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Diffstat (limited to 'contrib/llvm/lib/Target/X86/X86FrameLowering.cpp')
| -rw-r--r-- | contrib/llvm/lib/Target/X86/X86FrameLowering.cpp | 2698 |
1 files changed, 2698 insertions, 0 deletions
diff --git a/contrib/llvm/lib/Target/X86/X86FrameLowering.cpp b/contrib/llvm/lib/Target/X86/X86FrameLowering.cpp new file mode 100644 index 0000000..8b5fd27 --- /dev/null +++ b/contrib/llvm/lib/Target/X86/X86FrameLowering.cpp @@ -0,0 +1,2698 @@ +//===-- X86FrameLowering.cpp - X86 Frame Information ----------------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file contains the X86 implementation of TargetFrameLowering class. +// +//===----------------------------------------------------------------------===// + +#include "X86FrameLowering.h" +#include "X86InstrBuilder.h" +#include "X86InstrInfo.h" +#include "X86MachineFunctionInfo.h" +#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/Target/TargetOptions.h" +#include "llvm/Support/Debug.h" +#include <cstdlib> + +using namespace llvm; + +X86FrameLowering::X86FrameLowering(const X86Subtarget &STI, + unsigned StackAlignOverride) + : TargetFrameLowering(StackGrowsDown, StackAlignOverride, + STI.is64Bit() ? -8 : -4), + STI(STI), TII(*STI.getInstrInfo()), TRI(STI.getRegisterInfo()) { + // Cache a bunch of frame-related predicates for this subtarget. + SlotSize = TRI->getSlotSize(); + Is64Bit = STI.is64Bit(); + IsLP64 = STI.isTarget64BitLP64(); + // standard x86_64 and NaCl use 64-bit frame/stack pointers, x32 - 32-bit. + Uses64BitFramePtr = STI.isTarget64BitLP64() || STI.isTargetNaCl64(); + StackPtr = TRI->getStackRegister(); +} + +bool X86FrameLowering::hasReservedCallFrame(const MachineFunction &MF) const { + return !MF.getFrameInfo()->hasVarSizedObjects() && + !MF.getInfo<X86MachineFunctionInfo>()->getHasPushSequences(); +} + +/// 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<X86MachineFunctionInfo>()->getHasPushSequences(); +} + +/// hasFP - Return true if the specified function should have a dedicated frame +/// pointer register. This is true if the function has variable sized allocas +/// or if frame pointer elimination is disabled. +bool X86FrameLowering::hasFP(const MachineFunction &MF) const { + const MachineFrameInfo *MFI = MF.getFrameInfo(); + const MachineModuleInfo &MMI = MF.getMMI(); + + return (MF.getTarget().Options.DisableFramePointerElim(MF) || + TRI->needsStackRealignment(MF) || + MFI->hasVarSizedObjects() || + MFI->isFrameAddressTaken() || MFI->hasOpaqueSPAdjustment() || + MF.getInfo<X86MachineFunctionInfo>()->getForceFramePointer() || + MMI.callsUnwindInit() || MMI.hasEHFunclets() || MMI.callsEHReturn() || + MFI->hasStackMap() || MFI->hasPatchPoint()); +} + +static unsigned getSUBriOpcode(unsigned IsLP64, int64_t Imm) { + if (IsLP64) { + if (isInt<8>(Imm)) + return X86::SUB64ri8; + return X86::SUB64ri32; + } else { + if (isInt<8>(Imm)) + return X86::SUB32ri8; + return X86::SUB32ri; + } +} + +static unsigned getADDriOpcode(unsigned IsLP64, int64_t Imm) { + if (IsLP64) { + if (isInt<8>(Imm)) + return X86::ADD64ri8; + return X86::ADD64ri32; + } else { + if (isInt<8>(Imm)) + return X86::ADD32ri8; + return X86::ADD32ri; + } +} + +static unsigned getSUBrrOpcode(unsigned isLP64) { + return isLP64 ? X86::SUB64rr : X86::SUB32rr; +} + +static unsigned getADDrrOpcode(unsigned isLP64) { + return isLP64 ? X86::ADD64rr : X86::ADD32rr; +} + +static unsigned getANDriOpcode(bool IsLP64, int64_t Imm) { + if (IsLP64) { + if (isInt<8>(Imm)) + return X86::AND64ri8; + return X86::AND64ri32; + } + if (isInt<8>(Imm)) + return X86::AND32ri8; + return X86::AND32ri; +} + +static unsigned getLEArOpcode(unsigned IsLP64) { + return IsLP64 ? X86::LEA64r : X86::LEA32r; +} + +/// findDeadCallerSavedReg - Return a caller-saved register that isn't live +/// when it reaches the "return" instruction. We can then pop a stack object +/// to this register without worry about clobbering it. +static unsigned findDeadCallerSavedReg(MachineBasicBlock &MBB, + MachineBasicBlock::iterator &MBBI, + const X86RegisterInfo *TRI, + bool Is64Bit) { + const MachineFunction *MF = MBB.getParent(); + const Function *F = MF->getFunction(); + if (!F || MF->getMMI().callsEHReturn()) + return 0; + + const TargetRegisterClass &AvailableRegs = *TRI->getGPRsForTailCall(*MF); + + unsigned Opc = MBBI->getOpcode(); + switch (Opc) { + default: return 0; + case X86::RETL: + case X86::RETQ: + 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: { + SmallSet<uint16_t, 8> Uses; + for (unsigned i = 0, e = MBBI->getNumOperands(); i != e; ++i) { + MachineOperand &MO = MBBI->getOperand(i); + if (!MO.isReg() || MO.isDef()) + continue; + unsigned Reg = MO.getReg(); + if (!Reg) + continue; + for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI) + Uses.insert(*AI); + } + + for (auto CS : AvailableRegs) + if (!Uses.count(CS) && CS != X86::RIP) + return CS; + } + } + + return 0; +} + +static bool isEAXLiveIn(MachineFunction &MF) { + for (MachineRegisterInfo::livein_iterator II = MF.getRegInfo().livein_begin(), + EE = MF.getRegInfo().livein_end(); II != EE; ++II) { + unsigned Reg = II->first; + + if (Reg == X86::RAX || Reg == X86::EAX || Reg == X86::AX || + Reg == X86::AH || Reg == X86::AL) + return true; + } + + return false; +} + +/// Check 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. +void X86FrameLowering::emitSPUpdate(MachineBasicBlock &MBB, + MachineBasicBlock::iterator &MBBI, + int64_t NumBytes, bool InEpilogue) const { + bool isSub = NumBytes < 0; + uint64_t Offset = isSub ? -NumBytes : NumBytes; + + uint64_t Chunk = (1LL << 31) - 1; + DebugLoc DL = MBB.findDebugLoc(MBBI); + + while (Offset) { + if (Offset > Chunk) { + // Rather than emit a long series of instructions for large offsets, + // load the offset into a register and do one sub/add + unsigned Reg = 0; + + if (isSub && !isEAXLiveIn(*MBB.getParent())) + Reg = (unsigned)(Is64Bit ? X86::RAX : X86::EAX); + else + Reg = findDeadCallerSavedReg(MBB, MBBI, TRI, Is64Bit); + + if (Reg) { + unsigned Opc = Is64Bit ? X86::MOV64ri : X86::MOV32ri; + BuildMI(MBB, MBBI, DL, TII.get(Opc), Reg) + .addImm(Offset); + Opc = isSub + ? getSUBrrOpcode(Is64Bit) + : getADDrrOpcode(Is64Bit); + MachineInstr *MI = BuildMI(MBB, MBBI, DL, TII.get(Opc), StackPtr) + .addReg(StackPtr) + .addReg(Reg); + MI->getOperand(3).setIsDead(); // The EFLAGS implicit def is dead. + Offset = 0; + continue; + } + } + + uint64_t ThisVal = std::min(Offset, Chunk); + if (ThisVal == (Is64Bit ? 8 : 4)) { + // Use push / pop instead. + unsigned Reg = isSub + ? (unsigned)(Is64Bit ? X86::RAX : X86::EAX) + : findDeadCallerSavedReg(MBB, MBBI, TRI, Is64Bit); + if (Reg) { + 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; + } + } + + MachineInstrBuilder MI = BuildStackAdjustment( + MBB, MBBI, DL, isSub ? -ThisVal : ThisVal, InEpilogue); + if (isSub) + MI.setMIFlag(MachineInstr::FrameSetup); + else + MI.setMIFlag(MachineInstr::FrameDestroy); + + Offset -= ThisVal; + } +} + +MachineInstrBuilder X86FrameLowering::BuildStackAdjustment( + MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI, DebugLoc DL, + int64_t Offset, bool InEpilogue) const { + assert(Offset != 0 && "zero offset stack adjustment requested"); + + // On Atom, using LEA to adjust SP is preferred, but using it in the epilogue + // is tricky. + bool UseLEA; + if (!InEpilogue) { + // 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"); + } + + 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; +} + +int X86FrameLowering::mergeSPUpdates(MachineBasicBlock &MBB, + MachineBasicBlock::iterator &MBBI, + bool doMergeWithPrevious) const { + if ((doMergeWithPrevious && MBBI == MBB.begin()) || + (!doMergeWithPrevious && MBBI == MBB.end())) + return 0; + + MachineBasicBlock::iterator PI = doMergeWithPrevious ? std::prev(MBBI) : MBBI; + MachineBasicBlock::iterator NI = doMergeWithPrevious ? nullptr + : std::next(MBBI); + unsigned Opc = PI->getOpcode(); + int Offset = 0; + + 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){ + Offset += PI->getOperand(2).getImm(); + MBB.erase(PI); + if (!doMergeWithPrevious) MBBI = NI; + } else if ((Opc == X86::SUB64ri32 || Opc == X86::SUB64ri8 || + Opc == X86::SUB32ri || Opc == X86::SUB32ri8) && + PI->getOperand(0).getReg() == StackPtr) { + Offset -= PI->getOperand(2).getImm(); + MBB.erase(PI); + if (!doMergeWithPrevious) MBBI = NI; + } + + 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, + DebugLoc DL) const { + MachineFunction &MF = *MBB.getParent(); + MachineFrameInfo *MFI = MF.getFrameInfo(); + MachineModuleInfo &MMI = MF.getMMI(); + const MCRegisterInfo *MRI = MMI.getContext().getRegisterInfo(); + + // Add callee saved registers to move list. + const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo(); + if (CSI.empty()) return; + + // Calculate offsets. + for (std::vector<CalleeSavedInfo>::const_iterator + I = CSI.begin(), E = CSI.end(); I != E; ++I) { + int64_t Offset = MFI->getObjectOffset(I->getFrameIdx()); + unsigned Reg = I->getReg(); + + unsigned DwarfReg = MRI->getDwarfRegNum(Reg, true); + BuildCFI(MBB, MBBI, DL, + MCCFIInstruction::createOffset(nullptr, DwarfReg, Offset)); + } +} + +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); + } +} + +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<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; + if (Is64Bit) + CallOp = IsLargeCodeModel ? X86::CALL64r : X86::CALL64pcrel32; + else + CallOp = X86::CALLpcrel32; + + const char *Symbol; + if (Is64Bit) { + if (STI.isTargetCygMing()) { + Symbol = "___chkstk_ms"; + } else { + Symbol = "__chkstk"; + } + } else if (STI.isTargetCygMing()) + Symbol = "_alloca"; + else + 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. + if (Is64Bit && MF.getTarget().getCodeModel() == CodeModel::Large) { + // For the large code model, we have to call through a register. Use R11, + // as it is scratch in all supported calling conventions. + BuildMI(MBB, MBBI, DL, TII.get(X86::MOV64ri), X86::R11) + .addExternalSymbol(Symbol); + CI = BuildMI(MBB, MBBI, DL, TII.get(CallOp)).addReg(X86::R11); + } else { + CI = BuildMI(MBB, MBBI, DL, TII.get(CallOp)).addExternalSymbol(Symbol); + } + + unsigned AX = Is64Bit ? X86::RAX : X86::EAX; + unsigned SP = Is64Bit ? X86::RSP : X86::ESP; + CI.addReg(AX, RegState::Implicit) + .addReg(SP, RegState::Implicit) + .addReg(AX, RegState::Define | RegState::Implicit) + .addReg(SP, RegState::Define | RegState::Implicit) + .addReg(X86::EFLAGS, RegState::Define | RegState::Implicit); + + if (Is64Bit) { + // MSVC x64's __chkstk and cygwin/mingw's ___chkstk_ms do not adjust %rsp + // themselves. It also does not clobber %rax so we can reuse it when + // adjusting %rsp. + BuildMI(MBB, MBBI, DL, TII.get(X86::SUB64rr), X86::RSP) + .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 +/// automatically adjust the stack pointer. Adjust the stack pointer to allocate +/// space for local variables. Also emit labels used by the exception handler to +/// generate the exception handling frames. + +/* + Here's a gist of what gets emitted: + + ; Establish frame pointer, if needed + [if needs FP] + push %rbp + .cfi_def_cfa_offset 16 + .cfi_offset %rbp, -16 + .seh_pushreg %rpb + mov %rsp, %rbp + .cfi_def_cfa_register %rbp + + ; Spill general-purpose registers + [for all callee-saved GPRs] + pushq %<reg> + [if not needs FP] + .cfi_def_cfa_offset (offset from RETADDR) + .seh_pushreg %<reg> + + ; If the required stack alignment > default stack alignment + ; rsp needs to be re-aligned. This creates a "re-alignment gap" + ; of unknown size in the stack frame. + [if stack needs re-alignment] + and $MASK, %rsp + + ; Allocate space for locals + [if target is Windows and allocated space > 4096 bytes] + ; Windows needs special care for allocations larger + ; than one page. + mov $NNN, %rax + call ___chkstk_ms/___chkstk + sub %rax, %rsp + [else] + sub $NNN, %rsp + + [if needs FP] + .seh_stackalloc (size of XMM spill slots) + .seh_setframe %rbp, SEHFrameOffset ; = size of all spill slots + [else] + .seh_stackalloc NNN + + ; Spill XMMs + ; Note, that while only Windows 64 ABI specifies XMMs as callee-preserved, + ; they may get spilled on any platform, if the current function + ; calls @llvm.eh.unwind.init + [if needs FP] + [for all callee-saved XMM registers] + movaps %<xmm reg>, -MMM(%rbp) + [for all callee-saved XMM registers] + .seh_savexmm %<xmm reg>, (-MMM + SEHFrameOffset) + ; i.e. the offset relative to (%rbp - SEHFrameOffset) + [else] + [for all callee-saved XMM registers] + movaps %<xmm reg>, KKK(%rsp) + [for all callee-saved XMM registers] + .seh_savexmm %<xmm reg>, KKK + + .seh_endprologue + + [if needs base pointer] + mov %rsp, %rbx + [if needs to restore base pointer] + mov %rsp, -MMM(%rbp) + + ; Emit CFI info + [if needs FP] + [for all callee-saved registers] + .cfi_offset %<reg>, (offset from %rbp) + [else] + .cfi_def_cfa_offset (offset from RETADDR) + [for all callee-saved registers] + .cfi_offset %<reg>, (offset from %rsp) + + Notes: + - .seh directives are emitted only for Windows 64 ABI + - .cfi directives are emitted for all other ABIs + - for 32-bit code, substitute %e?? registers for %r?? +*/ + +void X86FrameLowering::emitPrologue(MachineFunction &MF, + MachineBasicBlock &MBB) const { + assert(&STI == &MF.getSubtarget<X86Subtarget>() && + "MF used frame lowering for wrong subtarget"); + MachineBasicBlock::iterator MBBI = MBB.begin(); + MachineFrameInfo *MFI = MF.getFrameInfo(); + const Function *Fn = MF.getFunction(); + MachineModuleInfo &MMI = MF.getMMI(); + 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(); + bool NeedsWinCFI = IsWin64Prologue && Fn->needsUnwindTableEntry(); + bool NeedsDwarfCFI = + !IsWin64Prologue && (MMI.hasDebugInfo() || Fn->needsUnwindTableEntry()); + unsigned FramePtr = TRI->getFrameRegister(MF); + const unsigned MachineFramePtr = + STI.isTarget64BitILP32() + ? 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. + 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); + + bool UseStackProbe = (STI.isOSWindows() && !STI.isTargetMachO()); + + // The default stack probe size is 4096 if the function has no stackprobesize + // attribute. + unsigned StackProbeSize = 4096; + if (Fn->hasFnAttribute("stack-probe-size")) + Fn->getFnAttribute("stack-probe-size") + .getValueAsString() + .getAsInteger(0, StackProbeSize); + + // If this is x86-64 and the Red Zone is not disabled, if we are a leaf + // function, and use up to 128 bytes of stack space, don't have a frame + // 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->hasFnAttribute(Attribute::NoRedZone) && + !TRI->needsStackRealignment(MF) && + !MFI->hasVarSizedObjects() && // No dynamic alloca. + !MFI->adjustsStack() && // No calls. + !IsWin64CC && // Win64 has no Red Zone + !MFI->hasOpaqueSPAdjustment() && // 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); + MFI->setStackSize(StackSize); + } + + // Insert stack pointer adjustment for later moving of return addr. Only + // applies to tail call optimized functions where the callee argument stack + // size is bigger than the callers. + if (TailCallReturnAddrDelta < 0) { + BuildStackAdjustment(MBB, MBBI, DL, TailCallReturnAddrDelta, + /*InEpilogue=*/false) + .setMIFlag(MachineInstr::FrameSetup); + } + + // Mapping for machine moves: + // + // DST: VirtualFP AND + // SRC: VirtualFP => DW_CFA_def_cfa_offset + // ELSE => DW_CFA_def_cfa + // + // SRC: VirtualFP AND + // DST: Register => DW_CFA_def_cfa_register + // + // ELSE + // OFFSET < 0 => DW_CFA_offset_extended_sf + // REG < 64 => DW_CFA_offset + Reg + // ELSE => DW_CFA_offset_extended + + 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; + + 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. + 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)) + .addReg(MachineFramePtr, RegState::Kill) + .setMIFlag(MachineInstr::FrameSetup); + + if (NeedsDwarfCFI) { + // Mark the place where EBP/RBP was saved. + // Define the current CFA rule to use the provided offset. + assert(StackSize); + BuildCFI(MBB, MBBI, DL, + MCCFIInstruction::createDefCfaOffset(nullptr, 2 * stackGrowth)); + + // Change the rule for the FramePtr to be an "offset" rule. + unsigned DwarfFramePtr = TRI->getDwarfRegNum(MachineFramePtr, true); + BuildCFI(MBB, MBBI, DL, MCCFIInstruction::createOffset( + nullptr, DwarfFramePtr, 2 * stackGrowth)); + } + + if (NeedsWinCFI) { + BuildMI(MBB, MBBI, DL, TII.get(X86::SEH_PushReg)) + .addImm(FramePtr) + .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 = TRI->getDwarfRegNum(MachineFramePtr, true); + BuildCFI(MBB, MBBI, DL, MCCFIInstruction::createDefCfaRegister( + nullptr, DwarfFramePtr)); + } + } + + // 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; + unsigned Reg = MBBI->getOperand(0).getReg(); + ++MBBI; + + if (!HasFP && NeedsDwarfCFI) { + // Mark callee-saved push instruction. + // Define the current CFA rule to use the provided offset. + assert(StackSize); + BuildCFI(MBB, MBBI, DL, + MCCFIInstruction::createDefCfaOffset(nullptr, StackOffset)); + StackOffset += stackGrowth; + } + + if (NeedsWinCFI) { + BuildMI(MBB, MBBI, DL, TII.get(X86::SEH_PushReg)).addImm(Reg).setMIFlag( + MachineInstr::FrameSetup); + } + } + + // 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 && !IsFunclet && TRI->needsStackRealignment(MF)) { + assert(HasFP && "There should be a frame pointer if stack is realigned."); + 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, true); + + // Adjust stack pointer: ESP -= numbytes. + + // Windows and cygwin/mingw require a prologue helper routine when allocating + // more than 4K bytes on the stack. Windows uses __chkstk and cygwin/mingw + // uses __alloca. __alloca and the 32-bit version of __chkstk will probe the + // stack and adjust the stack pointer in one go. The 64-bit version of + // __chkstk is only responsible for probing the stack. The 64-bit prologue is + // 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. + 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); + + if (isEAXAlive) { + // Sanity check that EAX is not livein for this function. + // It should not be, so throw an assert. + assert(!Is64Bit && "EAX is livein in x64 case!"); + + // Save EAX + BuildMI(MBB, MBBI, DL, TII.get(X86::PUSH32r)) + .addReg(X86::EAX, RegState::Kill) + .setMIFlag(MachineInstr::FrameSetup); + } + + if (Is64Bit) { + // Handle the 64-bit Windows ABI case where we need to call __chkstk. + // Function prologue is responsible for adjusting the stack pointer. + 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); + } + + // Call __chkstk, __chkstk_ms, or __alloca. + 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); + MI->setFlag(MachineInstr::FrameSetup); + MBB.insert(MBBI, MI); + } + } else if (NumBytes) { + 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; + 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); + 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)) { + const MachineInstr *FrameInstr = &*MBBI; + ++MBBI; + + 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 (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(SPOrEstablisher) + .setMIFlag(MachineInstr::FrameSetup); + if (X86FI->getRestoreBasePointer()) { + // 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(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) { + // Mark end of stack pointer adjustment. + if (!HasFP && NumBytes) { + // Define the current CFA rule to use the provided offset. + assert(StackSize); + BuildCFI(MBB, MBBI, DL, MCCFIInstruction::createDefCfaOffset( + nullptr, -StackSize + stackGrowth)); + } + + // Emit DWARF info specifying the offsets of the callee-saved registers. + if (PushedRegs) + emitCalleeSavedFrameMoves(MBB, MBBI, DL); + } +} + +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<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(); + X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>(); + 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 Is64BitILP32 = STI.isTarget64BitILP32(); + unsigned FramePtr = TRI->getFrameRegister(MF); + unsigned MachineFramePtr = + 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(); + uint64_t MaxAlign = calculateMaxStackAlign(MF); + unsigned CSSize = X86FI->getCalleeSavedFrameSize(); + uint64_t NumBytes = 0; + + 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; + + // 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) + .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 || !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()) + 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. 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); + 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, LEAAmount); + --MBBI; + } else { + unsigned Opc = (Uses64BitFramePtr ? X86::MOV64rr : X86::MOV32rr); + BuildMI(MBB, MBBI, DL, TII.get(Opc), StackPtr) + .addReg(FramePtr); + --MBBI; + } + } else if (NumBytes) { + // Adjust stack pointer back: ESP += numbytes. + emitSPUpdate(MBB, MBBI, NumBytes, /*InEpilogue=*/true); + --MBBI; + } + + // Windows unwinder will not invoke function's exception handler if IP is + // either in prologue or in epilogue. This behavior causes a problem when a + // call immediately precedes an epilogue, because the return address points + // 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 (NeedsWinCFI) + BuildMI(MBB, MBBI, DL, TII.get(X86::SEH_Epilogue)); + + // 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. + Offset += mergeSPUpdates(MBB, MBBI, true); + emitSPUpdate(MBB, MBBI, Offset, /*InEpilogue=*/true); + } +} + +// 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<X86MachineFunctionInfo>(); + unsigned CSSize = X86FI->getCalleeSavedFrameSize(); + uint64_t StackSize = MFI->getStackSize(); + bool HasFP = hasFP(MF); + bool IsWin64Prologue = MF.getTarget().getMCAsmInfo()->usesWindowsCFI(); + int64_t FPDelta = 0; + + if (IsWin64Prologue) { + assert(!MFI->hasCalls() || (StackSize % 16) == 8); + + // Calculate required stack adjustment. + uint64_t FrameSize = StackSize - SlotSize; + // If required, include space for extra hidden slot for stashing base pointer. + if (X86FI->getRestoreBasePointer()) + FrameSize += SlotSize; + uint64_t NumBytes = FrameSize - CSSize; + + uint64_t SEHFrameOffset = calculateSetFPREG(NumBytes); + if (FI && FI == X86FI->getFAIndex()) + return -SEHFrameOffset; + + // FPDelta is the offset from the "traditional" FP location of the old base + // pointer followed by return address and the location required by the + // restricted Win64 prologue. + // Add FPDelta to all offsets below that go through the frame pointer. + FPDelta = FrameSize - SEHFrameOffset; + assert((!MFI->hasCalls() || (FPDelta % 16) == 0) && + "FPDelta isn't aligned per the Win64 ABI!"); + } + + + if (TRI->hasBasePointer(MF)) { + assert(HasFP && "VLAs and dynamic stack realign, but no FP?!"); + if (FI < 0) { + // Skip the saved EBP. + return Offset + SlotSize + FPDelta; + } else { + assert((-(Offset + StackSize)) % MFI->getObjectAlignment(FI) == 0); + return Offset + StackSize; + } + } else if (TRI->needsStackRealignment(MF)) { + if (FI < 0) { + // Skip the saved EBP. + return Offset + SlotSize + FPDelta; + } else { + assert((-(Offset + StackSize)) % MFI->getObjectAlignment(FI) == 0); + return Offset + StackSize; + } + // FIXME: Support tail calls + } else { + if (!HasFP) + return Offset + StackSize; + + // Skip the saved EBP. + Offset += SlotSize; + + // Skip the RETADDR move area + int TailCallReturnAddrDelta = X86FI->getTCReturnAddrDelta(); + if (TailCallReturnAddrDelta < 0) + Offset -= TailCallReturnAddrDelta; + } + + return Offset + FPDelta; +} + +// 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 + // 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 + // one word (eight bytes). Obj0 is the stack slot we're trying to + // get to. + // + // ---------------------------------- + // | BP | Obj0 | Obj1 | ... | ObjN | + // ---------------------------------- + // ^ ^ ^ ^ + // A B C E + // + // A is the incoming stack pointer. + // (B - A) is the local area offset (-8 for x86-64) [1] + // (C - A) is the Offset returned by MFI->getObjectOffset for Obj0 [2] + // + // |(E - B)| is the StackSize (absolute value, positive). For a + // stack that grown down, this works out to be (B - E). [3] + // + // E is also the value of %rsp after stack has been set up, and we + // want (C - E) -- the value we can add to %rsp to get to Obj0. Now + // (C - E) == (C - A) - (B - A) + (B - E) + // { Using [1], [2] and [3] above } + // == getObjectOffset - LocalAreaOffset + StackSize + // + + // Get the Offset from the StackPointer + int Offset = MFI->getObjectOffset(FI) - getOffsetOfLocalArea(); + + return Offset + StackSize; +} + +bool X86FrameLowering::assignCalleeSavedSpillSlots( + MachineFunction &MF, const TargetRegisterInfo *TRI, + std::vector<CalleeSavedInfo> &CSI) const { + MachineFrameInfo *MFI = MF.getFrameInfo(); + X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>(); + + unsigned CalleeSavedFrameSize = 0; + int SpillSlotOffset = getOffsetOfLocalArea() + X86FI->getTCReturnAddrDelta(); + + if (hasFP(MF)) { + // emitPrologue always spills frame register the first thing. + SpillSlotOffset -= SlotSize; + MFI->CreateFixedSpillStackObject(SlotSize, SpillSlotOffset); + + // 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 = TRI->getFrameRegister(MF); + for (unsigned i = 0; i < CSI.size(); ++i) { + if (TRI->regsOverlap(CSI[i].getReg(),FPReg)) { + CSI.erase(CSI.begin() + i); + break; + } + } + } + + // Assign slots for GPRs. It increases frame size. + for (unsigned i = CSI.size(); i != 0; --i) { + unsigned Reg = CSI[i - 1].getReg(); + + if (!X86::GR64RegClass.contains(Reg) && !X86::GR32RegClass.contains(Reg)) + continue; + + SpillSlotOffset -= SlotSize; + CalleeSavedFrameSize += SlotSize; + + int SlotIndex = MFI->CreateFixedSpillStackObject(SlotSize, SpillSlotOffset); + CSI[i - 1].setFrameIdx(SlotIndex); + } + + X86FI->setCalleeSavedFrameSize(CalleeSavedFrameSize); + + // Assign slots for XMMs. + for (unsigned i = CSI.size(); i != 0; --i) { + unsigned Reg = CSI[i - 1].getReg(); + if (X86::GR64RegClass.contains(Reg) || X86::GR32RegClass.contains(Reg)) + continue; + + const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg); + // ensure alignment + SpillSlotOffset -= std::abs(SpillSlotOffset) % RC->getAlignment(); + // spill into slot + SpillSlotOffset -= RC->getSize(); + int SlotIndex = + MFI->CreateFixedSpillStackObject(RC->getSize(), SpillSlotOffset); + CSI[i - 1].setFrameIdx(SlotIndex); + MFI->ensureMaxAlignment(RC->getAlignment()); + } + + return true; +} + +bool X86FrameLowering::spillCalleeSavedRegisters( + MachineBasicBlock &MBB, MachineBasicBlock::iterator MI, + const std::vector<CalleeSavedInfo> &CSI, + 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) { + unsigned Reg = CSI[i - 1].getReg(); + + 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); + + BuildMI(MBB, MI, DL, TII.get(Opc)).addReg(Reg, RegState::Kill) + .setMIFlag(MachineInstr::FrameSetup); + } + + // Make XMM regs spilled. X86 does not have ability of push/pop XMM. + // 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)) + continue; + // Add the callee-saved register as live-in. It's killed at the spill. + MBB.addLiveIn(Reg); + const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg); + + TII.storeRegToStackSlot(MBB, MI, Reg, true, CSI[i - 1].getFrameIdx(), RC, + TRI); + --MI; + MI->setFlag(MachineInstr::FrameSetup); + ++MI; + } + + return true; +} + +bool X86FrameLowering::restoreCalleeSavedRegisters(MachineBasicBlock &MBB, + MachineBasicBlock::iterator MI, + const std::vector<CalleeSavedInfo> &CSI, + const TargetRegisterInfo *TRI) const { + 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. + for (unsigned i = 0, e = CSI.size(); i != e; ++i) { + unsigned Reg = CSI[i].getReg(); + if (X86::GR64RegClass.contains(Reg) || + X86::GR32RegClass.contains(Reg)) + continue; + + const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg); + TII.loadRegFromStackSlot(MBB, MI, Reg, CSI[i].getFrameIdx(), RC, TRI); + } + + // POP GPRs. + unsigned Opc = STI.is64Bit() ? X86::POP64r : X86::POP32r; + for (unsigned i = 0, e = CSI.size(); i != e; ++i) { + unsigned Reg = CSI[i].getReg(); + if (!X86::GR64RegClass.contains(Reg) && + !X86::GR32RegClass.contains(Reg)) + continue; + + BuildMI(MBB, MI, DL, TII.get(Opc), Reg) + .setMIFlag(MachineInstr::FrameDestroy); + } + return true; +} + +void X86FrameLowering::determineCalleeSaves(MachineFunction &MF, + BitVector &SavedRegs, + RegScavenger *RS) const { + TargetFrameLowering::determineCalleeSaves(MF, SavedRegs, RS); + + MachineFrameInfo *MFI = MF.getFrameInfo(); + + X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>(); + int64_t TailCallReturnAddrDelta = X86FI->getTCReturnAddrDelta(); + + if (TailCallReturnAddrDelta < 0) { + // create RETURNADDR area + // arg + // arg + // RETADDR + // { ... + // RETADDR area + // ... + // } + // [EBP] + MFI->CreateFixedObject(-TailCallReturnAddrDelta, + TailCallReturnAddrDelta - SlotSize, true); + } + + // Spill the BasePtr if it's used. + 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 +HasNestArgument(const MachineFunction *MF) { + const Function *F = MF->getFunction(); + for (Function::const_arg_iterator I = F->arg_begin(), E = F->arg_end(); + I != E; I++) { + if (I->hasNestAttr()) + return true; + } + return false; +} + +/// GetScratchRegister - Get a temp register for performing work in the +/// segmented stack and the Erlang/HiPE stack prologue. Depending on platform +/// and the properties of the function either one or two registers will be +/// needed. Set primary to true for the first register, false for the second. +static unsigned +GetScratchRegister(bool Is64Bit, bool IsLP64, const MachineFunction &MF, bool Primary) { + CallingConv::ID CallingConvention = MF.getFunction()->getCallingConv(); + + // Erlang stuff. + if (CallingConvention == CallingConv::HiPE) { + if (Is64Bit) + return Primary ? X86::R14 : X86::R13; + else + return Primary ? X86::EBX : X86::EDI; + } + + if (Is64Bit) { + if (IsLP64) + return Primary ? X86::R11 : X86::R12; + else + return Primary ? X86::R11D : X86::R12D; + } + + bool IsNested = HasNestArgument(&MF); + + if (CallingConvention == CallingConv::X86_FastCall || + CallingConvention == CallingConv::Fast) { + if (IsNested) + report_fatal_error("Segmented stacks does not support fastcall with " + "nested function."); + return Primary ? X86::EAX : X86::ECX; + } + if (IsNested) + return Primary ? X86::EDX : X86::EAX; + return Primary ? X86::ECX : X86::EAX; +} + +// The stack limit in the TCB is set to this many bytes above the actual stack +// limit. +static const uint64_t kSplitStackAvailable = 256; + +void X86FrameLowering::adjustForSegmentedStacks( + MachineFunction &MF, MachineBasicBlock &PrologueMBB) const { + MachineFrameInfo *MFI = MF.getFrameInfo(); + uint64_t StackSize; + unsigned TlsReg, TlsOffset; + DebugLoc DL; + + unsigned ScratchReg = GetScratchRegister(Is64Bit, IsLP64, MF, true); + assert(!MF.getRegInfo().isLiveIn(ScratchReg) && + "Scratch register is live-in"); + + if (MF.getFunction()->isVarArg()) + report_fatal_error("Segmented stacks do not support vararg functions."); + if (!STI.isTargetLinux() && !STI.isTargetDarwin() && !STI.isTargetWin32() && + !STI.isTargetWin64() && !STI.isTargetFreeBSD() && + !STI.isTargetDragonFly()) + report_fatal_error("Segmented stacks not supported on this platform."); + + // Eventually StackSize will be calculated by a link-time pass; which will + // also decide whether checking code needs to be injected into this particular + // prologue. + StackSize = MFI->getStackSize(); + + // Do not generate a prologue for functions with a stack of size zero + if (StackSize == 0) + return; + + MachineBasicBlock *allocMBB = MF.CreateMachineBasicBlock(); + MachineBasicBlock *checkMBB = MF.CreateMachineBasicBlock(); + X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>(); + bool IsNested = false; + + // We need to know if the function has a nest argument only in 64 bit mode. + if (Is64Bit) + IsNested = HasNestArgument(&MF); + + // 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 (const auto &LI : PrologueMBB.liveins()) { + allocMBB->addLiveIn(LI); + checkMBB->addLiveIn(LI); + } + + if (IsNested) + allocMBB->addLiveIn(IsLP64 ? X86::R10 : X86::R10D); + + MF.push_front(allocMBB); + MF.push_front(checkMBB); + + // When the frame size is less than 256 we just compare the stack + // boundary directly to the value of the stack pointer, per gcc. + bool CompareStackPointer = StackSize < kSplitStackAvailable; + + // Read the limit off the current stacklet off the stack_guard location. + if (Is64Bit) { + if (STI.isTargetLinux()) { + TlsReg = X86::FS; + TlsOffset = IsLP64 ? 0x70 : 0x40; + } else if (STI.isTargetDarwin()) { + TlsReg = X86::GS; + TlsOffset = 0x60 + 90*8; // See pthread_machdep.h. Steal TLS slot 90. + } else if (STI.isTargetWin64()) { + TlsReg = X86::GS; + TlsOffset = 0x28; // pvArbitrary, reserved for application use + } else if (STI.isTargetFreeBSD()) { + TlsReg = X86::FS; + TlsOffset = 0x18; + } else if (STI.isTargetDragonFly()) { + TlsReg = X86::FS; + TlsOffset = 0x20; // use tls_tcb.tcb_segstack + } else { + report_fatal_error("Segmented stacks not supported on this platform."); + } + + if (CompareStackPointer) + ScratchReg = IsLP64 ? X86::RSP : X86::ESP; + else + BuildMI(checkMBB, DL, TII.get(IsLP64 ? X86::LEA64r : X86::LEA64_32r), ScratchReg).addReg(X86::RSP) + .addImm(1).addReg(0).addImm(-StackSize).addReg(0); + + BuildMI(checkMBB, DL, TII.get(IsLP64 ? X86::CMP64rm : X86::CMP32rm)).addReg(ScratchReg) + .addReg(0).addImm(1).addReg(0).addImm(TlsOffset).addReg(TlsReg); + } else { + if (STI.isTargetLinux()) { + TlsReg = X86::GS; + TlsOffset = 0x30; + } else if (STI.isTargetDarwin()) { + TlsReg = X86::GS; + TlsOffset = 0x48 + 90*4; + } else if (STI.isTargetWin32()) { + TlsReg = X86::FS; + TlsOffset = 0x14; // pvArbitrary, reserved for application use + } else if (STI.isTargetDragonFly()) { + TlsReg = X86::FS; + TlsOffset = 0x10; // use tls_tcb.tcb_segstack + } else if (STI.isTargetFreeBSD()) { + report_fatal_error("Segmented stacks not supported on FreeBSD i386."); + } else { + report_fatal_error("Segmented stacks not supported on this platform."); + } + + if (CompareStackPointer) + ScratchReg = X86::ESP; + else + BuildMI(checkMBB, DL, TII.get(X86::LEA32r), ScratchReg).addReg(X86::ESP) + .addImm(1).addReg(0).addImm(-StackSize).addReg(0); + + if (STI.isTargetLinux() || STI.isTargetWin32() || STI.isTargetWin64() || + STI.isTargetDragonFly()) { + BuildMI(checkMBB, DL, TII.get(X86::CMP32rm)).addReg(ScratchReg) + .addReg(0).addImm(0).addReg(0).addImm(TlsOffset).addReg(TlsReg); + } else if (STI.isTargetDarwin()) { + + // TlsOffset doesn't fit into a mod r/m byte so we need an extra register. + unsigned ScratchReg2; + bool SaveScratch2; + if (CompareStackPointer) { + // The primary scratch register is available for holding the TLS offset. + ScratchReg2 = GetScratchRegister(Is64Bit, IsLP64, MF, true); + SaveScratch2 = false; + } else { + // Need to use a second register to hold the TLS offset + ScratchReg2 = GetScratchRegister(Is64Bit, IsLP64, MF, false); + + // Unfortunately, with fastcc the second scratch register may hold an + // argument. + SaveScratch2 = MF.getRegInfo().isLiveIn(ScratchReg2); + } + + // If Scratch2 is live-in then it needs to be saved. + assert((!MF.getRegInfo().isLiveIn(ScratchReg2) || SaveScratch2) && + "Scratch register is live-in and not saved"); + + if (SaveScratch2) + BuildMI(checkMBB, DL, TII.get(X86::PUSH32r)) + .addReg(ScratchReg2, RegState::Kill); + + BuildMI(checkMBB, DL, TII.get(X86::MOV32ri), ScratchReg2) + .addImm(TlsOffset); + BuildMI(checkMBB, DL, TII.get(X86::CMP32rm)) + .addReg(ScratchReg) + .addReg(ScratchReg2).addImm(1).addReg(0) + .addImm(0) + .addReg(TlsReg); + + if (SaveScratch2) + BuildMI(checkMBB, DL, TII.get(X86::POP32r), ScratchReg2); + } + } + + // 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); + + // 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. + if (Is64Bit) { + // Functions with nested arguments use R10, so it needs to be saved across + // the call to _morestack + + const unsigned RegAX = IsLP64 ? X86::RAX : X86::EAX; + const unsigned Reg10 = IsLP64 ? X86::R10 : X86::R10D; + const unsigned Reg11 = IsLP64 ? X86::R11 : X86::R11D; + const unsigned MOVrr = IsLP64 ? X86::MOV64rr : X86::MOV32rr; + const unsigned MOVri = IsLP64 ? X86::MOV64ri : X86::MOV32ri; + + if (IsNested) + BuildMI(allocMBB, DL, TII.get(MOVrr), RegAX).addReg(Reg10); + + BuildMI(allocMBB, DL, TII.get(MOVri), Reg10) + .addImm(StackSize); + BuildMI(allocMBB, DL, TII.get(MOVri), Reg11) + .addImm(X86FI->getArgumentStackSize()); + } else { + BuildMI(allocMBB, DL, TII.get(X86::PUSHi32)) + .addImm(X86FI->getArgumentStackSize()); + BuildMI(allocMBB, DL, TII.get(X86::PUSHi32)) + .addImm(StackSize); + } + + // __morestack is in libgcc + if (Is64Bit && MF.getTarget().getCodeModel() == CodeModel::Large) { + // Under the large code model, we cannot assume that __morestack lives + // within 2^31 bytes of the call site, so we cannot use pc-relative + // addressing. We cannot perform the call via a temporary register, + // as the rax register may be used to store the static chain, and all + // other suitable registers may be either callee-save or used for + // parameter passing. We cannot use the stack at this point either + // because __morestack manipulates the stack directly. + // + // To avoid these issues, perform an indirect call via a read-only memory + // location containing the address. + // + // This solution is not perfect, as it assumes that the .rodata section + // is laid out within 2^31 bytes of each function body, but this seems + // to be sufficient for JIT. + BuildMI(allocMBB, DL, TII.get(X86::CALL64m)) + .addReg(X86::RIP) + .addImm(0) + .addReg(0) + .addExternalSymbol("__morestack_addr") + .addReg(0); + MF.getMMI().setUsesMorestackAddr(true); + } else { + if (Is64Bit) + BuildMI(allocMBB, DL, TII.get(X86::CALL64pcrel32)) + .addExternalSymbol("__morestack"); + else + BuildMI(allocMBB, DL, TII.get(X86::CALLpcrel32)) + .addExternalSymbol("__morestack"); + } + + if (IsNested) + BuildMI(allocMBB, DL, TII.get(X86::MORESTACK_RET_RESTORE_R10)); + else + BuildMI(allocMBB, DL, TII.get(X86::MORESTACK_RET)); + + allocMBB->addSuccessor(&PrologueMBB); + + checkMBB->addSuccessor(allocMBB); + checkMBB->addSuccessor(&PrologueMBB); + +#ifdef XDEBUG + MF.verify(); +#endif +} + +/// Erlang programs may need a special prologue to handle the stack size they +/// might need at runtime. That is because Erlang/OTP does not implement a C +/// stack but uses a custom implementation of hybrid stack/heap architecture. +/// (for more information see Eric Stenman's Ph.D. thesis: +/// http://publications.uu.se/uu/fulltext/nbn_se_uu_diva-2688.pdf) +/// +/// CheckStack: +/// temp0 = sp - MaxStack +/// if( temp0 < SP_LIMIT(P) ) goto IncStack else goto OldStart +/// OldStart: +/// ... +/// IncStack: +/// 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, MachineBasicBlock &PrologueMBB) const { + MachineFrameInfo *MFI = MF.getFrameInfo(); + DebugLoc DL; + // HiPE-specific values + const unsigned HipeLeafWords = 24; + const unsigned CCRegisteredArgs = Is64Bit ? 6 : 5; + const unsigned Guaranteed = HipeLeafWords * SlotSize; + unsigned CallerStkArity = MF.getFunction()->arg_size() > CCRegisteredArgs ? + MF.getFunction()->arg_size() - CCRegisteredArgs : 0; + unsigned MaxStack = MFI->getStackSize() + CallerStkArity*SlotSize + SlotSize; + + assert(STI.isTargetLinux() && + "HiPE prologue is only supported on Linux operating systems."); + + // Compute the largest caller's frame that is needed to fit the callees' + // frames. This 'MaxStack' is computed from: + // + // a) the fixed frame size, which is the space needed for all spilled temps, + // b) outgoing on-stack parameter areas, and + // c) the minimum stack space this function needs to make available for the + // functions it calls (a tunable ABI property). + if (MFI->hasCalls()) { + unsigned MoreStackForCalls = 0; + + for (MachineFunction::iterator MBBI = MF.begin(), MBBE = MF.end(); + MBBI != MBBE; ++MBBI) + for (MachineBasicBlock::iterator MI = MBBI->begin(), ME = MBBI->end(); + MI != ME; ++MI) { + if (!MI->isCall()) + continue; + + // Get callee operand. + const MachineOperand &MO = MI->getOperand(0); + + // Only take account of global function calls (no closures etc.). + if (!MO.isGlobal()) + continue; + + const Function *F = dyn_cast<Function>(MO.getGlobal()); + if (!F) + continue; + + // Do not update 'MaxStack' for primitive and built-in functions + // (encoded with names either starting with "erlang."/"bif_" or not + // having a ".", such as a simple <Module>.<Function>.<Arity>, or an + // "_", such as the BIF "suspend_0") as they are executed on another + // stack. + if (F->getName().find("erlang.") != StringRef::npos || + F->getName().find("bif_") != StringRef::npos || + F->getName().find_first_of("._") == StringRef::npos) + continue; + + unsigned CalleeStkArity = + F->arg_size() > CCRegisteredArgs ? F->arg_size()-CCRegisteredArgs : 0; + if (HipeLeafWords - 1 > CalleeStkArity) + MoreStackForCalls = std::max(MoreStackForCalls, + (HipeLeafWords - 1 - CalleeStkArity) * SlotSize); + } + MaxStack += MoreStackForCalls; + } + + // 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 *stackCheckMBB = MF.CreateMachineBasicBlock(); + MachineBasicBlock *incStackMBB = MF.CreateMachineBasicBlock(); + + for (const auto &LI : PrologueMBB.liveins()) { + stackCheckMBB->addLiveIn(LI); + incStackMBB->addLiveIn(LI); + } + + MF.push_front(incStackMBB); + MF.push_front(stackCheckMBB); + + unsigned ScratchReg, SPReg, PReg, SPLimitOffset; + unsigned LEAop, CMPop, CALLop; + if (Is64Bit) { + SPReg = X86::RSP; + PReg = X86::RBP; + LEAop = X86::LEA64r; + CMPop = X86::CMP64rm; + CALLop = X86::CALL64pcrel32; + SPLimitOffset = 0x90; + } else { + SPReg = X86::ESP; + PReg = X86::EBP; + LEAop = X86::LEA32r; + CMPop = X86::CMP32rm; + CALLop = X86::CALLpcrel32; + SPLimitOffset = 0x4c; + } + + ScratchReg = GetScratchRegister(Is64Bit, IsLP64, MF, true); + assert(!MF.getRegInfo().isLiveIn(ScratchReg) && + "HiPE prologue scratch register is live-in"); + + // Create new MBB for StackCheck: + addRegOffset(BuildMI(stackCheckMBB, DL, TII.get(LEAop), ScratchReg), + SPReg, false, -MaxStack); + // 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); + + // Create new MBB for IncStack: + BuildMI(incStackMBB, DL, TII.get(CALLop)). + addExternalSymbol("inc_stack_0"); + addRegOffset(BuildMI(incStackMBB, DL, TII.get(LEAop), ScratchReg), + SPReg, false, -MaxStack); + addRegOffset(BuildMI(incStackMBB, DL, TII.get(CMPop)) + .addReg(ScratchReg), PReg, false, SPLimitOffset); + BuildMI(incStackMBB, DL, TII.get(X86::JLE_1)).addMBB(incStackMBB); + + 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 { + bool reserveCallFrame = hasReservedCallFrame(MF); + unsigned Opcode = I->getOpcode(); + bool isDestroy = Opcode == TII.getCallFrameDestroyOpcode(); + DebugLoc DL = I->getDebugLoc(); + uint64_t Amount = !reserveCallFrame ? I->getOperand(0).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, <amt>' and the + // adjcallstackdown instruction into 'add ESP, <amt>' + + // 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 = 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; + + 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 (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. + // 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; + 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<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); +} |
