-//=======- X86FrameLowering.cpp - X86 Frame Information --------*- C++ -*-====//
+//===-- X86FrameLowering.cpp - X86 Frame Information ----------------------===//
//
// The LLVM Compiler Infrastructure
//
#include "X86MachineFunctionInfo.h"
#include "X86Subtarget.h"
#include "X86TargetMachine.h"
-#include "llvm/Function.h"
+#include "llvm/ADT/SmallSet.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/IR/DataLayout.h"
+#include "llvm/IR/Function.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"
+#include "llvm/Target/TargetOptions.h"
using namespace llvm;
bool X86FrameLowering::hasFP(const MachineFunction &MF) const {
const MachineFrameInfo *MFI = MF.getFrameInfo();
const MachineModuleInfo &MMI = MF.getMMI();
- const TargetRegisterInfo *RI = TM.getRegisterInfo();
+ const TargetRegisterInfo *RegInfo = TM.getRegisterInfo();
return (MF.getTarget().Options.DisableFramePointerElim(MF) ||
- RI->needsStackRealignment(MF) ||
+ RegInfo->needsStackRealignment(MF) ||
MFI->hasVarSizedObjects() ||
- MFI->isFrameAddressTaken() ||
+ MFI->isFrameAddressTaken() || MF.hasMSInlineAsm() ||
MF.getInfo<X86MachineFunctionInfo>()->getForceFramePointer() ||
- MMI.callsUnwindInit());
+ MMI.callsUnwindInit() || MMI.callsEHReturn());
}
-static unsigned getSUBriOpcode(unsigned is64Bit, int64_t Imm) {
- if (is64Bit) {
+static unsigned getSUBriOpcode(unsigned IsLP64, int64_t Imm) {
+ if (IsLP64) {
if (isInt<8>(Imm))
return X86::SUB64ri8;
return X86::SUB64ri32;
}
}
-static unsigned getADDriOpcode(unsigned is64Bit, int64_t Imm) {
- if (is64Bit) {
+static unsigned getADDriOpcode(unsigned IsLP64, int64_t Imm) {
+ if (IsLP64) {
if (isInt<8>(Imm))
return X86::ADD64ri8;
return X86::ADD64ri32;
}
}
+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.
if (!F || MF->getMMI().callsEHReturn())
return 0;
- static const unsigned CallerSavedRegs32Bit[] = {
+ static const uint16_t CallerSavedRegs32Bit[] = {
X86::EAX, X86::EDX, X86::ECX, 0
};
- static const unsigned CallerSavedRegs64Bit[] = {
+ static const uint16_t CallerSavedRegs64Bit[] = {
X86::RAX, X86::RDX, X86::RCX, X86::RSI, X86::RDI,
X86::R8, X86::R9, X86::R10, X86::R11, 0
};
case X86::TCRETURNmi64:
case X86::EH_RETURN:
case X86::EH_RETURN64: {
- SmallSet<unsigned, 8> Uses;
+ 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())
unsigned Reg = MO.getReg();
if (!Reg)
continue;
- for (const unsigned *AsI = TRI.getOverlaps(Reg); *AsI; ++AsI)
- Uses.insert(*AsI);
+ for (MCRegAliasIterator AI(Reg, &TRI, true); AI.isValid(); ++AI)
+ Uses.insert(*AI);
}
- const unsigned *CS = Is64Bit ? CallerSavedRegs64Bit : CallerSavedRegs32Bit;
+ const uint16_t *CS = Is64Bit ? CallerSavedRegs64Bit : CallerSavedRegs32Bit;
for (; *CS; ++CS)
if (!Uses.count(*CS))
return *CS;
static
void emitSPUpdate(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI,
unsigned StackPtr, int64_t NumBytes,
- bool Is64Bit, const TargetInstrInfo &TII,
- const TargetRegisterInfo &TRI) {
+ bool Is64Bit, bool IsLP64, bool UseLEA,
+ const TargetInstrInfo &TII, const TargetRegisterInfo &TRI) {
bool isSub = NumBytes < 0;
uint64_t Offset = isSub ? -NumBytes : NumBytes;
- unsigned Opc = isSub ?
- getSUBriOpcode(Is64Bit, Offset) :
- getADDriOpcode(Is64Bit, Offset);
+ unsigned Opc;
+ if (UseLEA)
+ Opc = getLEArOpcode(IsLP64);
+ else
+ Opc = isSub
+ ? getSUBriOpcode(IsLP64, Offset)
+ : getADDriOpcode(IsLP64, Offset);
+
uint64_t Chunk = (1LL << 31) - 1;
DebugLoc DL = MBB.findDebugLoc(MBBI);
}
}
- MachineInstr *MI =
- BuildMI(MBB, MBBI, DL, TII.get(Opc), StackPtr)
- .addReg(StackPtr)
- .addImm(ThisVal);
+ 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);
- MI->getOperand(3).setIsDead(); // The EFLAGS implicit def is dead.
+
Offset -= ThisVal;
}
}
MachineBasicBlock::iterator PI = prior(MBBI);
unsigned Opc = PI->getOpcode();
if ((Opc == X86::ADD64ri32 || Opc == X86::ADD64ri8 ||
- Opc == X86::ADD32ri || Opc == X86::ADD32ri8) &&
+ 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();
}
/// mergeSPUpdates - Checks the instruction before/after the passed
-/// instruction. If it is an ADD/SUB instruction it is deleted argument and the
-/// stack adjustment is returned as a positive value for ADD and a negative for
+/// 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,
int Offset = 0;
if ((Opc == X86::ADD64ri32 || Opc == X86::ADD64ri8 ||
- Opc == X86::ADD32ri || Opc == X86::ADD32ri8) &&
+ 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 (CSI.empty()) return;
std::vector<MachineMove> &Moves = MMI.getFrameMoves();
- const TargetData *TD = TM.getTargetData();
+ const X86RegisterInfo *RegInfo = TM.getRegisterInfo();
bool HasFP = hasFP(MF);
// Calculate amount of bytes used for return address storing.
- int stackGrowth = -TD->getPointerSize();
+ int stackGrowth = -RegInfo->getSlotSize();
// FIXME: This is dirty hack. The code itself is pretty mess right now.
// It should be rewritten from scratch and generalized sometimes.
/// 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) {
- int Idx = 1;
- for (; *CURegs; ++CURegs, ++Idx)
+static int getCompactUnwindRegNum(const uint16_t *CURegs, unsigned Reg) {
+ for (int Idx = 1; *CURegs; ++CURegs, ++Idx)
if (*CURegs == Reg)
return Idx;
// 4 3
// 5 3
//
- static const unsigned CU32BitRegs[] = {
+ static const uint16_t CU32BitRegs[] = {
X86::EBX, X86::ECX, X86::EDX, X86::EDI, X86::ESI, X86::EBP, 0
};
- static const unsigned CU64BitRegs[] = {
+ static const uint16_t CU64BitRegs[] = {
X86::RBX, X86::R12, X86::R13, X86::R14, X86::R15, X86::RBP, 0
};
- const unsigned *CURegs = (Is64Bit ? CU64BitRegs : CU32BitRegs);
+ const uint16_t *CURegs = (Is64Bit ? CU64BitRegs : CU32BitRegs);
- for (unsigned i = CU_NUM_SAVED_REGS - RegCount; i < CU_NUM_SAVED_REGS; ++i) {
+ 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;
static uint32_t
encodeCompactUnwindRegistersWithFrame(unsigned SavedRegs[CU_NUM_SAVED_REGS],
bool Is64Bit) {
- static const unsigned CU32BitRegs[] = {
+ static const uint16_t CU32BitRegs[] = {
X86::EBX, X86::ECX, X86::EDX, X86::EDI, X86::ESI, X86::EBP, 0
};
- static const unsigned CU64BitRegs[] = {
+ static const uint16_t CU64BitRegs[] = {
X86::RBX, X86::R12, X86::R13, X86::R14, X86::R15, X86::RBP, 0
};
- const unsigned *CURegs = (Is64Bit ? CU64BitRegs : CU32BitRegs);
+ const uint16_t *CURegs = (Is64Bit ? CU64BitRegs : CU32BitRegs);
// Encode the registers in the order they were saved, 3-bits per register. The
- // registers are numbered from 1 to 6.
+ // registers are numbered from 1 to CU_NUM_SAVED_REGS.
uint32_t RegEnc = 0;
- for (int I = 5; I >= 0; --I) {
+ for (int I = CU_NUM_SAVED_REGS - 1, Idx = 0; I != -1; --I) {
unsigned Reg = SavedRegs[I];
- if (Reg == 0) break;
+ if (Reg == 0) continue;
+
int CURegNum = getCompactUnwindRegNum(CURegs, Reg);
- if (CURegNum == -1)
- return ~0U;
+ if (CURegNum == -1) return ~0U;
// Encode the 3-bit register number in order, skipping over 3-bits for each
// register.
- RegEnc |= (CURegNum & 0x7) << ((5 - I) * 3);
+ RegEnc |= (CURegNum & 0x7) << (Idx++ * 3);
}
- assert((RegEnc & 0x7FFF) == RegEnc && "Invalid compact register encoding!");
+ assert((RegEnc & 0x3FFFF) == RegEnc && "Invalid compact register encoding!");
return RegEnc;
}
unsigned FramePtr = RegInfo->getFrameRegister(MF);
unsigned StackPtr = RegInfo->getStackRegister();
- X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>();
- int TailCallReturnAddrDelta = X86FI->getTCReturnAddrDelta();
-
bool Is64Bit = STI.is64Bit();
bool HasFP = hasFP(MF);
unsigned SavedRegs[CU_NUM_SAVED_REGS] = { 0, 0, 0, 0, 0, 0 };
- int SavedRegIdx = CU_NUM_SAVED_REGS;
+ unsigned SavedRegIdx = 0;
unsigned OffsetSize = (Is64Bit ? 8 : 4);
unsigned PushInstrSize = 1;
unsigned MoveInstr = (Is64Bit ? X86::MOV64rr : X86::MOV32rr);
unsigned MoveInstrSize = (Is64Bit ? 3 : 2);
- unsigned SubtractInstr = getSUBriOpcode(Is64Bit, -TailCallReturnAddrDelta);
unsigned SubtractInstrIdx = (Is64Bit ? 3 : 2);
unsigned StackDivide = (Is64Bit ? 8 : 4);
if (Opc == PushInstr) {
// If there are too many saved registers, we cannot use compact encoding.
- if (--SavedRegIdx < 0) return 0;
+ if (SavedRegIdx >= CU_NUM_SAVED_REGS) return 0;
- SavedRegs[SavedRegIdx] = MI.getOperand(0).getReg();
+ SavedRegs[SavedRegIdx++] = MI.getOperand(0).getReg();
StackAdjust += OffsetSize;
InstrOffset += PushInstrSize;
} else if (Opc == MoveInstr) {
StackAdjust = 0;
memset(SavedRegs, 0, sizeof(SavedRegs));
- SavedRegIdx = CU_NUM_SAVED_REGS;
+ SavedRegIdx = 0;
InstrOffset += MoveInstrSize;
- } else if (Opc == SubtractInstr) {
+ } else if (Opc == X86::SUB64ri32 || Opc == X86::SUB64ri8 ||
+ Opc == X86::SUB32ri || Opc == X86::SUB32ri8) {
if (StackSize)
// We already have a stack size.
return 0;
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.
}
// Encode the number of registers saved.
- CompactUnwindEncoding |= ((CU_NUM_SAVED_REGS - SavedRegIdx) & 0x7) << 10;
+ CompactUnwindEncoding |= (SavedRegIdx & 0x7) << 10;
// Get the encoding of the saved registers when we don't have a frame
// pointer.
uint32_t RegEnc =
- encodeCompactUnwindRegistersWithoutFrame(SavedRegs,
- CU_NUM_SAVED_REGS - SavedRegIdx,
+ encodeCompactUnwindRegistersWithoutFrame(SavedRegs, SavedRegIdx,
Is64Bit);
if (RegEnc == ~0U) return 0;
return CompactUnwindEncoding;
}
+/// usesTheStack - This function checks if any of the users of EFLAGS
+/// copies the EFLAGS. We know that the code that lowers COPY of EFLAGS has
+/// to use the stack, and if we don't adjust the stack we clobber the first
+/// frame index.
+/// See X86InstrInfo::copyPhysReg.
+static bool usesTheStack(MachineFunction &MF) {
+ MachineRegisterInfo &MRI = MF.getRegInfo();
+
+ for (MachineRegisterInfo::reg_iterator ri = MRI.reg_begin(X86::EFLAGS),
+ re = MRI.reg_end(); ri != re; ++ri)
+ if (ri->isCopy())
+ return true;
+
+ return false;
+}
+
/// 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
uint64_t StackSize = MFI->getStackSize(); // Number of bytes to allocate.
bool HasFP = hasFP(MF);
bool Is64Bit = STI.is64Bit();
+ bool IsLP64 = STI.isTarget64BitLP64();
bool IsWin64 = STI.isTargetWin64();
+ bool UseLEA = STI.useLeaForSP();
unsigned StackAlign = getStackAlignment();
unsigned SlotSize = RegInfo->getSlotSize();
unsigned FramePtr = RegInfo->getFrameRegister(MF);
unsigned StackPtr = RegInfo->getStackRegister();
+ unsigned BasePtr = RegInfo->getBaseRegister();
DebugLoc DL;
// If we're forcing a stack realignment we can't rely on just the frame
// 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) &&
+ // stack pointer (we fit in the Red Zone). We also check that we don't
+ // push and pop from the stack.
+ if (Is64Bit && !Fn->getAttributes().hasAttribute(AttributeSet::FunctionIndex,
+ Attribute::NoRedZone) &&
!RegInfo->needsStackRealignment(MF) &&
!MFI->hasVarSizedObjects() && // No dynamic alloca.
!MFI->adjustsStack() && // No calls.
!IsWin64 && // Win64 has no Red Zone
+ !usesTheStack(MF) && // Don't push and pop.
!MF.getTarget().Options.EnableSegmentedStacks) { // Regular stack
uint64_t MinSize = X86FI->getCalleeSavedFrameSize();
if (HasFP) MinSize += SlotSize;
if (TailCallReturnAddrDelta < 0) {
MachineInstr *MI =
BuildMI(MBB, MBBI, DL,
- TII.get(getSUBriOpcode(Is64Bit, -TailCallReturnAddrDelta)),
+ TII.get(getSUBriOpcode(IsLP64, -TailCallReturnAddrDelta)),
StackPtr)
.addReg(StackPtr)
.addImm(-TailCallReturnAddrDelta)
// 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();
+ int stackGrowth = -SlotSize;
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();
+ if (RegInfo->needsStackRealignment(MF)) {
+ // Callee-saved registers are pushed on stack before the stack
+ // is realigned.
+ FrameSize -= X86FI->getCalleeSavedFrameSize();
+ NumBytes = (FrameSize + MaxAlign - 1) / MaxAlign * MaxAlign;
+ } else {
+ NumBytes = FrameSize - X86FI->getCalleeSavedFrameSize();
+ }
// Get the offset of the stack slot for the EBP register, which is
// guaranteed to be the last slot by processFunctionBeforeFrameFinalized.
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();
}
}
}
- DL = MBB.findDebugLoc(MBBI);
+ // Realign stack after we pushed callee-saved registers (so that we'll be
+ // able to calculate their offsets from the frame pointer).
+
+ // NOTE: We push the registers before realigning the stack, so
+ // vector callee-saved (xmm) registers may be saved w/o proper
+ // alignment in this way. However, currently these regs are saved in
+ // stack slots (see X86FrameLowering::spillCalleeSavedRegisters()), so
+ // this shouldn't be a problem.
+ if (RegInfo->needsStackRealignment(MF)) {
+ assert(HasFP && "There should be a frame pointer if stack is realigned.");
+ 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();
+ }
// 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
// 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,
- TII, *RegInfo);
+ emitSPUpdate(MBB, MBBI, StackPtr, -(int64_t)NumBytes, Is64Bit, IsLP64,
+ UseLEA, TII, *RegInfo);
if (isEAXAlive) {
// Restore EAX
MBB.insert(MBBI, MI);
}
} else if (NumBytes)
- emitSPUpdate(MBB, MBBI, StackPtr, -(int64_t)NumBytes, Is64Bit,
- TII, *RegInfo);
+ emitSPUpdate(MBB, MBBI, StackPtr, -(int64_t)NumBytes, Is64Bit, IsLP64,
+ UseLEA, TII, *RegInfo);
+
+ // If we need a base pointer, set it up here. It's whatever the value
+ // of the stack pointer is at this point. Any variable size objects
+ // will be allocated after this, so we can still use the base pointer
+ // to reference locals.
+ if (RegInfo->hasBasePointer(MF)) {
+ // Update the frame pointer with the current stack pointer.
+ unsigned Opc = Is64Bit ? X86::MOV64rr : X86::MOV32rr;
+ BuildMI(MBB, MBBI, DL, TII.get(Opc), BasePtr)
+ .addReg(StackPtr)
+ .setMIFlag(MachineInstr::FrameSetup);
+ }
if (( (!HasFP && NumBytes) || PushedRegs) && needsFrameMoves) {
// Mark end of stack pointer adjustment.
unsigned RetOpcode = MBBI->getOpcode();
DebugLoc DL = MBBI->getDebugLoc();
bool Is64Bit = STI.is64Bit();
+ bool IsLP64 = STI.isTarget64BitLP64();
+ bool UseLEA = STI.useLeaForSP();
unsigned StackAlign = getStackAlignment();
unsigned SlotSize = RegInfo->getSlotSize();
unsigned FramePtr = RegInfo->getFrameRegister(MF);
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;
+ if (RegInfo->needsStackRealignment(MF)) {
+ // Callee-saved registers were pushed on stack before the stack
+ // was realigned.
+ FrameSize -= CSSize;
+ NumBytes = (FrameSize + MaxAlign - 1) / MaxAlign * MaxAlign;
+ } else {
+ NumBytes = FrameSize - CSSize;
+ }
// Pop EBP.
BuildMI(MBB, MBBI, DL,
}
// 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->getDesc().isTerminator())
+ !PI->isTerminator())
break;
--MBBI;
}
+ MachineBasicBlock::iterator FirstCSPop = MBBI;
DL = MBBI->getDebugLoc();
// 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, 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);
+ if (RegInfo->needsStackRealignment(MF) || MFI->hasVarSizedObjects()) {
+ if (RegInfo->needsStackRealignment(MF))
+ MBBI = FirstCSPop;
+ if (CSSize != 0) {
+ unsigned Opc = getLEArOpcode(IsLP64);
+ addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(Opc), StackPtr),
+ FramePtr, false, -CSSize);
} else {
- BuildMI(MBB, MBBI, DL,
- TII.get(Is64Bit ? X86::MOV64rr : X86::MOV32rr), StackPtr)
+ unsigned Opc = (Is64Bit ? X86::MOV64rr : X86::MOV32rr);
+ BuildMI(MBB, MBBI, DL, TII.get(Opc), StackPtr)
.addReg(FramePtr);
}
} else if (NumBytes) {
// Adjust stack pointer back: ESP += numbytes.
- emitSPUpdate(MBB, MBBI, StackPtr, NumBytes, Is64Bit, TII, *RegInfo);
+ emitSPUpdate(MBB, MBBI, StackPtr, NumBytes, Is64Bit, IsLP64, UseLEA,
+ TII, *RegInfo);
}
// We're returning from function via eh_return.
if (Offset) {
// Check for possible merge with preceding ADD instruction.
Offset += mergeSPUpdates(MBB, MBBI, StackPtr, true);
- emitSPUpdate(MBB, MBBI, StackPtr, Offset, Is64Bit, TII, *RegInfo);
+ emitSPUpdate(MBB, MBBI, StackPtr, Offset, Is64Bit, IsLP64,
+ UseLEA, TII, *RegInfo);
}
// Jump to label or value in register.
}
MachineInstr *NewMI = prior(MBBI);
- for (unsigned i = 2, e = MBBI->getNumOperands(); i != e; ++i)
- NewMI->addOperand(MBBI->getOperand(i));
+ NewMI->copyImplicitOps(MF, MBBI);
// Delete the pseudo instruction TCRETURN.
MBB.erase(MBBI);
// Check for possible merge with preceding ADD instruction.
delta += mergeSPUpdates(MBB, MBBI, StackPtr, true);
- emitSPUpdate(MBB, MBBI, StackPtr, delta, Is64Bit, TII, *RegInfo);
+ emitSPUpdate(MBB, MBBI, StackPtr, delta, Is64Bit, IsLP64, UseLEA, TII,
+ *RegInfo);
}
}
int X86FrameLowering::getFrameIndexOffset(const MachineFunction &MF, int FI) const {
- const X86RegisterInfo *RI =
+ const X86RegisterInfo *RegInfo =
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 (RegInfo->hasBasePointer(MF)) {
+ assert (hasFP(MF) && "VLAs and dynamic stack realign, but no FP?!");
+ if (FI < 0) {
+ // Skip the saved EBP.
+ return Offset + RegInfo->getSlotSize();
+ } else {
+ assert((-(Offset + StackSize)) % MFI->getObjectAlignment(FI) == 0);
+ return Offset + StackSize;
+ }
+ } else if (RegInfo->needsStackRealignment(MF)) {
if (FI < 0) {
// Skip the saved EBP.
- Offset += RI->getSlotSize();
+ return Offset + RegInfo->getSlotSize();
} else {
assert((-(Offset + StackSize)) % MFI->getObjectAlignment(FI) == 0);
return Offset + StackSize;
return Offset + StackSize;
// Skip the saved EBP.
- Offset += RI->getSlotSize();
+ Offset += RegInfo->getSlotSize();
// Skip the RETADDR move area
const X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>();
return Offset;
}
+int X86FrameLowering::getFrameIndexReference(const MachineFunction &MF, int FI,
+ unsigned &FrameReg) const {
+ const X86RegisterInfo *RegInfo =
+ static_cast<const X86RegisterInfo*>(MF.getTarget().getRegisterInfo());
+ // We can't calculate offset from frame pointer if the stack is realigned,
+ // so enforce usage of stack/base pointer. The base pointer is used when we
+ // have dynamic allocas in addition to dynamic realignment.
+ if (RegInfo->hasBasePointer(MF))
+ FrameReg = RegInfo->getBaseRegister();
+ else if (RegInfo->needsStackRealignment(MF))
+ FrameReg = RegInfo->getStackRegister();
+ else
+ FrameReg = RegInfo->getFrameRegister(MF);
+ return getFrameIndexOffset(MF, FI);
+}
+
bool X86FrameLowering::spillCalleeSavedRegisters(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
const std::vector<CalleeSavedInfo> &CSI,
"Slot for EBP register must be last in order to be found!");
(void)FrameIdx;
}
+
+ // Spill the BasePtr if it's used.
+ if (RegInfo->hasBasePointer(MF))
+ MF.getRegInfo().setPhysRegUsed(RegInfo->getBaseRegister());
}
static bool
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, const MachineFunction &MF) {
- if (Is64Bit) {
- return X86::R11;
- } else {
- CallingConv::ID CallingConvention = MF.getFunction()->getCallingConv();
- bool IsNested = HasNestArgument(&MF);
-
- if (CallingConvention == CallingConv::X86_FastCall) {
- if (IsNested) {
- report_fatal_error("Segmented stacks does not support fastcall with "
- "nested function.");
- return -1;
- } else {
- return X86::EAX;
- }
- } else {
- if (IsNested)
- return X86::EDX;
- else
- return X86::ECX;
- }
+GetScratchRegister(bool Is64Bit, 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)
+ return Primary ? X86::R11 : X86::R12;
+
+ 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
bool Is64Bit = STI.is64Bit();
unsigned TlsReg, TlsOffset;
DebugLoc DL;
- const X86Subtarget *ST = &MF.getTarget().getSubtarget<X86Subtarget>();
- unsigned ScratchReg = GetScratchRegister(Is64Bit, MF);
+ 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())
- report_fatal_error("Segmented stacks supported only on linux.");
+ if (!STI.isTargetLinux() && !STI.isTargetDarwin() &&
+ !STI.isTargetWin32() && !STI.isTargetFreeBSD())
+ report_fatal_error("Segmented stacks not supported on this platform.");
MachineBasicBlock *allocMBB = MF.CreateMachineBasicBlock();
MachineBasicBlock *checkMBB = MF.CreateMachineBasicBlock();
// 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) {
- TlsReg = X86::FS;
- TlsOffset = 0x70;
+ if (STI.isTargetLinux()) {
+ TlsReg = X86::FS;
+ TlsOffset = 0x70;
+ } else if (STI.isTargetDarwin()) {
+ TlsReg = X86::GS;
+ TlsOffset = 0x60 + 90*8; // See pthread_machdep.h. Steal TLS slot 90.
+ } else if (STI.isTargetFreeBSD()) {
+ TlsReg = X86::FS;
+ TlsOffset = 0x18;
+ } else {
+ report_fatal_error("Segmented stacks not supported on this platform.");
+ }
- if (StackSize < kSplitStackAvailable)
+ if (CompareStackPointer)
ScratchReg = X86::RSP;
else
BuildMI(checkMBB, DL, TII.get(X86::LEA64r), ScratchReg).addReg(X86::RSP)
- .addImm(0).addReg(0).addImm(-StackSize).addReg(0);
+ .addImm(1).addReg(0).addImm(-StackSize).addReg(0);
BuildMI(checkMBB, DL, TII.get(X86::CMP64rm)).addReg(ScratchReg)
- .addReg(0).addImm(0).addReg(0).addImm(TlsOffset).addReg(TlsReg);
+ .addReg(0).addImm(1).addReg(0).addImm(TlsOffset).addReg(TlsReg);
} else {
- TlsReg = X86::GS;
- TlsOffset = 0x30;
+ 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.isTargetFreeBSD()) {
+ report_fatal_error("Segmented stacks not supported on FreeBSD i386.");
+ } else {
+ report_fatal_error("Segmented stacks not supported on this platform.");
+ }
- if (StackSize < kSplitStackAvailable)
+ if (CompareStackPointer)
ScratchReg = X86::ESP;
else
BuildMI(checkMBB, DL, TII.get(X86::LEA32r), ScratchReg).addReg(X86::ESP)
- .addImm(0).addReg(0).addImm(-StackSize).addReg(0);
+ .addImm(1).addReg(0).addImm(-StackSize).addReg(0);
+
+ if (STI.isTargetLinux() || STI.isTargetWin32()) {
+ 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, 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::CMP32rm)).addReg(ScratchReg)
- .addReg(0).addImm(0).addReg(0).addImm(TlsOffset).addReg(TlsReg);
+ 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::JG_4)).addMBB(&prologueMBB);
+ 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.
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) const {
+ const X86InstrInfo &TII = *TM.getInstrInfo();
+ MachineFrameInfo *MFI = MF.getFrameInfo();
+ const unsigned SlotSize = TM.getRegisterInfo()->getSlotSize();
+ const bool Is64Bit = STI.is64Bit();
+ 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 &prologueMBB = MF.front();
+ MachineBasicBlock *stackCheckMBB = MF.CreateMachineBasicBlock();
+ MachineBasicBlock *incStackMBB = MF.CreateMachineBasicBlock();
+
+ for (MachineBasicBlock::livein_iterator I = prologueMBB.livein_begin(),
+ E = prologueMBB.livein_end(); I != E; I++) {
+ stackCheckMBB->addLiveIn(*I);
+ incStackMBB->addLiveIn(*I);
+ }
+
+ 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, 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_4)).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_4)).addMBB(incStackMBB);
+
+ stackCheckMBB->addSuccessor(&prologueMBB, 99);
+ stackCheckMBB->addSuccessor(incStackMBB, 1);
+ incStackMBB->addSuccessor(&prologueMBB, 99);
+ incStackMBB->addSuccessor(incStackMBB, 1);
+ }
+#ifdef XDEBUG
+ MF.verify();
+#endif
+}
+
+void X86FrameLowering::
+eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
+ MachineBasicBlock::iterator I) const {
+ const X86InstrInfo &TII = *TM.getInstrInfo();
+ const X86RegisterInfo &RegInfo = *TM.getRegisterInfo();
+ unsigned StackPtr = RegInfo.getStackRegister();
+ bool reseveCallFrame = hasReservedCallFrame(MF);
+ int Opcode = I->getOpcode();
+ bool isDestroy = Opcode == TII.getCallFrameDestroyOpcode();
+ bool IsLP64 = STI.isTarget64BitLP64();
+ DebugLoc DL = I->getDebugLoc();
+ uint64_t Amount = !reseveCallFrame ? I->getOperand(0).getImm() : 0;
+ uint64_t CalleeAmt = isDestroy ? I->getOperand(1).getImm() : 0;
+ I = MBB.erase(I);
+
+ if (!reseveCallFrame) {
+ // 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>'
+ // TODO: consider using push / pop instead of sub + store / add
+ if (Amount == 0)
+ return;
+
+ // We need to keep the stack aligned properly. To do this, we round the
+ // amount of space needed for the outgoing arguments up to the next
+ // alignment boundary.
+ unsigned StackAlign = TM.getFrameLowering()->getStackAlignment();
+ Amount = (Amount + StackAlign - 1) / StackAlign * StackAlign;
+
+ MachineInstr *New = 0;
+ if (Opcode == TII.getCallFrameSetupOpcode()) {
+ New = BuildMI(MF, DL, TII.get(getSUBriOpcode(IsLP64, Amount)),
+ StackPtr)
+ .addReg(StackPtr)
+ .addImm(Amount);
+ } else {
+ assert(Opcode == TII.getCallFrameDestroyOpcode());
+
+ // Factor out the amount the callee already popped.
+ Amount -= CalleeAmt;
+
+ if (Amount) {
+ unsigned Opc = getADDriOpcode(IsLP64, Amount);
+ New = BuildMI(MF, DL, TII.get(Opc), StackPtr)
+ .addReg(StackPtr).addImm(Amount);
+ }
+ }
+
+ if (New) {
+ // The EFLAGS implicit def is dead.
+ New->getOperand(3).setIsDead();
+
+ // Replace the pseudo instruction with a new instruction.
+ MBB.insert(I, New);
+ }
+
+ return;
+ }
+
+ if (Opcode == TII.getCallFrameDestroyOpcode() && CalleeAmt) {
+ // If we are performing frame pointer elimination and if the callee pops
+ // something off the stack pointer, add it back. We do this until we have
+ // more advanced stack pointer tracking ability.
+ unsigned Opc = getSUBriOpcode(IsLP64, CalleeAmt);
+ MachineInstr *New = BuildMI(MF, DL, TII.get(Opc), StackPtr)
+ .addReg(StackPtr).addImm(CalleeAmt);
+
+ // The EFLAGS implicit def is dead.
+ New->getOperand(3).setIsDead();
+
+ // We are not tracking the stack pointer adjustment by the callee, so make
+ // sure we restore the stack pointer immediately after the call, there may
+ // be spill code inserted between the CALL and ADJCALLSTACKUP instructions.
+ MachineBasicBlock::iterator B = MBB.begin();
+ while (I != B && !llvm::prior(I)->isCall())
+ --I;
+ MBB.insert(I, New);
+ }
+}
+
projects / oota-llvm.git / blobdiff