X86MCCodeEmitter.cpp [plain text]
#define DEBUG_TYPE "x86-emitter"
#include "X86.h"
#include "X86InstrInfo.h"
#include "X86FixupKinds.h"
#include "llvm/MC/MCCodeEmitter.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCInst.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
namespace {
class X86MCCodeEmitter : public MCCodeEmitter {
X86MCCodeEmitter(const X86MCCodeEmitter &); void operator=(const X86MCCodeEmitter &); const TargetMachine &TM;
const TargetInstrInfo &TII;
MCContext &Ctx;
bool Is64BitMode;
public:
X86MCCodeEmitter(TargetMachine &tm, MCContext &ctx, bool is64Bit)
: TM(tm), TII(*TM.getInstrInfo()), Ctx(ctx) {
Is64BitMode = is64Bit;
}
~X86MCCodeEmitter() {}
unsigned getNumFixupKinds() const {
return 4;
}
const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const {
const static MCFixupKindInfo Infos[] = {
{ "reloc_pcrel_4byte", 0, 4 * 8 },
{ "reloc_pcrel_1byte", 0, 1 * 8 },
{ "reloc_riprel_4byte", 0, 4 * 8 },
{ "reloc_riprel_4byte_movq_load", 0, 4 * 8 }
};
if (Kind < FirstTargetFixupKind)
return MCCodeEmitter::getFixupKindInfo(Kind);
assert(unsigned(Kind - FirstTargetFixupKind) < getNumFixupKinds() &&
"Invalid kind!");
return Infos[Kind - FirstTargetFixupKind];
}
static unsigned GetX86RegNum(const MCOperand &MO) {
return X86RegisterInfo::getX86RegNum(MO.getReg());
}
void EmitByte(unsigned char C, unsigned &CurByte, raw_ostream &OS) const {
OS << (char)C;
++CurByte;
}
void EmitConstant(uint64_t Val, unsigned Size, unsigned &CurByte,
raw_ostream &OS) const {
for (unsigned i = 0; i != Size; ++i) {
EmitByte(Val & 255, CurByte, OS);
Val >>= 8;
}
}
void EmitImmediate(const MCOperand &Disp,
unsigned ImmSize, MCFixupKind FixupKind,
unsigned &CurByte, raw_ostream &OS,
SmallVectorImpl<MCFixup> &Fixups,
int ImmOffset = 0) const;
inline static unsigned char ModRMByte(unsigned Mod, unsigned RegOpcode,
unsigned RM) {
assert(Mod < 4 && RegOpcode < 8 && RM < 8 && "ModRM Fields out of range!");
return RM | (RegOpcode << 3) | (Mod << 6);
}
void EmitRegModRMByte(const MCOperand &ModRMReg, unsigned RegOpcodeFld,
unsigned &CurByte, raw_ostream &OS) const {
EmitByte(ModRMByte(3, RegOpcodeFld, GetX86RegNum(ModRMReg)), CurByte, OS);
}
void EmitSIBByte(unsigned SS, unsigned Index, unsigned Base,
unsigned &CurByte, raw_ostream &OS) const {
EmitByte(ModRMByte(SS, Index, Base), CurByte, OS);
}
void EmitMemModRMByte(const MCInst &MI, unsigned Op,
unsigned RegOpcodeField,
unsigned TSFlags, unsigned &CurByte, raw_ostream &OS,
SmallVectorImpl<MCFixup> &Fixups) const;
void EncodeInstruction(const MCInst &MI, raw_ostream &OS,
SmallVectorImpl<MCFixup> &Fixups) const;
};
}
MCCodeEmitter *llvm::createX86_32MCCodeEmitter(const Target &,
TargetMachine &TM,
MCContext &Ctx) {
return new X86MCCodeEmitter(TM, Ctx, false);
}
MCCodeEmitter *llvm::createX86_64MCCodeEmitter(const Target &,
TargetMachine &TM,
MCContext &Ctx) {
return new X86MCCodeEmitter(TM, Ctx, true);
}
static bool isDisp8(int Value) {
return Value == (signed char)Value;
}
static MCFixupKind getImmFixupKind(unsigned TSFlags) {
unsigned Size = X86II::getSizeOfImm(TSFlags);
bool isPCRel = X86II::isImmPCRel(TSFlags);
switch (Size) {
default: assert(0 && "Unknown immediate size");
case 1: return isPCRel ? MCFixupKind(X86::reloc_pcrel_1byte) : FK_Data_1;
case 4: return isPCRel ? MCFixupKind(X86::reloc_pcrel_4byte) : FK_Data_4;
case 2: assert(!isPCRel); return FK_Data_2;
case 8: assert(!isPCRel); return FK_Data_8;
}
}
void X86MCCodeEmitter::
EmitImmediate(const MCOperand &DispOp, unsigned Size, MCFixupKind FixupKind,
unsigned &CurByte, raw_ostream &OS,
SmallVectorImpl<MCFixup> &Fixups, int ImmOffset) const {
if (DispOp.isImm()) {
EmitConstant(DispOp.getImm()+ImmOffset, Size, CurByte, OS);
return;
}
const MCExpr *Expr = DispOp.getExpr();
if (FixupKind == MCFixupKind(X86::reloc_pcrel_4byte) ||
FixupKind == MCFixupKind(X86::reloc_riprel_4byte))
ImmOffset -= 4;
if (FixupKind == MCFixupKind(X86::reloc_pcrel_1byte))
ImmOffset -= 1;
if (ImmOffset)
Expr = MCBinaryExpr::CreateAdd(Expr, MCConstantExpr::Create(ImmOffset, Ctx),
Ctx);
Fixups.push_back(MCFixup::Create(CurByte, Expr, FixupKind));
EmitConstant(0, Size, CurByte, OS);
}
void X86MCCodeEmitter::EmitMemModRMByte(const MCInst &MI, unsigned Op,
unsigned RegOpcodeField,
unsigned TSFlags, unsigned &CurByte,
raw_ostream &OS,
SmallVectorImpl<MCFixup> &Fixups) const{
const MCOperand &Disp = MI.getOperand(Op+3);
const MCOperand &Base = MI.getOperand(Op);
const MCOperand &Scale = MI.getOperand(Op+1);
const MCOperand &IndexReg = MI.getOperand(Op+2);
unsigned BaseReg = Base.getReg();
if (BaseReg == X86::RIP) { assert(IndexReg.getReg() == 0 && Is64BitMode &&
"Invalid rip-relative address");
EmitByte(ModRMByte(0, RegOpcodeField, 5), CurByte, OS);
unsigned FixupKind = X86::reloc_riprel_4byte;
if (MI.getOpcode() == X86::MOV64rm_TC)
FixupKind = X86::reloc_riprel_4byte_movq_load;
int ImmSize = X86II::hasImm(TSFlags) ? X86II::getSizeOfImm(TSFlags) : 0;
EmitImmediate(Disp, 4, MCFixupKind(FixupKind),
CurByte, OS, Fixups, -ImmSize);
return;
}
unsigned BaseRegNo = BaseReg ? GetX86RegNum(Base) : -1U;
if ( IndexReg.getReg() == 0 &&
BaseRegNo != N86::ESP &&
(!Is64BitMode || BaseReg != 0)) {
if (BaseReg == 0) { EmitByte(ModRMByte(0, RegOpcodeField, 5), CurByte, OS);
EmitImmediate(Disp, 4, FK_Data_4, CurByte, OS, Fixups);
return;
}
if (Disp.isImm() && Disp.getImm() == 0 && BaseRegNo != N86::EBP) {
EmitByte(ModRMByte(0, RegOpcodeField, BaseRegNo), CurByte, OS);
return;
}
if (Disp.isImm() && isDisp8(Disp.getImm())) {
EmitByte(ModRMByte(1, RegOpcodeField, BaseRegNo), CurByte, OS);
EmitImmediate(Disp, 1, FK_Data_1, CurByte, OS, Fixups);
return;
}
EmitByte(ModRMByte(2, RegOpcodeField, BaseRegNo), CurByte, OS);
EmitImmediate(Disp, 4, FK_Data_4, CurByte, OS, Fixups);
return;
}
assert(IndexReg.getReg() != X86::ESP &&
IndexReg.getReg() != X86::RSP && "Cannot use ESP as index reg!");
bool ForceDisp32 = false;
bool ForceDisp8 = false;
if (BaseReg == 0) {
EmitByte(ModRMByte(0, RegOpcodeField, 4), CurByte, OS);
ForceDisp32 = true;
} else if (!Disp.isImm()) {
EmitByte(ModRMByte(2, RegOpcodeField, 4), CurByte, OS);
ForceDisp32 = true;
} else if (Disp.getImm() == 0 &&
BaseRegNo != N86::EBP) {
EmitByte(ModRMByte(0, RegOpcodeField, 4), CurByte, OS);
} else if (isDisp8(Disp.getImm())) {
EmitByte(ModRMByte(1, RegOpcodeField, 4), CurByte, OS);
ForceDisp8 = true; } else {
EmitByte(ModRMByte(2, RegOpcodeField, 4), CurByte, OS);
}
static const unsigned SSTable[] = { ~0, 0, 1, ~0, 2, ~0, ~0, ~0, 3 };
unsigned SS = SSTable[Scale.getImm()];
if (BaseReg == 0) {
unsigned IndexRegNo;
if (IndexReg.getReg())
IndexRegNo = GetX86RegNum(IndexReg);
else IndexRegNo = 4;
EmitSIBByte(SS, IndexRegNo, 5, CurByte, OS);
} else {
unsigned IndexRegNo;
if (IndexReg.getReg())
IndexRegNo = GetX86RegNum(IndexReg);
else
IndexRegNo = 4; EmitSIBByte(SS, IndexRegNo, GetX86RegNum(Base), CurByte, OS);
}
if (ForceDisp8)
EmitImmediate(Disp, 1, FK_Data_1, CurByte, OS, Fixups);
else if (ForceDisp32 || Disp.getImm() != 0)
EmitImmediate(Disp, 4, FK_Data_4, CurByte, OS, Fixups);
}
static unsigned DetermineREXPrefix(const MCInst &MI, unsigned TSFlags,
const TargetInstrDesc &Desc) {
if ((TSFlags & X86II::FormMask) == X86II::Pseudo)
return 0;
unsigned REX = 0;
if (TSFlags & X86II::REX_W)
REX |= 1 << 3;
if (MI.getNumOperands() == 0) return REX;
unsigned NumOps = MI.getNumOperands();
bool isTwoAddr = NumOps > 1 &&
Desc.getOperandConstraint(1, TOI::TIED_TO) != -1;
unsigned i = isTwoAddr ? 1 : 0;
for (; i != NumOps; ++i) {
const MCOperand &MO = MI.getOperand(i);
if (!MO.isReg()) continue;
unsigned Reg = MO.getReg();
if (!X86InstrInfo::isX86_64NonExtLowByteReg(Reg)) continue;
REX |= 0x40;
break;
}
switch (TSFlags & X86II::FormMask) {
case X86II::MRMInitReg: assert(0 && "FIXME: Remove this!");
case X86II::MRMSrcReg:
if (MI.getOperand(0).isReg() &&
X86InstrInfo::isX86_64ExtendedReg(MI.getOperand(0).getReg()))
REX |= 1 << 2;
i = isTwoAddr ? 2 : 1;
for (; i != NumOps; ++i) {
const MCOperand &MO = MI.getOperand(i);
if (MO.isReg() && X86InstrInfo::isX86_64ExtendedReg(MO.getReg()))
REX |= 1 << 0;
}
break;
case X86II::MRMSrcMem: {
if (MI.getOperand(0).isReg() &&
X86InstrInfo::isX86_64ExtendedReg(MI.getOperand(0).getReg()))
REX |= 1 << 2;
unsigned Bit = 0;
i = isTwoAddr ? 2 : 1;
for (; i != NumOps; ++i) {
const MCOperand &MO = MI.getOperand(i);
if (MO.isReg()) {
if (X86InstrInfo::isX86_64ExtendedReg(MO.getReg()))
REX |= 1 << Bit;
Bit++;
}
}
break;
}
case X86II::MRM0m: case X86II::MRM1m:
case X86II::MRM2m: case X86II::MRM3m:
case X86II::MRM4m: case X86II::MRM5m:
case X86II::MRM6m: case X86II::MRM7m:
case X86II::MRMDestMem: {
unsigned e = (isTwoAddr ? X86AddrNumOperands+1 : X86AddrNumOperands);
i = isTwoAddr ? 1 : 0;
if (NumOps > e && MI.getOperand(e).isReg() &&
X86InstrInfo::isX86_64ExtendedReg(MI.getOperand(e).getReg()))
REX |= 1 << 2;
unsigned Bit = 0;
for (; i != e; ++i) {
const MCOperand &MO = MI.getOperand(i);
if (MO.isReg()) {
if (X86InstrInfo::isX86_64ExtendedReg(MO.getReg()))
REX |= 1 << Bit;
Bit++;
}
}
break;
}
default:
if (MI.getOperand(0).isReg() &&
X86InstrInfo::isX86_64ExtendedReg(MI.getOperand(0).getReg()))
REX |= 1 << 0;
i = isTwoAddr ? 2 : 1;
for (unsigned e = NumOps; i != e; ++i) {
const MCOperand &MO = MI.getOperand(i);
if (MO.isReg() && X86InstrInfo::isX86_64ExtendedReg(MO.getReg()))
REX |= 1 << 2;
}
break;
}
return REX;
}
void X86MCCodeEmitter::
EncodeInstruction(const MCInst &MI, raw_ostream &OS,
SmallVectorImpl<MCFixup> &Fixups) const {
unsigned Opcode = MI.getOpcode();
const TargetInstrDesc &Desc = TII.get(Opcode);
unsigned TSFlags = Desc.TSFlags;
unsigned CurByte = 0;
if (TSFlags & X86II::LOCK)
EmitByte(0xF0, CurByte, OS);
switch (TSFlags & X86II::SegOvrMask) {
default: assert(0 && "Invalid segment!");
case 0: break; case X86II::FS:
EmitByte(0x64, CurByte, OS);
break;
case X86II::GS:
EmitByte(0x65, CurByte, OS);
break;
}
if ((TSFlags & X86II::Op0Mask) == X86II::REP)
EmitByte(0xF3, CurByte, OS);
if (TSFlags & X86II::OpSize)
EmitByte(0x66, CurByte, OS);
if (TSFlags & X86II::AdSize)
EmitByte(0x67, CurByte, OS);
bool Need0FPrefix = false;
switch (TSFlags & X86II::Op0Mask) {
default: assert(0 && "Invalid prefix!");
case 0: break; case X86II::REP: break; case X86II::TB: case X86II::T8: case X86II::TA: Need0FPrefix = true;
break;
case X86II::TF: EmitByte(0xF2, CurByte, OS);
Need0FPrefix = true;
break;
case X86II::XS: EmitByte(0xF3, CurByte, OS);
Need0FPrefix = true;
break;
case X86II::XD: EmitByte(0xF2, CurByte, OS);
Need0FPrefix = true;
break;
case X86II::D8: EmitByte(0xD8, CurByte, OS); break;
case X86II::D9: EmitByte(0xD9, CurByte, OS); break;
case X86II::DA: EmitByte(0xDA, CurByte, OS); break;
case X86II::DB: EmitByte(0xDB, CurByte, OS); break;
case X86II::DC: EmitByte(0xDC, CurByte, OS); break;
case X86II::DD: EmitByte(0xDD, CurByte, OS); break;
case X86II::DE: EmitByte(0xDE, CurByte, OS); break;
case X86II::DF: EmitByte(0xDF, CurByte, OS); break;
}
if (Is64BitMode) {
if (unsigned REX = DetermineREXPrefix(MI, TSFlags, Desc))
EmitByte(0x40 | REX, CurByte, OS);
}
if (Need0FPrefix)
EmitByte(0x0F, CurByte, OS);
switch (TSFlags & X86II::Op0Mask) {
case X86II::TF: case X86II::T8: EmitByte(0x38, CurByte, OS);
break;
case X86II::TA: EmitByte(0x3A, CurByte, OS);
break;
}
unsigned NumOps = Desc.getNumOperands();
unsigned CurOp = 0;
if (NumOps > 1 && Desc.getOperandConstraint(1, TOI::TIED_TO) != -1)
++CurOp;
else if (NumOps > 2 && Desc.getOperandConstraint(NumOps-1, TOI::TIED_TO)== 0)
--NumOps;
unsigned char BaseOpcode = X86II::getBaseOpcodeFor(TSFlags);
switch (TSFlags & X86II::FormMask) {
case X86II::MRMInitReg:
assert(0 && "FIXME: Remove this form when the JIT moves to MCCodeEmitter!");
default: errs() << "FORM: " << (TSFlags & X86II::FormMask) << "\n";
assert(0 && "Unknown FormMask value in X86MCCodeEmitter!");
case X86II::Pseudo: return; case X86II::RawFrm:
EmitByte(BaseOpcode, CurByte, OS);
break;
case X86II::AddRegFrm:
EmitByte(BaseOpcode + GetX86RegNum(MI.getOperand(CurOp++)), CurByte, OS);
break;
case X86II::MRMDestReg:
EmitByte(BaseOpcode, CurByte, OS);
EmitRegModRMByte(MI.getOperand(CurOp),
GetX86RegNum(MI.getOperand(CurOp+1)), CurByte, OS);
CurOp += 2;
break;
case X86II::MRMDestMem:
EmitByte(BaseOpcode, CurByte, OS);
EmitMemModRMByte(MI, CurOp,
GetX86RegNum(MI.getOperand(CurOp + X86AddrNumOperands)),
TSFlags, CurByte, OS, Fixups);
CurOp += X86AddrNumOperands + 1;
break;
case X86II::MRMSrcReg:
EmitByte(BaseOpcode, CurByte, OS);
EmitRegModRMByte(MI.getOperand(CurOp+1), GetX86RegNum(MI.getOperand(CurOp)),
CurByte, OS);
CurOp += 2;
break;
case X86II::MRMSrcMem: {
EmitByte(BaseOpcode, CurByte, OS);
int AddrOperands;
if (Opcode == X86::LEA64r || Opcode == X86::LEA64_32r ||
Opcode == X86::LEA16r || Opcode == X86::LEA32r)
AddrOperands = X86AddrNumOperands - 1; else
AddrOperands = X86AddrNumOperands;
EmitMemModRMByte(MI, CurOp+1, GetX86RegNum(MI.getOperand(CurOp)),
TSFlags, CurByte, OS, Fixups);
CurOp += AddrOperands + 1;
break;
}
case X86II::MRM0r: case X86II::MRM1r:
case X86II::MRM2r: case X86II::MRM3r:
case X86II::MRM4r: case X86II::MRM5r:
case X86II::MRM6r: case X86II::MRM7r:
EmitByte(BaseOpcode, CurByte, OS);
EmitRegModRMByte(MI.getOperand(CurOp++),
(TSFlags & X86II::FormMask)-X86II::MRM0r,
CurByte, OS);
break;
case X86II::MRM0m: case X86II::MRM1m:
case X86II::MRM2m: case X86II::MRM3m:
case X86II::MRM4m: case X86II::MRM5m:
case X86II::MRM6m: case X86II::MRM7m:
EmitByte(BaseOpcode, CurByte, OS);
EmitMemModRMByte(MI, CurOp, (TSFlags & X86II::FormMask)-X86II::MRM0m,
TSFlags, CurByte, OS, Fixups);
CurOp += X86AddrNumOperands;
break;
case X86II::MRM_C1:
EmitByte(BaseOpcode, CurByte, OS);
EmitByte(0xC1, CurByte, OS);
break;
case X86II::MRM_C2:
EmitByte(BaseOpcode, CurByte, OS);
EmitByte(0xC2, CurByte, OS);
break;
case X86II::MRM_C3:
EmitByte(BaseOpcode, CurByte, OS);
EmitByte(0xC3, CurByte, OS);
break;
case X86II::MRM_C4:
EmitByte(BaseOpcode, CurByte, OS);
EmitByte(0xC4, CurByte, OS);
break;
case X86II::MRM_C8:
EmitByte(BaseOpcode, CurByte, OS);
EmitByte(0xC8, CurByte, OS);
break;
case X86II::MRM_C9:
EmitByte(BaseOpcode, CurByte, OS);
EmitByte(0xC9, CurByte, OS);
break;
case X86II::MRM_E8:
EmitByte(BaseOpcode, CurByte, OS);
EmitByte(0xE8, CurByte, OS);
break;
case X86II::MRM_F0:
EmitByte(BaseOpcode, CurByte, OS);
EmitByte(0xF0, CurByte, OS);
break;
case X86II::MRM_F8:
EmitByte(BaseOpcode, CurByte, OS);
EmitByte(0xF8, CurByte, OS);
break;
case X86II::MRM_F9:
EmitByte(BaseOpcode, CurByte, OS);
EmitByte(0xF9, CurByte, OS);
break;
}
if (CurOp != NumOps)
EmitImmediate(MI.getOperand(CurOp++),
X86II::getSizeOfImm(TSFlags), getImmFixupKind(TSFlags),
CurByte, OS, Fixups);
#ifndef NDEBUG
if ( CurOp != NumOps) {
errs() << "Cannot encode all operands of: ";
MI.dump();
errs() << '\n';
abort();
}
#endif
}