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