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//===-- X86InstrBuilder.h - Functions to aid building x86 insts -*- C++ -*-===//
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// The LLVM Compiler Infrastructure
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//===----------------------------------------------------------------------===//
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// This file exposes functions that may be used with BuildMI from the
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// MachineInstrBuilder.h file to handle X86'isms in a clean way.
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// The BuildMem function may be used with the BuildMI function to add entire
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// memory references in a single, typed, function call. X86 memory references
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// can be very complex expressions (described in the README), so wrapping them
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// up behind an easier to use interface makes sense. Descriptions of the
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// functions are included below.
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// For reference, the order of operands for memory references is:
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// (Operand), Base, Scale, Index, Displacement.
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//===----------------------------------------------------------------------===//
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#ifndef X86INSTRBUILDER_H
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#define X86INSTRBUILDER_H
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#include "llvm/CodeGen/MachineFrameInfo.h"
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#include "llvm/CodeGen/MachineInstrBuilder.h"
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#include "llvm/CodeGen/MachineMemOperand.h"
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/// X86AddressMode - This struct holds a generalized full x86 address mode.
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/// The base register can be a frame index, which will eventually be replaced
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/// with BP or SP and Disp being offsetted accordingly. The displacement may
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/// also include the offset of a global value.
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struct X86AddressMode {
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const GlobalValue *GV;
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: BaseType(RegBase), Scale(1), IndexReg(0), Disp(0), GV(0), GVOpFlags(0) {
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void getFullAddress(SmallVectorImpl<MachineOperand> &MO) {
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assert(Scale == 1 || Scale == 2 || Scale == 4 || Scale == 8);
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if (BaseType == X86AddressMode::RegBase)
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MO.push_back(MachineOperand::CreateReg(Base.Reg, false, false,
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false, false, false, 0, false));
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assert(BaseType == X86AddressMode::FrameIndexBase);
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MO.push_back(MachineOperand::CreateFI(Base.FrameIndex));
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MO.push_back(MachineOperand::CreateImm(Scale));
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MO.push_back(MachineOperand::CreateReg(IndexReg, false, false,
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false, false, false, 0, false));
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MO.push_back(MachineOperand::CreateGA(GV, Disp, GVOpFlags));
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MO.push_back(MachineOperand::CreateImm(Disp));
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MO.push_back(MachineOperand::CreateReg(0, false, false,
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false, false, false, 0, false));
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/// addDirectMem - This function is used to add a direct memory reference to the
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/// current instruction -- that is, a dereference of an address in a register,
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/// with no scale, index or displacement. An example is: DWORD PTR [EAX].
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static inline const MachineInstrBuilder &
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addDirectMem(const MachineInstrBuilder &MIB, unsigned Reg) {
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// Because memory references are always represented with five
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// values, this adds: Reg, 1, NoReg, 0, NoReg to the instruction.
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return MIB.addReg(Reg).addImm(1).addReg(0).addImm(0).addReg(0);
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static inline const MachineInstrBuilder &
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addOffset(const MachineInstrBuilder &MIB, int Offset) {
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return MIB.addImm(1).addReg(0).addImm(Offset).addReg(0);
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/// addRegOffset - This function is used to add a memory reference of the form
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/// [Reg + Offset], i.e., one with no scale or index, but with a
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/// displacement. An example is: DWORD PTR [EAX + 4].
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static inline const MachineInstrBuilder &
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addRegOffset(const MachineInstrBuilder &MIB,
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unsigned Reg, bool isKill, int Offset) {
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return addOffset(MIB.addReg(Reg, getKillRegState(isKill)), Offset);
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/// addRegReg - This function is used to add a memory reference of the form:
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static inline const MachineInstrBuilder &addRegReg(const MachineInstrBuilder &MIB,
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unsigned Reg1, bool isKill1,
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unsigned Reg2, bool isKill2) {
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return MIB.addReg(Reg1, getKillRegState(isKill1)).addImm(1)
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.addReg(Reg2, getKillRegState(isKill2)).addImm(0).addReg(0);
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static inline const MachineInstrBuilder &
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addFullAddress(const MachineInstrBuilder &MIB,
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const X86AddressMode &AM) {
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assert(AM.Scale == 1 || AM.Scale == 2 || AM.Scale == 4 || AM.Scale == 8);
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if (AM.BaseType == X86AddressMode::RegBase)
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MIB.addReg(AM.Base.Reg);
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assert(AM.BaseType == X86AddressMode::FrameIndexBase);
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MIB.addFrameIndex(AM.Base.FrameIndex);
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MIB.addImm(AM.Scale).addReg(AM.IndexReg);
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MIB.addGlobalAddress(AM.GV, AM.Disp, AM.GVOpFlags);
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return MIB.addReg(0);
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/// addFrameReference - This function is used to add a reference to the base of
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/// an abstract object on the stack frame of the current function. This
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/// reference has base register as the FrameIndex offset until it is resolved.
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/// This allows a constant offset to be specified as well...
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static inline const MachineInstrBuilder &
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addFrameReference(const MachineInstrBuilder &MIB, int FI, int Offset = 0) {
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MachineInstr *MI = MIB;
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MachineFunction &MF = *MI->getParent()->getParent();
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MachineFrameInfo &MFI = *MF.getFrameInfo();
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const MCInstrDesc &MCID = MI->getDesc();
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Flags |= MachineMemOperand::MOLoad;
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Flags |= MachineMemOperand::MOStore;
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MachineMemOperand *MMO =
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MF.getMachineMemOperand(MachinePointerInfo::getFixedStack(FI, Offset),
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Flags, MFI.getObjectSize(FI),
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MFI.getObjectAlignment(FI));
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return addOffset(MIB.addFrameIndex(FI), Offset)
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/// addConstantPoolReference - This function is used to add a reference to the
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/// base of a constant value spilled to the per-function constant pool. The
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/// reference uses the abstract ConstantPoolIndex which is retained until
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/// either machine code emission or assembly output. In PIC mode on x86-32,
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/// the GlobalBaseReg parameter can be used to make this a
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/// GlobalBaseReg-relative reference.
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static inline const MachineInstrBuilder &
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addConstantPoolReference(const MachineInstrBuilder &MIB, unsigned CPI,
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unsigned GlobalBaseReg, unsigned char OpFlags) {
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return MIB.addReg(GlobalBaseReg).addImm(1).addReg(0)
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.addConstantPoolIndex(CPI, 0, OpFlags).addReg(0);
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} // End llvm namespace