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llvm-mirror/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp
Harald van Dijk 9e8b1c8ad9 [X32] Add Triple::isX32(), use it. 
So far, support for x86_64-linux-gnux32 has been handled by explicit
comparisons of Triple.getEnvironment() to GNUX32. This worked as long as
x86_64-linux-gnux32 was the only X32 environment to worry about, but we
now have x86_64-linux-muslx32 as well. To support this, this change adds
an isX32() function and uses it. It replaces all checks for GNUX32 or
MuslX32 by isX32(), except for the following:

- Triple::isGNUEnvironment() and Triple::isMusl() are supposed to treat
  GNUX32 and MuslX32 differently.
- computeTargetTriple() needs to be able to transform triples to add or
  remove X32 from the environment and needs to map GNU to GNUX32, and
  Musl to MuslX32.
- getMultiarchTriple() completely lacks any Musl support and retains the
  explicit check for GNUX32 as it can only return x86_64-linux-gnux32.

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D103777
2021-06-07 20:48:39 +01:00

1840 lines
62 KiB
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//===-- X86MCCodeEmitter.cpp - Convert X86 code to machine code -----------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements the X86MCCodeEmitter class.
//
//===----------------------------------------------------------------------===//
#include "MCTargetDesc/X86BaseInfo.h"
#include "MCTargetDesc/X86FixupKinds.h"
#include "MCTargetDesc/X86MCTargetDesc.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/MC/MCCodeEmitter.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCFixup.h"
#include "llvm/MC/MCInst.h"
#include "llvm/MC/MCInstrDesc.h"
#include "llvm/MC/MCInstrInfo.h"
#include "llvm/MC/MCRegisterInfo.h"
#include "llvm/MC/MCSubtargetInfo.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include <cassert>
#include <cstdint>
#include <cstdlib>
using namespace llvm;
#define DEBUG_TYPE "mccodeemitter"
namespace {
class X86MCCodeEmitter : public MCCodeEmitter {
const MCInstrInfo &MCII;
MCContext &Ctx;
public:
X86MCCodeEmitter(const MCInstrInfo &mcii, MCContext &ctx)
: MCII(mcii), Ctx(ctx) {}
X86MCCodeEmitter(const X86MCCodeEmitter &) = delete;
X86MCCodeEmitter &operator=(const X86MCCodeEmitter &) = delete;
~X86MCCodeEmitter() override = default;
void emitPrefix(const MCInst &MI, raw_ostream &OS,
const MCSubtargetInfo &STI) const override;
void encodeInstruction(const MCInst &MI, raw_ostream &OS,
SmallVectorImpl<MCFixup> &Fixups,
const MCSubtargetInfo &STI) const override;
private:
unsigned getX86RegNum(const MCOperand &MO) const;
unsigned getX86RegEncoding(const MCInst &MI, unsigned OpNum) const;
/// \param MI a single low-level machine instruction.
/// \param OpNum the operand #.
/// \returns true if the OpNumth operand of MI require a bit to be set in
/// REX prefix.
bool isREXExtendedReg(const MCInst &MI, unsigned OpNum) const;
void emitImmediate(const MCOperand &Disp, SMLoc Loc, unsigned ImmSize,
MCFixupKind FixupKind, uint64_t StartByte, raw_ostream &OS,
SmallVectorImpl<MCFixup> &Fixups, int ImmOffset = 0) const;
void emitRegModRMByte(const MCOperand &ModRMReg, unsigned RegOpcodeFld,
raw_ostream &OS) const;
void emitSIBByte(unsigned SS, unsigned Index, unsigned Base,
raw_ostream &OS) const;
void emitMemModRMByte(const MCInst &MI, unsigned Op, unsigned RegOpcodeField,
uint64_t TSFlags, bool HasREX, uint64_t StartByte,
raw_ostream &OS, SmallVectorImpl<MCFixup> &Fixups,
const MCSubtargetInfo &STI,
bool ForceSIB = false) const;
bool emitPrefixImpl(unsigned &CurOp, const MCInst &MI,
const MCSubtargetInfo &STI, raw_ostream &OS) const;
void emitVEXOpcodePrefix(int MemOperand, const MCInst &MI,
raw_ostream &OS) const;
void emitSegmentOverridePrefix(unsigned SegOperand, const MCInst &MI,
raw_ostream &OS) const;
bool emitOpcodePrefix(int MemOperand, const MCInst &MI,
const MCSubtargetInfo &STI, raw_ostream &OS) const;
bool emitREXPrefix(int MemOperand, const MCInst &MI,
const MCSubtargetInfo &STI, raw_ostream &OS) const;
};
} // end anonymous namespace
static uint8_t 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);
}
static void emitByte(uint8_t C, raw_ostream &OS) { OS << static_cast<char>(C); }
static void emitConstant(uint64_t Val, unsigned Size, raw_ostream &OS) {
// Output the constant in little endian byte order.
for (unsigned i = 0; i != Size; ++i) {
emitByte(Val & 255, OS);
Val >>= 8;
}
}
/// Determine if this immediate can fit in a disp8 or a compressed disp8 for
/// EVEX instructions. \p will be set to the value to pass to the ImmOffset
/// parameter of emitImmediate.
static bool isDispOrCDisp8(uint64_t TSFlags, int Value, int &ImmOffset) {
bool HasEVEX = (TSFlags & X86II::EncodingMask) == X86II::EVEX;
int CD8_Scale =
(TSFlags & X86II::CD8_Scale_Mask) >> X86II::CD8_Scale_Shift;
if (!HasEVEX || CD8_Scale == 0)
return isInt<8>(Value);
assert(isPowerOf2_32(CD8_Scale) && "Unexpected CD8 scale!");
if (Value & (CD8_Scale - 1)) // Unaligned offset
return false;
int CDisp8 = Value / CD8_Scale;
if (!isInt<8>(CDisp8))
return false;
// ImmOffset will be added to Value in emitImmediate leaving just CDisp8.
ImmOffset = CDisp8 - Value;
return true;
}
/// \returns 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);
if (X86II::isImmSigned(TSFlags)) {
switch (Size) {
default:
llvm_unreachable("Unsupported signed fixup size!");
case 4:
return MCFixupKind(X86::reloc_signed_4byte);
}
}
return MCFixup::getKindForSize(Size, isPCRel);
}
/// \param Op operand # of the memory operand.
///
/// \returns true if the specified instruction has a 16-bit memory operand.
static bool is16BitMemOperand(const MCInst &MI, unsigned Op,
const MCSubtargetInfo &STI) {
const MCOperand &Base = MI.getOperand(Op + X86::AddrBaseReg);
const MCOperand &Index = MI.getOperand(Op + X86::AddrIndexReg);
unsigned BaseReg = Base.getReg();
unsigned IndexReg = Index.getReg();
if (STI.hasFeature(X86::Mode16Bit) && BaseReg == 0 && IndexReg == 0)
return true;
if ((BaseReg != 0 &&
X86MCRegisterClasses[X86::GR16RegClassID].contains(BaseReg)) ||
(IndexReg != 0 &&
X86MCRegisterClasses[X86::GR16RegClassID].contains(IndexReg)))
return true;
return false;
}
/// \param Op operand # of the memory operand.
///
/// \returns true if the specified instruction has a 32-bit memory operand.
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;
if (BaseReg.getReg() == X86::EIP) {
assert(IndexReg.getReg() == 0 && "Invalid eip-based address.");
return true;
}
if (IndexReg.getReg() == X86::EIZ)
return true;
return false;
}
/// \param Op operand # of the memory operand.
///
/// \returns true if the specified instruction has a 64-bit memory operand.
#ifndef NDEBUG
static bool is64BitMemOperand(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::GR64RegClassID].contains(BaseReg.getReg())) ||
(IndexReg.getReg() != 0 &&
X86MCRegisterClasses[X86::GR64RegClassID].contains(IndexReg.getReg())))
return true;
return false;
}
#endif
enum GlobalOffsetTableExprKind { GOT_None, GOT_Normal, GOT_SymDiff };
/// Check if this expression starts with _GLOBAL_OFFSET_TABLE_ and if it is
/// of the form _GLOBAL_OFFSET_TABLE_-symbol. This is needed to support PIC on
/// ELF i386 as _GLOBAL_OFFSET_TABLE_ is magical. 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 GlobalOffsetTableExprKind
startsWithGlobalOffsetTable(const MCExpr *Expr) {
const MCExpr *RHS = nullptr;
if (Expr->getKind() == MCExpr::Binary) {
const MCBinaryExpr *BE = static_cast<const MCBinaryExpr *>(Expr);
Expr = BE->getLHS();
RHS = BE->getRHS();
}
if (Expr->getKind() != MCExpr::SymbolRef)
return GOT_None;
const MCSymbolRefExpr *Ref = static_cast<const MCSymbolRefExpr *>(Expr);
const MCSymbol &S = Ref->getSymbol();
if (S.getName() != "_GLOBAL_OFFSET_TABLE_")
return GOT_None;
if (RHS && RHS->getKind() == MCExpr::SymbolRef)
return GOT_SymDiff;
return GOT_Normal;
}
static bool hasSecRelSymbolRef(const MCExpr *Expr) {
if (Expr->getKind() == MCExpr::SymbolRef) {
const MCSymbolRefExpr *Ref = static_cast<const MCSymbolRefExpr *>(Expr);
return Ref->getKind() == MCSymbolRefExpr::VK_SECREL;
}
return false;
}
static bool isPCRel32Branch(const MCInst &MI, const MCInstrInfo &MCII) {
unsigned Opcode = MI.getOpcode();
const MCInstrDesc &Desc = MCII.get(Opcode);
if ((Opcode != X86::CALL64pcrel32 && Opcode != X86::JMP_4 &&
Opcode != X86::JCC_4) ||
getImmFixupKind(Desc.TSFlags) != FK_PCRel_4)
return false;
unsigned CurOp = X86II::getOperandBias(Desc);
const MCOperand &Op = MI.getOperand(CurOp);
if (!Op.isExpr())
return false;
const MCSymbolRefExpr *Ref = dyn_cast<MCSymbolRefExpr>(Op.getExpr());
return Ref && Ref->getKind() == MCSymbolRefExpr::VK_None;
}
unsigned X86MCCodeEmitter::getX86RegNum(const MCOperand &MO) const {
return Ctx.getRegisterInfo()->getEncodingValue(MO.getReg()) & 0x7;
}
unsigned X86MCCodeEmitter::getX86RegEncoding(const MCInst &MI,
unsigned OpNum) const {
return Ctx.getRegisterInfo()->getEncodingValue(MI.getOperand(OpNum).getReg());
}
/// \param MI a single low-level machine instruction.
/// \param OpNum the operand #.
/// \returns true if the OpNumth operand of MI require a bit to be set in
/// REX prefix.
bool X86MCCodeEmitter::isREXExtendedReg(const MCInst &MI,
unsigned OpNum) const {
return (getX86RegEncoding(MI, OpNum) >> 3) & 1;
}
void X86MCCodeEmitter::emitImmediate(const MCOperand &DispOp, SMLoc Loc,
unsigned Size, MCFixupKind FixupKind,
uint64_t StartByte, raw_ostream &OS,
SmallVectorImpl<MCFixup> &Fixups,
int ImmOffset) const {
const MCExpr *Expr = nullptr;
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, 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 == FK_Data_8 ||
FixupKind == MCFixupKind(X86::reloc_signed_4byte))) {
GlobalOffsetTableExprKind Kind = startsWithGlobalOffsetTable(Expr);
if (Kind != GOT_None) {
assert(ImmOffset == 0);
if (Size == 8) {
FixupKind = MCFixupKind(X86::reloc_global_offset_table8);
} else {
assert(Size == 4);
FixupKind = MCFixupKind(X86::reloc_global_offset_table);
}
if (Kind == GOT_Normal)
ImmOffset = static_cast<int>(OS.tell() - StartByte);
} else if (Expr->getKind() == MCExpr::SymbolRef) {
if (hasSecRelSymbolRef(Expr)) {
FixupKind = MCFixupKind(FK_SecRel_4);
}
} else if (Expr->getKind() == MCExpr::Binary) {
const MCBinaryExpr *Bin = static_cast<const MCBinaryExpr *>(Expr);
if (hasSecRelSymbolRef(Bin->getLHS()) ||
hasSecRelSymbolRef(Bin->getRHS())) {
FixupKind = MCFixupKind(FK_SecRel_4);
}
}
}
// 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) ||
FixupKind == MCFixupKind(X86::reloc_riprel_4byte_relax) ||
FixupKind == MCFixupKind(X86::reloc_riprel_4byte_relax_rex) ||
FixupKind == MCFixupKind(X86::reloc_branch_4byte_pcrel)) {
ImmOffset -= 4;
// If this is a pc-relative load off _GLOBAL_OFFSET_TABLE_:
// leaq _GLOBAL_OFFSET_TABLE_(%rip), %r15
// this needs to be a GOTPC32 relocation.
if (startsWithGlobalOffsetTable(Expr) != GOT_None)
FixupKind = MCFixupKind(X86::reloc_global_offset_table);
}
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(static_cast<uint32_t>(OS.tell() - StartByte),
Expr, FixupKind, Loc));
emitConstant(0, Size, OS);
}
void X86MCCodeEmitter::emitRegModRMByte(const MCOperand &ModRMReg,
unsigned RegOpcodeFld,
raw_ostream &OS) const {
emitByte(modRMByte(3, RegOpcodeFld, getX86RegNum(ModRMReg)), OS);
}
void X86MCCodeEmitter::emitSIBByte(unsigned SS, unsigned Index, unsigned Base,
raw_ostream &OS) const {
// SIB byte is in the same format as the modRMByte.
emitByte(modRMByte(SS, Index, Base), OS);
}
void X86MCCodeEmitter::emitMemModRMByte(const MCInst &MI, unsigned Op,
unsigned RegOpcodeField,
uint64_t TSFlags, bool HasREX,
uint64_t StartByte, raw_ostream &OS,
SmallVectorImpl<MCFixup> &Fixups,
const MCSubtargetInfo &STI,
bool ForceSIB) 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 ||
BaseReg == X86::EIP) { // [disp32+rIP] in X86-64 mode
assert(STI.hasFeature(X86::Mode64Bit) &&
"Rip-relative addressing requires 64-bit mode");
assert(IndexReg.getReg() == 0 && !ForceSIB &&
"Invalid rip-relative address");
emitByte(modRMByte(0, RegOpcodeField, 5), OS);
unsigned Opcode = MI.getOpcode();
unsigned FixupKind = [&]() {
// Enable relaxed relocation only for a MCSymbolRefExpr. We cannot use a
// relaxed relocation if an offset is present (e.g. x@GOTPCREL+4).
if (!(Disp.isExpr() && isa<MCSymbolRefExpr>(Disp.getExpr())))
return X86::reloc_riprel_4byte;
// Certain loads for GOT references can be relocated against the symbol
// directly if the symbol ends up in the same linkage unit.
switch (Opcode) {
default:
return X86::reloc_riprel_4byte;
case X86::MOV64rm:
// movq loads is a subset of reloc_riprel_4byte_relax_rex. It is a
// special case because COFF and Mach-O don't support ELF's more
// flexible R_X86_64_REX_GOTPCRELX relaxation.
assert(HasREX);
return X86::reloc_riprel_4byte_movq_load;
case X86::ADC32rm:
case X86::ADD32rm:
case X86::AND32rm:
case X86::CMP32rm:
case X86::MOV32rm:
case X86::OR32rm:
case X86::SBB32rm:
case X86::SUB32rm:
case X86::TEST32mr:
case X86::XOR32rm:
case X86::CALL64m:
case X86::JMP64m:
case X86::TAILJMPm64:
case X86::TEST64mr:
case X86::ADC64rm:
case X86::ADD64rm:
case X86::AND64rm:
case X86::CMP64rm:
case X86::OR64rm:
case X86::SBB64rm:
case X86::SUB64rm:
case X86::XOR64rm:
return HasREX ? X86::reloc_riprel_4byte_relax_rex
: X86::reloc_riprel_4byte_relax;
}
}();
// 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 displacement field of the instruction with
// the size of the immediate field. If we have this case, add it into the
// expression to emit.
// Note: rip-relative addressing using immediate displacement values should
// not be adjusted, assuming it was the user's intent.
int ImmSize = !Disp.isImm() && X86II::hasImm(TSFlags)
? X86II::getSizeOfImm(TSFlags)
: 0;
emitImmediate(Disp, MI.getLoc(), 4, MCFixupKind(FixupKind), StartByte, OS,
Fixups, -ImmSize);
return;
}
unsigned BaseRegNo = BaseReg ? getX86RegNum(Base) : -1U;
// 16-bit addressing forms of the ModR/M byte have a different encoding for
// the R/M field and are far more limited in which registers can be used.
if (is16BitMemOperand(MI, Op, STI)) {
if (BaseReg) {
// For 32-bit addressing, the row and column values in Table 2-2 are
// basically the same. It's AX/CX/DX/BX/SP/BP/SI/DI in that order, with
// some special cases. And getX86RegNum reflects that numbering.
// For 16-bit addressing it's more fun, as shown in the SDM Vol 2A,
// Table 2-1 "16-Bit Addressing Forms with the ModR/M byte". We can only
// use SI/DI/BP/BX, which have "row" values 4-7 in no particular order,
// while values 0-3 indicate the allowed combinations (base+index) of
// those: 0 for BX+SI, 1 for BX+DI, 2 for BP+SI, 3 for BP+DI.
//
// R16Table[] is a lookup from the normal RegNo, to the row values from
// Table 2-1 for 16-bit addressing modes. Where zero means disallowed.
static const unsigned R16Table[] = {0, 0, 0, 7, 0, 6, 4, 5};
unsigned RMfield = R16Table[BaseRegNo];
assert(RMfield && "invalid 16-bit base register");
if (IndexReg.getReg()) {
unsigned IndexReg16 = R16Table[getX86RegNum(IndexReg)];
assert(IndexReg16 && "invalid 16-bit index register");
// We must have one of SI/DI (4,5), and one of BP/BX (6,7).
assert(((IndexReg16 ^ RMfield) & 2) &&
"invalid 16-bit base/index register combination");
assert(Scale.getImm() == 1 &&
"invalid scale for 16-bit memory reference");
// Allow base/index to appear in either order (although GAS doesn't).
if (IndexReg16 & 2)
RMfield = (RMfield & 1) | ((7 - IndexReg16) << 1);
else
RMfield = (IndexReg16 & 1) | ((7 - RMfield) << 1);
}
if (Disp.isImm() && isInt<8>(Disp.getImm())) {
if (Disp.getImm() == 0 && RMfield != 6) {
// There is no displacement; just the register.
emitByte(modRMByte(0, RegOpcodeField, RMfield), OS);
return;
}
// Use the [REG]+disp8 form, including for [BP] which cannot be encoded.
emitByte(modRMByte(1, RegOpcodeField, RMfield), OS);
emitImmediate(Disp, MI.getLoc(), 1, FK_Data_1, StartByte, OS, Fixups);
return;
}
// This is the [REG]+disp16 case.
emitByte(modRMByte(2, RegOpcodeField, RMfield), OS);
} else {
assert(IndexReg.getReg() == 0 && "Unexpected index register!");
// There is no BaseReg; this is the plain [disp16] case.
emitByte(modRMByte(0, RegOpcodeField, 6), OS);
}
// Emit 16-bit displacement for plain disp16 or [REG]+disp16 cases.
emitImmediate(Disp, MI.getLoc(), 2, FK_Data_2, StartByte, OS, Fixups);
return;
}
// Check for presence of {disp8} or {disp32} pseudo prefixes.
bool UseDisp8 = MI.getFlags() & X86::IP_USE_DISP8;
bool UseDisp32 = MI.getFlags() & X86::IP_USE_DISP32;
// We only allow no displacement if no pseudo prefix is present.
bool AllowNoDisp = !UseDisp8 && !UseDisp32;
// Disp8 is allowed unless the {disp32} prefix is present.
bool AllowDisp8 = !UseDisp32;
// Determine whether a SIB byte is needed.
if (// The SIB byte must be used if there is an index register or the
// encoding requires a SIB byte.
!ForceSIB && 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).
(!STI.hasFeature(X86::Mode64Bit) || BaseReg != 0)) {
if (BaseReg == 0) { // [disp32] in X86-32 mode
emitByte(modRMByte(0, RegOpcodeField, 5), OS);
emitImmediate(Disp, MI.getLoc(), 4, FK_Data_4, StartByte, OS, Fixups);
return;
}
// If the base is not EBP/ESP/R12/R13 and there is no displacement, use
// simple indirect register encoding, this handles addresses like [EAX].
// The encoding for [EBP] or[R13] with no displacement means [disp32] so we
// handle it by emitting a displacement of 0 later.
if (BaseRegNo != N86::EBP) {
if (Disp.isImm() && Disp.getImm() == 0 && AllowNoDisp) {
emitByte(modRMByte(0, RegOpcodeField, BaseRegNo), OS);
return;
}
// If the displacement is @tlscall, treat it as a zero.
if (Disp.isExpr()) {
auto *Sym = dyn_cast<MCSymbolRefExpr>(Disp.getExpr());
if (Sym && Sym->getKind() == MCSymbolRefExpr::VK_TLSCALL) {
// This is exclusively used by call *a@tlscall(base). The relocation
// (R_386_TLSCALL or R_X86_64_TLSCALL) applies to the beginning.
Fixups.push_back(MCFixup::create(0, Sym, FK_NONE, MI.getLoc()));
emitByte(modRMByte(0, RegOpcodeField, BaseRegNo), OS);
return;
}
}
}
// Otherwise, if the displacement fits in a byte, encode as [REG+disp8].
// Including a compressed disp8 for EVEX instructions that support it.
// This also handles the 0 displacement for [EBP] or [R13]. We can't use
// disp8 if the {disp32} pseudo prefix is present.
if (Disp.isImm() && AllowDisp8) {
int ImmOffset = 0;
if (isDispOrCDisp8(TSFlags, Disp.getImm(), ImmOffset)) {
emitByte(modRMByte(1, RegOpcodeField, BaseRegNo), OS);
emitImmediate(Disp, MI.getLoc(), 1, FK_Data_1, StartByte, OS, Fixups,
ImmOffset);
return;
}
}
// Otherwise, emit the most general non-SIB encoding: [REG+disp32].
// Displacement may be 0 for [EBP] or [R13] case if {disp32} pseudo prefix
// prevented using disp8 above.
emitByte(modRMByte(2, RegOpcodeField, BaseRegNo), OS);
unsigned Opcode = MI.getOpcode();
unsigned FixupKind = Opcode == X86::MOV32rm ? X86::reloc_signed_4byte_relax
: X86::reloc_signed_4byte;
emitImmediate(Disp, MI.getLoc(), 4, MCFixupKind(FixupKind), StartByte, 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;
int ImmOffset = 0;
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.
BaseRegNo = 5;
emitByte(modRMByte(0, RegOpcodeField, 4), OS);
ForceDisp32 = true;
} else if (Disp.isImm() && Disp.getImm() == 0 && AllowNoDisp &&
// Base reg can't be EBP/RBP/R13 as that would end up with '5' as
// the base field, but that is the magic [*] nomenclature that
// indicates no base when mod=0. For these cases we'll emit a 0
// displacement instead.
BaseRegNo != N86::EBP) {
// Emit no displacement ModR/M byte
emitByte(modRMByte(0, RegOpcodeField, 4), OS);
} else if (Disp.isImm() && AllowDisp8 &&
isDispOrCDisp8(TSFlags, Disp.getImm(), ImmOffset)) {
// Displacement fits in a byte or matches an EVEX compressed disp8, use
// disp8 encoding. This also handles EBP/R13 base with 0 displacement unless
// {disp32} pseudo prefix was used.
emitByte(modRMByte(1, RegOpcodeField, 4), OS);
ForceDisp8 = true;
} else {
// Otherwise, emit the normal disp32 encoding.
emitByte(modRMByte(2, RegOpcodeField, 4), OS);
ForceDisp32 = true;
}
// 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()];
unsigned IndexRegNo = IndexReg.getReg() ? getX86RegNum(IndexReg) : 4;
emitSIBByte(SS, IndexRegNo, BaseRegNo, OS);
// Do we need to output a displacement?
if (ForceDisp8)
emitImmediate(Disp, MI.getLoc(), 1, FK_Data_1, StartByte, OS, Fixups,
ImmOffset);
else if (ForceDisp32)
emitImmediate(Disp, MI.getLoc(), 4, MCFixupKind(X86::reloc_signed_4byte),
StartByte, OS, Fixups);
}
/// Emit all instruction prefixes.
///
/// \returns true if REX prefix is used, otherwise returns false.
bool X86MCCodeEmitter::emitPrefixImpl(unsigned &CurOp, const MCInst &MI,
const MCSubtargetInfo &STI,
raw_ostream &OS) const {
uint64_t TSFlags = MCII.get(MI.getOpcode()).TSFlags;
// Determine where the memory operand starts, if present.
int MemoryOperand = X86II::getMemoryOperandNo(TSFlags);
// Emit segment override opcode prefix as needed.
if (MemoryOperand != -1) {
MemoryOperand += CurOp;
emitSegmentOverridePrefix(MemoryOperand + X86::AddrSegmentReg, MI, OS);
}
// Emit the repeat opcode prefix as needed.
unsigned Flags = MI.getFlags();
if (TSFlags & X86II::REP || Flags & X86::IP_HAS_REPEAT)
emitByte(0xF3, OS);
if (Flags & X86::IP_HAS_REPEAT_NE)
emitByte(0xF2, OS);
// Emit the address size opcode prefix as needed.
bool NeedAddressOverride;
uint64_t AdSize = TSFlags & X86II::AdSizeMask;
if ((STI.hasFeature(X86::Mode16Bit) && AdSize == X86II::AdSize32) ||
(STI.hasFeature(X86::Mode32Bit) && AdSize == X86II::AdSize16) ||
(STI.hasFeature(X86::Mode64Bit) && AdSize == X86II::AdSize32)) {
NeedAddressOverride = true;
} else if (MemoryOperand < 0) {
NeedAddressOverride = false;
} else if (STI.hasFeature(X86::Mode64Bit)) {
assert(!is16BitMemOperand(MI, MemoryOperand, STI));
NeedAddressOverride = is32BitMemOperand(MI, MemoryOperand);
} else if (STI.hasFeature(X86::Mode32Bit)) {
assert(!is64BitMemOperand(MI, MemoryOperand));
NeedAddressOverride = is16BitMemOperand(MI, MemoryOperand, STI);
} else {
assert(STI.hasFeature(X86::Mode16Bit));
assert(!is64BitMemOperand(MI, MemoryOperand));
NeedAddressOverride = !is16BitMemOperand(MI, MemoryOperand, STI);
}
if (NeedAddressOverride)
emitByte(0x67, OS);
// Encoding type for this instruction.
uint64_t Encoding = TSFlags & X86II::EncodingMask;
bool HasREX = false;
if (Encoding)
emitVEXOpcodePrefix(MemoryOperand, MI, OS);
else
HasREX = emitOpcodePrefix(MemoryOperand, MI, STI, OS);
uint64_t Form = TSFlags & X86II::FormMask;
switch (Form) {
default:
break;
case X86II::RawFrmDstSrc: {
unsigned siReg = MI.getOperand(1).getReg();
assert(((siReg == X86::SI && MI.getOperand(0).getReg() == X86::DI) ||
(siReg == X86::ESI && MI.getOperand(0).getReg() == X86::EDI) ||
(siReg == X86::RSI && MI.getOperand(0).getReg() == X86::RDI)) &&
"SI and DI register sizes do not match");
// Emit segment override opcode prefix as needed (not for %ds).
if (MI.getOperand(2).getReg() != X86::DS)
emitSegmentOverridePrefix(2, MI, OS);
// Emit AdSize prefix as needed.
if ((!STI.hasFeature(X86::Mode32Bit) && siReg == X86::ESI) ||
(STI.hasFeature(X86::Mode32Bit) && siReg == X86::SI))
emitByte(0x67, OS);
CurOp += 3; // Consume operands.
break;
}
case X86II::RawFrmSrc: {
unsigned siReg = MI.getOperand(0).getReg();
// Emit segment override opcode prefix as needed (not for %ds).
if (MI.getOperand(1).getReg() != X86::DS)
emitSegmentOverridePrefix(1, MI, OS);
// Emit AdSize prefix as needed.
if ((!STI.hasFeature(X86::Mode32Bit) && siReg == X86::ESI) ||
(STI.hasFeature(X86::Mode32Bit) && siReg == X86::SI))
emitByte(0x67, OS);
CurOp += 2; // Consume operands.
break;
}
case X86II::RawFrmDst: {
unsigned siReg = MI.getOperand(0).getReg();
// Emit AdSize prefix as needed.
if ((!STI.hasFeature(X86::Mode32Bit) && siReg == X86::EDI) ||
(STI.hasFeature(X86::Mode32Bit) && siReg == X86::DI))
emitByte(0x67, OS);
++CurOp; // Consume operand.
break;
}
case X86II::RawFrmMemOffs: {
// Emit segment override opcode prefix as needed.
emitSegmentOverridePrefix(1, MI, OS);
break;
}
}
return HasREX;
}
/// AVX instructions are encoded using a opcode prefix called VEX.
void X86MCCodeEmitter::emitVEXOpcodePrefix(int MemOperand, const MCInst &MI,
raw_ostream &OS) const {
const MCInstrDesc &Desc = MCII.get(MI.getOpcode());
uint64_t TSFlags = Desc.TSFlags;
assert(!(TSFlags & X86II::LOCK) && "Can't have LOCK VEX.");
uint64_t Encoding = TSFlags & X86II::EncodingMask;
bool HasEVEX_K = TSFlags & X86II::EVEX_K;
bool HasVEX_4V = TSFlags & X86II::VEX_4V;
bool HasEVEX_RC = TSFlags & X86II::EVEX_RC;
// 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)
//
uint8_t VEX_R = 0x1;
uint8_t EVEX_R2 = 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)
uint8_t 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)
//
uint8_t VEX_B = 0x1;
// VEX_W: opcode specific (use like REX.W, or used for
// opcode extension, or ignored, depending on the opcode byte)
uint8_t VEX_W = (TSFlags & X86II::VEX_W) ? 1 : 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
// 0b01000: XOP map select - 08h instructions with imm byte
// 0b01001: XOP map select - 09h instructions with no imm byte
// 0b01010: XOP map select - 0Ah instructions with imm dword
uint8_t VEX_5M;
switch (TSFlags & X86II::OpMapMask) {
default:
llvm_unreachable("Invalid prefix!");
case X86II::TB:
VEX_5M = 0x1;
break; // 0F
case X86II::T8:
VEX_5M = 0x2;
break; // 0F 38
case X86II::TA:
VEX_5M = 0x3;
break; // 0F 3A
case X86II::XOP8:
VEX_5M = 0x8;
break;
case X86II::XOP9:
VEX_5M = 0x9;
break;
case X86II::XOPA:
VEX_5M = 0xA;
break;
}
// VEX_4V (VEX vvvv field): a register specifier
// (in 1's complement form) or 1111 if unused.
uint8_t VEX_4V = 0xf;
uint8_t EVEX_V2 = 0x1;
// EVEX_L2/VEX_L (Vector Length):
//
// L2 L
// 0 0: scalar or 128-bit vector
// 0 1: 256-bit vector
// 1 0: 512-bit vector
//
uint8_t VEX_L = (TSFlags & X86II::VEX_L) ? 1 : 0;
uint8_t EVEX_L2 = (TSFlags & X86II::EVEX_L2) ? 1 : 0;
// VEX_PP: opcode extension providing equivalent
// functionality of a SIMD prefix
//
// 0b00: None
// 0b01: 66
// 0b10: F3
// 0b11: F2
//
uint8_t VEX_PP = 0;
switch (TSFlags & X86II::OpPrefixMask) {
case X86II::PD:
VEX_PP = 0x1;
break; // 66
case X86II::XS:
VEX_PP = 0x2;
break; // F3
case X86II::XD:
VEX_PP = 0x3;
break; // F2
}
// EVEX_U
uint8_t EVEX_U = 1; // Always '1' so far
// EVEX_z
uint8_t EVEX_z = (HasEVEX_K && (TSFlags & X86II::EVEX_Z)) ? 1 : 0;
// EVEX_b
uint8_t EVEX_b = (TSFlags & X86II::EVEX_B) ? 1 : 0;
// EVEX_rc
uint8_t EVEX_rc = 0;
// EVEX_aaa
uint8_t EVEX_aaa = 0;
bool EncodeRC = false;
// Classify VEX_B, VEX_4V, VEX_R, VEX_X
unsigned NumOps = Desc.getNumOperands();
unsigned CurOp = X86II::getOperandBias(Desc);
switch (TSFlags & X86II::FormMask) {
default:
llvm_unreachable("Unexpected form in emitVEXOpcodePrefix!");
case X86II::MRM_C0:
case X86II::RawFrm:
case X86II::PrefixByte:
break;
case X86II::MRMDestMemFSIB:
case X86II::MRMDestMem: {
// MRMDestMem instructions forms:
// MemAddr, src1(ModR/M)
// MemAddr, src1(VEX_4V), src2(ModR/M)
// MemAddr, src1(ModR/M), imm8
//
unsigned BaseRegEnc = getX86RegEncoding(MI, MemOperand + X86::AddrBaseReg);
VEX_B = ~(BaseRegEnc >> 3) & 1;
unsigned IndexRegEnc =
getX86RegEncoding(MI, MemOperand + X86::AddrIndexReg);
VEX_X = ~(IndexRegEnc >> 3) & 1;
if (!HasVEX_4V) // Only needed with VSIB which don't use VVVV.
EVEX_V2 = ~(IndexRegEnc >> 4) & 1;
CurOp += X86::AddrNumOperands;
if (HasEVEX_K)
EVEX_aaa = getX86RegEncoding(MI, CurOp++);
if (HasVEX_4V) {
unsigned VRegEnc = getX86RegEncoding(MI, CurOp++);
VEX_4V = ~VRegEnc & 0xf;
EVEX_V2 = ~(VRegEnc >> 4) & 1;
}
unsigned RegEnc = getX86RegEncoding(MI, CurOp++);
VEX_R = ~(RegEnc >> 3) & 1;
EVEX_R2 = ~(RegEnc >> 4) & 1;
break;
}
case X86II::MRMSrcMemFSIB:
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(Imm[7:4])
//
// FMA4:
// dst(ModR/M.reg), src1(VEX_4V), src2(ModR/M), src3(Imm[7:4])
unsigned RegEnc = getX86RegEncoding(MI, CurOp++);
VEX_R = ~(RegEnc >> 3) & 1;
EVEX_R2 = ~(RegEnc >> 4) & 1;
if (HasEVEX_K)
EVEX_aaa = getX86RegEncoding(MI, CurOp++);
if (HasVEX_4V) {
unsigned VRegEnc = getX86RegEncoding(MI, CurOp++);
VEX_4V = ~VRegEnc & 0xf;
EVEX_V2 = ~(VRegEnc >> 4) & 1;
}
unsigned BaseRegEnc = getX86RegEncoding(MI, MemOperand + X86::AddrBaseReg);
VEX_B = ~(BaseRegEnc >> 3) & 1;
unsigned IndexRegEnc =
getX86RegEncoding(MI, MemOperand + X86::AddrIndexReg);
VEX_X = ~(IndexRegEnc >> 3) & 1;
if (!HasVEX_4V) // Only needed with VSIB which don't use VVVV.
EVEX_V2 = ~(IndexRegEnc >> 4) & 1;
break;
}
case X86II::MRMSrcMem4VOp3: {
// Instruction format for 4VOp3:
// src1(ModR/M), MemAddr, src3(VEX_4V)
unsigned RegEnc = getX86RegEncoding(MI, CurOp++);
VEX_R = ~(RegEnc >> 3) & 1;
unsigned BaseRegEnc = getX86RegEncoding(MI, MemOperand + X86::AddrBaseReg);
VEX_B = ~(BaseRegEnc >> 3) & 1;
unsigned IndexRegEnc =
getX86RegEncoding(MI, MemOperand + X86::AddrIndexReg);
VEX_X = ~(IndexRegEnc >> 3) & 1;
VEX_4V = ~getX86RegEncoding(MI, CurOp + X86::AddrNumOperands) & 0xf;
break;
}
case X86II::MRMSrcMemOp4: {
// dst(ModR/M.reg), src1(VEX_4V), src2(Imm[7:4]), src3(ModR/M),
unsigned RegEnc = getX86RegEncoding(MI, CurOp++);
VEX_R = ~(RegEnc >> 3) & 1;
unsigned VRegEnc = getX86RegEncoding(MI, CurOp++);
VEX_4V = ~VRegEnc & 0xf;
unsigned BaseRegEnc = getX86RegEncoding(MI, MemOperand + X86::AddrBaseReg);
VEX_B = ~(BaseRegEnc >> 3) & 1;
unsigned IndexRegEnc =
getX86RegEncoding(MI, MemOperand + X86::AddrIndexReg);
VEX_X = ~(IndexRegEnc >> 3) & 1;
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
// src1(VEX_4V), MemAddr
if (HasVEX_4V) {
unsigned VRegEnc = getX86RegEncoding(MI, CurOp++);
VEX_4V = ~VRegEnc & 0xf;
EVEX_V2 = ~(VRegEnc >> 4) & 1;
}
if (HasEVEX_K)
EVEX_aaa = getX86RegEncoding(MI, CurOp++);
unsigned BaseRegEnc = getX86RegEncoding(MI, MemOperand + X86::AddrBaseReg);
VEX_B = ~(BaseRegEnc >> 3) & 1;
unsigned IndexRegEnc =
getX86RegEncoding(MI, MemOperand + X86::AddrIndexReg);
VEX_X = ~(IndexRegEnc >> 3) & 1;
if (!HasVEX_4V) // Only needed with VSIB which don't use VVVV.
EVEX_V2 = ~(IndexRegEnc >> 4) & 1;
break;
}
case X86II::MRMSrcReg: {
// MRMSrcReg instructions forms:
// dst(ModR/M), src1(VEX_4V), src2(ModR/M), src3(Imm[7:4])
// dst(ModR/M), src1(ModR/M)
// dst(ModR/M), src1(ModR/M), imm8
//
// FMA4:
// dst(ModR/M.reg), src1(VEX_4V), src2(Imm[7:4]), src3(ModR/M),
unsigned RegEnc = getX86RegEncoding(MI, CurOp++);
VEX_R = ~(RegEnc >> 3) & 1;
EVEX_R2 = ~(RegEnc >> 4) & 1;
if (HasEVEX_K)
EVEX_aaa = getX86RegEncoding(MI, CurOp++);
if (HasVEX_4V) {
unsigned VRegEnc = getX86RegEncoding(MI, CurOp++);
VEX_4V = ~VRegEnc & 0xf;
EVEX_V2 = ~(VRegEnc >> 4) & 1;
}
RegEnc = getX86RegEncoding(MI, CurOp++);
VEX_B = ~(RegEnc >> 3) & 1;
VEX_X = ~(RegEnc >> 4) & 1;
if (EVEX_b) {
if (HasEVEX_RC) {
unsigned RcOperand = NumOps - 1;
assert(RcOperand >= CurOp);
EVEX_rc = MI.getOperand(RcOperand).getImm();
assert(EVEX_rc <= 3 && "Invalid rounding control!");
}
EncodeRC = true;
}
break;
}
case X86II::MRMSrcReg4VOp3: {
// Instruction format for 4VOp3:
// src1(ModR/M), src2(ModR/M), src3(VEX_4V)
unsigned RegEnc = getX86RegEncoding(MI, CurOp++);
VEX_R = ~(RegEnc >> 3) & 1;
RegEnc = getX86RegEncoding(MI, CurOp++);
VEX_B = ~(RegEnc >> 3) & 1;
VEX_4V = ~getX86RegEncoding(MI, CurOp++) & 0xf;
break;
}
case X86II::MRMSrcRegOp4: {
// dst(ModR/M.reg), src1(VEX_4V), src2(Imm[7:4]), src3(ModR/M),
unsigned RegEnc = getX86RegEncoding(MI, CurOp++);
VEX_R = ~(RegEnc >> 3) & 1;
unsigned VRegEnc = getX86RegEncoding(MI, CurOp++);
VEX_4V = ~VRegEnc & 0xf;
// Skip second register source (encoded in Imm[7:4])
++CurOp;
RegEnc = getX86RegEncoding(MI, CurOp++);
VEX_B = ~(RegEnc >> 3) & 1;
VEX_X = ~(RegEnc >> 4) & 1;
break;
}
case X86II::MRMDestReg: {
// MRMDestReg instructions forms:
// dst(ModR/M), src(ModR/M)
// dst(ModR/M), src(ModR/M), imm8
// dst(ModR/M), src1(VEX_4V), src2(ModR/M)
unsigned RegEnc = getX86RegEncoding(MI, CurOp++);
VEX_B = ~(RegEnc >> 3) & 1;
VEX_X = ~(RegEnc >> 4) & 1;
if (HasEVEX_K)
EVEX_aaa = getX86RegEncoding(MI, CurOp++);
if (HasVEX_4V) {
unsigned VRegEnc = getX86RegEncoding(MI, CurOp++);
VEX_4V = ~VRegEnc & 0xf;
EVEX_V2 = ~(VRegEnc >> 4) & 1;
}
RegEnc = getX86RegEncoding(MI, CurOp++);
VEX_R = ~(RegEnc >> 3) & 1;
EVEX_R2 = ~(RegEnc >> 4) & 1;
if (EVEX_b)
EncodeRC = true;
break;
}
case X86II::MRMr0: {
// MRMr0 instructions forms:
// 11:rrr:000
// dst(ModR/M)
unsigned RegEnc = getX86RegEncoding(MI, CurOp++);
VEX_R = ~(RegEnc >> 3) & 1;
EVEX_R2 = ~(RegEnc >> 4) & 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: {
// MRM0r-MRM7r instructions forms:
// dst(VEX_4V), src(ModR/M), imm8
if (HasVEX_4V) {
unsigned VRegEnc = getX86RegEncoding(MI, CurOp++);
VEX_4V = ~VRegEnc & 0xf;
EVEX_V2 = ~(VRegEnc >> 4) & 1;
}
if (HasEVEX_K)
EVEX_aaa = getX86RegEncoding(MI, CurOp++);
unsigned RegEnc = getX86RegEncoding(MI, CurOp++);
VEX_B = ~(RegEnc >> 3) & 1;
VEX_X = ~(RegEnc >> 4) & 1;
break;
}
}
if (Encoding == X86II::VEX || Encoding == X86II::XOP) {
// 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 |
// +-----+ +-------------------+
//
// XOP uses a similar prefix:
// +-----+ +--------------+ +-------------------+
// | 8Fh | | RXB | m-mmmm | | W | vvvv | L | pp |
// +-----+ +--------------+ +-------------------+
uint8_t LastByte = VEX_PP | (VEX_L << 2) | (VEX_4V << 3);
// Can we use the 2 byte VEX prefix?
if (!(MI.getFlags() & X86::IP_USE_VEX3) && Encoding == X86II::VEX &&
VEX_B && VEX_X && !VEX_W && (VEX_5M == 1)) {
emitByte(0xC5, OS);
emitByte(LastByte | (VEX_R << 7), OS);
return;
}
// 3 byte VEX prefix
emitByte(Encoding == X86II::XOP ? 0x8F : 0xC4, OS);
emitByte(VEX_R << 7 | VEX_X << 6 | VEX_B << 5 | VEX_5M, OS);
emitByte(LastByte | (VEX_W << 7), OS);
} else {
assert(Encoding == X86II::EVEX && "unknown encoding!");
// EVEX opcode prefix can have 4 bytes
//
// +-----+ +--------------+ +-------------------+ +------------------------+
// | 62h | | RXBR' | 00mm | | W | vvvv | U | pp | | z | L'L | b | v' | aaa |
// +-----+ +--------------+ +-------------------+ +------------------------+
assert((VEX_5M & 0x3) == VEX_5M &&
"More than 2 significant bits in VEX.m-mmmm fields for EVEX!");
emitByte(0x62, OS);
emitByte((VEX_R << 7) | (VEX_X << 6) | (VEX_B << 5) | (EVEX_R2 << 4) |
VEX_5M,
OS);
emitByte((VEX_W << 7) | (VEX_4V << 3) | (EVEX_U << 2) | VEX_PP, OS);
if (EncodeRC)
emitByte((EVEX_z << 7) | (EVEX_rc << 5) | (EVEX_b << 4) | (EVEX_V2 << 3) |
EVEX_aaa,
OS);
else
emitByte((EVEX_z << 7) | (EVEX_L2 << 6) | (VEX_L << 5) | (EVEX_b << 4) |
(EVEX_V2 << 3) | EVEX_aaa,
OS);
}
}
/// Emit REX prefix which specifies
/// 1) 64-bit instructions,
/// 2) non-default operand size, and
/// 3) use of X86-64 extended registers.
///
/// \returns true if REX prefix is used, otherwise returns false.
bool X86MCCodeEmitter::emitREXPrefix(int MemOperand, const MCInst &MI,
const MCSubtargetInfo &STI,
raw_ostream &OS) const {
uint8_t REX = [&, MemOperand]() {
uint8_t REX = 0;
bool UsesHighByteReg = false;
const MCInstrDesc &Desc = MCII.get(MI.getOpcode());
uint64_t TSFlags = Desc.TSFlags;
if (TSFlags & X86II::REX_W)
REX |= 1 << 3; // set REX.W
if (MI.getNumOperands() == 0)
return REX;
unsigned NumOps = MI.getNumOperands();
unsigned CurOp = X86II::getOperandBias(Desc);
// If it accesses SPL, BPL, SIL, or DIL, then it requires a 0x40 REX prefix.
for (unsigned i = CurOp; i != NumOps; ++i) {
const MCOperand &MO = MI.getOperand(i);
if (MO.isReg()) {
unsigned Reg = MO.getReg();
if (Reg == X86::AH || Reg == X86::BH || Reg == X86::CH ||
Reg == X86::DH)
UsesHighByteReg = true;
if (X86II::isX86_64NonExtLowByteReg(Reg))
// FIXME: The caller of determineREXPrefix slaps this prefix onto
// anything that returns non-zero.
REX |= 0x40; // REX fixed encoding prefix
} else if (MO.isExpr() && STI.getTargetTriple().isX32()) {
// GOTTPOFF and TLSDESC relocations require a REX prefix to allow
// linker optimizations: even if the instructions we see may not require
// any prefix, they may be replaced by instructions that do. This is
// handled as a special case here so that it also works for hand-written
// assembly without the user needing to write REX, as with GNU as.
const auto *Ref = dyn_cast<MCSymbolRefExpr>(MO.getExpr());
if (Ref && (Ref->getKind() == MCSymbolRefExpr::VK_GOTTPOFF ||
Ref->getKind() == MCSymbolRefExpr::VK_TLSDESC)) {
REX |= 0x40; // REX fixed encoding prefix
}
}
}
switch (TSFlags & X86II::FormMask) {
case X86II::AddRegFrm:
REX |= isREXExtendedReg(MI, CurOp++) << 0; // REX.B
break;
case X86II::MRMSrcReg:
case X86II::MRMSrcRegCC:
REX |= isREXExtendedReg(MI, CurOp++) << 2; // REX.R
REX |= isREXExtendedReg(MI, CurOp++) << 0; // REX.B
break;
case X86II::MRMSrcMem:
case X86II::MRMSrcMemCC:
REX |= isREXExtendedReg(MI, CurOp++) << 2; // REX.R
REX |= isREXExtendedReg(MI, MemOperand + X86::AddrBaseReg) << 0; // REX.B
REX |= isREXExtendedReg(MI, MemOperand + X86::AddrIndexReg) << 1; // REX.X
CurOp += X86::AddrNumOperands;
break;
case X86II::MRMDestReg:
REX |= isREXExtendedReg(MI, CurOp++) << 0; // REX.B
REX |= isREXExtendedReg(MI, CurOp++) << 2; // REX.R
break;
case X86II::MRMDestMem:
REX |= isREXExtendedReg(MI, MemOperand + X86::AddrBaseReg) << 0; // REX.B
REX |= isREXExtendedReg(MI, MemOperand + X86::AddrIndexReg) << 1; // REX.X
CurOp += X86::AddrNumOperands;
REX |= isREXExtendedReg(MI, CurOp++) << 2; // REX.R
break;
case X86II::MRMXmCC:
case X86II::MRMXm:
case X86II::MRM0m:
case X86II::MRM1m:
case X86II::MRM2m:
case X86II::MRM3m:
case X86II::MRM4m:
case X86II::MRM5m:
case X86II::MRM6m:
case X86II::MRM7m:
REX |= isREXExtendedReg(MI, MemOperand + X86::AddrBaseReg) << 0; // REX.B
REX |= isREXExtendedReg(MI, MemOperand + X86::AddrIndexReg) << 1; // REX.X
break;
case X86II::MRMXrCC:
case X86II::MRMXr:
case X86II::MRM0r:
case X86II::MRM1r:
case X86II::MRM2r:
case X86II::MRM3r:
case X86II::MRM4r:
case X86II::MRM5r:
case X86II::MRM6r:
case X86II::MRM7r:
REX |= isREXExtendedReg(MI, CurOp++) << 0; // REX.B
break;
case X86II::MRMr0:
REX |= isREXExtendedReg(MI, CurOp++) << 2; // REX.R
break;
case X86II::MRMDestMemFSIB:
llvm_unreachable("FSIB format never need REX prefix!");
}
if (REX && UsesHighByteReg)
report_fatal_error(
"Cannot encode high byte register in REX-prefixed instruction");
return REX;
}();
if (!REX)
return false;
emitByte(0x40 | REX, OS);
return true;
}
/// Emit segment override opcode prefix as needed.
void X86MCCodeEmitter::emitSegmentOverridePrefix(unsigned SegOperand,
const MCInst &MI,
raw_ostream &OS) const {
// Check for explicit segment override on memory operand.
if (unsigned Reg = MI.getOperand(SegOperand).getReg())
emitByte(X86::getSegmentOverridePrefixForReg(Reg), OS);
}
/// Emit all instruction prefixes prior to the opcode.
///
/// \param MemOperand the operand # of the start of a memory operand if present.
/// If not present, it is -1.
///
/// \returns true if REX prefix is used, otherwise returns false.
bool X86MCCodeEmitter::emitOpcodePrefix(int MemOperand, const MCInst &MI,
const MCSubtargetInfo &STI,
raw_ostream &OS) const {
const MCInstrDesc &Desc = MCII.get(MI.getOpcode());
uint64_t TSFlags = Desc.TSFlags;
// Emit the operand size opcode prefix as needed.
if ((TSFlags & X86II::OpSizeMask) ==
(STI.hasFeature(X86::Mode16Bit) ? X86II::OpSize32 : X86II::OpSize16))
emitByte(0x66, OS);
// Emit the LOCK opcode prefix.
if (TSFlags & X86II::LOCK || MI.getFlags() & X86::IP_HAS_LOCK)
emitByte(0xF0, OS);
// Emit the NOTRACK opcode prefix.
if (TSFlags & X86II::NOTRACK || MI.getFlags() & X86::IP_HAS_NOTRACK)
emitByte(0x3E, OS);
switch (TSFlags & X86II::OpPrefixMask) {
case X86II::PD: // 66
emitByte(0x66, OS);
break;
case X86II::XS: // F3
emitByte(0xF3, OS);
break;
case X86II::XD: // F2
emitByte(0xF2, OS);
break;
}
// Handle REX prefix.
assert((STI.hasFeature(X86::Mode64Bit) || !(TSFlags & X86II::REX_W)) &&
"REX.W requires 64bit mode.");
bool HasREX = STI.hasFeature(X86::Mode64Bit)
? emitREXPrefix(MemOperand, MI, STI, OS)
: false;
// 0x0F escape code must be emitted just before the opcode.
switch (TSFlags & X86II::OpMapMask) {
case X86II::TB: // Two-byte opcode map
case X86II::T8: // 0F 38
case X86II::TA: // 0F 3A
case X86II::ThreeDNow: // 0F 0F, second 0F emitted by caller.
emitByte(0x0F, OS);
break;
}
switch (TSFlags & X86II::OpMapMask) {
case X86II::T8: // 0F 38
emitByte(0x38, OS);
break;
case X86II::TA: // 0F 3A
emitByte(0x3A, OS);
break;
}
return HasREX;
}
void X86MCCodeEmitter::emitPrefix(const MCInst &MI, raw_ostream &OS,
const MCSubtargetInfo &STI) const {
unsigned Opcode = MI.getOpcode();
const MCInstrDesc &Desc = MCII.get(Opcode);
uint64_t TSFlags = Desc.TSFlags;
// Pseudo instructions don't get encoded.
if (X86II::isPseudo(TSFlags))
return;
unsigned CurOp = X86II::getOperandBias(Desc);
emitPrefixImpl(CurOp, MI, STI, OS);
}
void X86MCCodeEmitter::encodeInstruction(const MCInst &MI, raw_ostream &OS,
SmallVectorImpl<MCFixup> &Fixups,
const MCSubtargetInfo &STI) const {
unsigned Opcode = MI.getOpcode();
const MCInstrDesc &Desc = MCII.get(Opcode);
uint64_t TSFlags = Desc.TSFlags;
// Pseudo instructions don't get encoded.
if (X86II::isPseudo(TSFlags))
return;
unsigned NumOps = Desc.getNumOperands();
unsigned CurOp = X86II::getOperandBias(Desc);
uint64_t StartByte = OS.tell();
bool HasREX = emitPrefixImpl(CurOp, MI, STI, OS);
// It uses the VEX.VVVV field?
bool HasVEX_4V = TSFlags & X86II::VEX_4V;
bool HasVEX_I8Reg = (TSFlags & X86II::ImmMask) == X86II::Imm8Reg;
// It uses the EVEX.aaa field?
bool HasEVEX_K = TSFlags & X86II::EVEX_K;
bool HasEVEX_RC = TSFlags & X86II::EVEX_RC;
// Used if a register is encoded in 7:4 of immediate.
unsigned I8RegNum = 0;
uint8_t BaseOpcode = X86II::getBaseOpcodeFor(TSFlags);
if ((TSFlags & X86II::OpMapMask) == X86II::ThreeDNow)
BaseOpcode = 0x0F; // Weird 3DNow! encoding.
unsigned OpcodeOffset = 0;
uint64_t Form = TSFlags & X86II::FormMask;
switch (Form) {
default:
errs() << "FORM: " << Form << "\n";
llvm_unreachable("Unknown FormMask value in X86MCCodeEmitter!");
case X86II::Pseudo:
llvm_unreachable("Pseudo instruction shouldn't be emitted");
case X86II::RawFrmDstSrc:
case X86II::RawFrmSrc:
case X86II::RawFrmDst:
case X86II::PrefixByte:
emitByte(BaseOpcode, OS);
break;
case X86II::AddCCFrm: {
// This will be added to the opcode in the fallthrough.
OpcodeOffset = MI.getOperand(NumOps - 1).getImm();
assert(OpcodeOffset < 16 && "Unexpected opcode offset!");
--NumOps; // Drop the operand from the end.
LLVM_FALLTHROUGH;
case X86II::RawFrm:
emitByte(BaseOpcode + OpcodeOffset, OS);
if (!STI.hasFeature(X86::Mode64Bit) || !isPCRel32Branch(MI, MCII))
break;
const MCOperand &Op = MI.getOperand(CurOp++);
emitImmediate(Op, MI.getLoc(), X86II::getSizeOfImm(TSFlags),
MCFixupKind(X86::reloc_branch_4byte_pcrel), StartByte, OS,
Fixups);
break;
}
case X86II::RawFrmMemOffs:
emitByte(BaseOpcode, OS);
emitImmediate(MI.getOperand(CurOp++), MI.getLoc(),
X86II::getSizeOfImm(TSFlags), getImmFixupKind(TSFlags),
StartByte, OS, Fixups);
++CurOp; // skip segment operand
break;
case X86II::RawFrmImm8:
emitByte(BaseOpcode, OS);
emitImmediate(MI.getOperand(CurOp++), MI.getLoc(),
X86II::getSizeOfImm(TSFlags), getImmFixupKind(TSFlags),
StartByte, OS, Fixups);
emitImmediate(MI.getOperand(CurOp++), MI.getLoc(), 1, FK_Data_1, StartByte,
OS, Fixups);
break;
case X86II::RawFrmImm16:
emitByte(BaseOpcode, OS);
emitImmediate(MI.getOperand(CurOp++), MI.getLoc(),
X86II::getSizeOfImm(TSFlags), getImmFixupKind(TSFlags),
StartByte, OS, Fixups);
emitImmediate(MI.getOperand(CurOp++), MI.getLoc(), 2, FK_Data_2, StartByte,
OS, Fixups);
break;
case X86II::AddRegFrm:
emitByte(BaseOpcode + getX86RegNum(MI.getOperand(CurOp++)), OS);
break;
case X86II::MRMDestReg: {
emitByte(BaseOpcode, OS);
unsigned SrcRegNum = CurOp + 1;
if (HasEVEX_K) // Skip writemask
++SrcRegNum;
if (HasVEX_4V) // Skip 1st src (which is encoded in VEX_VVVV)
++SrcRegNum;
emitRegModRMByte(MI.getOperand(CurOp),
getX86RegNum(MI.getOperand(SrcRegNum)), OS);
CurOp = SrcRegNum + 1;
break;
}
case X86II::MRMDestMemFSIB:
case X86II::MRMDestMem: {
emitByte(BaseOpcode, OS);
unsigned SrcRegNum = CurOp + X86::AddrNumOperands;
if (HasEVEX_K) // Skip writemask
++SrcRegNum;
if (HasVEX_4V) // Skip 1st src (which is encoded in VEX_VVVV)
++SrcRegNum;
bool ForceSIB = (Form == X86II::MRMDestMemFSIB);
emitMemModRMByte(MI, CurOp, getX86RegNum(MI.getOperand(SrcRegNum)), TSFlags,
HasREX, StartByte, OS, Fixups, STI, ForceSIB);
CurOp = SrcRegNum + 1;
break;
}
case X86II::MRMSrcReg: {
emitByte(BaseOpcode, OS);
unsigned SrcRegNum = CurOp + 1;
if (HasEVEX_K) // Skip writemask
++SrcRegNum;
if (HasVEX_4V) // Skip 1st src (which is encoded in VEX_VVVV)
++SrcRegNum;
emitRegModRMByte(MI.getOperand(SrcRegNum),
getX86RegNum(MI.getOperand(CurOp)), OS);
CurOp = SrcRegNum + 1;
if (HasVEX_I8Reg)
I8RegNum = getX86RegEncoding(MI, CurOp++);
// do not count the rounding control operand
if (HasEVEX_RC)
--NumOps;
break;
}
case X86II::MRMSrcReg4VOp3: {
emitByte(BaseOpcode, OS);
unsigned SrcRegNum = CurOp + 1;
emitRegModRMByte(MI.getOperand(SrcRegNum),
getX86RegNum(MI.getOperand(CurOp)), OS);
CurOp = SrcRegNum + 1;
++CurOp; // Encoded in VEX.VVVV
break;
}
case X86II::MRMSrcRegOp4: {
emitByte(BaseOpcode, OS);
unsigned SrcRegNum = CurOp + 1;
// Skip 1st src (which is encoded in VEX_VVVV)
++SrcRegNum;
// Capture 2nd src (which is encoded in Imm[7:4])
assert(HasVEX_I8Reg && "MRMSrcRegOp4 should imply VEX_I8Reg");
I8RegNum = getX86RegEncoding(MI, SrcRegNum++);
emitRegModRMByte(MI.getOperand(SrcRegNum),
getX86RegNum(MI.getOperand(CurOp)), OS);
CurOp = SrcRegNum + 1;
break;
}
case X86II::MRMSrcRegCC: {
unsigned FirstOp = CurOp++;
unsigned SecondOp = CurOp++;
unsigned CC = MI.getOperand(CurOp++).getImm();
emitByte(BaseOpcode + CC, OS);
emitRegModRMByte(MI.getOperand(SecondOp),
getX86RegNum(MI.getOperand(FirstOp)), OS);
break;
}
case X86II::MRMSrcMemFSIB:
case X86II::MRMSrcMem: {
unsigned FirstMemOp = CurOp + 1;
if (HasEVEX_K) // Skip writemask
++FirstMemOp;
if (HasVEX_4V)
++FirstMemOp; // Skip the register source (which is encoded in VEX_VVVV).
emitByte(BaseOpcode, OS);
bool ForceSIB = (Form == X86II::MRMSrcMemFSIB);
emitMemModRMByte(MI, FirstMemOp, getX86RegNum(MI.getOperand(CurOp)),
TSFlags, HasREX, StartByte, OS, Fixups, STI, ForceSIB);
CurOp = FirstMemOp + X86::AddrNumOperands;
if (HasVEX_I8Reg)
I8RegNum = getX86RegEncoding(MI, CurOp++);
break;
}
case X86II::MRMSrcMem4VOp3: {
unsigned FirstMemOp = CurOp + 1;
emitByte(BaseOpcode, OS);
emitMemModRMByte(MI, FirstMemOp, getX86RegNum(MI.getOperand(CurOp)),
TSFlags, HasREX, StartByte, OS, Fixups, STI);
CurOp = FirstMemOp + X86::AddrNumOperands;
++CurOp; // Encoded in VEX.VVVV.
break;
}
case X86II::MRMSrcMemOp4: {
unsigned FirstMemOp = CurOp + 1;
++FirstMemOp; // Skip the register source (which is encoded in VEX_VVVV).
// Capture second register source (encoded in Imm[7:4])
assert(HasVEX_I8Reg && "MRMSrcRegOp4 should imply VEX_I8Reg");
I8RegNum = getX86RegEncoding(MI, FirstMemOp++);
emitByte(BaseOpcode, OS);
emitMemModRMByte(MI, FirstMemOp, getX86RegNum(MI.getOperand(CurOp)),
TSFlags, HasREX, StartByte, OS, Fixups, STI);
CurOp = FirstMemOp + X86::AddrNumOperands;
break;
}
case X86II::MRMSrcMemCC: {
unsigned RegOp = CurOp++;
unsigned FirstMemOp = CurOp;
CurOp = FirstMemOp + X86::AddrNumOperands;
unsigned CC = MI.getOperand(CurOp++).getImm();
emitByte(BaseOpcode + CC, OS);
emitMemModRMByte(MI, FirstMemOp, getX86RegNum(MI.getOperand(RegOp)),
TSFlags, HasREX, StartByte, OS, Fixups, STI);
break;
}
case X86II::MRMXrCC: {
unsigned RegOp = CurOp++;
unsigned CC = MI.getOperand(CurOp++).getImm();
emitByte(BaseOpcode + CC, OS);
emitRegModRMByte(MI.getOperand(RegOp), 0, OS);
break;
}
case X86II::MRMXr:
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;
if (HasEVEX_K) // Skip writemask
++CurOp;
emitByte(BaseOpcode, OS);
emitRegModRMByte(MI.getOperand(CurOp++),
(Form == X86II::MRMXr) ? 0 : Form - X86II::MRM0r, OS);
break;
case X86II::MRMr0:
emitByte(BaseOpcode, OS);
emitByte(modRMByte(3, getX86RegNum(MI.getOperand(CurOp++)),0), OS);
break;
case X86II::MRMXmCC: {
unsigned FirstMemOp = CurOp;
CurOp = FirstMemOp + X86::AddrNumOperands;
unsigned CC = MI.getOperand(CurOp++).getImm();
emitByte(BaseOpcode + CC, OS);
emitMemModRMByte(MI, FirstMemOp, 0, TSFlags, HasREX, StartByte, OS, Fixups,
STI);
break;
}
case X86II::MRMXm:
case X86II::MRM0m:
case X86II::MRM1m:
case X86II::MRM2m:
case X86II::MRM3m:
case X86II::MRM4m:
case X86II::MRM5m:
case X86II::MRM6m:
case X86II::MRM7m:
if (HasVEX_4V) // Skip the register dst (which is encoded in VEX_VVVV).
++CurOp;
if (HasEVEX_K) // Skip writemask
++CurOp;
emitByte(BaseOpcode, OS);
emitMemModRMByte(MI, CurOp,
(Form == X86II::MRMXm) ? 0 : Form - X86II::MRM0m, TSFlags,
HasREX, StartByte, OS, Fixups, STI);
CurOp += X86::AddrNumOperands;
break;
case X86II::MRM0X:
case X86II::MRM1X:
case X86II::MRM2X:
case X86II::MRM3X:
case X86II::MRM4X:
case X86II::MRM5X:
case X86II::MRM6X:
case X86II::MRM7X:
emitByte(BaseOpcode, OS);
emitByte(0xC0 + ((Form - X86II::MRM0X) << 3), OS);
break;
case X86II::MRM_C0:
case X86II::MRM_C1:
case X86II::MRM_C2:
case X86II::MRM_C3:
case X86II::MRM_C4:
case X86II::MRM_C5:
case X86II::MRM_C6:
case X86II::MRM_C7:
case X86II::MRM_C8:
case X86II::MRM_C9:
case X86II::MRM_CA:
case X86II::MRM_CB:
case X86II::MRM_CC:
case X86II::MRM_CD:
case X86II::MRM_CE:
case X86II::MRM_CF:
case X86II::MRM_D0:
case X86II::MRM_D1:
case X86II::MRM_D2:
case X86II::MRM_D3:
case X86II::MRM_D4:
case X86II::MRM_D5:
case X86II::MRM_D6:
case X86II::MRM_D7:
case X86II::MRM_D8:
case X86II::MRM_D9:
case X86II::MRM_DA:
case X86II::MRM_DB:
case X86II::MRM_DC:
case X86II::MRM_DD:
case X86II::MRM_DE:
case X86II::MRM_DF:
case X86II::MRM_E0:
case X86II::MRM_E1:
case X86II::MRM_E2:
case X86II::MRM_E3:
case X86II::MRM_E4:
case X86II::MRM_E5:
case X86II::MRM_E6:
case X86II::MRM_E7:
case X86II::MRM_E8:
case X86II::MRM_E9:
case X86II::MRM_EA:
case X86II::MRM_EB:
case X86II::MRM_EC:
case X86II::MRM_ED:
case X86II::MRM_EE:
case X86II::MRM_EF:
case X86II::MRM_F0:
case X86II::MRM_F1:
case X86II::MRM_F2:
case X86II::MRM_F3:
case X86II::MRM_F4:
case X86II::MRM_F5:
case X86II::MRM_F6:
case X86II::MRM_F7:
case X86II::MRM_F8:
case X86II::MRM_F9:
case X86II::MRM_FA:
case X86II::MRM_FB:
case X86II::MRM_FC:
case X86II::MRM_FD:
case X86II::MRM_FE:
case X86II::MRM_FF:
emitByte(BaseOpcode, OS);
emitByte(0xC0 + Form - X86II::MRM_C0, OS);
break;
}
if (HasVEX_I8Reg) {
// The last source register of a 4 operand instruction in AVX is encoded
// in bits[7:4] of a immediate byte.
assert(I8RegNum < 16 && "Register encoding out of range");
I8RegNum <<= 4;
if (CurOp != NumOps) {
unsigned Val = MI.getOperand(CurOp++).getImm();
assert(Val < 16 && "Immediate operand value out of range");
I8RegNum |= Val;
}
emitImmediate(MCOperand::createImm(I8RegNum), MI.getLoc(), 1, FK_Data_1,
StartByte, OS, Fixups);
} else {
// If there is a remaining operand, it must be a trailing immediate. Emit it
// according to the right size for the instruction. Some instructions
// (SSE4a extrq and insertq) have two trailing immediates.
while (CurOp != NumOps && NumOps - CurOp <= 2) {
emitImmediate(MI.getOperand(CurOp++), MI.getLoc(),
X86II::getSizeOfImm(TSFlags), getImmFixupKind(TSFlags),
StartByte, OS, Fixups);
}
}
if ((TSFlags & X86II::OpMapMask) == X86II::ThreeDNow)
emitByte(X86II::getBaseOpcodeFor(TSFlags), OS);
assert(OS.tell() - StartByte <= 15 &&
"The size of instruction must be no longer than 15.");
#ifndef NDEBUG
// FIXME: Verify.
if (/*!Desc.isVariadic() &&*/ CurOp != NumOps) {
errs() << "Cannot encode all operands of: ";
MI.dump();
errs() << '\n';
abort();
}
#endif
}
MCCodeEmitter *llvm::createX86MCCodeEmitter(const MCInstrInfo &MCII,
const MCRegisterInfo &MRI,
MCContext &Ctx) {
return new X86MCCodeEmitter(MCII, Ctx);
}
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