diff options
Diffstat (limited to 'lib/Target/X86/X86FrameLowering.cpp')
| -rw-r--r-- | lib/Target/X86/X86FrameLowering.cpp | 1162 |
1 files changed, 969 insertions, 193 deletions
diff --git a/lib/Target/X86/X86FrameLowering.cpp b/lib/Target/X86/X86FrameLowering.cpp index 3a21b57f0157..242d0333ef9a 100644 --- a/lib/Target/X86/X86FrameLowering.cpp +++ b/lib/Target/X86/X86FrameLowering.cpp @@ -18,25 +18,23 @@ #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 <cstdlib> using namespace llvm; -// FIXME: completely move here. -extern cl::opt<bool> ForceStackAlign; - X86FrameLowering::X86FrameLowering(const X86Subtarget &STI, unsigned StackAlignOverride) : TargetFrameLowering(StackGrowsDown, StackAlignOverride, @@ -80,6 +78,27 @@ X86FrameLowering::needsFrameIndexResolution(const MachineFunction &MF) const { MF.getInfo<X86MachineFunctionInfo>()->getHasPushSequences(); } +/// usesTheStack - This function checks if any of the users of EFLAGS +/// copies the EFLAGS. We know that the code that lowers COPY of EFLAGS has +/// to use the stack, and if we don't adjust the stack we clobber the first +/// frame index. +/// See X86InstrInfo::copyPhysReg. +static bool usesTheStack(const MachineFunction &MF) { + const MachineRegisterInfo &MRI = MF.getRegInfo(); + + // Conservativley assume that inline assembly might use the stack. + if (MF.hasInlineAsm()) + return true; + + return any_of(MRI.reg_instructions(X86::EFLAGS), + [](const MachineInstr &RI) { return RI.isCopy(); }); +} + +static bool doesStackUseImplyFP(const MachineFunction &MF) { + bool IsWin64Prologue = MF.getTarget().getMCAsmInfo()->usesWindowsCFI(); + return IsWin64Prologue && usesTheStack(MF); +} + /// hasFP - Return true if the specified function should have a dedicated frame /// pointer register. This is true if the function has variable sized allocas /// or if frame pointer elimination is disabled. @@ -92,8 +111,9 @@ bool X86FrameLowering::hasFP(const MachineFunction &MF) const { MFI->hasVarSizedObjects() || MFI->isFrameAddressTaken() || MFI->hasOpaqueSPAdjustment() || MF.getInfo<X86MachineFunctionInfo>()->getForceFramePointer() || - MMI.callsUnwindInit() || MMI.callsEHReturn() || - MFI->hasStackMap() || MFI->hasPatchPoint()); + MMI.callsUnwindInit() || MMI.hasEHFunclets() || MMI.callsEHReturn() || + MFI->hasStackMap() || MFI->hasPatchPoint() || + doesStackUseImplyFP(MF)); } static unsigned getSUBriOpcode(unsigned IsLP64, int64_t Imm) { @@ -148,21 +168,14 @@ 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) { @@ -191,10 +204,9 @@ static unsigned findDeadCallerSavedReg(MachineBasicBlock &MBB, 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; } } @@ -214,8 +226,12 @@ static bool isEAXLiveIn(MachineFunction &MF) { return false; } -/// Check whether or not the terminators of \p MBB needs to read EFLAGS. -static bool terminatorsNeedFlagsAsInput(const MachineBasicBlock &MBB) { +/// 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()) { @@ -225,15 +241,27 @@ static bool terminatorsNeedFlagsAsInput(const MachineBasicBlock &MBB) { if (Reg != X86::EFLAGS) continue; - // This terminator needs an eflag that is not defined - // by a previous terminator. + // 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) - break; + 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; } @@ -289,6 +317,8 @@ void X86FrameLowering::emitSPUpdate(MachineBasicBlock &MBB, .addReg(Reg, getDefRegState(!isSub) | getUndefRegState(isSub)); if (isSub) MI->setFlag(MachineInstr::FrameSetup); + else + MI->setFlag(MachineInstr::FrameDestroy); Offset -= ThisVal; continue; } @@ -298,6 +328,8 @@ void X86FrameLowering::emitSPUpdate(MachineBasicBlock &MBB, MBB, MBBI, DL, isSub ? -ThisVal : ThisVal, InEpilogue); if (isSub) MI.setMIFlag(MachineInstr::FrameSetup); + else + MI.setMIFlag(MachineInstr::FrameDestroy); Offset -= ThisVal; } @@ -312,7 +344,11 @@ MachineInstrBuilder X86FrameLowering::BuildStackAdjustment( // is tricky. bool UseLEA; if (!InEpilogue) { - UseLEA = STI.useLeaForSP(); + // 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 @@ -321,10 +357,10 @@ MachineInstrBuilder X86FrameLowering::BuildStackAdjustment( // and is an optimization anyway. UseLEA = canUseLEAForSPInEpilogue(*MBB.getParent()); if (UseLEA && !STI.useLeaForSP()) - UseLEA = terminatorsNeedFlagsAsInput(MBB); + UseLEA = flagsNeedToBePreservedBeforeTheTerminators(MBB); // If that assert breaks, that means we do not do the right thing // in canUseAsEpilogue. - assert((UseLEA || !terminatorsNeedFlagsAsInput(MBB)) && + assert((UseLEA || !flagsNeedToBePreservedBeforeTheTerminators(MBB)) && "We shouldn't have allowed this insertion point"); } @@ -347,30 +383,6 @@ MachineInstrBuilder X86FrameLowering::BuildStackAdjustment( return MI; } -/// 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); - } -} - int X86FrameLowering::mergeSPUpdates(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI, bool doMergeWithPrevious) const { @@ -436,27 +448,265 @@ X86FrameLowering::emitCalleeSavedFrameMoves(MachineBasicBlock &MBB, } } -/// usesTheStack - This function checks if any of the users of EFLAGS -/// copies the EFLAGS. We know that the code that lowers COPY of EFLAGS has -/// to use the stack, and if we don't adjust the stack we clobber the first -/// frame index. -/// See X86InstrInfo::copyPhysReg. -static bool usesTheStack(const MachineFunction &MF) { - const MachineRegisterInfo &MRI = MF.getRegInfo(); +MachineInstr *X86FrameLowering::emitStackProbe(MachineFunction &MF, + MachineBasicBlock &MBB, + MachineBasicBlock::iterator MBBI, + DebugLoc DL, + bool InProlog) const { + const X86Subtarget &STI = MF.getSubtarget<X86Subtarget>(); + 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); + } +} - for (MachineRegisterInfo::reg_instr_iterator - ri = MRI.reg_instr_begin(X86::EFLAGS), re = MRI.reg_instr_end(); - ri != re; ++ri) - if (ri->isCopy()) - return true; +void X86FrameLowering::inlineStackProbe(MachineFunction &MF, + MachineBasicBlock &PrologMBB) const { + const StringRef ChkStkStubSymbol = "__chkstk_stub"; + MachineInstr *ChkStkStub = nullptr; - return false; + 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(); + } } -void X86FrameLowering::emitStackProbeCall(MachineFunction &MF, - MachineBasicBlock &MBB, - MachineBasicBlock::iterator MBBI, - DebugLoc DL) const { +MachineInstr *X86FrameLowering::emitStackProbeInline( + MachineFunction &MF, MachineBasicBlock &MBB, + MachineBasicBlock::iterator MBBI, DebugLoc DL, bool InProlog) const { + const X86Subtarget &STI = MF.getSubtarget<X86Subtarget>(); + 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<X86MachineFunctionInfo>(); + 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; @@ -478,6 +728,7 @@ 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. @@ -507,6 +758,26 @@ 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) { @@ -526,7 +797,7 @@ uint64_t X86FrameLowering::calculateMaxStackAlign(const MachineFunction &MF) con const MachineFrameInfo *MFI = MF.getFrameInfo(); uint64_t MaxAlign = MFI->getMaxAlignment(); // Desired stack alignment. unsigned StackAlign = getStackAlignment(); - if (ForceStackAlign) { + if (MF.getFunction()->hasFnAttribute("stackrealign")) { if (MFI->hasCalls()) MaxAlign = (StackAlign > MaxAlign) ? StackAlign : MaxAlign; else if (MaxAlign < SlotSize) @@ -537,15 +808,14 @@ uint64_t X86FrameLowering::calculateMaxStackAlign(const MachineFunction &MF) con void X86FrameLowering::BuildStackAlignAND(MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI, - DebugLoc DL, + DebugLoc DL, unsigned Reg, uint64_t MaxAlign) const { uint64_t Val = -MaxAlign; - MachineInstr *MI = - BuildMI(MBB, MBBI, DL, TII.get(getANDriOpcode(Uses64BitFramePtr, Val)), - StackPtr) - .addReg(StackPtr) - .addImm(Val) - .setMIFlag(MachineInstr::FrameSetup); + 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(); @@ -646,6 +916,13 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF, X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>(); 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); bool IsWin64CC = STI.isCallingConvWin64(Fn->getCallingConv()); bool IsWin64Prologue = MF.getTarget().getMCAsmInfo()->usesWindowsCFI(); @@ -655,9 +932,11 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF, unsigned FramePtr = TRI->getFrameRegister(MF); const unsigned MachineFramePtr = STI.isTarget64BitILP32() - ? getX86SubSuperRegister(FramePtr, MVT::i64, false) - : FramePtr; + ? getX86SubSuperRegister(FramePtr, 64) : 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; // Add RETADDR move area to callee saved frame size. @@ -723,6 +1002,24 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF, 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; @@ -739,7 +1036,11 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF, // 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)) @@ -765,35 +1066,46 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF, .setMIFlag(MachineInstr::FrameSetup); } - if (!IsWin64Prologue) { + 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 = TRI->getDwarfRegNum(MachineFramePtr, true); - BuildCFI(MBB, MBBI, DL, - MCCFIInstruction::createDefCfaRegister(nullptr, DwarfFramePtr)); + 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; @@ -818,9 +1130,9 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF, // Realign stack after we pushed callee-saved registers (so that we'll be // able to calculate their offsets from the frame pointer). // Don't do this for Win64, it needs to realign the stack after the prologue. - if (!IsWin64Prologue && TRI->needsStackRealignment(MF)) { + if (!IsWin64Prologue && !IsFunclet && TRI->needsStackRealignment(MF)) { assert(HasFP && "There should be a frame pointer if stack is realigned."); - BuildStackAlignAND(MBB, MBBI, DL, MaxAlign); + BuildStackAlignAND(MBB, MBBI, DL, StackPtr, MaxAlign); } // If there is an SUB32ri of ESP immediately before this instruction, merge @@ -839,7 +1151,7 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF, // increments is necessary to ensure that the guard pages used by the OS // virtual memory manager are allocated in correct sequence. uint64_t AlignedNumBytes = NumBytes; - if (IsWin64Prologue && TRI->needsStackRealignment(MF)) + if (IsWin64Prologue && !IsFunclet && TRI->needsStackRealignment(MF)) AlignedNumBytes = RoundUpToAlignment(AlignedNumBytes, MaxAlign); if (AlignedNumBytes >= StackProbeSize && UseStackProbe) { // Check whether EAX is livein for this function. @@ -876,26 +1188,18 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF, // 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); } @@ -909,19 +1213,72 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF, .setMIFlag(MachineInstr::FrameSetup); int SEHFrameOffset = 0; + 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) { - SEHFrameOffset = calculateSetFPREG(NumBytes); + // 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), - StackPtr, false, SEHFrameOffset); + SPOrEstablisher, false, SEHFrameOffset); else - BuildMI(MBB, MBBI, DL, TII.get(X86::MOV64rr), FramePtr).addReg(StackPtr); + BuildMI(MBB, MBBI, DL, TII.get(X86::MOV64rr), FramePtr) + .addReg(SPOrEstablisher); - if (NeedsWinCFI) + // 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); + 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); + } } while (MBBI != MBB.end() && MBBI->getFlag(MachineInstr::FrameSetup)) { @@ -932,7 +1289,8 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF, int FI; if (unsigned Reg = TII.isStoreToStackSlot(FrameInstr, FI)) { if (X86::FR64RegClass.contains(Reg)) { - int Offset = getFrameIndexOffset(MF, FI); + unsigned IgnoredFrameReg; + int Offset = getFrameIndexReference(MF, FI, IgnoredFrameReg); Offset += SEHFrameOffset; BuildMI(MBB, MBBI, DL, TII.get(X86::SEH_SaveXMM)) @@ -948,14 +1306,33 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF, 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, MaxAlign); + 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 @@ -964,7 +1341,7 @@ void X86FrameLowering::emitPrologue(MachineFunction &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 @@ -972,18 +1349,21 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF, 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()) { + 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; - addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(Opm)), BasePtr, true, - getFrameIndexOffset(MF, X86FI->getSEHFramePtrSaveIndex())) + 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); } @@ -1015,6 +1395,69 @@ bool X86FrameLowering::canUseLEAForSPInEpilogue( 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<unsigned>(Offset); +} + +unsigned +X86FrameLowering::getWinEHFuncletFrameSize(const MachineFunction &MF) const { + // This is the size of the pushed CSRs. + unsigned CSSize = + MF.getInfo<X86MachineFunctionInfo>()->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(); @@ -1027,12 +1470,13 @@ void X86FrameLowering::emitEpilogue(MachineFunction &MF, const bool Is64BitILP32 = STI.isTarget64BitILP32(); unsigned FramePtr = TRI->getFrameRegister(MF); unsigned MachineFramePtr = - Is64BitILP32 ? getX86SubSuperRegister(FramePtr, MVT::i64, false) - : FramePtr; + Is64BitILP32 ? getX86SubSuperRegister(FramePtr, 64) : FramePtr; 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(); @@ -1040,7 +1484,27 @@ void X86FrameLowering::emitEpilogue(MachineFunction &MF, unsigned CSSize = X86FI->getCalleeSavedFrameSize(); uint64_t NumBytes = 0; - if (hasFP(MF)) { + if (MBBI->getOpcode() == X86::CATCHRET) { + // SEH shouldn't use catchret. + assert(!isAsynchronousEHPersonality( + classifyEHPersonality(MF.getFunction()->getPersonalityFn())) && + "SEH should not use CATCHRET"); + + 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; NumBytes = FrameSize - CSSize; @@ -1052,7 +1516,8 @@ void X86FrameLowering::emitEpilogue(MachineFunction &MF, // 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; } @@ -1063,26 +1528,50 @@ void X86FrameLowering::emitEpilogue(MachineFunction &MF, 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; + 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 (TRI->needsStackRealignment(MF) || MFI->hasVarSizedObjects()) { + // 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; unsigned SEHFrameOffset = calculateSetFPREG(SEHStackAllocAmt); @@ -1134,9 +1623,24 @@ void X86FrameLowering::emitEpilogue(MachineFunction &MF, } } -int X86FrameLowering::getFrameIndexOffset(const MachineFunction &MF, - int FI) const { +// 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 @@ -1207,48 +1711,62 @@ int X86FrameLowering::getFrameIndexOffset(const MachineFunction &MF, return Offset + FPDelta; } -int X86FrameLowering::getFrameIndexReference(const MachineFunction &MF, int FI, - unsigned &FrameReg) const { - // 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); - return getFrameIndexOffset(MF, FI); -} - -// 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 - // 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(!TRI->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<X86MachineFunctionInfo>()->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 @@ -1280,15 +1798,6 @@ 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 { - assert(!TRI->hasBasePointer(MF) && "we don't handle this case"); - - FrameReg = TRI->getStackRegister(); - return getFrameIndexOffsetFromSP(MF, FI); -} bool X86FrameLowering::assignCalleeSavedSpillSlots( MachineFunction &MF, const TargetRegisterInfo *TRI, @@ -1358,6 +1867,11 @@ bool X86FrameLowering::spillCalleeSavedRegisters( const TargetRegisterInfo *TRI) const { DebugLoc DL = MBB.findDebugLoc(MI); + // 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; for (unsigned i = CSI.size(); i != 0; --i) { @@ -1399,6 +1913,22 @@ bool X86FrameLowering::restoreCalleeSavedRegisters(MachineBasicBlock &MBB, if (CSI.empty()) return false; + 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; + } + } + DebugLoc DL = MBB.findDebugLoc(MI); // Reload XMMs from stack frame. @@ -1420,7 +1950,8 @@ 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; } @@ -1450,8 +1981,16 @@ void X86FrameLowering::determineCalleeSaves(MachineFunction &MF, } // Spill the BasePtr if it's used. - if (TRI->hasBasePointer(MF)) + 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 @@ -1545,11 +2084,9 @@ void X86FrameLowering::adjustForSegmentedStacks( // 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) @@ -1682,8 +2219,6 @@ void X86FrameLowering::adjustForSegmentedStacks( .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()); @@ -1821,11 +2356,9 @@ void X86FrameLowering::adjustForHiPEPrologue( 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); @@ -1870,16 +2403,84 @@ void X86FrameLowering::adjustForHiPEPrologue( .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::adjustStackWithPops(MachineBasicBlock &MBB, + MachineBasicBlock::iterator MBBI, DebugLoc DL, int Offset) const { + + if (Offset <= 0) + return false; + + if (Offset % SlotSize) + return false; + + int NumPops = Offset / SlotSize; + // This is only worth it if we have at most 2 pops. + if (NumPops != 1 && NumPops != 2) + return false; + + // 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 Prev = std::prev(MBBI); + if (!Prev->isCall() || !Prev->getOperand(1).isRegMask()) + return false; + + unsigned Regs[2]; + unsigned FoundRegs = 0; + + auto RegMask = Prev->getOperand(1); + + 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; + + bool IsDef = false; + for (const MachineOperand &MO : Prev->implicit_operands()) { + if (MO.isReg() && MO.isDef() && MO.getReg() == Candidate) { + IsDef = true; + break; + } + } + + if (IsDef) + continue; + + 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 { @@ -1895,8 +2496,6 @@ eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB, // If the stack pointer can be changed after prologue, turn the // adjcallstackup instruction into a 'sub ESP, <amt>' and the // adjcallstackdown instruction into 'add ESP, <amt>' - 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 @@ -1904,15 +2503,68 @@ eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB, 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<X86MachineFunctionInfo>()->getHasPushSequences()) + BuildCFI(MBB, I, DL, + MCCFIInstruction::createGnuArgsSize(nullptr, Amount)); + + if (Amount == 0) + return; + // Factor out the amount that gets handled inside the sequence // (Pushes of argument for frame setup, callee pops for frame destroy) Amount -= InternalAmt; + // 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 (Amount) { // Add Amount to SP to destroy a frame, and subtract to setup. int Offset = isDestroy ? Amount : -Amount; - BuildStackAdjustment(MBB, I, DL, Offset, /*InEpilogue=*/false); + + 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; } @@ -1933,12 +2585,136 @@ eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB, 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 none of the terminators reads the - // EFLAGS, and if one uses it, conservatively assume this is not + // 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 !terminatorsNeedFlagsAsInput(MBB); + 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<X86MachineFunctionInfo>(); + 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<X86MachineFunctionInfo>()->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); } |