234 lines
8.4 KiB
C++
234 lines
8.4 KiB
C++
//===-- X86InstrBuilder.h - Functions to aid building x86 insts -*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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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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//===----------------------------------------------------------------------===//
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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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//
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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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//
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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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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIB_TARGET_X86_X86INSTRBUILDER_H
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#define LLVM_LIB_TARGET_X86_X86INSTRBUILDER_H
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/CodeGen/MachineFrameInfo.h"
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#include "llvm/CodeGen/MachineFunction.h"
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#include "llvm/CodeGen/MachineInstr.h"
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#include "llvm/CodeGen/MachineInstrBuilder.h"
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#include "llvm/CodeGen/MachineMemOperand.h"
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#include "llvm/CodeGen/MachineOperand.h"
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#include "llvm/MC/MCInstrDesc.h"
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#include <cassert>
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namespace llvm {
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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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enum {
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RegBase,
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FrameIndexBase
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} BaseType;
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union {
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unsigned Reg;
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int FrameIndex;
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} Base;
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unsigned Scale;
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unsigned IndexReg;
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int Disp;
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const GlobalValue *GV;
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unsigned GVOpFlags;
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X86AddressMode()
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: BaseType(RegBase), Scale(1), IndexReg(0), Disp(0), GV(nullptr),
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GVOpFlags(0) {
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Base.Reg = 0;
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}
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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, false,
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false, false, false, 0, false));
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else {
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assert(BaseType == X86AddressMode::FrameIndexBase);
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MO.push_back(MachineOperand::CreateFI(Base.FrameIndex));
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}
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MO.push_back(MachineOperand::CreateImm(Scale));
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MO.push_back(MachineOperand::CreateReg(IndexReg, false, false, false, false,
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false, false, 0, false));
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if (GV)
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MO.push_back(MachineOperand::CreateGA(GV, Disp, GVOpFlags));
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else
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MO.push_back(MachineOperand::CreateImm(Disp));
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MO.push_back(MachineOperand::CreateReg(0, false, false, false, false, false,
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false, 0, false));
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}
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};
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/// Compute the addressing mode from an machine instruction starting with the
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/// given operand.
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static inline X86AddressMode getAddressFromInstr(const MachineInstr *MI,
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unsigned Operand) {
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X86AddressMode AM;
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const MachineOperand &Op0 = MI->getOperand(Operand);
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if (Op0.isReg()) {
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AM.BaseType = X86AddressMode::RegBase;
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AM.Base.Reg = Op0.getReg();
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} else {
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AM.BaseType = X86AddressMode::FrameIndexBase;
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AM.Base.FrameIndex = Op0.getIndex();
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}
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const MachineOperand &Op1 = MI->getOperand(Operand + 1);
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AM.Scale = Op1.getImm();
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const MachineOperand &Op2 = MI->getOperand(Operand + 2);
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AM.IndexReg = Op2.getReg();
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const MachineOperand &Op3 = MI->getOperand(Operand + 3);
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if (Op3.isGlobal())
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AM.GV = Op3.getGlobal();
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else
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AM.Disp = Op3.getImm();
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return AM;
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}
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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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///
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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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}
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/// Replace the address used in the instruction with the direct memory
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/// reference.
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static inline void setDirectAddressInInstr(MachineInstr *MI, unsigned Operand,
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unsigned Reg) {
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// Direct memory address is in a form of: Reg, 1 (Scale), NoReg, 0, NoReg.
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MI->getOperand(Operand).setReg(Reg);
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MI->getOperand(Operand + 1).setImm(1);
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MI->getOperand(Operand + 2).setReg(0);
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MI->getOperand(Operand + 3).setImm(0);
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MI->getOperand(Operand + 4).setReg(0);
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}
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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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}
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static inline const MachineInstrBuilder &
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addOffset(const MachineInstrBuilder &MIB, const MachineOperand& Offset) {
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return MIB.addImm(1).addReg(0).add(Offset).addReg(0);
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}
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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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///
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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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}
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/// addRegReg - This function is used to add a memory reference of the form:
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/// [Reg + Reg].
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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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}
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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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else {
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assert(AM.BaseType == X86AddressMode::FrameIndexBase);
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MIB.addFrameIndex(AM.Base.FrameIndex);
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}
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MIB.addImm(AM.Scale).addReg(AM.IndexReg);
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if (AM.GV)
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MIB.addGlobalAddress(AM.GV, AM.Disp, AM.GVOpFlags);
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else
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MIB.addImm(AM.Disp);
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return MIB.addReg(0);
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}
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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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///
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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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auto Flags = MachineMemOperand::MONone;
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if (MCID.mayLoad())
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Flags |= MachineMemOperand::MOLoad;
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if (MCID.mayStore())
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Flags |= MachineMemOperand::MOStore;
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MachineMemOperand *MMO = MF.getMachineMemOperand(
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MachinePointerInfo::getFixedStack(MF, FI, Offset), Flags,
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MFI.getObjectSize(FI), MFI.getObjectAlignment(FI));
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return addOffset(MIB.addFrameIndex(FI), Offset)
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.addMemOperand(MMO);
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}
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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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///
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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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//FIXME: factor this
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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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}
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} // end namespace llvm
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#endif // LLVM_LIB_TARGET_X86_X86INSTRBUILDER_H
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