| //===-- 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/Function.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/MC/MCAsmInfo.h" |
| #include "llvm/MC/MCSymbol.h" |
| #include "llvm/Target/TargetData.h" |
| #include "llvm/Target/TargetOptions.h" |
| #include "llvm/Support/CommandLine.h" |
| #include "llvm/ADT/SmallSet.h" |
| |
| using namespace llvm; |
| |
| // FIXME: completely move here. |
| extern cl::opt<bool> ForceStackAlign; |
| |
| bool X86FrameLowering::hasReservedCallFrame(const MachineFunction &MF) const { |
| return !MF.getFrameInfo()->hasVarSizedObjects(); |
| } |
| |
| /// 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(); |
| const TargetRegisterInfo *RI = TM.getRegisterInfo(); |
| |
| return (MF.getTarget().Options.DisableFramePointerElim(MF) || |
| RI->needsStackRealignment(MF) || |
| MFI->hasVarSizedObjects() || |
| MFI->isFrameAddressTaken() || |
| MF.getInfo<X86MachineFunctionInfo>()->getForceFramePointer() || |
| MMI.callsUnwindInit()); |
| } |
| |
| static unsigned getSUBriOpcode(unsigned is64Bit, int64_t Imm) { |
| if (is64Bit) { |
| 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 is64Bit, int64_t Imm) { |
| if (is64Bit) { |
| if (isInt<8>(Imm)) |
| return X86::ADD64ri8; |
| return X86::ADD64ri32; |
| } else { |
| if (isInt<8>(Imm)) |
| return X86::ADD32ri8; |
| return X86::ADD32ri; |
| } |
| } |
| |
| static unsigned getLEArOpcode(unsigned is64Bit) { |
| return is64Bit ? 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 TargetRegisterInfo &TRI, |
| bool Is64Bit) { |
| const MachineFunction *MF = MBB.getParent(); |
| const Function *F = MF->getFunction(); |
| if (!F || MF->getMMI().callsEHReturn()) |
| return 0; |
| |
| static const uint16_t CallerSavedRegs32Bit[] = { |
| X86::EAX, X86::EDX, X86::ECX, 0 |
| }; |
| |
| static const uint16_t CallerSavedRegs64Bit[] = { |
| X86::RAX, X86::RDX, X86::RCX, X86::RSI, X86::RDI, |
| X86::R8, X86::R9, X86::R10, X86::R11, 0 |
| }; |
| |
| unsigned Opc = MBBI->getOpcode(); |
| switch (Opc) { |
| default: return 0; |
| case X86::RET: |
| case X86::RETI: |
| 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 (const uint16_t *AsI = TRI.getOverlaps(Reg); *AsI; ++AsI) |
| Uses.insert(*AsI); |
| } |
| |
| const uint16_t *CS = Is64Bit ? CallerSavedRegs64Bit : CallerSavedRegs32Bit; |
| for (; *CS; ++CS) |
| if (!Uses.count(*CS)) |
| return *CS; |
| } |
| } |
| |
| return 0; |
| } |
| |
| |
| /// emitSPUpdate - Emit a series of instructions to increment / decrement the |
| /// stack pointer by a constant value. |
| static |
| void emitSPUpdate(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI, |
| unsigned StackPtr, int64_t NumBytes, |
| bool Is64Bit, bool UseLEA, |
| const TargetInstrInfo &TII, const TargetRegisterInfo &TRI) { |
| bool isSub = NumBytes < 0; |
| uint64_t Offset = isSub ? -NumBytes : NumBytes; |
| unsigned Opc; |
| if (UseLEA) |
| Opc = getLEArOpcode(Is64Bit); |
| else |
| Opc = isSub |
| ? getSUBriOpcode(Is64Bit, Offset) |
| : getADDriOpcode(Is64Bit, Offset); |
| |
| uint64_t Chunk = (1LL << 31) - 1; |
| DebugLoc DL = MBB.findDebugLoc(MBBI); |
| |
| while (Offset) { |
| uint64_t ThisVal = (Offset > Chunk) ? Chunk : Offset; |
| 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) { |
| 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); |
| Offset -= ThisVal; |
| continue; |
| } |
| } |
| |
| MachineInstr *MI = NULL; |
| |
| if (UseLEA) { |
| MI = addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(Opc), StackPtr), |
| StackPtr, false, isSub ? -ThisVal : ThisVal); |
| } else { |
| MI = BuildMI(MBB, MBBI, DL, TII.get(Opc), StackPtr) |
| .addReg(StackPtr) |
| .addImm(ThisVal); |
| MI->getOperand(3).setIsDead(); // The EFLAGS implicit def is dead. |
| } |
| |
| if (isSub) |
| MI->setFlag(MachineInstr::FrameSetup); |
| |
| Offset -= ThisVal; |
| } |
| } |
| |
| /// mergeSPUpdatesUp - Merge two stack-manipulating instructions upper iterator. |
| static |
| void mergeSPUpdatesUp(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI, |
| unsigned StackPtr, uint64_t *NumBytes = NULL) { |
| if (MBBI == MBB.begin()) return; |
| |
| MachineBasicBlock::iterator PI = prior(MBBI); |
| unsigned Opc = PI->getOpcode(); |
| if ((Opc == X86::ADD64ri32 || Opc == X86::ADD64ri8 || |
| Opc == X86::ADD32ri || Opc == X86::ADD32ri8 || |
| Opc == X86::LEA32r || Opc == X86::LEA64_32r) && |
| PI->getOperand(0).getReg() == StackPtr) { |
| if (NumBytes) |
| *NumBytes += PI->getOperand(2).getImm(); |
| MBB.erase(PI); |
| } else if ((Opc == X86::SUB64ri32 || Opc == X86::SUB64ri8 || |
| Opc == X86::SUB32ri || Opc == X86::SUB32ri8) && |
| PI->getOperand(0).getReg() == StackPtr) { |
| if (NumBytes) |
| *NumBytes -= PI->getOperand(2).getImm(); |
| MBB.erase(PI); |
| } |
| } |
| |
| /// mergeSPUpdatesDown - Merge two stack-manipulating instructions lower iterator. |
| static |
| void mergeSPUpdatesDown(MachineBasicBlock &MBB, |
| MachineBasicBlock::iterator &MBBI, |
| unsigned StackPtr, uint64_t *NumBytes = NULL) { |
| // FIXME: THIS ISN'T RUN!!! |
| return; |
| |
| if (MBBI == MBB.end()) return; |
| |
| MachineBasicBlock::iterator NI = llvm::next(MBBI); |
| if (NI == MBB.end()) return; |
| |
| unsigned Opc = NI->getOpcode(); |
| if ((Opc == X86::ADD64ri32 || Opc == X86::ADD64ri8 || |
| Opc == X86::ADD32ri || Opc == X86::ADD32ri8) && |
| NI->getOperand(0).getReg() == StackPtr) { |
| if (NumBytes) |
| *NumBytes -= NI->getOperand(2).getImm(); |
| MBB.erase(NI); |
| MBBI = NI; |
| } else if ((Opc == X86::SUB64ri32 || Opc == X86::SUB64ri8 || |
| Opc == X86::SUB32ri || Opc == X86::SUB32ri8) && |
| NI->getOperand(0).getReg() == StackPtr) { |
| if (NumBytes) |
| *NumBytes += NI->getOperand(2).getImm(); |
| MBB.erase(NI); |
| MBBI = NI; |
| } |
| } |
| |
| /// mergeSPUpdates - Checks the instruction before/after the passed |
| /// instruction. If it is an ADD/SUB/LEA instruction it is deleted argument and the |
| /// stack adjustment is returned as a positive value for ADD/LEA and a negative for |
| /// SUB. |
| static int mergeSPUpdates(MachineBasicBlock &MBB, |
| MachineBasicBlock::iterator &MBBI, |
| unsigned StackPtr, |
| bool doMergeWithPrevious) { |
| if ((doMergeWithPrevious && MBBI == MBB.begin()) || |
| (!doMergeWithPrevious && MBBI == MBB.end())) |
| return 0; |
| |
| MachineBasicBlock::iterator PI = doMergeWithPrevious ? prior(MBBI) : MBBI; |
| MachineBasicBlock::iterator NI = doMergeWithPrevious ? 0 : llvm::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; |
| } |
| |
| static bool isEAXLiveIn(MachineFunction &MF) { |
| for (MachineRegisterInfo::livein_iterator II = MF.getRegInfo().livein_begin(), |
| EE = MF.getRegInfo().livein_end(); II != EE; ++II) { |
| unsigned Reg = II->first; |
| |
| if (Reg == X86::EAX || Reg == X86::AX || |
| Reg == X86::AH || Reg == X86::AL) |
| return true; |
| } |
| |
| return false; |
| } |
| |
| void X86FrameLowering::emitCalleeSavedFrameMoves(MachineFunction &MF, |
| MCSymbol *Label, |
| unsigned FramePtr) const { |
| MachineFrameInfo *MFI = MF.getFrameInfo(); |
| MachineModuleInfo &MMI = MF.getMMI(); |
| |
| // Add callee saved registers to move list. |
| const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo(); |
| if (CSI.empty()) return; |
| |
| std::vector<MachineMove> &Moves = MMI.getFrameMoves(); |
| const TargetData *TD = TM.getTargetData(); |
| bool HasFP = hasFP(MF); |
| |
| // Calculate amount of bytes used for return address storing. |
| int stackGrowth = -TD->getPointerSize(); |
| |
| // FIXME: This is dirty hack. The code itself is pretty mess right now. |
| // It should be rewritten from scratch and generalized sometimes. |
| |
| // Determine maximum offset (minimum due to stack growth). |
| int64_t MaxOffset = 0; |
| for (std::vector<CalleeSavedInfo>::const_iterator |
| I = CSI.begin(), E = CSI.end(); I != E; ++I) |
| MaxOffset = std::min(MaxOffset, |
| MFI->getObjectOffset(I->getFrameIdx())); |
| |
| // Calculate offsets. |
| int64_t saveAreaOffset = (HasFP ? 3 : 2) * stackGrowth; |
| 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(); |
| Offset = MaxOffset - Offset + saveAreaOffset; |
| |
| // Don't output a new machine move if we're re-saving the frame |
| // pointer. This happens when the PrologEpilogInserter has inserted an extra |
| // "PUSH" of the frame pointer -- the "emitPrologue" method automatically |
| // generates one when frame pointers are used. If we generate a "machine |
| // move" for this extra "PUSH", the linker will lose track of the fact that |
| // the frame pointer should have the value of the first "PUSH" when it's |
| // trying to unwind. |
| // |
| // FIXME: This looks inelegant. It's possibly correct, but it's covering up |
| // another bug. I.e., one where we generate a prolog like this: |
| // |
| // pushl %ebp |
| // movl %esp, %ebp |
| // pushl %ebp |
| // pushl %esi |
| // ... |
| // |
| // The immediate re-push of EBP is unnecessary. At the least, it's an |
| // optimization bug. EBP can be used as a scratch register in certain |
| // cases, but probably not when we have a frame pointer. |
| if (HasFP && FramePtr == Reg) |
| continue; |
| |
| MachineLocation CSDst(MachineLocation::VirtualFP, Offset); |
| MachineLocation CSSrc(Reg); |
| Moves.push_back(MachineMove(Label, CSDst, CSSrc)); |
| } |
| } |
| |
| /// getCompactUnwindRegNum - Get the compact unwind number for a given |
| /// register. The number corresponds to the enum lists in |
| /// compact_unwind_encoding.h. |
| static int getCompactUnwindRegNum(const unsigned *CURegs, unsigned Reg) { |
| for (int Idx = 1; *CURegs; ++CURegs, ++Idx) |
| if (*CURegs == Reg) |
| return Idx; |
| |
| return -1; |
| } |
| |
| // Number of registers that can be saved in a compact unwind encoding. |
| #define CU_NUM_SAVED_REGS 6 |
| |
| /// encodeCompactUnwindRegistersWithoutFrame - Create the permutation encoding |
| /// used with frameless stacks. It is passed the number of registers to be saved |
| /// and an array of the registers saved. |
| static uint32_t |
| encodeCompactUnwindRegistersWithoutFrame(unsigned SavedRegs[CU_NUM_SAVED_REGS], |
| unsigned RegCount, bool Is64Bit) { |
| // The saved registers are numbered from 1 to 6. In order to encode the order |
| // in which they were saved, we re-number them according to their place in the |
| // register order. The re-numbering is relative to the last re-numbered |
| // register. E.g., if we have registers {6, 2, 4, 5} saved in that order: |
| // |
| // Orig Re-Num |
| // ---- ------ |
| // 6 6 |
| // 2 2 |
| // 4 3 |
| // 5 3 |
| // |
| static const unsigned CU32BitRegs[] = { |
| X86::EBX, X86::ECX, X86::EDX, X86::EDI, X86::ESI, X86::EBP, 0 |
| }; |
| static const unsigned CU64BitRegs[] = { |
| X86::RBX, X86::R12, X86::R13, X86::R14, X86::R15, X86::RBP, 0 |
| }; |
| const unsigned *CURegs = (Is64Bit ? CU64BitRegs : CU32BitRegs); |
| |
| for (unsigned i = 0; i != CU_NUM_SAVED_REGS; ++i) { |
| int CUReg = getCompactUnwindRegNum(CURegs, SavedRegs[i]); |
| if (CUReg == -1) return ~0U; |
| SavedRegs[i] = CUReg; |
| } |
| |
| // Reverse the list. |
| std::swap(SavedRegs[0], SavedRegs[5]); |
| std::swap(SavedRegs[1], SavedRegs[4]); |
| std::swap(SavedRegs[2], SavedRegs[3]); |
| |
| uint32_t RenumRegs[CU_NUM_SAVED_REGS]; |
| for (unsigned i = CU_NUM_SAVED_REGS - RegCount; i < CU_NUM_SAVED_REGS; ++i) { |
| unsigned Countless = 0; |
| for (unsigned j = CU_NUM_SAVED_REGS - RegCount; j < i; ++j) |
| if (SavedRegs[j] < SavedRegs[i]) |
| ++Countless; |
| |
| RenumRegs[i] = SavedRegs[i] - Countless - 1; |
| } |
| |
| // Take the renumbered values and encode them into a 10-bit number. |
| uint32_t permutationEncoding = 0; |
| switch (RegCount) { |
| case 6: |
| permutationEncoding |= 120 * RenumRegs[0] + 24 * RenumRegs[1] |
| + 6 * RenumRegs[2] + 2 * RenumRegs[3] |
| + RenumRegs[4]; |
| break; |
| case 5: |
| permutationEncoding |= 120 * RenumRegs[1] + 24 * RenumRegs[2] |
| + 6 * RenumRegs[3] + 2 * RenumRegs[4] |
| + RenumRegs[5]; |
| break; |
| case 4: |
| permutationEncoding |= 60 * RenumRegs[2] + 12 * RenumRegs[3] |
| + 3 * RenumRegs[4] + RenumRegs[5]; |
| break; |
| case 3: |
| permutationEncoding |= 20 * RenumRegs[3] + 4 * RenumRegs[4] |
| + RenumRegs[5]; |
| break; |
| case 2: |
| permutationEncoding |= 5 * RenumRegs[4] + RenumRegs[5]; |
| break; |
| case 1: |
| permutationEncoding |= RenumRegs[5]; |
| break; |
| } |
| |
| assert((permutationEncoding & 0x3FF) == permutationEncoding && |
| "Invalid compact register encoding!"); |
| return permutationEncoding; |
| } |
| |
| /// encodeCompactUnwindRegistersWithFrame - Return the registers encoded for a |
| /// compact encoding with a frame pointer. |
| static uint32_t |
| encodeCompactUnwindRegistersWithFrame(unsigned SavedRegs[CU_NUM_SAVED_REGS], |
| bool Is64Bit) { |
| static const unsigned CU32BitRegs[] = { |
| X86::EBX, X86::ECX, X86::EDX, X86::EDI, X86::ESI, X86::EBP, 0 |
| }; |
| static const unsigned CU64BitRegs[] = { |
| X86::RBX, X86::R12, X86::R13, X86::R14, X86::R15, X86::RBP, 0 |
| }; |
| const unsigned *CURegs = (Is64Bit ? CU64BitRegs : CU32BitRegs); |
| |
| // Encode the registers in the order they were saved, 3-bits per register. The |
| // registers are numbered from 1 to CU_NUM_SAVED_REGS. |
| uint32_t RegEnc = 0; |
| for (int I = CU_NUM_SAVED_REGS - 1, Idx = 0; I != -1; --I) { |
| unsigned Reg = SavedRegs[I]; |
| if (Reg == 0) continue; |
| |
| int CURegNum = getCompactUnwindRegNum(CURegs, Reg); |
| if (CURegNum == -1) return ~0U; |
| |
| // Encode the 3-bit register number in order, skipping over 3-bits for each |
| // register. |
| RegEnc |= (CURegNum & 0x7) << (Idx++ * 3); |
| } |
| |
| assert((RegEnc & 0x3FFFF) == RegEnc && "Invalid compact register encoding!"); |
| return RegEnc; |
| } |
| |
| uint32_t X86FrameLowering::getCompactUnwindEncoding(MachineFunction &MF) const { |
| const X86RegisterInfo *RegInfo = TM.getRegisterInfo(); |
| unsigned FramePtr = RegInfo->getFrameRegister(MF); |
| unsigned StackPtr = RegInfo->getStackRegister(); |
| |
| bool Is64Bit = STI.is64Bit(); |
| bool HasFP = hasFP(MF); |
| |
| unsigned SavedRegs[CU_NUM_SAVED_REGS] = { 0, 0, 0, 0, 0, 0 }; |
| unsigned SavedRegIdx = 0; |
| |
| unsigned OffsetSize = (Is64Bit ? 8 : 4); |
| |
| unsigned PushInstr = (Is64Bit ? X86::PUSH64r : X86::PUSH32r); |
| unsigned PushInstrSize = 1; |
| unsigned MoveInstr = (Is64Bit ? X86::MOV64rr : X86::MOV32rr); |
| unsigned MoveInstrSize = (Is64Bit ? 3 : 2); |
| unsigned SubtractInstrIdx = (Is64Bit ? 3 : 2); |
| |
| unsigned StackDivide = (Is64Bit ? 8 : 4); |
| |
| unsigned InstrOffset = 0; |
| unsigned StackAdjust = 0; |
| unsigned StackSize = 0; |
| |
| MachineBasicBlock &MBB = MF.front(); // Prologue is in entry BB. |
| bool ExpectEnd = false; |
| for (MachineBasicBlock::iterator |
| MBBI = MBB.begin(), MBBE = MBB.end(); MBBI != MBBE; ++MBBI) { |
| MachineInstr &MI = *MBBI; |
| unsigned Opc = MI.getOpcode(); |
| if (Opc == X86::PROLOG_LABEL) continue; |
| if (!MI.getFlag(MachineInstr::FrameSetup)) break; |
| |
| // We don't exect any more prolog instructions. |
| if (ExpectEnd) return 0; |
| |
| if (Opc == PushInstr) { |
| // If there are too many saved registers, we cannot use compact encoding. |
| if (SavedRegIdx >= CU_NUM_SAVED_REGS) return 0; |
| |
| SavedRegs[SavedRegIdx++] = MI.getOperand(0).getReg(); |
| StackAdjust += OffsetSize; |
| InstrOffset += PushInstrSize; |
| } else if (Opc == MoveInstr) { |
| unsigned SrcReg = MI.getOperand(1).getReg(); |
| unsigned DstReg = MI.getOperand(0).getReg(); |
| |
| if (DstReg != FramePtr || SrcReg != StackPtr) |
| return 0; |
| |
| StackAdjust = 0; |
| memset(SavedRegs, 0, sizeof(SavedRegs)); |
| SavedRegIdx = 0; |
| InstrOffset += MoveInstrSize; |
| } else if (Opc == X86::SUB64ri32 || Opc == X86::SUB64ri8 || |
| Opc == X86::SUB32ri || Opc == X86::SUB32ri8) { |
| if (StackSize) |
| // We already have a stack size. |
| return 0; |
| |
| if (!MI.getOperand(0).isReg() || |
| MI.getOperand(0).getReg() != MI.getOperand(1).getReg() || |
| MI.getOperand(0).getReg() != StackPtr || !MI.getOperand(2).isImm()) |
| // We need this to be a stack adjustment pointer. Something like: |
| // |
| // %RSP<def> = SUB64ri8 %RSP, 48 |
| return 0; |
| |
| StackSize = MI.getOperand(2).getImm() / StackDivide; |
| SubtractInstrIdx += InstrOffset; |
| ExpectEnd = true; |
| } |
| } |
| |
| // Encode that we are using EBP/RBP as the frame pointer. |
| uint32_t CompactUnwindEncoding = 0; |
| StackAdjust /= StackDivide; |
| if (HasFP) { |
| if ((StackAdjust & 0xFF) != StackAdjust) |
| // Offset was too big for compact encoding. |
| return 0; |
| |
| // Get the encoding of the saved registers when we have a frame pointer. |
| uint32_t RegEnc = encodeCompactUnwindRegistersWithFrame(SavedRegs, Is64Bit); |
| if (RegEnc == ~0U) return 0; |
| |
| CompactUnwindEncoding |= 0x01000000; |
| CompactUnwindEncoding |= (StackAdjust & 0xFF) << 16; |
| CompactUnwindEncoding |= RegEnc & 0x7FFF; |
| } else { |
| ++StackAdjust; |
| uint32_t TotalStackSize = StackAdjust + StackSize; |
| if ((TotalStackSize & 0xFF) == TotalStackSize) { |
| // Frameless stack with a small stack size. |
| CompactUnwindEncoding |= 0x02000000; |
| |
| // Encode the stack size. |
| CompactUnwindEncoding |= (TotalStackSize & 0xFF) << 16; |
| } else { |
| if ((StackAdjust & 0x7) != StackAdjust) |
| // The extra stack adjustments are too big for us to handle. |
| return 0; |
| |
| // Frameless stack with an offset too large for us to encode compactly. |
| CompactUnwindEncoding |= 0x03000000; |
| |
| // Encode the offset to the nnnnnn value in the 'subl $nnnnnn, ESP' |
| // instruction. |
| CompactUnwindEncoding |= (SubtractInstrIdx & 0xFF) << 16; |
| |
| // Encode any extra stack stack adjustments (done via push instructions). |
| CompactUnwindEncoding |= (StackAdjust & 0x7) << 13; |
| } |
| |
| // Encode the number of registers saved. |
| CompactUnwindEncoding |= (SavedRegIdx & 0x7) << 10; |
| |
| // Get the encoding of the saved registers when we don't have a frame |
| // pointer. |
| uint32_t RegEnc = |
| encodeCompactUnwindRegistersWithoutFrame(SavedRegs, SavedRegIdx, |
| Is64Bit); |
| if (RegEnc == ~0U) return 0; |
| |
| // Encode the register encoding. |
| CompactUnwindEncoding |= RegEnc & 0x3FF; |
| } |
| |
| return CompactUnwindEncoding; |
| } |
| |
| /// 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. |
| void X86FrameLowering::emitPrologue(MachineFunction &MF) const { |
| MachineBasicBlock &MBB = MF.front(); // Prologue goes in entry BB. |
| MachineBasicBlock::iterator MBBI = MBB.begin(); |
| MachineFrameInfo *MFI = MF.getFrameInfo(); |
| const Function *Fn = MF.getFunction(); |
| const X86RegisterInfo *RegInfo = TM.getRegisterInfo(); |
| const X86InstrInfo &TII = *TM.getInstrInfo(); |
| MachineModuleInfo &MMI = MF.getMMI(); |
| X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>(); |
| bool needsFrameMoves = MMI.hasDebugInfo() || |
| Fn->needsUnwindTableEntry(); |
| uint64_t MaxAlign = MFI->getMaxAlignment(); // Desired stack alignment. |
| uint64_t StackSize = MFI->getStackSize(); // Number of bytes to allocate. |
| bool HasFP = hasFP(MF); |
| bool Is64Bit = STI.is64Bit(); |
| bool IsWin64 = STI.isTargetWin64(); |
| bool UseLEA = STI.useLeaForSP(); |
| unsigned StackAlign = getStackAlignment(); |
| unsigned SlotSize = RegInfo->getSlotSize(); |
| unsigned FramePtr = RegInfo->getFrameRegister(MF); |
| unsigned StackPtr = RegInfo->getStackRegister(); |
| DebugLoc DL; |
| |
| // If we're forcing a stack realignment we can't rely on just the frame |
| // info, we need to know the ABI stack alignment as well in case we |
| // have a call out. Otherwise just make sure we have some alignment - we'll |
| // go with the minimum SlotSize. |
| if (ForceStackAlign) { |
| if (MFI->hasCalls()) |
| MaxAlign = (StackAlign > MaxAlign) ? StackAlign : MaxAlign; |
| else if (MaxAlign < SlotSize) |
| MaxAlign = SlotSize; |
| } |
| |
| // Add RETADDR move area to callee saved frame size. |
| int TailCallReturnAddrDelta = X86FI->getTCReturnAddrDelta(); |
| if (TailCallReturnAddrDelta < 0) |
| X86FI->setCalleeSavedFrameSize( |
| X86FI->getCalleeSavedFrameSize() - TailCallReturnAddrDelta); |
| |
| // 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). |
| if (Is64Bit && !Fn->hasFnAttr(Attribute::NoRedZone) && |
| !RegInfo->needsStackRealignment(MF) && |
| !MFI->hasVarSizedObjects() && // No dynamic alloca. |
| !MFI->adjustsStack() && // No calls. |
| !IsWin64 && // Win64 has no Red Zone |
| !MF.getTarget().Options.EnableSegmentedStacks) { // 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) { |
| MachineInstr *MI = |
| BuildMI(MBB, MBBI, DL, |
| TII.get(getSUBriOpcode(Is64Bit, -TailCallReturnAddrDelta)), |
| StackPtr) |
| .addReg(StackPtr) |
| .addImm(-TailCallReturnAddrDelta) |
| .setMIFlag(MachineInstr::FrameSetup); |
| MI->getOperand(3).setIsDead(); // The EFLAGS implicit def is dead. |
| } |
| |
| // 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 |
| |
| std::vector<MachineMove> &Moves = MMI.getFrameMoves(); |
| const TargetData *TD = MF.getTarget().getTargetData(); |
| uint64_t NumBytes = 0; |
| int stackGrowth = -TD->getPointerSize(); |
| |
| if (HasFP) { |
| // Calculate required stack adjustment. |
| uint64_t FrameSize = StackSize - SlotSize; |
| if (RegInfo->needsStackRealignment(MF)) |
| FrameSize = (FrameSize + MaxAlign - 1) / MaxAlign * MaxAlign; |
| |
| NumBytes = FrameSize - X86FI->getCalleeSavedFrameSize(); |
| |
| // Get the offset of the stack slot for the EBP register, which is |
| // guaranteed to be the last slot by processFunctionBeforeFrameFinalized. |
| // Update the frame offset adjustment. |
| MFI->setOffsetAdjustment(-NumBytes); |
| |
| // Save EBP/RBP into the appropriate stack slot. |
| BuildMI(MBB, MBBI, DL, TII.get(Is64Bit ? X86::PUSH64r : X86::PUSH32r)) |
| .addReg(FramePtr, RegState::Kill) |
| .setMIFlag(MachineInstr::FrameSetup); |
| |
| if (needsFrameMoves) { |
| // Mark the place where EBP/RBP was saved. |
| MCSymbol *FrameLabel = MMI.getContext().CreateTempSymbol(); |
| BuildMI(MBB, MBBI, DL, TII.get(X86::PROLOG_LABEL)) |
| .addSym(FrameLabel); |
| |
| // Define the current CFA rule to use the provided offset. |
| if (StackSize) { |
| MachineLocation SPDst(MachineLocation::VirtualFP); |
| MachineLocation SPSrc(MachineLocation::VirtualFP, 2 * stackGrowth); |
| Moves.push_back(MachineMove(FrameLabel, SPDst, SPSrc)); |
| } else { |
| MachineLocation SPDst(StackPtr); |
| MachineLocation SPSrc(StackPtr, stackGrowth); |
| Moves.push_back(MachineMove(FrameLabel, SPDst, SPSrc)); |
| } |
| |
| // Change the rule for the FramePtr to be an "offset" rule. |
| MachineLocation FPDst(MachineLocation::VirtualFP, 2 * stackGrowth); |
| MachineLocation FPSrc(FramePtr); |
| Moves.push_back(MachineMove(FrameLabel, FPDst, FPSrc)); |
| } |
| |
| // Update EBP with the new base value. |
| BuildMI(MBB, MBBI, DL, |
| TII.get(Is64Bit ? X86::MOV64rr : X86::MOV32rr), FramePtr) |
| .addReg(StackPtr) |
| .setMIFlag(MachineInstr::FrameSetup); |
| |
| if (needsFrameMoves) { |
| // Mark effective beginning of when frame pointer becomes valid. |
| MCSymbol *FrameLabel = MMI.getContext().CreateTempSymbol(); |
| BuildMI(MBB, MBBI, DL, TII.get(X86::PROLOG_LABEL)) |
| .addSym(FrameLabel); |
| |
| // Define the current CFA to use the EBP/RBP register. |
| MachineLocation FPDst(FramePtr); |
| MachineLocation FPSrc(MachineLocation::VirtualFP); |
| Moves.push_back(MachineMove(FrameLabel, FPDst, FPSrc)); |
| } |
| |
| // Mark the FramePtr as live-in in every block except the entry. |
| for (MachineFunction::iterator I = llvm::next(MF.begin()), E = MF.end(); |
| I != E; ++I) |
| I->addLiveIn(FramePtr); |
| |
| // Realign stack |
| if (RegInfo->needsStackRealignment(MF)) { |
| MachineInstr *MI = |
| BuildMI(MBB, MBBI, DL, |
| TII.get(Is64Bit ? X86::AND64ri32 : X86::AND32ri), StackPtr) |
| .addReg(StackPtr) |
| .addImm(-MaxAlign) |
| .setMIFlag(MachineInstr::FrameSetup); |
| |
| // The EFLAGS implicit def is dead. |
| MI->getOperand(3).setIsDead(); |
| } |
| } else { |
| NumBytes = StackSize - X86FI->getCalleeSavedFrameSize(); |
| } |
| |
| // Skip the callee-saved push instructions. |
| bool PushedRegs = false; |
| int StackOffset = 2 * stackGrowth; |
| |
| while (MBBI != MBB.end() && |
| (MBBI->getOpcode() == X86::PUSH32r || |
| MBBI->getOpcode() == X86::PUSH64r)) { |
| PushedRegs = true; |
| MBBI->setFlag(MachineInstr::FrameSetup); |
| ++MBBI; |
| |
| if (!HasFP && needsFrameMoves) { |
| // Mark callee-saved push instruction. |
| MCSymbol *Label = MMI.getContext().CreateTempSymbol(); |
| BuildMI(MBB, MBBI, DL, TII.get(X86::PROLOG_LABEL)).addSym(Label); |
| |
| // Define the current CFA rule to use the provided offset. |
| unsigned Ptr = StackSize ? MachineLocation::VirtualFP : StackPtr; |
| MachineLocation SPDst(Ptr); |
| MachineLocation SPSrc(Ptr, StackOffset); |
| Moves.push_back(MachineMove(Label, SPDst, SPSrc)); |
| StackOffset += stackGrowth; |
| } |
| } |
| |
| DL = MBB.findDebugLoc(MBBI); |
| |
| // If there is an SUB32ri of ESP immediately before this instruction, merge |
| // the two. This can be the case when tail call elimination is enabled and |
| // the callee has more arguments then the caller. |
| NumBytes -= mergeSPUpdates(MBB, MBBI, StackPtr, true); |
| |
| // If there is an ADD32ri or SUB32ri of ESP immediately after this |
| // instruction, merge the two instructions. |
| mergeSPUpdatesDown(MBB, MBBI, StackPtr, &NumBytes); |
| |
| // 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. |
| if (NumBytes >= 4096 && STI.isTargetCOFF() && !STI.isTargetEnvMacho()) { |
| const char *StackProbeSymbol; |
| bool isSPUpdateNeeded = false; |
| |
| if (Is64Bit) { |
| if (STI.isTargetCygMing()) |
| StackProbeSymbol = "___chkstk"; |
| else { |
| StackProbeSymbol = "__chkstk"; |
| isSPUpdateNeeded = true; |
| } |
| } else if (STI.isTargetCygMing()) |
| StackProbeSymbol = "_alloca"; |
| else |
| StackProbeSymbol = "_chkstk"; |
| |
| // 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. |
| 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); |
| } |
| |
| BuildMI(MBB, MBBI, DL, |
| TII.get(Is64Bit ? X86::W64ALLOCA : X86::CALLpcrel32)) |
| .addExternalSymbol(StackProbeSymbol) |
| .addReg(StackPtr, RegState::Define | RegState::Implicit) |
| .addReg(X86::EFLAGS, RegState::Define | RegState::Implicit) |
| .setMIFlag(MachineInstr::FrameSetup); |
| |
| // MSVC x64's __chkstk needs to adjust %rsp. |
| // FIXME: %rax preserves the offset and should be available. |
| if (isSPUpdateNeeded) |
| emitSPUpdate(MBB, MBBI, StackPtr, -(int64_t)NumBytes, Is64Bit, |
| UseLEA, TII, *RegInfo); |
| |
| 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, StackPtr, -(int64_t)NumBytes, Is64Bit, |
| UseLEA, TII, *RegInfo); |
| |
| if (( (!HasFP && NumBytes) || PushedRegs) && needsFrameMoves) { |
| // Mark end of stack pointer adjustment. |
| MCSymbol *Label = MMI.getContext().CreateTempSymbol(); |
| BuildMI(MBB, MBBI, DL, TII.get(X86::PROLOG_LABEL)) |
| .addSym(Label); |
| |
| if (!HasFP && NumBytes) { |
| // Define the current CFA rule to use the provided offset. |
| if (StackSize) { |
| MachineLocation SPDst(MachineLocation::VirtualFP); |
| MachineLocation SPSrc(MachineLocation::VirtualFP, |
| -StackSize + stackGrowth); |
| Moves.push_back(MachineMove(Label, SPDst, SPSrc)); |
| } else { |
| MachineLocation SPDst(StackPtr); |
| MachineLocation SPSrc(StackPtr, stackGrowth); |
| Moves.push_back(MachineMove(Label, SPDst, SPSrc)); |
| } |
| } |
| |
| // Emit DWARF info specifying the offsets of the callee-saved registers. |
| if (PushedRegs) |
| emitCalleeSavedFrameMoves(MF, Label, HasFP ? FramePtr : StackPtr); |
| } |
| |
| // Darwin 10.7 and greater has support for compact unwind encoding. |
| if (STI.getTargetTriple().isMacOSX() && |
| !STI.getTargetTriple().isMacOSXVersionLT(10, 7)) |
| MMI.setCompactUnwindEncoding(getCompactUnwindEncoding(MF)); |
| } |
| |
| void X86FrameLowering::emitEpilogue(MachineFunction &MF, |
| MachineBasicBlock &MBB) const { |
| const MachineFrameInfo *MFI = MF.getFrameInfo(); |
| X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>(); |
| const X86RegisterInfo *RegInfo = TM.getRegisterInfo(); |
| const X86InstrInfo &TII = *TM.getInstrInfo(); |
| MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr(); |
| assert(MBBI != MBB.end() && "Returning block has no instructions"); |
| unsigned RetOpcode = MBBI->getOpcode(); |
| DebugLoc DL = MBBI->getDebugLoc(); |
| bool Is64Bit = STI.is64Bit(); |
| bool UseLEA = STI.useLeaForSP(); |
| unsigned StackAlign = getStackAlignment(); |
| unsigned SlotSize = RegInfo->getSlotSize(); |
| unsigned FramePtr = RegInfo->getFrameRegister(MF); |
| unsigned StackPtr = RegInfo->getStackRegister(); |
| |
| switch (RetOpcode) { |
| default: |
| llvm_unreachable("Can only insert epilog into returning blocks"); |
| case X86::RET: |
| case X86::RETI: |
| case X86::TCRETURNdi: |
| case X86::TCRETURNri: |
| case X86::TCRETURNmi: |
| case X86::TCRETURNdi64: |
| case X86::TCRETURNri64: |
| case X86::TCRETURNmi64: |
| case X86::EH_RETURN: |
| case X86::EH_RETURN64: |
| break; // These are ok |
| } |
| |
| // Get the number of bytes to allocate from the FrameInfo. |
| uint64_t StackSize = MFI->getStackSize(); |
| uint64_t MaxAlign = MFI->getMaxAlignment(); |
| unsigned CSSize = X86FI->getCalleeSavedFrameSize(); |
| uint64_t NumBytes = 0; |
| |
| // If we're forcing a stack realignment we can't rely on just the frame |
| // info, we need to know the ABI stack alignment as well in case we |
| // have a call out. Otherwise just make sure we have some alignment - we'll |
| // go with the minimum. |
| if (ForceStackAlign) { |
| if (MFI->hasCalls()) |
| MaxAlign = (StackAlign > MaxAlign) ? StackAlign : MaxAlign; |
| else |
| MaxAlign = MaxAlign ? MaxAlign : 4; |
| } |
| |
| if (hasFP(MF)) { |
| // Calculate required stack adjustment. |
| uint64_t FrameSize = StackSize - SlotSize; |
| if (RegInfo->needsStackRealignment(MF)) |
| FrameSize = (FrameSize + MaxAlign - 1)/MaxAlign*MaxAlign; |
| |
| NumBytes = FrameSize - CSSize; |
| |
| // Pop EBP. |
| BuildMI(MBB, MBBI, DL, |
| TII.get(Is64Bit ? X86::POP64r : X86::POP32r), FramePtr); |
| } else { |
| NumBytes = StackSize - CSSize; |
| } |
| |
| // Skip the callee-saved pop instructions. |
| MachineBasicBlock::iterator LastCSPop = MBBI; |
| while (MBBI != MBB.begin()) { |
| MachineBasicBlock::iterator PI = prior(MBBI); |
| unsigned Opc = PI->getOpcode(); |
| |
| if (Opc != X86::POP32r && Opc != X86::POP64r && Opc != X86::DBG_VALUE && |
| !PI->isTerminator()) |
| break; |
| |
| --MBBI; |
| } |
| |
| DL = MBBI->getDebugLoc(); |
| |
| // If there is an ADD32ri or SUB32ri of ESP immediately before this |
| // instruction, merge the two instructions. |
| if (NumBytes || MFI->hasVarSizedObjects()) |
| mergeSPUpdatesUp(MBB, MBBI, StackPtr, &NumBytes); |
| |
| // If dynamic alloca is used, then reset esp to point to the last callee-saved |
| // slot before popping them off! Same applies for the case, when stack was |
| // realigned. |
| if (RegInfo->needsStackRealignment(MF)) { |
| // We cannot use LEA here, because stack pointer was realigned. We need to |
| // deallocate local frame back. |
| if (CSSize) { |
| emitSPUpdate(MBB, MBBI, StackPtr, NumBytes, Is64Bit, UseLEA, TII, |
| *RegInfo); |
| MBBI = prior(LastCSPop); |
| } |
| |
| BuildMI(MBB, MBBI, DL, |
| TII.get(Is64Bit ? X86::MOV64rr : X86::MOV32rr), |
| StackPtr).addReg(FramePtr); |
| } else if (MFI->hasVarSizedObjects()) { |
| if (CSSize) { |
| unsigned Opc = Is64Bit ? X86::LEA64r : X86::LEA32r; |
| MachineInstr *MI = |
| addRegOffset(BuildMI(MF, DL, TII.get(Opc), StackPtr), |
| FramePtr, false, -CSSize); |
| MBB.insert(MBBI, MI); |
| } else { |
| BuildMI(MBB, MBBI, DL, |
| TII.get(Is64Bit ? X86::MOV64rr : X86::MOV32rr), StackPtr) |
| .addReg(FramePtr); |
| } |
| } else if (NumBytes) { |
| // Adjust stack pointer back: ESP += numbytes. |
| emitSPUpdate(MBB, MBBI, StackPtr, NumBytes, Is64Bit, UseLEA, TII, *RegInfo); |
| } |
| |
| // We're returning from function via eh_return. |
| if (RetOpcode == X86::EH_RETURN || RetOpcode == X86::EH_RETURN64) { |
| MBBI = MBB.getLastNonDebugInstr(); |
| MachineOperand &DestAddr = MBBI->getOperand(0); |
| assert(DestAddr.isReg() && "Offset should be in register!"); |
| BuildMI(MBB, MBBI, DL, |
| TII.get(Is64Bit ? X86::MOV64rr : X86::MOV32rr), |
| StackPtr).addReg(DestAddr.getReg()); |
| } else if (RetOpcode == X86::TCRETURNri || RetOpcode == X86::TCRETURNdi || |
| RetOpcode == X86::TCRETURNmi || |
| RetOpcode == X86::TCRETURNri64 || RetOpcode == X86::TCRETURNdi64 || |
| RetOpcode == X86::TCRETURNmi64) { |
| bool isMem = RetOpcode == X86::TCRETURNmi || RetOpcode == X86::TCRETURNmi64; |
| // Tail call return: adjust the stack pointer and jump to callee. |
| MBBI = MBB.getLastNonDebugInstr(); |
| MachineOperand &JumpTarget = MBBI->getOperand(0); |
| MachineOperand &StackAdjust = MBBI->getOperand(isMem ? 5 : 1); |
| assert(StackAdjust.isImm() && "Expecting immediate value."); |
| |
| // Adjust stack pointer. |
| int StackAdj = StackAdjust.getImm(); |
| int MaxTCDelta = X86FI->getTCReturnAddrDelta(); |
| int Offset = 0; |
| assert(MaxTCDelta <= 0 && "MaxTCDelta should never be positive"); |
| |
| // Incoporate the retaddr area. |
| Offset = StackAdj-MaxTCDelta; |
| assert(Offset >= 0 && "Offset should never be negative"); |
| |
| if (Offset) { |
| // Check for possible merge with preceding ADD instruction. |
| Offset += mergeSPUpdates(MBB, MBBI, StackPtr, true); |
| emitSPUpdate(MBB, MBBI, StackPtr, Offset, Is64Bit, UseLEA, TII, *RegInfo); |
| } |
| |
| // Jump to label or value in register. |
| if (RetOpcode == X86::TCRETURNdi || RetOpcode == X86::TCRETURNdi64) { |
| MachineInstrBuilder MIB = |
| BuildMI(MBB, MBBI, DL, TII.get((RetOpcode == X86::TCRETURNdi) |
| ? X86::TAILJMPd : X86::TAILJMPd64)); |
| if (JumpTarget.isGlobal()) |
| MIB.addGlobalAddress(JumpTarget.getGlobal(), JumpTarget.getOffset(), |
| JumpTarget.getTargetFlags()); |
| else { |
| assert(JumpTarget.isSymbol()); |
| MIB.addExternalSymbol(JumpTarget.getSymbolName(), |
| JumpTarget.getTargetFlags()); |
| } |
| } else if (RetOpcode == X86::TCRETURNmi || RetOpcode == X86::TCRETURNmi64) { |
| MachineInstrBuilder MIB = |
| BuildMI(MBB, MBBI, DL, TII.get((RetOpcode == X86::TCRETURNmi) |
| ? X86::TAILJMPm : X86::TAILJMPm64)); |
| for (unsigned i = 0; i != 5; ++i) |
| MIB.addOperand(MBBI->getOperand(i)); |
| } else if (RetOpcode == X86::TCRETURNri64) { |
| BuildMI(MBB, MBBI, DL, TII.get(X86::TAILJMPr64)). |
| addReg(JumpTarget.getReg(), RegState::Kill); |
| } else { |
| BuildMI(MBB, MBBI, DL, TII.get(X86::TAILJMPr)). |
| addReg(JumpTarget.getReg(), RegState::Kill); |
| } |
| |
| MachineInstr *NewMI = prior(MBBI); |
| for (unsigned i = 2, e = MBBI->getNumOperands(); i != e; ++i) |
| NewMI->addOperand(MBBI->getOperand(i)); |
| |
| // Delete the pseudo instruction TCRETURN. |
| MBB.erase(MBBI); |
| } else if ((RetOpcode == X86::RET || RetOpcode == X86::RETI) && |
| (X86FI->getTCReturnAddrDelta() < 0)) { |
| // Add the return addr area delta back since we are not tail calling. |
| int delta = -1*X86FI->getTCReturnAddrDelta(); |
| MBBI = MBB.getLastNonDebugInstr(); |
| |
| // Check for possible merge with preceding ADD instruction. |
| delta += mergeSPUpdates(MBB, MBBI, StackPtr, true); |
| emitSPUpdate(MBB, MBBI, StackPtr, delta, Is64Bit, UseLEA, TII, *RegInfo); |
| } |
| } |
| |
| int X86FrameLowering::getFrameIndexOffset(const MachineFunction &MF, int FI) const { |
| const X86RegisterInfo *RI = |
| static_cast<const X86RegisterInfo*>(MF.getTarget().getRegisterInfo()); |
| const MachineFrameInfo *MFI = MF.getFrameInfo(); |
| int Offset = MFI->getObjectOffset(FI) - getOffsetOfLocalArea(); |
| uint64_t StackSize = MFI->getStackSize(); |
| |
| if (RI->needsStackRealignment(MF)) { |
| if (FI < 0) { |
| // Skip the saved EBP. |
| Offset += RI->getSlotSize(); |
| } else { |
| assert((-(Offset + StackSize)) % MFI->getObjectAlignment(FI) == 0); |
| return Offset + StackSize; |
| } |
| // FIXME: Support tail calls |
| } else { |
| if (!hasFP(MF)) |
| return Offset + StackSize; |
| |
| // Skip the saved EBP. |
| Offset += RI->getSlotSize(); |
| |
| // Skip the RETADDR move area |
| const X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>(); |
| int TailCallReturnAddrDelta = X86FI->getTCReturnAddrDelta(); |
| if (TailCallReturnAddrDelta < 0) |
| Offset -= TailCallReturnAddrDelta; |
| } |
| |
| return Offset; |
| } |
| |
| bool X86FrameLowering::spillCalleeSavedRegisters(MachineBasicBlock &MBB, |
| MachineBasicBlock::iterator MI, |
| const std::vector<CalleeSavedInfo> &CSI, |
| const TargetRegisterInfo *TRI) const { |
| if (CSI.empty()) |
| return false; |
| |
| DebugLoc DL = MBB.findDebugLoc(MI); |
| |
| MachineFunction &MF = *MBB.getParent(); |
| |
| unsigned SlotSize = STI.is64Bit() ? 8 : 4; |
| unsigned FPReg = TRI->getFrameRegister(MF); |
| unsigned CalleeFrameSize = 0; |
| |
| const TargetInstrInfo &TII = *MF.getTarget().getInstrInfo(); |
| X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>(); |
| |
| // 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); |
| if (Reg == FPReg) |
| // X86RegisterInfo::emitPrologue will handle spilling of frame register. |
| continue; |
| CalleeFrameSize += SlotSize; |
| BuildMI(MBB, MI, DL, TII.get(Opc)).addReg(Reg, RegState::Kill) |
| .setMIFlag(MachineInstr::FrameSetup); |
| } |
| |
| X86FI->setCalleeSavedFrameSize(CalleeFrameSize); |
| |
| // Make XMM regs spilled. X86 does not have ability of push/pop XMM. |
| // It can be done by spilling XMMs to stack frame. |
| // Note that only Win64 ABI might spill 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; |
| // 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); |
| } |
| |
| return true; |
| } |
| |
| bool X86FrameLowering::restoreCalleeSavedRegisters(MachineBasicBlock &MBB, |
| MachineBasicBlock::iterator MI, |
| const std::vector<CalleeSavedInfo> &CSI, |
| const TargetRegisterInfo *TRI) const { |
| if (CSI.empty()) |
| return false; |
| |
| DebugLoc DL = MBB.findDebugLoc(MI); |
| |
| MachineFunction &MF = *MBB.getParent(); |
| const TargetInstrInfo &TII = *MF.getTarget().getInstrInfo(); |
| |
| // 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 FPReg = TRI->getFrameRegister(MF); |
| 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; |
| if (Reg == FPReg) |
| // X86RegisterInfo::emitEpilogue will handle restoring of frame register. |
| continue; |
| BuildMI(MBB, MI, DL, TII.get(Opc), Reg); |
| } |
| return true; |
| } |
| |
| void |
| X86FrameLowering::processFunctionBeforeCalleeSavedScan(MachineFunction &MF, |
| RegScavenger *RS) const { |
| MachineFrameInfo *MFI = MF.getFrameInfo(); |
| const X86RegisterInfo *RegInfo = TM.getRegisterInfo(); |
| unsigned SlotSize = RegInfo->getSlotSize(); |
| |
| X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>(); |
| int32_t TailCallReturnAddrDelta = X86FI->getTCReturnAddrDelta(); |
| |
| if (TailCallReturnAddrDelta < 0) { |
| // create RETURNADDR area |
| // arg |
| // arg |
| // RETADDR |
| // { ... |
| // RETADDR area |
| // ... |
| // } |
| // [EBP] |
| MFI->CreateFixedObject(-TailCallReturnAddrDelta, |
| (-1U*SlotSize)+TailCallReturnAddrDelta, true); |
| } |
| |
| if (hasFP(MF)) { |
| assert((TailCallReturnAddrDelta <= 0) && |
| "The Delta should always be zero or negative"); |
| const TargetFrameLowering &TFI = *MF.getTarget().getFrameLowering(); |
| |
| // Create a frame entry for the EBP register that must be saved. |
| int FrameIdx = MFI->CreateFixedObject(SlotSize, |
| -(int)SlotSize + |
| TFI.getOffsetOfLocalArea() + |
| TailCallReturnAddrDelta, |
| true); |
| assert(FrameIdx == MFI->getObjectIndexBegin() && |
| "Slot for EBP register must be last in order to be found!"); |
| (void)FrameIdx; |
| } |
| } |
| |
| 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 register for performing work in the segmented |
| /// 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, const MachineFunction &MF, bool Primary) { |
| if (Is64Bit) |
| return Primary ? X86::R11 : X86::R12; |
| |
| CallingConv::ID CallingConvention = MF.getFunction()->getCallingConv(); |
| 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) const { |
| MachineBasicBlock &prologueMBB = MF.front(); |
| MachineFrameInfo *MFI = MF.getFrameInfo(); |
| const X86InstrInfo &TII = *TM.getInstrInfo(); |
| uint64_t StackSize; |
| bool Is64Bit = STI.is64Bit(); |
| unsigned TlsReg, TlsOffset; |
| DebugLoc DL; |
| const X86Subtarget *ST = &MF.getTarget().getSubtarget<X86Subtarget>(); |
| |
| unsigned ScratchReg = GetScratchRegister(Is64Bit, 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 (!ST->isTargetLinux() && !ST->isTargetDarwin() && |
| !ST->isTargetWin32() && !ST->isTargetFreeBSD()) |
| report_fatal_error("Segmented stacks not supported on this platform."); |
| |
| 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 (MachineBasicBlock::livein_iterator i = prologueMBB.livein_begin(), |
| e = prologueMBB.livein_end(); i != e; i++) { |
| allocMBB->addLiveIn(*i); |
| checkMBB->addLiveIn(*i); |
| } |
| |
| if (IsNested) |
| allocMBB->addLiveIn(X86::R10); |
| |
| MF.push_front(allocMBB); |
| MF.push_front(checkMBB); |
| |
| // 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(); |
| |
| // 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 (ST->isTargetLinux()) { |
| TlsReg = X86::FS; |
| TlsOffset = 0x70; |
| } else if (ST->isTargetDarwin()) { |
| TlsReg = X86::GS; |
| TlsOffset = 0x60 + 90*8; // See pthread_machdep.h. Steal TLS slot 90. |
| } else if (ST->isTargetFreeBSD()) { |
| TlsReg = X86::FS; |
| TlsOffset = 0x18; |
| } else { |
| report_fatal_error("Segmented stacks not supported on this platform."); |
| } |
| |
| if (CompareStackPointer) |
| ScratchReg = X86::RSP; |
| else |
| BuildMI(checkMBB, DL, TII.get(X86::LEA64r), ScratchReg).addReg(X86::RSP) |
| .addImm(1).addReg(0).addImm(-StackSize).addReg(0); |
| |
| BuildMI(checkMBB, DL, TII.get(X86::CMP64rm)).addReg(ScratchReg) |
| .addReg(0).addImm(1).addReg(0).addImm(TlsOffset).addReg(TlsReg); |
| } else { |
| if (ST->isTargetLinux()) { |
| TlsReg = X86::GS; |
| TlsOffset = 0x30; |
| } else if (ST->isTargetDarwin()) { |
| TlsReg = X86::GS; |
| TlsOffset = 0x48 + 90*4; |
| } else if (ST->isTargetWin32()) { |
| TlsReg = X86::FS; |
| TlsOffset = 0x14; // pvArbitrary, reserved for application use |
| } else if (ST->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 (ST->isTargetLinux() || ST->isTargetWin32()) { |
| BuildMI(checkMBB, DL, TII.get(X86::CMP32rm)).addReg(ScratchReg) |
| .addReg(0).addImm(0).addReg(0).addImm(TlsOffset).addReg(TlsReg); |
| } else if (ST->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, MF, true); |
| SaveScratch2 = false; |
| } else { |
| // Need to use a second register to hold the TLS offset |
| ScratchReg2 = GetScratchRegister(Is64Bit, MF, false); |
| |
| // Unfortunately, with fastcc the second scratch register may hold an arg |
| 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_4)).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 |
| |
| if (IsNested) |
| BuildMI(allocMBB, DL, TII.get(X86::MOV64rr), X86::RAX).addReg(X86::R10); |
| |
| BuildMI(allocMBB, DL, TII.get(X86::MOV64ri), X86::R10) |
| .addImm(StackSize); |
| BuildMI(allocMBB, DL, TII.get(X86::MOV64ri), X86::R11) |
| .addImm(X86FI->getArgumentStackSize()); |
| MF.getRegInfo().setPhysRegUsed(X86::R10); |
| MF.getRegInfo().setPhysRegUsed(X86::R11); |
| } 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) |
| 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 |
| } |
