//===-- X86/X86MCCodeEmitter.cpp - Convert X86 code to machine code -------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the X86MCCodeEmitter class.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "mccodeemitter"
#include "MCTargetDesc/X86MCTargetDesc.h"
#include "MCTargetDesc/X86BaseInfo.h"
#include "MCTargetDesc/X86FixupKinds.h"
#include "llvm/MC/MCCodeEmitter.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCInst.h"
#include "llvm/MC/MCInstrInfo.h"
#include "llvm/MC/MCRegisterInfo.h"
#include "llvm/MC/MCSubtargetInfo.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
namespace {
class X86MCCodeEmitter : public MCCodeEmitter {
X86MCCodeEmitter(const X86MCCodeEmitter &); // DO NOT IMPLEMENT
void operator=(const X86MCCodeEmitter &); // DO NOT IMPLEMENT
const MCInstrInfo &MCII;
const MCSubtargetInfo &STI;
MCContext &Ctx;
public:
X86MCCodeEmitter(const MCInstrInfo &mcii, const MCSubtargetInfo &sti,
MCContext &ctx)
: MCII(mcii), STI(sti), Ctx(ctx) {
}
~X86MCCodeEmitter() {}
bool is64BitMode() const {
// FIXME: Can tablegen auto-generate this?
return (STI.getFeatureBits() & X86::Mode64Bit) != 0;
}
static unsigned GetX86RegNum(const MCOperand &MO) {
return X86_MC::getX86RegNum(MO.getReg());
}
// On regular x86, both XMM0-XMM7 and XMM8-XMM15 are encoded in the range
// 0-7 and the difference between the 2 groups is given by the REX prefix.
// In the VEX prefix, registers are seen sequencially from 0-15 and encoded
// in 1's complement form, example:
//
// ModRM field => XMM9 => 1
// VEX.VVVV => XMM9 => ~9
//
// See table 4-35 of Intel AVX Programming Reference for details.
static unsigned char getVEXRegisterEncoding(const MCInst &MI,
unsigned OpNum) {
unsigned SrcReg = MI.getOperand(OpNum).getReg();
unsigned SrcRegNum = GetX86RegNum(MI.getOperand(OpNum));
if ((SrcReg >= X86::XMM8 && SrcReg <= X86::XMM15) ||
(SrcReg >= X86::YMM8 && SrcReg <= X86::YMM15))
SrcRegNum += 8;
// The registers represented through VEX_VVVV should
// be encoded in 1's complement form.
return (~SrcRegNum) & 0xf;
}
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 {
// Output the constant in little endian byte order.
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 {
// SIB byte is in the same format as the ModRMByte.
EmitByte(ModRMByte(SS, Index, Base), CurByte, OS);
}
void EmitMemModRMByte(const MCInst &MI, unsigned Op,
unsigned RegOpcodeField,
uint64_t TSFlags, unsigned &CurByte, raw_ostream &OS,
SmallVectorImpl<MCFixup> &Fixups) const;
void EncodeInstruction(const MCInst &MI, raw_ostream &OS,
SmallVectorImpl<MCFixup> &Fixups) const;
void EmitVEXOpcodePrefix(uint64_t TSFlags, unsigned &CurByte, int MemOperand,
const MCInst &MI, const MCInstrDesc &Desc,
raw_ostream &OS) const;
void EmitSegmentOverridePrefix(uint64_t TSFlags, unsigned &CurByte,
int MemOperand, const MCInst &MI,
raw_ostream &OS) const;
void EmitOpcodePrefix(uint64_t TSFlags, unsigned &CurByte, int MemOperand,
const MCInst &MI, const MCInstrDesc &Desc,
raw_ostream &OS) const;
};
} // end anonymous namespace
MCCodeEmitter *llvm::createX86MCCodeEmitter(const MCInstrInfo &MCII,
const MCSubtargetInfo &STI,
MCContext &Ctx) {
return new X86MCCodeEmitter(MCII, STI, Ctx);
}
/// isDisp8 - Return true if this signed displacement fits in a 8-bit
/// sign-extended field.
static bool isDisp8(int Value) {
return Value == (signed char)Value;
}
/// getImmFixupKind - Return the appropriate fixup kind to use for an immediate
/// in an instruction with the specified TSFlags.
static MCFixupKind getImmFixupKind(uint64_t TSFlags) {
unsigned Size = X86II::getSizeOfImm(TSFlags);
bool isPCRel = X86II::isImmPCRel(TSFlags);
return MCFixup::getKindForSize(Size, isPCRel);
}
/// Is32BitMemOperand - Return true if the specified instruction with a memory
/// operand should emit the 0x67 prefix byte in 64-bit mode due to a 32-bit
/// memory operand. Op specifies the operand # of the memoperand.
static bool Is32BitMemOperand(const MCInst &MI, unsigned Op) {
const MCOperand &BaseReg = MI.getOperand(Op+X86::AddrBaseReg);
const MCOperand &IndexReg = MI.getOperand(Op+X86::AddrIndexReg);
if ((BaseReg.getReg() != 0 &&
X86MCRegisterClasses[X86::GR32RegClassID].contains(BaseReg.getReg())) ||
(IndexReg.getReg() != 0 &&
X86MCRegisterClasses[X86::GR32RegClassID].contains(IndexReg.getReg())))
return true;
return false;
}
/// StartsWithGlobalOffsetTable - Return true for the simple cases where this
/// expression starts with _GLOBAL_OFFSET_TABLE_. This is a needed to support
/// PIC on ELF i386 as that symbol is magic. We check only simple case that
/// are know to be used: _GLOBAL_OFFSET_TABLE_ by itself or at the start
/// of a binary expression.
static bool StartsWithGlobalOffsetTable(const MCExpr *Expr) {
if (Expr->getKind() == MCExpr::Binary) {
const MCBinaryExpr *BE = static_cast<const MCBinaryExpr *>(Expr);
Expr = BE->getLHS();
}
if (Expr->getKind() != MCExpr::SymbolRef)
return false;
const MCSymbolRefExpr *Ref = static_cast<const MCSymbolRefExpr*>(Expr);
const MCSymbol &S = Ref->getSymbol();
return S.getName() == "_GLOBAL_OFFSET_TABLE_";
}
void X86MCCodeEmitter::
EmitImmediate(const MCOperand &DispOp, unsigned Size, MCFixupKind FixupKind,
unsigned &CurByte, raw_ostream &OS,
SmallVectorImpl<MCFixup> &Fixups, int ImmOffset) const {
const MCExpr *Expr = NULL;
if (DispOp.isImm()) {
// If this is a simple integer displacement that doesn't require a
// relocation, emit it now.
if (FixupKind != FK_PCRel_1 &&
FixupKind != FK_PCRel_2 &&
FixupKind != FK_PCRel_4) {
EmitConstant(DispOp.getImm()+ImmOffset, Size, CurByte, OS);
return;
}
Expr = MCConstantExpr::Create(DispOp.getImm(), Ctx);
} else {
Expr = DispOp.getExpr();
}
// If we have an immoffset, add it to the expression.
if ((FixupKind == FK_Data_4 ||
FixupKind == MCFixupKind(X86::reloc_signed_4byte)) &&
StartsWithGlobalOffsetTable(Expr)) {
assert(ImmOffset == 0);
FixupKind = MCFixupKind(X86::reloc_global_offset_table);
ImmOffset = CurByte;
}
// If the fixup is pc-relative, we need to bias the value to be relative to
// the start of the field, not the end of the field.
if (FixupKind == FK_PCRel_4 ||
FixupKind == MCFixupKind(X86::reloc_riprel_4byte) ||
FixupKind == MCFixupKind(X86::reloc_riprel_4byte_movq_load))
ImmOffset -= 4;
if (FixupKind == FK_PCRel_2)
ImmOffset -= 2;
if (FixupKind == FK_PCRel_1)
ImmOffset -= 1;
if (ImmOffset)
Expr = MCBinaryExpr::CreateAdd(Expr, MCConstantExpr::Create(ImmOffset, Ctx),
Ctx);
// Emit a symbolic constant as a fixup and 4 zeros.
Fixups.push_back(MCFixup::Create(CurByte, Expr, FixupKind));
EmitConstant(0, Size, CurByte, OS);
}
void X86MCCodeEmitter::EmitMemModRMByte(const MCInst &MI, unsigned Op,
unsigned RegOpcodeField,
uint64_t TSFlags, unsigned &CurByte,
raw_ostream &OS,
SmallVectorImpl<MCFixup> &Fixups) const{
const MCOperand &Disp = MI.getOperand(Op+X86::AddrDisp);
const MCOperand &Base = MI.getOperand(Op+X86::AddrBaseReg);
const MCOperand &Scale = MI.getOperand(Op+X86::AddrScaleAmt);
const MCOperand &IndexReg = MI.getOperand(Op+X86::AddrIndexReg);
unsigned BaseReg = Base.getReg();
// Handle %rip relative addressing.
if (BaseReg == X86::RIP) { // [disp32+RIP] in X86-64 mode
assert(is64BitMode() && "Rip-relative addressing requires 64-bit mode");
assert(IndexReg.getReg() == 0 && "Invalid rip-relative address");
EmitByte(ModRMByte(0, RegOpcodeField, 5), CurByte, OS);
unsigned FixupKind = X86::reloc_riprel_4byte;
// movq loads are handled with a special relocation form which allows the
// linker to eliminate some loads for GOT references which end up in the
// same linkage unit.
if (MI.getOpcode() == X86::MOV64rm)
FixupKind = X86::reloc_riprel_4byte_movq_load;
// rip-relative addressing is actually relative to the *next* instruction.
// Since an immediate can follow the mod/rm byte for an instruction, this
// means that we need to bias the immediate field of the instruction with
// the size of the immediate field. If we have this case, add it into the
// expression to emit.
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;
// Determine whether a SIB byte is needed.
// If no BaseReg, issue a RIP relative instruction only if the MCE can
// resolve addresses on-the-fly, otherwise use SIB (Intel Manual 2A, table
// 2-7) and absolute references.
if (// The SIB byte must be used if there is an index register.
IndexReg.getReg() == 0 &&
// The SIB byte must be used if the base is ESP/RSP/R12, all of which
// encode to an R/M value of 4, which indicates that a SIB byte is
// present.
BaseRegNo != N86::ESP &&
// If there is no base register and we're in 64-bit mode, we need a SIB
// byte to emit an addr that is just 'disp32' (the non-RIP relative form).
(!is64BitMode() || BaseReg != 0)) {
if (BaseReg == 0) { // [disp32] in X86-32 mode
EmitByte(ModRMByte(0, RegOpcodeField, 5), CurByte, OS);
EmitImmediate(Disp, 4, FK_Data_4, CurByte, OS, Fixups);
return;
}
// If the base is not EBP/ESP and there is no displacement, use simple
// indirect register encoding, this handles addresses like [EAX]. The
// encoding for [EBP] with no displacement means [disp32] so we handle it
// by emitting a displacement of 0 below.
if (Disp.isImm() && Disp.getImm() == 0 && BaseRegNo != N86::EBP) {
EmitByte(ModRMByte(0, RegOpcodeField, BaseRegNo), CurByte, OS);
return;
}
// Otherwise, if the displacement fits in a byte, encode as [REG+disp8].
if (Disp.isImm() && isDisp8(Disp.getImm())) {
EmitByte(ModRMByte(1, RegOpcodeField, BaseRegNo), CurByte, OS);
EmitImmediate(Disp, 1, FK_Data_1, CurByte, OS, Fixups);
return;
}
// Otherwise, emit the most general non-SIB encoding: [REG+disp32]
EmitByte(ModRMByte(2, RegOpcodeField, BaseRegNo), CurByte, OS);
EmitImmediate(Disp, 4, MCFixupKind(X86::reloc_signed_4byte), CurByte, OS,
Fixups);
return;
}
// We need a SIB byte, so start by outputting the ModR/M byte first
assert(IndexReg.getReg() != X86::ESP &&
IndexReg.getReg() != X86::RSP && "Cannot use ESP as index reg!");
bool ForceDisp32 = false;
bool ForceDisp8 = false;
if (BaseReg == 0) {
// If there is no base register, we emit the special case SIB byte with
// MOD=0, BASE=5, to JUST get the index, scale, and displacement.
EmitByte(ModRMByte(0, RegOpcodeField, 4), CurByte, OS);
ForceDisp32 = true;
} else if (!Disp.isImm()) {
// Emit the normal disp32 encoding.
EmitByte(ModRMByte(2, RegOpcodeField, 4), CurByte, OS);
ForceDisp32 = true;
} else if (Disp.getImm() == 0 &&
// Base reg can't be anything that ends up with '5' as the base
// reg, it is the magic [*] nomenclature that indicates no base.
BaseRegNo != N86::EBP) {
// Emit no displacement ModR/M byte
EmitByte(ModRMByte(0, RegOpcodeField, 4), CurByte, OS);
} else if (isDisp8(Disp.getImm())) {
// Emit the disp8 encoding.
EmitByte(ModRMByte(1, RegOpcodeField, 4), CurByte, OS);
ForceDisp8 = true; // Make sure to force 8 bit disp if Base=EBP
} else {
// Emit the normal disp32 encoding.
EmitByte(ModRMByte(2, RegOpcodeField, 4), CurByte, OS);
}
// Calculate what the SS field value should be...
static const unsigned SSTable[] = { ~0U, 0, 1, ~0U, 2, ~0U, ~0U, ~0U, 3 };
unsigned SS = SSTable[Scale.getImm()];
if (BaseReg == 0) {
// Handle the SIB byte for the case where there is no base, see Intel
// Manual 2A, table 2-7. The displacement has already been output.
unsigned IndexRegNo;
if (IndexReg.getReg())
IndexRegNo = GetX86RegNum(IndexReg);
else // Examples: [ESP+1*<noreg>+4] or [scaled idx]+disp32 (MOD=0,BASE=5)
IndexRegNo = 4;
EmitSIBByte(SS, IndexRegNo, 5, CurByte, OS);
} else {
unsigned IndexRegNo;
if (IndexReg.getReg())
IndexRegNo = GetX86RegNum(IndexReg);
else
IndexRegNo = 4; // For example [ESP+1*<noreg>+4]
EmitSIBByte(SS, IndexRegNo, GetX86RegNum(Base), CurByte, OS);
}
// Do we need to output a displacement?
if (ForceDisp8)
EmitImmediate(Disp, 1, FK_Data_1, CurByte, OS, Fixups);
else if (ForceDisp32 || Disp.getImm() != 0)
EmitImmediate(Disp, 4, MCFixupKind(X86::reloc_signed_4byte), CurByte, OS,
Fixups);
}
/// EmitVEXOpcodePrefix - AVX instructions are encoded using a opcode prefix
/// called VEX.
void X86MCCodeEmitter::EmitVEXOpcodePrefix(uint64_t TSFlags, unsigned &CurByte,
int MemOperand, const MCInst &MI,
const MCInstrDesc &Desc,
raw_ostream &OS) const {
bool HasVEX_4V = false;
if ((TSFlags >> X86II::VEXShift) & X86II::VEX_4V)
HasVEX_4V = true;
// VEX_R: opcode externsion equivalent to REX.R in
// 1's complement (inverted) form
//
// 1: Same as REX_R=0 (must be 1 in 32-bit mode)
// 0: Same as REX_R=1 (64 bit mode only)
//
unsigned char VEX_R = 0x1;
// VEX_X: equivalent to REX.X, only used when a
// register is used for index in SIB Byte.
//
// 1: Same as REX.X=0 (must be 1 in 32-bit mode)
// 0: Same as REX.X=1 (64-bit mode only)
unsigned char VEX_X = 0x1;
// VEX_B:
//
// 1: Same as REX_B=0 (ignored in 32-bit mode)
// 0: Same as REX_B=1 (64 bit mode only)
//
unsigned char VEX_B = 0x1;
// VEX_W: opcode specific (use like REX.W, or used for
// opcode extension, or ignored, depending on the opcode byte)
unsigned char VEX_W = 0;
// VEX_5M (VEX m-mmmmm field):
//
// 0b00000: Reserved for future use
// 0b00001: implied 0F leading opcode
// 0b00010: implied 0F 38 leading opcode bytes
// 0b00011: implied 0F 3A leading opcode bytes
// 0b00100-0b11111: Reserved for future use
//
unsigned char VEX_5M = 0x1;
// VEX_4V (VEX vvvv field): a register specifier
// (in 1's complement form) or 1111 if unused.
unsigned char VEX_4V = 0xf;
// VEX_L (Vector Length):
//
// 0: scalar or 128-bit vector
// 1: 256-bit vector
//
unsigned char VEX_L = 0;
// VEX_PP: opcode extension providing equivalent
// functionality of a SIMD prefix
//
// 0b00: None
// 0b01: 66
// 0b10: F3
// 0b11: F2
//
unsigned char VEX_PP = 0;
// Encode the operand size opcode prefix as needed.
if (TSFlags & X86II::OpSize)
VEX_PP = 0x01;
if ((TSFlags >> X86II::VEXShift) & X86II::VEX_W)
VEX_W = 1;
if ((TSFlags >> X86II::VEXShift) & X86II::VEX_L)
VEX_L = 1;
switch (TSFlags & X86II::Op0Mask) {
default: assert(0 && "Invalid prefix!");
case X86II::T8: // 0F 38
VEX_5M = 0x2;
break;
case X86II::TA: // 0F 3A
VEX_5M = 0x3;
break;
case X86II::TF: // F2 0F 38
VEX_PP = 0x3;
VEX_5M = 0x2;
break;
case X86II::XS: // F3 0F
VEX_PP = 0x2;
break;
case X86II::XD: // F2 0F
VEX_PP = 0x3;
break;
case X86II::A6: // Bypass: Not used by VEX
case X86II::A7: // Bypass: Not used by VEX
case X86II::TB: // Bypass: Not used by VEX
case 0:
break; // No prefix!
}
// Set the vector length to 256-bit if YMM0-YMM15 is used
for (unsigned i = 0; i != MI.getNumOperands(); ++i) {
if (!MI.getOperand(i).isReg())
continue;
unsigned SrcReg = MI.getOperand(i).getReg();
if (SrcReg >= X86::YMM0 && SrcReg <= X86::YMM15)
VEX_L = 1;
}
// Classify VEX_B, VEX_4V, VEX_R, VEX_X
unsigned CurOp = 0;
switch (TSFlags & X86II::FormMask) {
case X86II::MRMInitReg: assert(0 && "FIXME: Remove this!");
case X86II::MRMDestMem: {
// MRMDestMem instructions forms:
// MemAddr, src1(ModR/M)
// MemAddr, src1(VEX_4V), src2(ModR/M)
// MemAddr, src1(ModR/M), imm8
//
if (X86II::isX86_64ExtendedReg(MI.getOperand(X86::AddrBaseReg).getReg()))
VEX_B = 0x0;
if (X86II::isX86_64ExtendedReg(MI.getOperand(X86::AddrIndexReg).getReg()))
VEX_X = 0x0;
CurOp = X86::AddrNumOperands;
if (HasVEX_4V)
VEX_4V = getVEXRegisterEncoding(MI, CurOp++);
const MCOperand &MO = MI.getOperand(CurOp);
if (MO.isReg() && X86II::isX86_64ExtendedReg(MO.getReg()))
VEX_R = 0x0;
break;
}
case X86II::MRMSrcMem: {
// MRMSrcMem instructions forms:
// src1(ModR/M), MemAddr
// src1(ModR/M), src2(VEX_4V), MemAddr
// src1(ModR/M), MemAddr, imm8
// src1(ModR/M), MemAddr, src2(VEX_I8IMM)
//
if (X86II::isX86_64ExtendedReg(MI.getOperand(0).getReg()))
VEX_R = 0x0;
unsigned MemAddrOffset = 1;
if (HasVEX_4V) {
VEX_4V = getVEXRegisterEncoding(MI, 1);
MemAddrOffset++;
}
if (X86II::isX86_64ExtendedReg(
MI.getOperand(MemAddrOffset+X86::AddrBaseReg).getReg()))
VEX_B = 0x0;
if (X86II::isX86_64ExtendedReg(
MI.getOperand(MemAddrOffset+X86::AddrIndexReg).getReg()))
VEX_X = 0x0;
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:
// MRM[0-9]m instructions forms:
// MemAddr
if (X86II::isX86_64ExtendedReg(MI.getOperand(X86::AddrBaseReg).getReg()))
VEX_B = 0x0;
if (X86II::isX86_64ExtendedReg(MI.getOperand(X86::AddrIndexReg).getReg()))
VEX_X = 0x0;
break;
case X86II::MRMSrcReg:
// MRMSrcReg instructions forms:
// dst(ModR/M), src1(VEX_4V), src2(ModR/M), src3(VEX_I8IMM)
// dst(ModR/M), src1(ModR/M)
// dst(ModR/M), src1(ModR/M), imm8
//
if (X86II::isX86_64ExtendedReg(MI.getOperand(CurOp).getReg()))
VEX_R = 0x0;
CurOp++;
if (HasVEX_4V)
VEX_4V = getVEXRegisterEncoding(MI, CurOp++);
if (X86II::isX86_64ExtendedReg(MI.getOperand(CurOp).getReg()))
VEX_B = 0x0;
break;
case X86II::MRMDestReg:
// MRMDestReg instructions forms:
// dst(ModR/M), src(ModR/M)
// dst(ModR/M), src(ModR/M), imm8
if (X86II::isX86_64ExtendedReg(MI.getOperand(0).getReg()))
VEX_B = 0x0;
if (X86II::isX86_64ExtendedReg(MI.getOperand(1).getReg()))
VEX_R = 0x0;
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:
// MRM0r-MRM7r instructions forms:
// dst(VEX_4V), src(ModR/M), imm8
VEX_4V = getVEXRegisterEncoding(MI, 0);
if (X86II::isX86_64ExtendedReg(MI.getOperand(1).getReg()))
VEX_B = 0x0;
break;
default: // RawFrm
break;
}
// Emit segment override opcode prefix as needed.
EmitSegmentOverridePrefix(TSFlags, CurByte, MemOperand, MI, OS);
// VEX opcode prefix can have 2 or 3 bytes
//
// 3 bytes:
// +-----+ +--------------+ +-------------------+
// | C4h | | RXB | m-mmmm | | W | vvvv | L | pp |
// +-----+ +--------------+ +-------------------+
// 2 bytes:
// +-----+ +-------------------+
// | C5h | | R | vvvv | L | pp |
// +-----+ +-------------------+
//
unsigned char LastByte = VEX_PP | (VEX_L << 2) | (VEX_4V << 3);
if (VEX_B && VEX_X && !VEX_W && (VEX_5M == 1)) { // 2 byte VEX prefix
EmitByte(0xC5, CurByte, OS);
EmitByte(LastByte | (VEX_R << 7), CurByte, OS);
return;
}
// 3 byte VEX prefix
EmitByte(0xC4, CurByte, OS);
EmitByte(VEX_R << 7 | VEX_X << 6 | VEX_B << 5 | VEX_5M, CurByte, OS);
EmitByte(LastByte | (VEX_W << 7), CurByte, OS);
}
/// DetermineREXPrefix - Determine if the MCInst has to be encoded with a X86-64
/// REX prefix which specifies 1) 64-bit instructions, 2) non-default operand
/// size, and 3) use of X86-64 extended registers.
static unsigned DetermineREXPrefix(const MCInst &MI, uint64_t TSFlags,
const MCInstrDesc &Desc) {
unsigned REX = 0;
if (TSFlags & X86II::REX_W)
REX |= 1 << 3; // set REX.W
if (MI.getNumOperands() == 0) return REX;
unsigned NumOps = MI.getNumOperands();
// FIXME: MCInst should explicitize the two-addrness.
bool isTwoAddr = NumOps > 1 &&
Desc.getOperandConstraint(1, MCOI::TIED_TO) != -1;
// If it accesses SPL, BPL, SIL, or DIL, then it requires a 0x40 REX prefix.
unsigned i = isTwoAddr ? 1 : 0;
for (; i != NumOps; ++i) {
const MCOperand &MO = MI.getOperand(i);
if (!MO.isReg()) continue;
unsigned Reg = MO.getReg();
if (!X86II::isX86_64NonExtLowByteReg(Reg)) continue;
// FIXME: The caller of DetermineREXPrefix slaps this prefix onto anything
// that returns non-zero.
REX |= 0x40; // REX fixed encoding prefix
break;
}
switch (TSFlags & X86II::FormMask) {
case X86II::MRMInitReg: assert(0 && "FIXME: Remove this!");
case X86II::MRMSrcReg:
if (MI.getOperand(0).isReg() &&
X86II::isX86_64ExtendedReg(MI.getOperand(0).getReg()))
REX |= 1 << 2; // set REX.R
i = isTwoAddr ? 2 : 1;
for (; i != NumOps; ++i) {
const MCOperand &MO = MI.getOperand(i);
if (MO.isReg() && X86II::isX86_64ExtendedReg(MO.getReg()))
REX |= 1 << 0; // set REX.B
}
break;
case X86II::MRMSrcMem: {
if (MI.getOperand(0).isReg() &&
X86II::isX86_64ExtendedReg(MI.getOperand(0).getReg()))
REX |= 1 << 2; // set REX.R
unsigned Bit = 0;
i = isTwoAddr ? 2 : 1;
for (; i != NumOps; ++i) {
const MCOperand &MO = MI.getOperand(i);
if (MO.isReg()) {
if (X86II::isX86_64ExtendedReg(MO.getReg()))
REX |= 1 << Bit; // set REX.B (Bit=0) and REX.X (Bit=1)
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 ? X86::AddrNumOperands+1 : X86::AddrNumOperands);
i = isTwoAddr ? 1 : 0;
if (NumOps > e && MI.getOperand(e).isReg() &&
X86II::isX86_64ExtendedReg(MI.getOperand(e).getReg()))
REX |= 1 << 2; // set REX.R
unsigned Bit = 0;
for (; i != e; ++i) {
const MCOperand &MO = MI.getOperand(i);
if (MO.isReg()) {
if (X86II::isX86_64ExtendedReg(MO.getReg()))
REX |= 1 << Bit; // REX.B (Bit=0) and REX.X (Bit=1)
Bit++;
}
}
break;
}
default:
if (MI.getOperand(0).isReg() &&
X86II::isX86_64ExtendedReg(MI.getOperand(0).getReg()))
REX |= 1 << 0; // set REX.B
i = isTwoAddr ? 2 : 1;
for (unsigned e = NumOps; i != e; ++i) {
const MCOperand &MO = MI.getOperand(i);
if (MO.isReg() && X86II::isX86_64ExtendedReg(MO.getReg()))
REX |= 1 << 2; // set REX.R
}
break;
}
return REX;
}
/// EmitSegmentOverridePrefix - Emit segment override opcode prefix as needed
void X86MCCodeEmitter::EmitSegmentOverridePrefix(uint64_t TSFlags,
unsigned &CurByte, int MemOperand,
const MCInst &MI,
raw_ostream &OS) const {
switch (TSFlags & X86II::SegOvrMask) {
default: assert(0 && "Invalid segment!");
case 0:
// No segment override, check for explicit one on memory operand.
if (MemOperand != -1) { // If the instruction has a memory operand.
switch (MI.getOperand(MemOperand+X86::AddrSegmentReg).getReg()) {
default: assert(0 && "Unknown segment register!");
case 0: break;
case X86::CS: EmitByte(0x2E, CurByte, OS); break;
case X86::SS: EmitByte(0x36, CurByte, OS); break;
case X86::DS: EmitByte(0x3E, CurByte, OS); break;
case X86::ES: EmitByte(0x26, CurByte, OS); break;
case X86::FS: EmitByte(0x64, CurByte, OS); break;
case X86::GS: EmitByte(0x65, CurByte, OS); break;
}
}
break;
case X86II::FS:
EmitByte(0x64, CurByte, OS);
break;
case X86II::GS:
EmitByte(0x65, CurByte, OS);
break;
}
}
/// EmitOpcodePrefix - Emit all instruction prefixes prior to the opcode.
///
/// MemOperand is the operand # of the start of a memory operand if present. If
/// Not present, it is -1.
void X86MCCodeEmitter::EmitOpcodePrefix(uint64_t TSFlags, unsigned &CurByte,
int MemOperand, const MCInst &MI,
const MCInstrDesc &Desc,
raw_ostream &OS) const {
// Emit the lock opcode prefix as needed.
if (TSFlags & X86II::LOCK)
EmitByte(0xF0, CurByte, OS);
// Emit segment override opcode prefix as needed.
EmitSegmentOverridePrefix(TSFlags, CurByte, MemOperand, MI, OS);
// Emit the repeat opcode prefix as needed.
if ((TSFlags & X86II::Op0Mask) == X86II::REP)
EmitByte(0xF3, CurByte, OS);
// Emit the address size opcode prefix as needed.
if ((TSFlags & X86II::AdSize) ||
(MemOperand != -1 && is64BitMode() && Is32BitMemOperand(MI, MemOperand)))
EmitByte(0x67, CurByte, OS);
// Emit the operand size opcode prefix as needed.
if (TSFlags & X86II::OpSize)
EmitByte(0x66, CurByte, OS);
bool Need0FPrefix = false;
switch (TSFlags & X86II::Op0Mask) {
default: assert(0 && "Invalid prefix!");
case 0: break; // No prefix!
case X86II::REP: break; // already handled.
case X86II::TB: // Two-byte opcode prefix
case X86II::T8: // 0F 38
case X86II::TA: // 0F 3A
case X86II::A6: // 0F A6
case X86II::A7: // 0F A7
Need0FPrefix = true;
break;
case X86II::TF: // F2 0F 38
EmitByte(0xF2, CurByte, OS);
Need0FPrefix = true;
break;
case X86II::XS: // F3 0F
EmitByte(0xF3, CurByte, OS);
Need0FPrefix = true;
break;
case X86II::XD: // F2 0F
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;
}
// Handle REX prefix.
// FIXME: Can this come before F2 etc to simplify emission?
if (is64BitMode()) {
if (unsigned REX = DetermineREXPrefix(MI, TSFlags, Desc))
EmitByte(0x40 | REX, CurByte, OS);
}
// 0x0F escape code must be emitted just before the opcode.
if (Need0FPrefix)
EmitByte(0x0F, CurByte, OS);
// FIXME: Pull this up into previous switch if REX can be moved earlier.
switch (TSFlags & X86II::Op0Mask) {
case X86II::TF: // F2 0F 38
case X86II::T8: // 0F 38
EmitByte(0x38, CurByte, OS);
break;
case X86II::TA: // 0F 3A
EmitByte(0x3A, CurByte, OS);
break;
case X86II::A6: // 0F A6
EmitByte(0xA6, CurByte, OS);
break;
case X86II::A7: // 0F A7
EmitByte(0xA7, CurByte, OS);
break;
}
}
void X86MCCodeEmitter::
EncodeInstruction(const MCInst &MI, raw_ostream &OS,
SmallVectorImpl<MCFixup> &Fixups) const {
unsigned Opcode = MI.getOpcode();
const MCInstrDesc &Desc = MCII.get(Opcode);
uint64_t TSFlags = Desc.TSFlags;
// Pseudo instructions don't get encoded.
if ((TSFlags & X86II::FormMask) == X86II::Pseudo)
return;
// If this is a two-address instruction, skip one of the register operands.
// FIXME: This should be handled during MCInst lowering.
unsigned NumOps = Desc.getNumOperands();
unsigned CurOp = 0;
if (NumOps > 1 && Desc.getOperandConstraint(1, MCOI::TIED_TO) != -1)
++CurOp;
else if (NumOps > 2 && Desc.getOperandConstraint(NumOps-1, MCOI::TIED_TO)== 0)
// Skip the last source operand that is tied_to the dest reg. e.g. LXADD32
--NumOps;
// Keep track of the current byte being emitted.
unsigned CurByte = 0;
// Is this instruction encoded using the AVX VEX prefix?
bool HasVEXPrefix = false;
// It uses the VEX.VVVV field?
bool HasVEX_4V = false;
if ((TSFlags >> X86II::VEXShift) & X86II::VEX)
HasVEXPrefix = true;
if ((TSFlags >> X86II::VEXShift) & X86II::VEX_4V)
HasVEX_4V = true;
// Determine where the memory operand starts, if present.
int MemoryOperand = X86II::getMemoryOperandNo(TSFlags);
if (MemoryOperand != -1) MemoryOperand += CurOp;
if (!HasVEXPrefix)
EmitOpcodePrefix(TSFlags, CurByte, MemoryOperand, MI, Desc, OS);
else
EmitVEXOpcodePrefix(TSFlags, CurByte, MemoryOperand, MI, Desc, OS);
unsigned char BaseOpcode = X86II::getBaseOpcodeFor(TSFlags);
if ((TSFlags >> X86II::VEXShift) & X86II::Has3DNow0F0FOpcode)
BaseOpcode = 0x0F; // Weird 3DNow! encoding.
unsigned SrcRegNum = 0;
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:
assert(0 && "Pseudo instruction shouldn't be emitted");
case X86II::RawFrm:
EmitByte(BaseOpcode, CurByte, OS);
break;
case X86II::RawFrmImm8:
EmitByte(BaseOpcode, CurByte, OS);
EmitImmediate(MI.getOperand(CurOp++),
X86II::getSizeOfImm(TSFlags), getImmFixupKind(TSFlags),
CurByte, OS, Fixups);
EmitImmediate(MI.getOperand(CurOp++), 1, FK_Data_1, CurByte, OS, Fixups);
break;
case X86II::RawFrmImm16:
EmitByte(BaseOpcode, CurByte, OS);
EmitImmediate(MI.getOperand(CurOp++),
X86II::getSizeOfImm(TSFlags), getImmFixupKind(TSFlags),
CurByte, OS, Fixups);
EmitImmediate(MI.getOperand(CurOp++), 2, FK_Data_2, CurByte, OS, Fixups);
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);
SrcRegNum = CurOp + X86::AddrNumOperands;
if (HasVEX_4V) // Skip 1st src (which is encoded in VEX_VVVV)
SrcRegNum++;
EmitMemModRMByte(MI, CurOp,
GetX86RegNum(MI.getOperand(SrcRegNum)),
TSFlags, CurByte, OS, Fixups);
CurOp = SrcRegNum + 1;
break;
case X86II::MRMSrcReg:
EmitByte(BaseOpcode, CurByte, OS);
SrcRegNum = CurOp + 1;
if (HasVEX_4V) // Skip 1st src (which is encoded in VEX_VVVV)
SrcRegNum++;
EmitRegModRMByte(MI.getOperand(SrcRegNum),
GetX86RegNum(MI.getOperand(CurOp)), CurByte, OS);
CurOp = SrcRegNum + 1;
break;
case X86II::MRMSrcMem: {
int AddrOperands = X86::AddrNumOperands;
unsigned FirstMemOp = CurOp+1;
if (HasVEX_4V) {
++AddrOperands;
++FirstMemOp; // Skip the register source (which is encoded in VEX_VVVV).
}
EmitByte(BaseOpcode, CurByte, OS);
EmitMemModRMByte(MI, FirstMemOp, 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:
if (HasVEX_4V) // Skip the register dst (which is encoded in VEX_VVVV).
CurOp++;
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 += X86::AddrNumOperands;
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;
case X86II::MRM_D0:
EmitByte(BaseOpcode, CurByte, OS);
EmitByte(0xD0, CurByte, OS);
break;
case X86II::MRM_D1:
EmitByte(BaseOpcode, CurByte, OS);
EmitByte(0xD1, CurByte, OS);
break;
}
// If there is a remaining operand, it must be a trailing immediate. Emit it
// according to the right size for the instruction.
if (CurOp != NumOps) {
// The last source register of a 4 operand instruction in AVX is encoded
// in bits[7:4] of a immediate byte, and bits[3:0] are ignored.
if ((TSFlags >> X86II::VEXShift) & X86II::VEX_I8IMM) {
const MCOperand &MO = MI.getOperand(CurOp++);
bool IsExtReg = X86II::isX86_64ExtendedReg(MO.getReg());
unsigned RegNum = (IsExtReg ? (1 << 7) : 0);
RegNum |= GetX86RegNum(MO) << 4;
EmitImmediate(MCOperand::CreateImm(RegNum), 1, FK_Data_1, CurByte, OS,
Fixups);
} else {
unsigned FixupKind;
// FIXME: Is there a better way to know that we need a signed relocation?
if (MI.getOpcode() == X86::ADD64ri32 ||
MI.getOpcode() == X86::MOV64ri32 ||
MI.getOpcode() == X86::MOV64mi32 ||
MI.getOpcode() == X86::PUSH64i32)
FixupKind = X86::reloc_signed_4byte;
else
FixupKind = getImmFixupKind(TSFlags);
EmitImmediate(MI.getOperand(CurOp++),
X86II::getSizeOfImm(TSFlags), MCFixupKind(FixupKind),
CurByte, OS, Fixups);
}
}
if ((TSFlags >> X86II::VEXShift) & X86II::Has3DNow0F0FOpcode)
EmitByte(X86II::getBaseOpcodeFor(TSFlags), CurByte, OS);
#ifndef NDEBUG
// FIXME: Verify.
if (/*!Desc.isVariadic() &&*/ CurOp != NumOps) {
errs() << "Cannot encode all operands of: ";
MI.dump();
errs() << '\n';
abort();
}
#endif
}