRegister(RegClass), + LimitReg = InProlog ? (unsigned)X86::RCX + : MRI.createVirtualRegister(RegClass), + JoinReg = InProlog ? (unsigned)X86::RCX + : MRI.createVirtualRegister(RegClass), + ProbeReg = InProlog ? (unsigned)X86::RCX + : MRI.createVirtualRegister(RegClass); + + // SP-relative offsets where we can save RCX and RDX. + int64_t RCXShadowSlot = 0; + int64_t RDXShadowSlot = 0; + + // If inlining in the prolog, save RCX and RDX. + // Future optimization: don't save or restore if not live in. + if (InProlog) { + // Compute the offsets. We need to account for things already + // pushed onto the stack at this point: return address, frame + // pointer (if used), and callee saves. + X86MachineFunctionInfo *X86FI = MF.getInfo(); + const int64_t CalleeSaveSize = X86FI->getCalleeSavedFrameSize(); + const bool HasFP = hasFP(MF); + RCXShadowSlot = 8 + CalleeSaveSize + (HasFP ? 8 : 0); + RDXShadowSlot = RCXShadowSlot + 8; + // Emit the saves. + addRegOffset(BuildMI(&MBB, DL, TII.get(X86::MOV64mr)), X86::RSP, false, + RCXShadowSlot) + .addReg(X86::RCX); + addRegOffset(BuildMI(&MBB, DL, TII.get(X86::MOV64mr)), X86::RSP, false, + RDXShadowSlot) + .addReg(X86::RDX); + } else { + // Not in the prolog. Copy RAX to a virtual reg. + BuildMI(&MBB, DL, TII.get(X86::MOV64rr), SizeReg).addReg(X86::RAX); + } + + // Add code to MBB to check for overflow and set the new target stack pointer + // to zero if so. + BuildMI(&MBB, DL, TII.get(X86::XOR64rr), ZeroReg) + .addReg(ZeroReg, RegState::Undef) + .addReg(ZeroReg, RegState::Undef); + BuildMI(&MBB, DL, TII.get(X86::MOV64rr), CopyReg).addReg(X86::RSP); + BuildMI(&MBB, DL, TII.get(X86::SUB64rr), TestReg) + .addReg(CopyReg) + .addReg(SizeReg); + BuildMI(&MBB, DL, TII.get(X86::CMOVB64rr), FinalReg) + .addReg(TestReg) + .addReg(ZeroReg); + + // FinalReg now holds final stack pointer value, or zero if + // allocation would overflow. Compare against the current stack + // limit from the thread environment block. Note this limit is the + // lowest touched page on the stack, not the point at which the OS + // will cause an overflow exception, so this is just an optimization + // to avoid unnecessarily touching pages that are below the current + // SP but already commited to the stack by the OS. + BuildMI(&MBB, DL, TII.get(X86::MOV64rm), LimitReg) + .addReg(0) + .addImm(1) + .addReg(0) + .addImm(ThreadEnvironmentStackLimit) + .addReg(X86::GS); + BuildMI(&MBB, DL, TII.get(X86::CMP64rr)).addReg(FinalReg).addReg(LimitReg); + // Jump if the desired stack pointer is at or above the stack limit. + BuildMI(&MBB, DL, TII.get(X86::JAE_1)).addMBB(ContinueMBB); + + // Add code to roundMBB to round the final stack pointer to a page boundary. + BuildMI(RoundMBB, DL, TII.get(X86::AND64ri32), RoundedReg) + .addReg(FinalReg) + .addImm(PageMask); + BuildMI(RoundMBB, DL, TII.get(X86::JMP_1)).addMBB(LoopMBB); + + // LimitReg now holds the current stack limit, RoundedReg page-rounded + // final RSP value. Add code to loopMBB to decrement LimitReg page-by-page + // and probe until we reach RoundedReg. + if (!InProlog) { + BuildMI(LoopMBB, DL, TII.get(X86::PHI), JoinReg) + .addReg(LimitReg) + .addMBB(RoundMBB) + .addReg(ProbeReg) + .addMBB(LoopMBB); + } + + addRegOffset(BuildMI(LoopMBB, DL, TII.get(X86::LEA64r), ProbeReg), JoinReg, + false, -PageSize); + + // Probe by storing a byte onto the stack. + BuildMI(LoopMBB, DL, TII.get(X86::MOV8mi)) + .addReg(ProbeReg) + .addImm(1) + .addReg(0) + .addImm(0) + .addReg(0) + .addImm(0); + BuildMI(LoopMBB, DL, TII.get(X86::CMP64rr)) + .addReg(RoundedReg) + .addReg(ProbeReg); + BuildMI(LoopMBB, DL, TII.get(X86::JNE_1)).addMBB(LoopMBB); + + MachineBasicBlock::iterator ContinueMBBI = ContinueMBB->getFirstNonPHI(); + + // If in prolog, restore RDX and RCX. + if (InProlog) { + addRegOffset(BuildMI(*ContinueMBB, ContinueMBBI, DL, TII.get(X86::MOV64rm), + X86::RCX), + X86::RSP, false, RCXShadowSlot); + addRegOffset(BuildMI(*ContinueMBB, ContinueMBBI, DL, TII.get(X86::MOV64rm), + X86::RDX), + X86::RSP, false, RDXShadowSlot); + } + + // Now that the probing is done, add code to continueMBB to update + // the stack pointer for real. + BuildMI(*ContinueMBB, ContinueMBBI, DL, TII.get(X86::SUB64rr), X86::RSP) + .addReg(X86::RSP) + .addReg(SizeReg); + + // Add the control flow edges we need. + MBB.addSuccessor(ContinueMBB); + MBB.addSuccessor(RoundMBB); + RoundMBB->addSuccessor(LoopMBB); + LoopMBB->addSuccessor(ContinueMBB); + LoopMBB->addSuccessor(LoopMBB); + + // Mark all the instructions added to the prolog as frame setup. + if (InProlog) { + for (++BeforeMBBI; BeforeMBBI != MBB.end(); ++BeforeMBBI) { + BeforeMBBI->setFlag(MachineInstr::FrameSetup); + } + for (MachineInstr &MI : *RoundMBB) { + MI.setFlag(MachineInstr::FrameSetup); + } + for (MachineInstr &MI : *LoopMBB) { + MI.setFlag(MachineInstr::FrameSetup); + } + for (MachineBasicBlock::iterator CMBBI = ContinueMBB->begin(); + CMBBI != ContinueMBBI; ++CMBBI) { + CMBBI->setFlag(MachineInstr::FrameSetup); + } + } + + // Possible TODO: physreg liveness for InProlog case. + + return ContinueMBBI; +} + +MachineInstr *X86FrameLowering::emitStackProbeCall( + MachineFunction &MF, MachineBasicBlock &MBB, + MachineBasicBlock::iterator MBBI, DebugLoc DL, bool InProlog) const { bool IsLargeCodeModel = MF.getTarget().getCodeModel() == CodeModel::Large; unsigned CallOp; @@ -436,6 +723,7 @@ void X86FrameLowering::emitStackProbeCall(MachineFunction &MF, Symbol = "_chkstk"; MachineInstrBuilder CI; + MachineBasicBlock::iterator ExpansionMBBI = std::prev(MBBI); // All current stack probes take AX and SP as input, clobber flags, and // preserve all registers. x86_64 probes leave RSP unmodified. @@ -465,6 +753,67 @@ void X86FrameLowering::emitStackProbeCall(MachineFunction &MF, .addReg(X86::RSP) .addReg(X86::RAX); } + + if (InProlog) { + // Apply the frame setup flag to all inserted instrs. + for (++ExpansionMBBI; ExpansionMBBI != MBBI; ++ExpansionMBBI) + ExpansionMBBI->setFlag(MachineInstr::FrameSetup); + } + + return MBBI; +} + +MachineInstr *X86FrameLowering::emitStackProbeInlineStub( + MachineFunction &MF, MachineBasicBlock &MBB, + MachineBasicBlock::iterator MBBI, DebugLoc DL, bool InProlog) const { + + assert(InProlog && "ChkStkStub called outside prolog!"); + + BuildMI(MBB, MBBI, DL, TII.get(X86::CALLpcrel32)) + .addExternalSymbol("__chkstk_stub"); + + return MBBI; +} + +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 (MF.getFunction()->hasFnAttribute("stackrealign")) { + 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, unsigned Reg, + uint64_t MaxAlign) const { + uint64_t Val = -MaxAlign; + unsigned AndOp = getANDriOpcode(Uses64BitFramePtr, Val); + MachineInstr *MI = BuildMI(MBB, MBBI, DL, TII.get(AndOp), Reg) + .addReg(Reg) + .addImm(Val) + .setMIFlag(MachineInstr::FrameSetup); + + // The EFLAGS implicit def is dead. + MI->getOperand(3).setIsDead(); } /// emitPrologue - Push callee-saved registers onto the stack, which @@ -551,52 +900,45 @@ 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() && + "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(MF.getSubtarget().getRegisterInfo()); - const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo(); MachineModuleInfo &MMI = MF.getMMI(); X86MachineFunctionInfo *X86FI = MF.getInfo(); - 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 IsFunclet = MBB.isEHFuncletEntry(); + EHPersonality Personality = EHPersonality::Unknown; + if (Fn->hasPersonalityFn()) + Personality = classifyEHPersonality(Fn->getPersonalityFn()); + bool FnHasClrFunclet = + MMI.hasEHFunclets() && Personality == EHPersonality::CoreCLR; + bool IsClrFunclet = IsFunclet && FnHasClrFunclet; bool HasFP = hasFP(MF); - const X86Subtarget &STI = MF.getTarget().getSubtarget(); - 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) : FramePtr; + unsigned BasePtr = TRI->getBaseRegister(); + + // Debug location must be unknown since the first debug location is used + // to determine the end of the prologue. 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); @@ -616,14 +958,13 @@ 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); @@ -634,14 +975,9 @@ 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: @@ -661,25 +997,45 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF) const { uint64_t NumBytes = 0; int stackGrowth = -SlotSize; + // Find the funclet establisher parameter + unsigned Establisher = X86::NoRegister; + if (IsClrFunclet) + Establisher = Uses64BitFramePtr ? X86::RCX : X86::ECX; + else if (IsFunclet) + Establisher = Uses64BitFramePtr ? X86::RDX : X86::EDX; + + if (IsWin64Prologue && IsFunclet && !IsClrFunclet) { + // Immediately spill establisher into the home slot. + // The runtime cares about this. + // MOV64mr %rdx, 16(%rsp) + unsigned MOVmr = Uses64BitFramePtr ? X86::MOV64mr : X86::MOV32mr; + addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(MOVmr)), StackPtr, true, 16) + .addReg(Establisher) + .setMIFlag(MachineInstr::FrameSetup); + MBB.addLiveIn(Establisher); + } + if (HasFP) { // 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; - 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. // Update the frame offset adjustment. - MFI->setOffsetAdjustment(-NumBytes); + if (!IsFunclet) + MFI->setOffsetAdjustment(-NumBytes); + else + assert(MFI->getOffsetAdjustment() == -(int)NumBytes && + "should calculate same local variable offset for funclets"); // Save EBP/RBP into the appropriate stack slot. BuildMI(MBB, MBBI, DL, TII.get(Is64Bit ? X86::PUSH64r : X86::PUSH32r)) @@ -690,54 +1046,61 @@ 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 && !IsFunclet) { + // 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); + if (NeedsDwarfCFI) { + // Mark effective beginning of when frame pointer becomes valid. + // Define the current CFA to use the EBP/RBP register. + unsigned DwarfFramePtr = TRI->getDwarfRegNum(MachineFramePtr, true); + BuildCFI(MBB, MBBI, DL, MCCFIInstruction::createDefCfaRegister( + nullptr, DwarfFramePtr)); + } } - // Mark the FramePtr as live-in in every block. - for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I) - I->addLiveIn(MachineFramePtr); + // Mark the FramePtr as live-in in every block. Don't do this again for + // funclet prologues. + if (!IsFunclet) { + for (MachineBasicBlock &EveryMBB : MF) + EveryMBB.addLiveIn(MachineFramePtr); + } } else { + assert(!IsFunclet && "funclets without FPs not yet implemented"); NumBytes = StackSize - X86FI->getCalleeSavedFrameSize(); } + // For EH funclets, only allocate enough space for outgoing calls. Save the + // NumBytes value that we would've used for the parent frame. + unsigned ParentFrameNumBytes = NumBytes; + if (IsFunclet) + NumBytes = getWinEHFuncletFrameSize(MF); + // Skip the callee-saved push instructions. bool PushedRegs = false; int StackOffset = 2 * stackGrowth; while (MBBI != MBB.end() && + MBBI->getFlag(MachineInstr::FrameSetup) && (MBBI->getOpcode() == X86::PUSH32r || MBBI->getOpcode() == X86::PUSH64r)) { PushedRegs = true; @@ -748,14 +1111,12 @@ 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); } @@ -763,28 +1124,16 @@ 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 && !IsFunclet && 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, StackPtr, 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. @@ -796,7 +1145,10 @@ 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 && !IsFunclet && TRI->needsStackRealignment(MF)) + AlignedNumBytes = RoundUpToAlignment(AlignedNumBytes, MaxAlign); + if (AlignedNumBytes >= StackProbeSize && UseStackProbe) { // Check whether EAX is livein for this function. bool isEAXAlive = isEAXLiveIn(MF); @@ -814,123 +1166,202 @@ 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. BuildMI(MBB, MBBI, DL, TII.get(X86::MOV32ri), X86::EAX) - .addImm(isEAXAlive ? NumBytes - 4 : NumBytes) - .setMIFlag(MachineInstr::FrameSetup); + .addImm(isEAXAlive ? NumBytes - 4 : NumBytes) + .setMIFlag(MachineInstr::FrameSetup); } - // Save a pointer to the MI where we set AX. - MachineBasicBlock::iterator SetRAX = MBBI; - --SetRAX; - // Call __chkstk, __chkstk_ms, or __alloca. - emitStackProbeCall(MF, MBB, MBBI, DL); - - // Apply the frame setup flag to all inserted instrs. - for (; SetRAX != MBBI; ++SetRAX) - SetRAX->setFlag(MachineInstr::FrameSetup); + emitStackProbe(MF, MBB, MBBI, DL, true); if (isEAXAlive) { // Restore EAX - MachineInstr *MI = addRegOffset(BuildMI(MF, DL, TII.get(X86::MOV32rm), - X86::EAX), - StackPtr, false, NumBytes - 4); + MachineInstr *MI = + addRegOffset(BuildMI(MF, DL, TII.get(X86::MOV32rm), X86::EAX), + StackPtr, false, NumBytes - 4); MI->setFlag(MachineInstr::FrameSetup); 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); - } + unsigned SPOrEstablisher; + if (IsFunclet) { + if (IsClrFunclet) { + // The establisher parameter passed to a CLR funclet is actually a pointer + // to the (mostly empty) frame of its nearest enclosing funclet; we have + // to find the root function establisher frame by loading the PSPSym from + // the intermediate frame. + unsigned PSPSlotOffset = getPSPSlotOffsetFromSP(MF); + MachinePointerInfo NoInfo; + MBB.addLiveIn(Establisher); + addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(X86::MOV64rm), Establisher), + Establisher, false, PSPSlotOffset) + .addMemOperand(MF.getMachineMemOperand( + NoInfo, MachineMemOperand::MOLoad, SlotSize, SlotSize)); + ; + // Save the root establisher back into the current funclet's (mostly + // empty) frame, in case a sub-funclet or the GC needs it. + addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(X86::MOV64mr)), StackPtr, + false, PSPSlotOffset) + .addReg(Establisher) + .addMemOperand( + MF.getMachineMemOperand(NoInfo, MachineMemOperand::MOStore | + MachineMemOperand::MOVolatile, + SlotSize, SlotSize)); + } + SPOrEstablisher = Establisher; + } else { + SPOrEstablisher = StackPtr; + } + + if (IsWin64Prologue && HasFP) { + // Set RBP to a small fixed offset from RSP. In the funclet case, we base + // this calculation on the incoming establisher, which holds the value of + // RSP from the parent frame at the end of the prologue. + SEHFrameOffset = calculateSetFPREG(ParentFrameNumBytes); + if (SEHFrameOffset) + addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(X86::LEA64r), FramePtr), + SPOrEstablisher, false, SEHFrameOffset); + else + BuildMI(MBB, MBBI, DL, TII.get(X86::MOV64rr), FramePtr) + .addReg(SPOrEstablisher); + // If this is not a funclet, emit the CFI describing our frame pointer. + if (NeedsWinCFI && !IsFunclet) { 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); - } + if (isAsynchronousEHPersonality(Personality)) + MF.getWinEHFuncInfo()->SEHSetFrameOffset = SEHFrameOffset; + } + } else if (IsFunclet && STI.is32Bit()) { + // Reset EBP / ESI to something good for funclets. + MBBI = restoreWin32EHStackPointers(MBB, MBBI, DL); + // If we're a catch funclet, we can be returned to via catchret. Save ESP + // into the registration node so that the runtime will restore it for us. + if (!MBB.isCleanupFuncletEntry()) { + assert(Personality == EHPersonality::MSVC_CXX); + unsigned FrameReg; + int FI = MF.getWinEHFuncInfo()->EHRegNodeFrameIndex; + int64_t EHRegOffset = getFrameIndexReference(MF, FI, FrameReg); + // ESP is the first field, so no extra displacement is needed. + addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(X86::MOV32mr)), FrameReg, + false, EHRegOffset) + .addReg(X86::ESP); } } - // 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)) { + unsigned IgnoredFrameReg; + int Offset = getFrameIndexReference(MF, FI, IgnoredFrameReg); + 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); + + if (FnHasClrFunclet && !IsFunclet) { + // Save the so-called Initial-SP (i.e. the value of the stack pointer + // immediately after the prolog) into the PSPSlot so that funclets + // and the GC can recover it. + unsigned PSPSlotOffset = getPSPSlotOffsetFromSP(MF); + auto PSPInfo = MachinePointerInfo::getFixedStack( + MF, MF.getWinEHFuncInfo()->PSPSymFrameIdx); + addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(X86::MOV64mr)), StackPtr, false, + PSPSlotOffset) + .addReg(StackPtr) + .addMemOperand(MF.getMachineMemOperand( + PSPInfo, MachineMemOperand::MOStore | MachineMemOperand::MOVolatile, + SlotSize, SlotSize)); + } + + // 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, SPOrEstablisher, MaxAlign); } + // We already dealt with stack realignment and funclets above. + if (IsFunclet && STI.is32Bit()) + return; + // 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) - .addReg(StackPtr) + .addReg(SPOrEstablisher) .setMIFlag(MachineInstr::FrameSetup); if (X86FI->getRestoreBasePointer()) { - // Stash value of base pointer. Saving RSP instead of EBP shortens dependence chain. + // Stash value of base pointer. Saving RSP instead of EBP shortens + // dependence chain. Used by SjLj EH. unsigned Opm = Uses64BitFramePtr ? X86::MOV64mr : X86::MOV32mr; addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(Opm)), FramePtr, true, X86FI->getRestoreBasePointerOffset()) - .addReg(StackPtr) + .addReg(SPOrEstablisher) .setMIFlag(MachineInstr::FrameSetup); } + + if (X86FI->getHasSEHFramePtrSave() && !IsFunclet) { + // Stash the value of the frame pointer relative to the base pointer for + // Win32 EH. This supports Win32 EH, which does the inverse of the above: + // it recovers the frame pointer from the base pointer rather than the + // other way around. + unsigned Opm = Uses64BitFramePtr ? X86::MOV64mr : X86::MOV32mr; + unsigned UsedReg; + int Offset = + getFrameIndexReference(MF, X86FI->getSEHFramePtrSaveIndex(), UsedReg); + assert(UsedReg == BasePtr); + addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(Opm)), UsedReg, true, Offset) + .addReg(FramePtr) + .setMIFlag(MachineInstr::FrameSetup); + } } if (((!HasFP && NumBytes) || PushedRegs) && NeedsDwarfCFI) { @@ -938,12 +1369,8 @@ 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. @@ -952,117 +1379,211 @@ 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); +} + +static bool isFuncletReturnInstr(MachineInstr *MI) { + switch (MI->getOpcode()) { + case X86::CATCHRET: + case X86::CLEANUPRET: + return true; + default: + return false; + } + llvm_unreachable("impossible"); +} + +// CLR funclets use a special "Previous Stack Pointer Symbol" slot on the +// stack. It holds a pointer to the bottom of the root function frame. The +// establisher frame pointer passed to a nested funclet may point to the +// (mostly empty) frame of its parent funclet, but it will need to find +// the frame of the root function to access locals. To facilitate this, +// every funclet copies the pointer to the bottom of the root function +// frame into a PSPSym slot in its own (mostly empty) stack frame. Using the +// same offset for the PSPSym in the root function frame that's used in the +// funclets' frames allows each funclet to dynamically accept any ancestor +// frame as its establisher argument (the runtime doesn't guarantee the +// immediate parent for some reason lost to history), and also allows the GC, +// which uses the PSPSym for some bookkeeping, to find it in any funclet's +// frame with only a single offset reported for the entire method. +unsigned +X86FrameLowering::getPSPSlotOffsetFromSP(const MachineFunction &MF) const { + const WinEHFuncInfo &Info = *MF.getWinEHFuncInfo(); + // getFrameIndexReferenceFromSP has an out ref parameter for the stack + // pointer register; pass a dummy that we ignore + unsigned SPReg; + int Offset = getFrameIndexReferenceFromSP(MF, Info.PSPSymFrameIdx, SPReg); + assert(Offset >= 0); + return static_cast(Offset); +} + +unsigned +X86FrameLowering::getWinEHFuncletFrameSize(const MachineFunction &MF) const { + // This is the size of the pushed CSRs. + unsigned CSSize = + MF.getInfo()->getCalleeSavedFrameSize(); + // This is the amount of stack a funclet needs to allocate. + unsigned UsedSize; + EHPersonality Personality = + classifyEHPersonality(MF.getFunction()->getPersonalityFn()); + if (Personality == EHPersonality::CoreCLR) { + // CLR funclets need to hold enough space to include the PSPSym, at the + // same offset from the stack pointer (immediately after the prolog) as it + // resides at in the main function. + UsedSize = getPSPSlotOffsetFromSP(MF) + SlotSize; + } else { + // Other funclets just need enough stack for outgoing call arguments. + UsedSize = MF.getFrameInfo()->getMaxCallFrameSize(); + } + // RBP is not included in the callee saved register block. After pushing RBP, + // everything is 16 byte aligned. Everything we allocate before an outgoing + // call must also be 16 byte aligned. + unsigned FrameSizeMinusRBP = + RoundUpToAlignment(CSSize + UsedSize, getStackAlignment()); + // Subtract out the size of the callee saved registers. This is how much stack + // each funclet will allocate. + return FrameSizeMinusRBP - CSSize; +} + void X86FrameLowering::emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const { const MachineFrameInfo *MFI = MF.getFrameInfo(); X86MachineFunctionInfo *X86FI = MF.getInfo(); - const X86RegisterInfo *RegInfo = - static_cast(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(); - 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(); + unsigned FramePtr = TRI->getFrameRegister(MF); + unsigned MachineFramePtr = + Is64BitILP32 ? getX86SubSuperRegister(FramePtr, MVT::i64) : FramePtr; - 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 - } + bool IsWin64Prologue = MF.getTarget().getMCAsmInfo()->usesWindowsCFI(); + bool NeedsWinCFI = + IsWin64Prologue && MF.getFunction()->needsUnwindTableEntry(); + bool IsFunclet = isFuncletReturnInstr(MBBI); + MachineBasicBlock *TargetMBB = nullptr; // 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 (MBBI->getOpcode() == X86::CATCHRET) { + // SEH shouldn't use catchret. + assert(!isAsynchronousEHPersonality( + classifyEHPersonality(MF.getFunction()->getPersonalityFn())) && + "SEH should not use CATCHRET"); - if (hasFP(MF)) { + NumBytes = getWinEHFuncletFrameSize(MF); + assert(hasFP(MF) && "EH funclets without FP not yet implemented"); + TargetMBB = MBBI->getOperand(0).getMBB(); + + // Pop EBP. + BuildMI(MBB, MBBI, DL, TII.get(Is64Bit ? X86::POP64r : X86::POP32r), + MachineFramePtr) + .setMIFlag(MachineInstr::FrameDestroy); + } else if (MBBI->getOpcode() == X86::CLEANUPRET) { + NumBytes = getWinEHFuncletFrameSize(MF); + assert(hasFP(MF) && "EH funclets without FP not yet implemented"); + BuildMI(MBB, MBBI, DL, TII.get(Is64Bit ? X86::POP64r : X86::POP32r), + MachineFramePtr) + .setMIFlag(MachineInstr::FrameDestroy); + } else 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, - TII.get(Is64Bit ? X86::POP64r : X86::POP32r), MachineFramePtr); + TII.get(Is64Bit ? X86::POP64r : X86::POP32r), MachineFramePtr) + .setMIFlag(MachineInstr::FrameDestroy); } else { NumBytes = StackSize - CSSize; } + uint64_t SEHStackAllocAmt = NumBytes; // Skip the callee-saved pop instructions. while (MBBI != MBB.begin()) { MachineBasicBlock::iterator PI = std::prev(MBBI); unsigned Opc = PI->getOpcode(); - if (Opc != X86::POP32r && Opc != X86::POP64r && Opc != X86::DBG_VALUE && - !PI->isTerminator()) + if ((Opc != X86::POP32r || !PI->getFlag(MachineInstr::FrameDestroy)) && + (Opc != X86::POP64r || !PI->getFlag(MachineInstr::FrameDestroy)) && + Opc != X86::DBG_VALUE && !PI->isTerminator()) break; --MBBI; } MachineBasicBlock::iterator FirstCSPop = MBBI; - DL = MBBI->getDebugLoc(); + if (TargetMBB) { + // Fill EAX/RAX with the address of the target block. + unsigned ReturnReg = STI.is64Bit() ? X86::RAX : X86::EAX; + if (STI.is64Bit()) { + // LEA64r TargetMBB(%rip), %rax + BuildMI(MBB, FirstCSPop, DL, TII.get(X86::LEA64r), ReturnReg) + .addReg(X86::RIP) + .addImm(0) + .addReg(0) + .addMBB(TargetMBB) + .addReg(0); + } else { + // MOV32ri $TargetMBB, %eax + BuildMI(MBB, FirstCSPop, DL, TII.get(X86::MOV32ri), ReturnReg) + .addMBB(TargetMBB); + } + // Record that we've taken the address of TargetMBB and no longer just + // reference it in a terminator. + TargetMBB->setHasAddressTaken(); + } + + if (MBBI != MBB.end()) + DL = MBBI->getDebugLoc(); // If there is an ADD32ri or SUB32ri of ESP immediately before this // instruction, merge the two instructions. if (NumBytes || MFI->hasVarSizedObjects()) - mergeSPUpdatesUp(MBB, MBBI, StackPtr, &NumBytes); + NumBytes += mergeSPUpdates(MBB, MBBI, true); // 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)) + // realigned. Don't do this if this was a funclet epilogue, since the funclets + // will not do realignment or dynamic stack allocation. + if ((TRI->needsStackRealignment(MF) || MFI->hasVarSizedObjects()) && + !IsFunclet) { + 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); @@ -1072,8 +1593,7 @@ 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; } @@ -1083,180 +1603,165 @@ 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(MF.getSubtarget().getRegisterInfo()); +// NOTE: this only has a subset of the full frame index logic. In +// particular, the FI < 0 and AfterFPPop logic is handled in +// X86RegisterInfo::eliminateFrameIndex, but not here. Possibly +// (probably?) it should be moved into here. +int X86FrameLowering::getFrameIndexReference(const MachineFunction &MF, int FI, + unsigned &FrameReg) const { const MachineFrameInfo *MFI = MF.getFrameInfo(); + + // 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 (TRI->hasBasePointer(MF)) + FrameReg = TRI->getBaseRegister(); + else if (TRI->needsStackRealignment(MF)) + FrameReg = TRI->getStackRegister(); + else + FrameReg = TRI->getFrameRegister(MF); + + // 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(); + unsigned CSSize = X86FI->getCalleeSavedFrameSize(); uint64_t StackSize = MFI->getStackSize(); + bool HasFP = hasFP(MF); + bool IsWin64Prologue = MF.getTarget().getMCAsmInfo()->usesWindowsCFI(); + int64_t FPDelta = 0; + + if (IsWin64Prologue) { + assert(!MFI->hasCalls() || (StackSize % 16) == 8); - if (RegInfo->hasBasePointer(MF)) { - assert (hasFP(MF) && "VLAs and dynamic stack realign, but no FP?!"); + // 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(); int TailCallReturnAddrDelta = X86FI->getTCReturnAddrDelta(); if (TailCallReturnAddrDelta < 0) Offset -= TailCallReturnAddrDelta; } - return Offset; -} - -int X86FrameLowering::getFrameIndexReference(const MachineFunction &MF, int FI, - unsigned &FrameReg) const { - const X86RegisterInfo *RegInfo = - static_cast(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(); - else - FrameReg = RegInfo->getFrameRegister(MF); - return getFrameIndexOffset(MF, FI); + return Offset + FPDelta; } -// Simplified from getFrameIndexOffset keeping only StackPointer cases -int X86FrameLowering::getFrameIndexOffsetFromSP(const MachineFunction &MF, int FI) const { +// Simplified from getFrameIndexReference keeping only StackPointer cases +int X86FrameLowering::getFrameIndexReferenceFromSP(const MachineFunction &MF, + int FI, + unsigned &FrameReg) const { const MachineFrameInfo *MFI = MF.getFrameInfo(); // Does not include any dynamic realign. const uint64_t StackSize = MFI->getStackSize(); { #ifndef NDEBUG - const X86RegisterInfo *RegInfo = - static_cast(MF.getSubtarget().getRegisterInfo()); - // Note: LLVM arranges the stack as: - // Args > Saved RetPC (<--FP) > CSRs > dynamic alignment (<--BP) - // > "Stack Slots" (<--SP) - // We can always address StackSlots from RSP. We can usually (unless - // needsStackRealignment) address CSRs from RSP, but sometimes need to - // address them from RBP. FixedObjects can be placed anywhere in the stack - // frame depending on their specific requirements (i.e. we can actually - // refer to arguments to the function which are stored in the *callers* - // 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"); - - // We don't handle tail calls, and shouldn't be seeing them - // either. + // LLVM arranges the stack as follows: + // ... + // ARG2 + // ARG1 + // RETADDR + // PUSH RBP <-- RBP points here + // PUSH CSRs + // ~~~~~~~ <-- possible stack realignment (non-win64) + // ... + // STACK OBJECTS + // ... <-- RSP after prologue points here + // ~~~~~~~ <-- possible stack realignment (win64) + // + // if (hasVarSizedObjects()): + // ... <-- "base pointer" (ESI/RBX) points here + // DYNAMIC ALLOCAS + // ... <-- RSP points here + // + // Case 1: In the simple case of no stack realignment and no dynamic + // allocas, both "fixed" stack objects (arguments and CSRs) are addressable + // with fixed offsets from RSP. + // + // Case 2: In the case of stack realignment with no dynamic allocas, fixed + // stack objects are addressed with RBP and regular stack objects with RSP. + // + // Case 3: In the case of dynamic allocas and stack realignment, RSP is used + // to address stack arguments for outgoing calls and nothing else. The "base + // pointer" points to local variables, and RBP points to fixed objects. + // + // In cases 2 and 3, we can only answer for non-fixed stack objects, and the + // answer we give is relative to the SP after the prologue, and not the + // SP in the middle of the function. + + assert((!MFI->isFixedObjectIndex(FI) || !TRI->needsStackRealignment(MF) || + STI.isTargetWin64()) && + "offset from fixed object to SP is not static"); + + // We don't handle tail calls, and shouldn't be seeing them either. int TailCallReturnAddrDelta = MF.getInfo()->getTCReturnAddrDelta(); assert(!(TailCallReturnAddrDelta < 0) && "we don't handle this case!"); #endif } + // Fill in FrameReg output argument. + FrameReg = TRI->getStackRegister(); + // This is how the math works out: // // %rsp grows (i.e. gets lower) left to right. Each box below is @@ -1288,25 +1793,11 @@ 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(MF.getSubtarget().getRegisterInfo()); - - assert(!RegInfo->hasBasePointer(MF) && "we don't handle this case"); - - FrameReg = RegInfo->getStackRegister(); - return getFrameIndexOffsetFromSP(MF, FI); -} bool X86FrameLowering::assignCalleeSavedSpillSlots( MachineFunction &MF, const TargetRegisterInfo *TRI, std::vector &CSI) const { MachineFrameInfo *MFI = MF.getFrameInfo(); - const X86RegisterInfo *RegInfo = - static_cast(MF.getSubtarget().getRegisterInfo()); - unsigned SlotSize = RegInfo->getSlotSize(); X86MachineFunctionInfo *X86FI = MF.getInfo(); unsigned CalleeSavedFrameSize = 0; @@ -1320,7 +1811,7 @@ 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); @@ -1351,7 +1842,7 @@ 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 @@ -1371,9 +1862,10 @@ 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(); + // Don't save CSRs in 32-bit EH funclets. The caller saves EBX, EBP, ESI, EDI + // for us, and there are no XMM CSRs on Win32. + if (MBB.isEHFuncletEntry() && STI.is32Bit() && STI.isOSWindows()) + return true; // Push GPRs. It increases frame size. unsigned Opc = STI.is64Bit() ? X86::PUSH64r : X86::PUSH32r; @@ -1393,8 +1885,7 @@ 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); @@ -1417,11 +1908,23 @@ bool X86FrameLowering::restoreCalleeSavedRegisters(MachineBasicBlock &MBB, if (CSI.empty()) return false; - DebugLoc DL = MBB.findDebugLoc(MI); + if (isFuncletReturnInstr(MI) && STI.isOSWindows()) { + // Don't restore CSRs in 32-bit EH funclets. Matches + // spillCalleeSavedRegisters. + if (STI.is32Bit()) + return true; + // Don't restore CSRs before an SEH catchret. SEH except blocks do not form + // funclets. emitEpilogue transforms these to normal jumps. + if (MI->getOpcode() == X86::CATCHRET) { + const Function *Func = MBB.getParent()->getFunction(); + bool IsSEH = isAsynchronousEHPersonality( + classifyEHPersonality(Func->getPersonalityFn())); + if (IsSEH) + return true; + } + } - MachineFunction &MF = *MBB.getParent(); - const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo(); - const X86Subtarget &STI = MF.getTarget().getSubtarget(); + DebugLoc DL = MBB.findDebugLoc(MI); // Reload XMMs from stack frame. for (unsigned i = 0, e = CSI.size(); i != e; ++i) { @@ -1442,18 +1945,18 @@ bool X86FrameLowering::restoreCalleeSavedRegisters(MachineBasicBlock &MBB, !X86::GR32RegClass.contains(Reg)) continue; - BuildMI(MBB, MI, DL, TII.get(Opc), Reg); + BuildMI(MBB, MI, DL, TII.get(Opc), Reg) + .setMIFlag(MachineInstr::FrameDestroy); } return true; } -void -X86FrameLowering::processFunctionBeforeCalleeSavedScan(MachineFunction &MF, - RegScavenger *RS) const { +void X86FrameLowering::determineCalleeSaves(MachineFunction &MF, + BitVector &SavedRegs, + RegScavenger *RS) const { + TargetFrameLowering::determineCalleeSaves(MF, SavedRegs, RS); + MachineFrameInfo *MFI = MF.getFrameInfo(); - const X86RegisterInfo *RegInfo = - static_cast(MF.getSubtarget().getRegisterInfo()); - unsigned SlotSize = RegInfo->getSlotSize(); X86MachineFunctionInfo *X86FI = MF.getInfo(); int64_t TailCallReturnAddrDelta = X86FI->getTCReturnAddrDelta(); @@ -1473,8 +1976,16 @@ X86FrameLowering::processFunctionBeforeCalleeSavedScan(MachineFunction &MF, } // Spill the BasePtr if it's used. - if (RegInfo->hasBasePointer(MF)) - MF.getRegInfo().setPhysRegUsed(RegInfo->getBaseRegister()); + if (TRI->hasBasePointer(MF)) { + SavedRegs.set(TRI->getBaseRegister()); + + // Allocate a spill slot for EBP if we have a base pointer and EH funclets. + if (MF.getMMI().hasEHFunclets()) { + int FI = MFI->CreateSpillStackObject(SlotSize, SlotSize); + X86FI->setHasSEHFramePtrSave(true); + X86FI->setSEHFramePtrSaveIndex(FI); + } + } } static bool @@ -1529,15 +2040,10 @@ 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(); - bool Is64Bit = STI.is64Bit(); - const bool IsLP64 = STI.isTarget64BitLP64(); unsigned TlsReg, TlsOffset; DebugLoc DL; @@ -1573,10 +2079,9 @@ 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++) { - allocMBB->addLiveIn(*i); - checkMBB->addLiveIn(*i); + for (const auto &LI : PrologueMBB.liveins()) { + allocMBB->addLiveIn(LI); + checkMBB->addLiveIn(LI); } if (IsNested) @@ -1688,7 +2193,7 @@ 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. @@ -1709,8 +2214,6 @@ X86FrameLowering::adjustForSegmentedStacks(MachineFunction &MF) const { .addImm(StackSize); BuildMI(allocMBB, DL, TII.get(MOVri), Reg11) .addImm(X86FI->getArgumentStackSize()); - MF.getRegInfo().setPhysRegUsed(Reg10); - MF.getRegInfo().setPhysRegUsed(Reg11); } else { BuildMI(allocMBB, DL, TII.get(X86::PUSHi32)) .addImm(X86FI->getArgumentStackSize()); @@ -1755,10 +2258,10 @@ 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(); @@ -1780,15 +2283,9 @@ 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(MF.getSubtarget().getRegisterInfo()) - ->getSlotSize(); - const X86Subtarget &STI = MF.getTarget().getSubtarget(); - const bool Is64Bit = STI.is64Bit(); - const bool IsLP64 = STI.isTarget64BitLP64(); DebugLoc DL; // HiPE-specific values const unsigned HipeLeafWords = 24; @@ -1851,14 +2348,12 @@ 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++) { - stackCheckMBB->addLiveIn(*I); - incStackMBB->addLiveIn(*I); + for (const auto &LI : PrologueMBB.liveins()) { + stackCheckMBB->addLiveIn(LI); + incStackMBB->addLiveIn(LI); } MF.push_front(incStackMBB); @@ -1892,7 +2387,7 @@ 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)). @@ -1903,197 +2398,318 @@ 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(incStackMBB, 1); - incStackMBB->addSuccessor(&prologueMBB, 99); - incStackMBB->addSuccessor(incStackMBB, 1); + stackCheckMBB->addSuccessor(&PrologueMBB, {99, 100}); + stackCheckMBB->addSuccessor(incStackMBB, {1, 100}); + incStackMBB->addSuccessor(&PrologueMBB, {99, 100}); + incStackMBB->addSuccessor(incStackMBB, {1, 100}); } #ifdef XDEBUG MF.verify(); #endif } -bool X86FrameLowering:: -convertArgMovsToPushes(MachineFunction &MF, MachineBasicBlock &MBB, - MachineBasicBlock::iterator I, uint64_t Amount) const { - const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo(); - const X86RegisterInfo &RegInfo = *static_cast( - MF.getSubtarget().getRegisterInfo()); - unsigned StackPtr = RegInfo.getStackRegister(); - - // Scan the call setup sequence for the pattern we're looking for. - // We only handle a simple case now - a sequence of MOV32mi or MOV32mr - // instructions, that push a sequence of 32-bit values onto the stack, with - // no gaps. - std::map MovMap; - do { - int Opcode = I->getOpcode(); - if (Opcode != X86::MOV32mi && Opcode != X86::MOV32mr) - break; - - // We only want movs of the form: - // movl imm/r32, k(%ecx) - // If we run into something else, bail - // Note that AddrBaseReg may, counterintuitively, not be a register... - if (!I->getOperand(X86::AddrBaseReg).isReg() || - (I->getOperand(X86::AddrBaseReg).getReg() != StackPtr) || - !I->getOperand(X86::AddrScaleAmt).isImm() || - (I->getOperand(X86::AddrScaleAmt).getImm() != 1) || - (I->getOperand(X86::AddrIndexReg).getReg() != X86::NoRegister) || - (I->getOperand(X86::AddrSegmentReg).getReg() != X86::NoRegister) || - !I->getOperand(X86::AddrDisp).isImm()) - return false; - - int64_t StackDisp = I->getOperand(X86::AddrDisp).getImm(); - - // We don't want to consider the unaligned case. - if (StackDisp % 4) - return false; +bool X86FrameLowering::adjustStackWithPops(MachineBasicBlock &MBB, + MachineBasicBlock::iterator MBBI, DebugLoc DL, int Offset) const { - // If the same stack slot is being filled twice, something's fishy. - if (!MovMap.insert(std::pair(StackDisp, I)).second) - return false; + if (Offset <= 0) + return false; - ++I; - } while (I != MBB.end()); + if (Offset % SlotSize) + return false; - // We now expect the end of the sequence - a call and a stack adjust. - if (I == MBB.end()) + int NumPops = Offset / SlotSize; + // This is only worth it if we have at most 2 pops. + if (NumPops != 1 && NumPops != 2) return false; - if (!I->isCall()) + + // Handle only the trivial case where the adjustment directly follows + // a call. This is the most common one, anyway. + if (MBBI == MBB.begin()) return false; - MachineBasicBlock::iterator Call = I; - if ((++I)->getOpcode() != TII.getCallFrameDestroyOpcode()) + MachineBasicBlock::iterator Prev = std::prev(MBBI); + if (!Prev->isCall() || !Prev->getOperand(1).isRegMask()) return false; - // Now, go through the map, and see that we don't have any gaps, - // but only a series of 32-bit MOVs. - // Since std::map provides ordered iteration, the original order - // of the MOVs doesn't matter. - int64_t ExpectedDist = 0; - for (auto MMI = MovMap.begin(), MME = MovMap.end(); MMI != MME; - ++MMI, ExpectedDist += 4) - if (MMI->first != ExpectedDist) - return false; + unsigned Regs[2]; + unsigned FoundRegs = 0; - // Ok, everything looks fine. Do the transformation. - DebugLoc DL = I->getDebugLoc(); + auto RegMask = Prev->getOperand(1); - // It's possible the original stack adjustment amount was larger than - // that done by the pushes. If so, we still need a SUB. - Amount -= ExpectedDist; - if (Amount) { - MachineInstr* Sub = BuildMI(MBB, Call, DL, - TII.get(getSUBriOpcode(false, Amount)), StackPtr) - .addReg(StackPtr).addImm(Amount); - Sub->getOperand(3).setIsDead(); - } + auto &RegClass = + Is64Bit ? X86::GR64_NOREX_NOSPRegClass : X86::GR32_NOREX_NOSPRegClass; + // Try to find up to NumPops free registers. + for (auto Candidate : RegClass) { + + // Poor man's liveness: + // Since we're immediately after a call, any register that is clobbered + // by the call and not defined by it can be considered dead. + if (!RegMask.clobbersPhysReg(Candidate)) + continue; - // Now, iterate through the map in reverse order, and replace the movs - // with pushes. MOVmi/MOVmr doesn't have any defs, so need to replace uses. - for (auto MMI = MovMap.rbegin(), MME = MovMap.rend(); MMI != MME; ++MMI) { - MachineBasicBlock::iterator MOV = MMI->second; - MachineOperand PushOp = MOV->getOperand(X86::AddrNumOperands); + bool IsDef = false; + for (const MachineOperand &MO : Prev->implicit_operands()) { + if (MO.isReg() && MO.isDef() && MO.getReg() == Candidate) { + IsDef = true; + break; + } + } - // Replace MOVmr with PUSH32r, and MOVmi with PUSHi of appropriate size - int PushOpcode = X86::PUSH32r; - if (MOV->getOpcode() == X86::MOV32mi) - PushOpcode = getPUSHiOpcode(false, PushOp); + if (IsDef) + continue; - BuildMI(MBB, Call, DL, TII.get(PushOpcode)).addOperand(PushOp); - MBB.erase(MOV); + Regs[FoundRegs++] = Candidate; + if (FoundRegs == (unsigned)NumPops) + break; } + if (FoundRegs == 0) + return false; + + // If we found only one free register, but need two, reuse the same one twice. + while (FoundRegs < (unsigned)NumPops) + Regs[FoundRegs++] = Regs[0]; + + for (int i = 0; i < NumPops; ++i) + BuildMI(MBB, MBBI, DL, + TII.get(STI.is64Bit() ? X86::POP64r : X86::POP32r), Regs[i]); + return true; } void X86FrameLowering:: eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB, MachineBasicBlock::iterator I) const { - const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo(); - const X86RegisterInfo &RegInfo = *static_cast( - 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(); - bool IsLP64 = STI.isTarget64BitLP64(); DebugLoc DL = I->getDebugLoc(); uint64_t Amount = !reserveCallFrame ? I->getOperand(0).getImm() : 0; - uint64_t CalleeAmt = isDestroy ? I->getOperand(1).getImm() : 0; + uint64_t InternalAmt = (isDestroy || Amount) ? I->getOperand(1).getImm() : 0; I = MBB.erase(I); if (!reserveCallFrame) { // If the stack pointer can be changed after prologue, turn the // adjcallstackup instruction into a 'sub ESP, ' and the // adjcallstackdown instruction into 'add ESP, ' - if (Amount == 0) - return; // 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; - if (Opcode == TII.getCallFrameSetupOpcode()) { - // Try to convert movs to the stack into pushes. - // We currently only look for a pattern that appears in 32-bit - // calling conventions. - if (!IsLP64 && convertArgMovsToPushes(MF, MBB, I, Amount)) - return; - - New = BuildMI(MF, DL, TII.get(getSUBriOpcode(IsLP64, Amount)), - StackPtr) - .addReg(StackPtr) - .addImm(Amount); - } else { - assert(Opcode == TII.getCallFrameDestroyOpcode()); + unsigned StackAlign = getStackAlignment(); + Amount = RoundUpToAlignment(Amount, StackAlign); + + MachineModuleInfo &MMI = MF.getMMI(); + const Function *Fn = MF.getFunction(); + bool WindowsCFI = MF.getTarget().getMCAsmInfo()->usesWindowsCFI(); + bool DwarfCFI = !WindowsCFI && + (MMI.hasDebugInfo() || Fn->needsUnwindTableEntry()); + + // If we have any exception handlers in this function, and we adjust + // the SP before calls, we may need to indicate this to the unwinder + // using GNU_ARGS_SIZE. Note that this may be necessary even when + // Amount == 0, because the preceding function may have set a non-0 + // GNU_ARGS_SIZE. + // TODO: We don't need to reset this between subsequent functions, + // if it didn't change. + bool HasDwarfEHHandlers = !WindowsCFI && + !MF.getMMI().getLandingPads().empty(); + + if (HasDwarfEHHandlers && !isDestroy && + MF.getInfo()->getHasPushSequences()) + BuildCFI(MBB, I, DL, + MCCFIInstruction::createGnuArgsSize(nullptr, Amount)); + + if (Amount == 0) + return; - // Factor out the amount the callee already popped. - Amount -= CalleeAmt; + // 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) { - unsigned Opc = getADDriOpcode(IsLP64, Amount); - New = BuildMI(MF, DL, TII.get(Opc), StackPtr) - .addReg(StackPtr).addImm(Amount); - } - } + // TODO: This is needed only if we require precise CFA. + // If this is a callee-pop calling convention, emit a CFA adjust for + // the amount the callee popped. + if (isDestroy && InternalAmt && DwarfCFI && !hasFP(MF)) + BuildCFI(MBB, I, DL, + MCCFIInstruction::createAdjustCfaOffset(nullptr, -InternalAmt)); - if (New) { - // The EFLAGS implicit def is dead. - New->getOperand(3).setIsDead(); + if (Amount) { + // Add Amount to SP to destroy a frame, and subtract to setup. + int Offset = isDestroy ? Amount : -Amount; - // Replace the pseudo instruction with a new instruction. - MBB.insert(I, New); + if (!(Fn->optForMinSize() && + adjustStackWithPops(MBB, I, DL, Offset))) + BuildStackAdjustment(MBB, I, DL, Offset, /*InEpilogue=*/false); + } + + if (DwarfCFI && !hasFP(MF)) { + // If we don't have FP, but need to generate unwind information, + // we need to set the correct CFA offset after the stack adjustment. + // How much we adjust the CFA offset depends on whether we're emitting + // CFI only for EH purposes or for debugging. EH only requires the CFA + // offset to be correct at each call site, while for debugging we want + // it to be more precise. + int CFAOffset = Amount; + // TODO: When not using precise CFA, we also need to adjust for the + // InternalAmt here. + + if (CFAOffset) { + CFAOffset = isDestroy ? -CFAOffset : CFAOffset; + BuildCFI(MBB, I, DL, + MCCFIInstruction::createAdjustCfaOffset(nullptr, CFAOffset)); + } } return; } - if (Opcode == TII.getCallFrameDestroyOpcode() && CalleeAmt) { + 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, CalleeAmt); - MachineInstr *New = BuildMI(MF, DL, TII.get(Opc), StackPtr) - .addReg(StackPtr).addImm(CalleeAmt); - - // 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!"); + + // Win64 has strict requirements in terms of epilogue and we are + // not taking a chance at messing with them. + // I.e., unless this block is already an exit block, we can't use + // it as an epilogue. + if (STI.isTargetWin64() && !MBB.succ_empty() && !MBB.isReturnBlock()) + return false; + + 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 we do not need to preserve it, + // otherwise, conservatively assume this is not + // safe to insert the epilogue here. + return !flagsNeedToBePreservedBeforeTheTerminators(MBB); +} + +bool X86FrameLowering::enableShrinkWrapping(const MachineFunction &MF) const { + // If we may need to emit frameless compact unwind information, give + // up as this is currently broken: PR25614. + return MF.getFunction()->hasFnAttribute(Attribute::NoUnwind) || hasFP(MF); +} + +MachineBasicBlock::iterator X86FrameLowering::restoreWin32EHStackPointers( + MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI, + DebugLoc DL, bool RestoreSP) const { + assert(STI.isTargetWindowsMSVC() && "funclets only supported in MSVC env"); + assert(STI.isTargetWin32() && "EBP/ESI restoration only required on win32"); + assert(STI.is32Bit() && !Uses64BitFramePtr && + "restoring EBP/ESI on non-32-bit target"); + + MachineFunction &MF = *MBB.getParent(); + unsigned FramePtr = TRI->getFrameRegister(MF); + unsigned BasePtr = TRI->getBaseRegister(); + WinEHFuncInfo &FuncInfo = *MF.getWinEHFuncInfo(); + X86MachineFunctionInfo *X86FI = MF.getInfo(); + MachineFrameInfo *MFI = MF.getFrameInfo(); + + // FIXME: Don't set FrameSetup flag in catchret case. + + int FI = FuncInfo.EHRegNodeFrameIndex; + int EHRegSize = MFI->getObjectSize(FI); + + if (RestoreSP) { + // MOV32rm -EHRegSize(%ebp), %esp + addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(X86::MOV32rm), X86::ESP), + X86::EBP, true, -EHRegSize) + .setMIFlag(MachineInstr::FrameSetup); + } + + unsigned UsedReg; + int EHRegOffset = getFrameIndexReference(MF, FI, UsedReg); + int EndOffset = -EHRegOffset - EHRegSize; + FuncInfo.EHRegNodeEndOffset = EndOffset; + + if (UsedReg == FramePtr) { + // ADD $offset, %ebp + unsigned ADDri = getADDriOpcode(false, EndOffset); + BuildMI(MBB, MBBI, DL, TII.get(ADDri), FramePtr) + .addReg(FramePtr) + .addImm(EndOffset) + .setMIFlag(MachineInstr::FrameSetup) + ->getOperand(3) + .setIsDead(); + assert(EndOffset >= 0 && + "end of registration object above normal EBP position!"); + } else if (UsedReg == BasePtr) { + // LEA offset(%ebp), %esi + addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(X86::LEA32r), BasePtr), + FramePtr, false, EndOffset) + .setMIFlag(MachineInstr::FrameSetup); + // MOV32rm SavedEBPOffset(%esi), %ebp + assert(X86FI->getHasSEHFramePtrSave()); + int Offset = + getFrameIndexReference(MF, X86FI->getSEHFramePtrSaveIndex(), UsedReg); + assert(UsedReg == BasePtr); + addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(X86::MOV32rm), FramePtr), + UsedReg, true, Offset) + .setMIFlag(MachineInstr::FrameSetup); + } else { + llvm_unreachable("32-bit frames with WinEH must use FramePtr or BasePtr"); + } + return MBBI; +} + +unsigned X86FrameLowering::getWinEHParentFrameOffset(const MachineFunction &MF) const { + // RDX, the parent frame pointer, is homed into 16(%rsp) in the prologue. + unsigned Offset = 16; + // RBP is immediately pushed. + Offset += SlotSize; + // All callee-saved registers are then pushed. + Offset += MF.getInfo()->getCalleeSavedFrameSize(); + // Every funclet allocates enough stack space for the largest outgoing call. + Offset += getWinEHFuncletFrameSize(MF); + return Offset; +} + +void X86FrameLowering::processFunctionBeforeFrameFinalized( + MachineFunction &MF, RegScavenger *RS) const { + // If this function isn't doing Win64-style C++ EH, we don't need to do + // anything. + const Function *Fn = MF.getFunction(); + if (!STI.is64Bit() || !MF.getMMI().hasEHFunclets() || + classifyEHPersonality(Fn->getPersonalityFn()) != EHPersonality::MSVC_CXX) + return; + + // Win64 C++ EH needs to allocate the UnwindHelp object at some fixed offset + // relative to RSP after the prologue. Find the offset of the last fixed + // object, so that we can allocate a slot immediately following it. If there + // were no fixed objects, use offset -SlotSize, which is immediately after the + // return address. Fixed objects have negative frame indices. + MachineFrameInfo *MFI = MF.getFrameInfo(); + int64_t MinFixedObjOffset = -SlotSize; + for (int I = MFI->getObjectIndexBegin(); I < 0; ++I) + MinFixedObjOffset = std::min(MinFixedObjOffset, MFI->getObjectOffset(I)); + + int64_t UnwindHelpOffset = MinFixedObjOffset - SlotSize; + int UnwindHelpFI = + MFI->CreateFixedObject(SlotSize, UnwindHelpOffset, /*Immutable=*/false); + MF.getWinEHFuncInfo()->UnwindHelpFrameIdx = UnwindHelpFI; + + // Store -2 into UnwindHelp on function entry. We have to scan forwards past + // other frame setup instructions. + MachineBasicBlock &MBB = MF.front(); + auto MBBI = MBB.begin(); + while (MBBI != MBB.end() && MBBI->getFlag(MachineInstr::FrameSetup)) + ++MBBI; + + DebugLoc DL = MBB.findDebugLoc(MBBI); + addFrameReference(BuildMI(MBB, MBBI, DL, TII.get(X86::MOV64mi32)), + UnwindHelpFI) + .addImm(-2); +}