-//=======- X86FrameLowering.cpp - X86 Frame Information ------------*- C++ -*-====//
+//=======- X86FrameLowering.cpp - X86 Frame Information --------*- C++ -*-====//
//
// The LLVM Compiler Infrastructure
//
#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/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"
const MachineModuleInfo &MMI = MF.getMMI();
const TargetRegisterInfo *RI = TM.getRegisterInfo();
- return (DisableFramePointerElim(MF) ||
+ return (MF.getTarget().Options.DisableFramePointerElim(MF) ||
RI->needsStackRealignment(MF) ||
MFI->hasVarSizedObjects() ||
MFI->isFrameAddressTaken() ||
return 0;
static const unsigned CallerSavedRegs32Bit[] = {
- X86::EAX, X86::EDX, X86::ECX
+ X86::EAX, X86::EDX, X86::ECX, 0
};
static const unsigned CallerSavedRegs64Bit[] = {
X86::RAX, X86::RDX, X86::RCX, X86::RSI, X86::RDI,
- X86::R8, X86::R9, X86::R10, X86::R11
+ X86::R8, X86::R9, X86::R10, X86::R11, 0
};
unsigned Opc = MBBI->getOpcode();
void mergeSPUpdatesDown(MachineBasicBlock &MBB,
MachineBasicBlock::iterator &MBBI,
unsigned StackPtr, uint64_t *NumBytes = NULL) {
- // FIXME: THIS ISN'T RUN!!!
+ // FIXME: THIS ISN'T RUN!!!
return;
if (MBBI == MBB.end()) return;
}
void X86FrameLowering::emitCalleeSavedFrameMoves(MachineFunction &MF,
- MCSymbol *Label,
- unsigned FramePtr) const {
+ MCSymbol *Label,
+ unsigned FramePtr) const {
MachineFrameInfo *MFI = MF.getFrameInfo();
MachineModuleInfo &MMI = MF.getMMI();
}
}
+/// 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
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
// 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
+ !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);
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);
+ BuildMI(MBB, MBBI, DL, TII.get(X86::PROLOG_LABEL))
+ .addSym(FrameLabel);
// Define the current CFA rule to use the provided offset.
if (StackSize) {
Moves.push_back(MachineMove(FrameLabel, FPDst, FPSrc));
}
- // Update EBP with the new base value...
+ // Update EBP with the new base value.
BuildMI(MBB, MBBI, DL,
TII.get(Is64Bit ? X86::MOV64rr : X86::MOV32rr), FramePtr)
.addReg(StackPtr)
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);
+ BuildMI(MBB, MBBI, DL, TII.get(X86::PROLOG_LABEL))
+ .addSym(FrameLabel);
// Define the current CFA to use the EBP/RBP register.
MachineLocation FPDst(FramePtr);
if (RegInfo->needsStackRealignment(MF)) {
MachineInstr *MI =
BuildMI(MBB, MBBI, DL,
- TII.get(Is64Bit ? X86::AND64ri32 : X86::AND32ri),
- StackPtr).addReg(StackPtr).addImm(-MaxAlign);
+ 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();
(MBBI->getOpcode() == X86::PUSH32r ||
MBBI->getOpcode() == X86::PUSH64r)) {
PushedRegs = true;
+ MBBI->setFlag(MachineInstr::FrameSetup);
++MBBI;
if (!HasFP && needsFrameMoves) {
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;
+ unsigned Ptr = StackSize ? MachineLocation::VirtualFP : StackPtr;
MachineLocation SPDst(Ptr);
MachineLocation SPSrc(Ptr, StackOffset);
Moves.push_back(MachineMove(Label, SPDst, SPSrc));
// Save EAX
BuildMI(MBB, MBBI, DL, TII.get(X86::PUSH32r))
- .addReg(X86::EAX, RegState::Kill);
+ .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);
+ .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);
+ .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);
+ .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.
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)
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);
+ 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 (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 {
+ MachineBasicBlock &MBB) const {
const MachineFrameInfo *MFI = MF.getFrameInfo();
X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>();
const X86RegisterInfo *RegInfo = TM.getRegisterInfo();
unsigned Opc = PI->getOpcode();
if (Opc != X86::POP32r && Opc != X86::POP64r && Opc != X86::DBG_VALUE &&
- !PI->getDesc().isTerminator())
+ !PI->isTerminator())
break;
--MBBI;
}
}
-void
-X86FrameLowering::getInitialFrameState(std::vector<MachineMove> &Moves) const {
- // Calculate amount of bytes used for return address storing
- int stackGrowth = (STI.is64Bit() ? -8 : -4);
- const X86RegisterInfo *RI = TM.getRegisterInfo();
-
- // Initial state of the frame pointer is esp+stackGrowth.
- MachineLocation Dst(MachineLocation::VirtualFP);
- MachineLocation Src(RI->getStackRegister(), stackGrowth);
- Moves.push_back(MachineMove(0, Dst, Src));
-
- // Add return address to move list
- MachineLocation CSDst(RI->getStackRegister(), stackGrowth);
- MachineLocation CSSrc(RI->getRARegister());
- Moves.push_back(MachineMove(0, CSDst, CSSrc));
-}
-
int X86FrameLowering::getFrameIndexOffset(const MachineFunction &MF, int FI) const {
const X86RegisterInfo *RI =
static_cast<const X86RegisterInfo*>(MF.getTarget().getRegisterInfo());
// Skip the saved EBP.
Offset += RI->getSlotSize();
} else {
- unsigned Align = MFI->getObjectAlignment(FI);
- assert((-(Offset + StackSize)) % Align == 0);
- Align = 0;
+ assert((-(Offset + StackSize)) % MFI->getObjectAlignment(FI) == 0);
return Offset + StackSize;
}
// FIXME: Support tail calls
true);
assert(FrameIdx == MFI->getObjectIndexBegin() &&
"Slot for EBP register must be last in order to be found!");
- FrameIdx = 0;
+ (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;
+ } else {
+ 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 -1;
+ } else {
+ return Primary ? X86::EAX : X86::ECX;
+ }
+ } else {
+ if (IsNested)
+ return Primary ? X86::EDX : X86::EAX;
+ else
+ 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
}
projects / oota-llvm.git / blobdiff