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024126ee23
without getting an assertion from ilist that we are dereferencing ilist<T>::end(). git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@11345 91177308-0d34-0410-b5e6-96231b3b80d8
282 lines
10 KiB
C++
282 lines
10 KiB
C++
//===- X86RegisterInfo.cpp - X86 Register Information -----------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file was developed by the LLVM research group and is distributed under
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// the University of Illinois Open Source License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file contains the X86 implementation of the MRegisterInfo class. This
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// file is responsible for the frame pointer elimination optimization on X86.
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//
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//===----------------------------------------------------------------------===//
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#include "X86.h"
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#include "X86RegisterInfo.h"
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#include "X86InstrBuilder.h"
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#include "llvm/Constants.h"
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#include "llvm/Type.h"
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#include "llvm/CodeGen/ValueTypes.h"
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#include "llvm/CodeGen/MachineInstrBuilder.h"
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#include "llvm/CodeGen/MachineFunction.h"
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#include "llvm/CodeGen/MachineFrameInfo.h"
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#include "llvm/Target/TargetMachine.h"
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#include "llvm/Target/TargetFrameInfo.h"
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#include "Support/CommandLine.h"
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namespace llvm {
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namespace {
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cl::opt<bool>
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NoFPElim("disable-fp-elim",
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cl::desc("Disable frame pointer elimination optimization"));
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}
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X86RegisterInfo::X86RegisterInfo()
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: X86GenRegisterInfo(X86::ADJCALLSTACKDOWN, X86::ADJCALLSTACKUP) {}
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static unsigned getIdx(const TargetRegisterClass *RC) {
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switch (RC->getSize()) {
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default: assert(0 && "Invalid data size!");
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case 1: return 0;
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case 2: return 1;
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case 4: return 2;
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case 10: return 3;
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}
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}
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int X86RegisterInfo::storeRegToStackSlot(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator MI,
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unsigned SrcReg, int FrameIdx,
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const TargetRegisterClass *RC) const {
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static const unsigned Opcode[] =
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{ X86::MOVrm8, X86::MOVrm16, X86::MOVrm32, X86::FSTPr80 };
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MachineInstr *I = addFrameReference(BuildMI(Opcode[getIdx(RC)], 5),
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FrameIdx).addReg(SrcReg);
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MBB.insert(MI, I);
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return 1;
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}
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int X86RegisterInfo::loadRegFromStackSlot(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator MI,
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unsigned DestReg, int FrameIdx,
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const TargetRegisterClass *RC) const{
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static const unsigned Opcode[] =
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{ X86::MOVmr8, X86::MOVmr16, X86::MOVmr32, X86::FLDr80 };
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unsigned OC = Opcode[getIdx(RC)];
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MBB.insert(MI, addFrameReference(BuildMI(OC, 4, DestReg), FrameIdx));
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return 1;
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}
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int X86RegisterInfo::copyRegToReg(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator MI,
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unsigned DestReg, unsigned SrcReg,
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const TargetRegisterClass *RC) const {
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static const unsigned Opcode[] =
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{ X86::MOVrr8, X86::MOVrr16, X86::MOVrr32, X86::FpMOV };
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MBB.insert(MI, BuildMI(Opcode[getIdx(RC)],1,DestReg).addReg(SrcReg));
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return 1;
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}
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//===----------------------------------------------------------------------===//
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// Stack Frame Processing methods
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//===----------------------------------------------------------------------===//
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// hasFP - Return true if the specified function should have a dedicated frame
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// pointer register. This is true if the function has variable sized allocas or
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// if frame pointer elimination is disabled.
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//
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static bool hasFP(MachineFunction &MF) {
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return NoFPElim || MF.getFrameInfo()->hasVarSizedObjects();
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}
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int X86RegisterInfo::eliminateCallFramePseudoInstr(MachineFunction &MF,
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MachineBasicBlock &MBB,
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MachineBasicBlock::iterator I) const {
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MachineInstr *New = 0, *Old = I;
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if (hasFP(MF)) {
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// If we have a frame pointer, turn the adjcallstackup instruction into a
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// 'sub ESP, <amt>' and the adjcallstackdown instruction into 'add ESP,
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// <amt>'
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unsigned Amount = Old->getOperand(0).getImmedValue();
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if (Amount != 0) {
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// We need to keep the stack aligned properly. To do this, we round the
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// amount of space needed for the outgoing arguments up to the next
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// alignment boundary.
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unsigned Align = MF.getTarget().getFrameInfo().getStackAlignment();
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Amount = (Amount+Align-1)/Align*Align;
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if (Old->getOpcode() == X86::ADJCALLSTACKDOWN) {
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New=BuildMI(X86::SUBri32, 1, X86::ESP, MOTy::UseAndDef).addZImm(Amount);
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} else {
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assert(Old->getOpcode() == X86::ADJCALLSTACKUP);
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New=BuildMI(X86::ADDri32, 1, X86::ESP, MOTy::UseAndDef).addZImm(Amount);
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}
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}
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}
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if (New) {
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// Replace the pseudo instruction with a new instruction...
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MBB.insert(MBB.erase(I), New);
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return 0;
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} else {
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MBB.erase(I);
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return -1;
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}
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}
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int X86RegisterInfo::eliminateFrameIndex(MachineFunction &MF,
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MachineBasicBlock::iterator II) const {
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unsigned i = 0;
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MachineInstr &MI = *II;
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while (!MI.getOperand(i).isFrameIndex()) {
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++i;
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assert(i < MI.getNumOperands() && "Instr doesn't have FrameIndex operand!");
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}
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int FrameIndex = MI.getOperand(i).getFrameIndex();
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// This must be part of a four operand memory reference. Replace the
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// FrameIndex with base register with EBP. Add add an offset to the offset.
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MI.SetMachineOperandReg(i, hasFP(MF) ? X86::EBP : X86::ESP);
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// Now add the frame object offset to the offset from EBP.
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int Offset = MF.getFrameInfo()->getObjectOffset(FrameIndex) +
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MI.getOperand(i+3).getImmedValue()+4;
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if (!hasFP(MF))
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Offset += MF.getFrameInfo()->getStackSize();
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MI.SetMachineOperandConst(i+3, MachineOperand::MO_SignExtendedImmed, Offset);
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return 0;
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}
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int X86RegisterInfo::processFunctionBeforeFrameFinalized(MachineFunction &MF)
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const {
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if (hasFP(MF)) {
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// Create a frame entry for the EBP register that must be saved.
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int FrameIdx = MF.getFrameInfo()->CreateStackObject(4, 4);
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assert(FrameIdx == MF.getFrameInfo()->getObjectIndexEnd()-1 &&
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"Slot for EBP register must be last in order to be found!");
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}
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return 0;
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}
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int X86RegisterInfo::emitPrologue(MachineFunction &MF) const {
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MachineBasicBlock &MBB = MF.front(); // Prolog goes in entry BB
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MachineBasicBlock::iterator MBBI = MBB.begin();
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MachineFrameInfo *MFI = MF.getFrameInfo();
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MachineInstr *MI;
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unsigned oldSize = MBB.size();
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// Get the number of bytes to allocate from the FrameInfo
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unsigned NumBytes = MFI->getStackSize();
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if (hasFP(MF)) {
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// Get the offset of the stack slot for the EBP register... which is
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// guaranteed to be the last slot by processFunctionBeforeFrameFinalized.
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int EBPOffset = MFI->getObjectOffset(MFI->getObjectIndexEnd()-1)+4;
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if (NumBytes) { // adjust stack pointer: ESP -= numbytes
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MI= BuildMI(X86::SUBri32, 1, X86::ESP, MOTy::UseAndDef).addZImm(NumBytes);
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MBB.insert(MBBI, MI);
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}
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// Save EBP into the appropriate stack slot...
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MI = addRegOffset(BuildMI(X86::MOVrm32, 5), // mov [ESP-<offset>], EBP
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X86::ESP, EBPOffset+NumBytes).addReg(X86::EBP);
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MBB.insert(MBBI, MI);
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// Update EBP with the new base value...
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if (NumBytes == 0) // mov EBP, ESP
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MI = BuildMI(X86::MOVrr32, 2, X86::EBP).addReg(X86::ESP);
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else // lea EBP, [ESP+StackSize]
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MI = addRegOffset(BuildMI(X86::LEAr32, 5, X86::EBP), X86::ESP, NumBytes);
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MBB.insert(MBBI, MI);
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} else {
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// When we have no frame pointer, we reserve argument space for call sites
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// in the function immediately on entry to the current function. This
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// eliminates the need for add/sub ESP brackets around call sites.
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//
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NumBytes += MFI->getMaxCallFrameSize();
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// Round the size to a multiple of the alignment (don't forget the 4 byte
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// offset though).
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unsigned Align = MF.getTarget().getFrameInfo().getStackAlignment();
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NumBytes = ((NumBytes+4)+Align-1)/Align*Align - 4;
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// Update frame info to pretend that this is part of the stack...
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MFI->setStackSize(NumBytes);
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if (NumBytes) {
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// adjust stack pointer: ESP -= numbytes
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MI= BuildMI(X86::SUBri32, 1, X86::ESP, MOTy::UseAndDef).addZImm(NumBytes);
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MBB.insert(MBBI, MI);
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}
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}
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return MBB.size() - oldSize;
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}
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int X86RegisterInfo::emitEpilogue(MachineFunction &MF,
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MachineBasicBlock &MBB) const {
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unsigned oldSize = MBB.size();
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const MachineFrameInfo *MFI = MF.getFrameInfo();
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MachineBasicBlock::iterator MBBI = MBB.end(); --MBBI;
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MachineInstr *MI;
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assert(MBBI->getOpcode() == X86::RET &&
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"Can only insert epilog into returning blocks");
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if (hasFP(MF)) {
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// Get the offset of the stack slot for the EBP register... which is
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// guaranteed to be the last slot by processFunctionBeforeFrameFinalized.
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int EBPOffset = MFI->getObjectOffset(MFI->getObjectIndexEnd()-1)+4;
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// mov ESP, EBP
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MI = BuildMI(X86::MOVrr32, 1,X86::ESP).addReg(X86::EBP);
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MBB.insert(MBBI, MI);
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// mov EBP, [ESP-<offset>]
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MI = addRegOffset(BuildMI(X86::MOVmr32, 5, X86::EBP), X86::ESP, EBPOffset);
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MBB.insert(MBBI, MI);
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} else {
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// Get the number of bytes allocated from the FrameInfo...
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unsigned NumBytes = MFI->getStackSize();
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if (NumBytes) { // adjust stack pointer back: ESP += numbytes
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MI =BuildMI(X86::ADDri32, 1, X86::ESP, MOTy::UseAndDef).addZImm(NumBytes);
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MBB.insert(MBBI, MI);
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}
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}
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return MBB.size() - oldSize;
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}
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} // End llvm namespace
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#include "X86GenRegisterInfo.inc"
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namespace llvm {
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const TargetRegisterClass*
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X86RegisterInfo::getRegClassForType(const Type* Ty) const {
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switch (Ty->getPrimitiveID()) {
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case Type::LongTyID:
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case Type::ULongTyID: assert(0 && "Long values can't fit in registers!");
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default: assert(0 && "Invalid type to getClass!");
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case Type::BoolTyID:
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case Type::SByteTyID:
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case Type::UByteTyID: return &R8Instance;
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case Type::ShortTyID:
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case Type::UShortTyID: return &R16Instance;
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case Type::IntTyID:
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case Type::UIntTyID:
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case Type::PointerTyID: return &R32Instance;
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case Type::FloatTyID:
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case Type::DoubleTyID: return &RFPInstance;
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}
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}
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} // End llvm namespace
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