diff options
Diffstat (limited to 'lib/Target/X86/X86FrameLowering.cpp')
-rw-r--r-- | lib/Target/X86/X86FrameLowering.cpp | 85 |
1 files changed, 83 insertions, 2 deletions
diff --git a/lib/Target/X86/X86FrameLowering.cpp b/lib/Target/X86/X86FrameLowering.cpp index 2b3d8538af..a05cf5c346 100644 --- a/lib/Target/X86/X86FrameLowering.cpp +++ b/lib/Target/X86/X86FrameLowering.cpp @@ -55,8 +55,8 @@ bool X86FrameLowering::hasFP(const MachineFunction &MF) const { MMI.callsUnwindInit() || MMI.callsEHReturn()); } -static unsigned getSUBriOpcode(unsigned isLP64, int64_t Imm) { - if (isLP64) { +static unsigned getSUBriOpcode(unsigned IsLP64, int64_t Imm) { + if (IsLP64) { if (isInt<8>(Imm)) return X86::SUB64ri8; return X86::SUB64ri32; @@ -1756,3 +1756,84 @@ void X86FrameLowering::adjustForHiPEPrologue(MachineFunction &MF) const { 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); + } +} + |