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llvm / llvm-project / 37d72991c136244fe53be02f5af0ad643247a1e6 / . / llvm / lib / Target / X86 / Disassembler / X86Disassembler.cpp
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//===-- X86Disassembler.cpp - Disassembler for x86 and x86_64 -------------===//
//
// 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 is part of the X86 Disassembler.
// It contains code to translate the data produced by the decoder into
// MCInsts.
//
//
// The X86 disassembler is a table-driven disassembler for the 16-, 32-, and
// 64-bit X86 instruction sets. The main decode sequence for an assembly
// instruction in this disassembler is:
//
// 1. Read the prefix bytes and determine the attributes of the instruction.
// These attributes, recorded in enum attributeBits
// (X86DisassemblerDecoderCommon.h), form a bitmask. The table CONTEXTS_SYM
// provides a mapping from bitmasks to contexts, which are represented by
// enum InstructionContext (ibid.).
//
// 2. Read the opcode, and determine what kind of opcode it is. The
// disassembler distinguishes four kinds of opcodes, which are enumerated in
// OpcodeType (X86DisassemblerDecoderCommon.h): one-byte (0xnn), two-byte
// (0x0f 0xnn), three-byte-38 (0x0f 0x38 0xnn), or three-byte-3a
// (0x0f 0x3a 0xnn). Mandatory prefixes are treated as part of the context.
//
// 3. Depending on the opcode type, look in one of four ClassDecision structures
// (X86DisassemblerDecoderCommon.h). Use the opcode class to determine which
// OpcodeDecision (ibid.) to look the opcode in. Look up the opcode, to get
// a ModRMDecision (ibid.).
//
// 4. Some instructions, such as escape opcodes or extended opcodes, or even
// instructions that have ModRM*Reg / ModRM*Mem forms in LLVM, need the
// ModR/M byte to complete decode. The ModRMDecision's type is an entry from
// ModRMDecisionType (X86DisassemblerDecoderCommon.h) that indicates if the
// ModR/M byte is required and how to interpret it.
//
// 5. After resolving the ModRMDecision, the disassembler has a unique ID
// of type InstrUID (X86DisassemblerDecoderCommon.h). Looking this ID up in
// INSTRUCTIONS_SYM yields the name of the instruction and the encodings and
// meanings of its operands.
//
// 6. For each operand, its encoding is an entry from OperandEncoding
// (X86DisassemblerDecoderCommon.h) and its type is an entry from
// OperandType (ibid.). The encoding indicates how to read it from the
// instruction; the type indicates how to interpret the value once it has
// been read. For example, a register operand could be stored in the R/M
// field of the ModR/M byte, the REG field of the ModR/M byte, or added to
// the main opcode. This is orthogonal from its meaning (an GPR or an XMM
// register, for instance). Given this information, the operands can be
// extracted and interpreted.
//
// 7. As the last step, the disassembler translates the instruction information
// and operands into a format understandable by the client - in this case, an
// MCInst for use by the MC infrastructure.
//
// The disassembler is broken broadly into two parts: the table emitter that
// emits the instruction decode tables discussed above during compilation, and
// the disassembler itself. The table emitter is documented in more detail in
// utils/TableGen/X86DisassemblerEmitter.h.
//
// X86Disassembler.cpp contains the code responsible for step 7, and for
// invoking the decoder to execute steps 1-6.
// X86DisassemblerDecoderCommon.h contains the definitions needed by both the
// table emitter and the disassembler.
// X86DisassemblerDecoder.h contains the public interface of the decoder,
// factored out into C for possible use by other projects.
// X86DisassemblerDecoder.c contains the source code of the decoder, which is
// responsible for steps 1-6.
//
//===----------------------------------------------------------------------===//
#include "MCTargetDesc/X86BaseInfo.h"
#include "MCTargetDesc/X86MCTargetDesc.h"
#include "TargetInfo/X86TargetInfo.h"
#include "X86DisassemblerDecoder.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCDisassembler/MCDisassembler.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCInst.h"
#include "llvm/MC/MCInstrInfo.h"
#include "llvm/MC/MCSubtargetInfo.h"
#include "llvm/MC/TargetRegistry.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
using namespace llvm::X86Disassembler;
#define DEBUG_TYPE "x86-disassembler"
#define debug(s) LLVM_DEBUG(dbgs() << __LINE__ << ": " << s);
// Specifies whether a ModR/M byte is needed and (if so) which
// instruction each possible value of the ModR/M byte corresponds to. Once
// this information is known, we have narrowed down to a single instruction.
struct ModRMDecision {
uint8_t modrm_type;
uint16_t instructionIDs;
};
// Specifies which set of ModR/M->instruction tables to look at
// given a particular opcode.
struct OpcodeDecision {
ModRMDecision modRMDecisions[256];
};
// Specifies which opcode->instruction tables to look at given
// a particular context (set of attributes). Since there are many possible
// contexts, the decoder first uses CONTEXTS_SYM to determine which context
// applies given a specific set of attributes. Hence there are only IC_max
// entries in this table, rather than 2^(ATTR_max).
struct ContextDecision {
OpcodeDecision opcodeDecisions[IC_max];
};
#include "X86GenDisassemblerTables.inc"
static InstrUID decode(OpcodeType type, InstructionContext insnContext,
uint8_t opcode, uint8_t modRM) {
const struct ModRMDecision *dec;
switch (type) {
case ONEBYTE:
dec = &ONEBYTE_SYM.opcodeDecisions[insnContext].modRMDecisions[opcode];
break;
case TWOBYTE:
dec = &TWOBYTE_SYM.opcodeDecisions[insnContext].modRMDecisions[opcode];
break;
case THREEBYTE_38:
dec = &THREEBYTE38_SYM.opcodeDecisions[insnContext].modRMDecisions[opcode];
break;
case THREEBYTE_3A:
dec = &THREEBYTE3A_SYM.opcodeDecisions[insnContext].modRMDecisions[opcode];
break;
case XOP8_MAP:
dec = &XOP8_MAP_SYM.opcodeDecisions[insnContext].modRMDecisions[opcode];
break;
case XOP9_MAP:
dec = &XOP9_MAP_SYM.opcodeDecisions[insnContext].modRMDecisions[opcode];
break;
case XOPA_MAP:
dec = &XOPA_MAP_SYM.opcodeDecisions[insnContext].modRMDecisions[opcode];
break;
case THREEDNOW_MAP:
dec =
&THREEDNOW_MAP_SYM.opcodeDecisions[insnContext].modRMDecisions[opcode];
break;
case MAP5:
dec = &MAP5_SYM.opcodeDecisions[insnContext].modRMDecisions[opcode];
break;
case MAP6:
dec = &MAP6_SYM.opcodeDecisions[insnContext].modRMDecisions[opcode];
break;
}
switch (dec->modrm_type) {
default:
llvm_unreachable("Corrupt table! Unknown modrm_type");
return 0;
case MODRM_ONEENTRY:
return modRMTable[dec->instructionIDs];
case MODRM_SPLITRM:
if (modFromModRM(modRM) == 0x3)
return modRMTable[dec->instructionIDs + 1];
return modRMTable[dec->instructionIDs];
case MODRM_SPLITREG:
if (modFromModRM(modRM) == 0x3)
return modRMTable[dec->instructionIDs + ((modRM & 0x38) >> 3) + 8];
return modRMTable[dec->instructionIDs + ((modRM & 0x38) >> 3)];
case MODRM_SPLITMISC:
if (modFromModRM(modRM) == 0x3)
return modRMTable[dec->instructionIDs + (modRM & 0x3f) + 8];
return modRMTable[dec->instructionIDs + ((modRM & 0x38) >> 3)];
case MODRM_FULL:
return modRMTable[dec->instructionIDs + modRM];
}
}
static bool peek(struct InternalInstruction *insn, uint8_t &byte) {
uint64_t offset = insn->readerCursor - insn->startLocation;
if (offset >= insn->bytes.size())
return true;
byte = insn->bytes[offset];
return false;
}
template <typename T> static bool consume(InternalInstruction *insn, T &ptr) {
auto r = insn->bytes;
uint64_t offset = insn->readerCursor - insn->startLocation;
if (offset + sizeof(T) > r.size())
return true;
T ret = 0;
for (unsigned i = 0; i < sizeof(T); ++i)
ret |= (uint64_t)r[offset + i] << (i * 8);
ptr = ret;
insn->readerCursor += sizeof(T);
return false;
}
static bool isREX(struct InternalInstruction *insn, uint8_t prefix) {
return insn->mode == MODE_64BIT && prefix >= 0x40 && prefix <= 0x4f;
}
// Consumes all of an instruction's prefix bytes, and marks the
// instruction as having them. Also sets the instruction's default operand,
// address, and other relevant data sizes to report operands correctly.
//
// insn must not be empty.
static int readPrefixes(struct InternalInstruction *insn) {
bool isPrefix = true;
uint8_t byte = 0;
uint8_t nextByte;
LLVM_DEBUG(dbgs() << "readPrefixes()");
while (isPrefix) {
// If we fail reading prefixes, just stop here and let the opcode reader
// deal with it.
if (consume(insn, byte))
break;
// If the byte is a LOCK/REP/REPNE prefix and not a part of the opcode, then
// break and let it be disassembled as a normal "instruction".
if (insn->readerCursor - 1 == insn->startLocation && byte == 0xf0) // LOCK
break;
if ((byte == 0xf2 || byte == 0xf3) && !peek(insn, nextByte)) {
// If the byte is 0xf2 or 0xf3, and any of the following conditions are
// met:
// - it is followed by a LOCK (0xf0) prefix
// - it is followed by an xchg instruction
// then it should be disassembled as a xacquire/xrelease not repne/rep.
if (((nextByte == 0xf0) ||
((nextByte & 0xfe) == 0x86 || (nextByte & 0xf8) == 0x90))) {
insn->xAcquireRelease = true;
if (!(byte == 0xf3 && nextByte == 0x90)) // PAUSE instruction support
break;
}
// Also if the byte is 0xf3, and the following condition is met:
// - it is followed by a "mov mem, reg" (opcode 0x88/0x89) or
// "mov mem, imm" (opcode 0xc6/0xc7) instructions.
// then it should be disassembled as an xrelease not rep.
if (byte == 0xf3 && (nextByte == 0x88 || nextByte == 0x89 ||
nextByte == 0xc6 || nextByte == 0xc7)) {
insn->xAcquireRelease = true;
break;
}
if (isREX(insn, nextByte)) {
uint8_t nnextByte;
// Go to REX prefix after the current one
if (consume(insn, nnextByte))
return -1;
// We should be able to read next byte after REX prefix
if (peek(insn, nnextByte))
return -1;
--insn->readerCursor;
}
}
switch (byte) {
case 0xf0: // LOCK
insn->hasLockPrefix = true;
break;
case 0xf2: // REPNE/REPNZ
case 0xf3: { // REP or REPE/REPZ
uint8_t nextByte;
if (peek(insn, nextByte))
break;
// TODO:
// 1. There could be several 0x66
// 2. if (nextByte == 0x66) and nextNextByte != 0x0f then
// it's not mandatory prefix
// 3. if (nextByte >= 0x40 && nextByte <= 0x4f) it's REX and we need
// 0x0f exactly after it to be mandatory prefix
if (isREX(insn, nextByte) || nextByte == 0x0f || nextByte == 0x66)
// The last of 0xf2 /0xf3 is mandatory prefix
insn->mandatoryPrefix = byte;
insn->repeatPrefix = byte;
break;
}
case 0x2e: // CS segment override -OR- Branch not taken
insn->segmentOverride = SEG_OVERRIDE_CS;
break;
case 0x36: // SS segment override -OR- Branch taken
insn->segmentOverride = SEG_OVERRIDE_SS;
break;
case 0x3e: // DS segment override
insn->segmentOverride = SEG_OVERRIDE_DS;
break;
case 0x26: // ES segment override
insn->segmentOverride = SEG_OVERRIDE_ES;
break;
case 0x64: // FS segment override
insn->segmentOverride = SEG_OVERRIDE_FS;
break;
case 0x65: // GS segment override
insn->segmentOverride = SEG_OVERRIDE_GS;
break;
case 0x66: { // Operand-size override {
uint8_t nextByte;
insn->hasOpSize = true;
if (peek(insn, nextByte))
break;
// 0x66 can't overwrite existing mandatory prefix and should be ignored
if (!insn->mandatoryPrefix && (nextByte == 0x0f || isREX(insn, nextByte)))
insn->mandatoryPrefix = byte;
break;
}
case 0x67: // Address-size override
insn->hasAdSize = true;
break;
default: // Not a prefix byte
isPrefix = false;
break;
}
if (isPrefix)
LLVM_DEBUG(dbgs() << format("Found prefix 0x%hhx", byte));
}
insn->vectorExtensionType = TYPE_NO_VEX_XOP;
if (byte == 0x62) {
uint8_t byte1, byte2;
if (consume(insn, byte1)) {
LLVM_DEBUG(dbgs() << "Couldn't read second byte of EVEX prefix");
return -1;
}
if (peek(insn, byte2)) {
LLVM_DEBUG(dbgs() << "Couldn't read third byte of EVEX prefix");
return -1;
}
if ((insn->mode == MODE_64BIT || (byte1 & 0xc0) == 0xc0) &&
((~byte1 & 0x8) == 0x8) && ((byte2 & 0x4) == 0x4)) {
insn->vectorExtensionType = TYPE_EVEX;
} else {
--insn->readerCursor; // unconsume byte1
--insn->readerCursor; // unconsume byte
}
if (insn->vectorExtensionType == TYPE_EVEX) {
insn->vectorExtensionPrefix[0] = byte;
insn->vectorExtensionPrefix[1] = byte1;
if (consume(insn, insn->vectorExtensionPrefix[2])) {
LLVM_DEBUG(dbgs() << "Couldn't read third byte of EVEX prefix");
return -1;
}
if (consume(insn, insn->vectorExtensionPrefix[3])) {
LLVM_DEBUG(dbgs() << "Couldn't read fourth byte of EVEX prefix");
return -1;
}
// We simulate the REX prefix for simplicity's sake
if (insn->mode == MODE_64BIT) {
insn->rexPrefix = 0x40 |
(wFromEVEX3of4(insn->vectorExtensionPrefix[2]) << 3) |
(rFromEVEX2of4(insn->vectorExtensionPrefix[1]) << 2) |
(xFromEVEX2of4(insn->vectorExtensionPrefix[1]) << 1) |
(bFromEVEX2of4(insn->vectorExtensionPrefix[1]) << 0);
}
LLVM_DEBUG(
dbgs() << format(
"Found EVEX prefix 0x%hhx 0x%hhx 0x%hhx 0x%hhx",
insn->vectorExtensionPrefix[0], insn->vectorExtensionPrefix[1],
insn->vectorExtensionPrefix[2], insn->vectorExtensionPrefix[3]));
}
} else if (byte == 0xc4) {
uint8_t byte1;
if (peek(insn, byte1)) {
LLVM_DEBUG(dbgs() << "Couldn't read second byte of VEX");
return -1;
}
if (insn->mode == MODE_64BIT || (byte1 & 0xc0) == 0xc0)
insn->vectorExtensionType = TYPE_VEX_3B;
else
--insn->readerCursor;
if (insn->vectorExtensionType == TYPE_VEX_3B) {
insn->vectorExtensionPrefix[0] = byte;
consume(insn, insn->vectorExtensionPrefix[1]);
consume(insn, insn->vectorExtensionPrefix[2]);
// We simulate the REX prefix for simplicity's sake
if (insn->mode == MODE_64BIT)
insn->rexPrefix = 0x40 |
(wFromVEX3of3(insn->vectorExtensionPrefix[2]) << 3) |
(rFromVEX2of3(insn->vectorExtensionPrefix[1]) << 2) |
(xFromVEX2of3(insn->vectorExtensionPrefix[1]) << 1) |
(bFromVEX2of3(insn->vectorExtensionPrefix[1]) << 0);
LLVM_DEBUG(dbgs() << format("Found VEX prefix 0x%hhx 0x%hhx 0x%hhx",
insn->vectorExtensionPrefix[0],
insn->vectorExtensionPrefix[1],
insn->vectorExtensionPrefix[2]));
}
} else if (byte == 0xc5) {
uint8_t byte1;
if (peek(insn, byte1)) {
LLVM_DEBUG(dbgs() << "Couldn't read second byte of VEX");
return -1;
}
if (insn->mode == MODE_64BIT || (byte1 & 0xc0) == 0xc0)
insn->vectorExtensionType = TYPE_VEX_2B;
else
--insn->readerCursor;
if (insn->vectorExtensionType == TYPE_VEX_2B) {
insn->vectorExtensionPrefix[0] = byte;
consume(insn, insn->vectorExtensionPrefix[1]);
if (insn->mode == MODE_64BIT)
insn->rexPrefix =
0x40 | (rFromVEX2of2(insn->vectorExtensionPrefix[1]) << 2);
switch (ppFromVEX2of2(insn->vectorExtensionPrefix[1])) {
default:
break;
case VEX_PREFIX_66:
insn->hasOpSize = true;
break;
}
LLVM_DEBUG(dbgs() << format("Found VEX prefix 0x%hhx 0x%hhx",
insn->vectorExtensionPrefix[0],
insn->vectorExtensionPrefix[1]));
}
} else if (byte == 0x8f) {
uint8_t byte1;
if (peek(insn, byte1)) {
LLVM_DEBUG(dbgs() << "Couldn't read second byte of XOP");
return -1;
}
if ((byte1 & 0x38) != 0x0) // 0 in these 3 bits is a POP instruction.
insn->vectorExtensionType = TYPE_XOP;
else
--insn->readerCursor;
if (insn->vectorExtensionType == TYPE_XOP) {
insn->vectorExtensionPrefix[0] = byte;
consume(insn, insn->vectorExtensionPrefix[1]);
consume(insn, insn->vectorExtensionPrefix[2]);
// We simulate the REX prefix for simplicity's sake
if (insn->mode == MODE_64BIT)
insn->rexPrefix = 0x40 |
(wFromXOP3of3(insn->vectorExtensionPrefix[2]) << 3) |
(rFromXOP2of3(insn->vectorExtensionPrefix[1]) << 2) |
(xFromXOP2of3(insn->vectorExtensionPrefix[1]) << 1) |
(bFromXOP2of3(insn->vectorExtensionPrefix[1]) << 0);
switch (ppFromXOP3of3(insn->vectorExtensionPrefix[2])) {
default:
break;
case VEX_PREFIX_66:
insn->hasOpSize = true;
break;
}
LLVM_DEBUG(dbgs() << format("Found XOP prefix 0x%hhx 0x%hhx 0x%hhx",
insn->vectorExtensionPrefix[0],
insn->vectorExtensionPrefix[1],
insn->vectorExtensionPrefix[2]));
}
} else if (isREX(insn, byte)) {
if (peek(insn, nextByte))
return -1;
insn->rexPrefix = byte;
LLVM_DEBUG(dbgs() << format("Found REX prefix 0x%hhx", byte));
} else
--insn->readerCursor;
if (insn->mode == MODE_16BIT) {
insn->registerSize = (insn->hasOpSize ? 4 : 2);
insn->addressSize = (insn->hasAdSize ? 4 : 2);
insn->displacementSize = (insn->hasAdSize ? 4 : 2);
insn->immediateSize = (insn->hasOpSize ? 4 : 2);
} else if (insn->mode == MODE_32BIT) {
insn->registerSize = (insn->hasOpSize ? 2 : 4);
insn->addressSize = (insn->hasAdSize ? 2 : 4);
insn->displacementSize = (insn->hasAdSize ? 2 : 4);
insn->immediateSize = (insn->hasOpSize ? 2 : 4);
} else if (insn->mode == MODE_64BIT) {
if (insn->rexPrefix && wFromREX(insn->rexPrefix)) {
insn->registerSize = 8;
insn->addressSize = (insn->hasAdSize ? 4 : 8);
insn->displacementSize = 4;
insn->immediateSize = 4;
insn->hasOpSize = false;
} else {
insn->registerSize = (insn->hasOpSize ? 2 : 4);
insn->addressSize = (insn->hasAdSize ? 4 : 8);
insn->displacementSize = (insn->hasOpSize ? 2 : 4);
insn->immediateSize = (insn->hasOpSize ? 2 : 4);
}
}
return 0;
}
// Consumes the SIB byte to determine addressing information.
static int readSIB(struct InternalInstruction *insn) {
SIBBase sibBaseBase = SIB_BASE_NONE;
uint8_t index, base;
LLVM_DEBUG(dbgs() << "readSIB()");
switch (insn->addressSize) {
case 2:
default:
llvm_unreachable("SIB-based addressing doesn't work in 16-bit mode");
case 4:
insn->sibIndexBase = SIB_INDEX_EAX;
sibBaseBase = SIB_BASE_EAX;
break;
case 8:
insn->sibIndexBase = SIB_INDEX_RAX;
sibBaseBase = SIB_BASE_RAX;
break;
}
if (consume(insn, insn->sib))
return -1;
index = indexFromSIB(insn->sib) | (xFromREX(insn->rexPrefix) << 3);
if (index == 0x4) {
insn->sibIndex = SIB_INDEX_NONE;
} else {
insn->sibIndex = (SIBIndex)(insn->sibIndexBase + index);
}
insn->sibScale = 1 << scaleFromSIB(insn->sib);
base = baseFromSIB(insn->sib) | (bFromREX(insn->rexPrefix) << 3);
switch (base) {
case 0x5:
case 0xd:
switch (modFromModRM(insn->modRM)) {
case 0x0:
insn->eaDisplacement = EA_DISP_32;
insn->sibBase = SIB_BASE_NONE;
break;
case 0x1:
insn->eaDisplacement = EA_DISP_8;
insn->sibBase = (SIBBase)(sibBaseBase + base);
break;
case 0x2:
insn->eaDisplacement = EA_DISP_32;
insn->sibBase = (SIBBase)(sibBaseBase + base);
break;
default:
llvm_unreachable("Cannot have Mod = 0b11 and a SIB byte");
}
break;
default:
insn->sibBase = (SIBBase)(sibBaseBase + base);
break;
}
return 0;
}
static int readDisplacement(struct InternalInstruction *insn) {
int8_t d8;
int16_t d16;
int32_t d32;
LLVM_DEBUG(dbgs() << "readDisplacement()");
insn->displacementOffset = insn->readerCursor - insn->startLocation;
switch (insn->eaDisplacement) {
case EA_DISP_NONE:
break;
case EA_DISP_8:
if (consume(insn, d8))
return -1;
insn->displacement = d8;
break;
case EA_DISP_16:
if (consume(insn, d16))
return -1;
insn->displacement = d16;
break;
case EA_DISP_32:
if (consume(insn, d32))
return -1;
insn->displacement = d32;
break;
}
return 0;
}
// Consumes all addressing information (ModR/M byte, SIB byte, and displacement.
static int readModRM(struct InternalInstruction *insn) {
uint8_t mod, rm, reg, evexrm;
LLVM_DEBUG(dbgs() << "readModRM()");
if (insn->consumedModRM)
return 0;
if (consume(insn, insn->modRM))
return -1;
insn->consumedModRM = true;
mod = modFromModRM(insn->modRM);
rm = rmFromModRM(insn->modRM);
reg = regFromModRM(insn->modRM);
// This goes by insn->registerSize to pick the correct register, which messes
// up if we're using (say) XMM or 8-bit register operands. That gets fixed in
// fixupReg().
switch (insn->registerSize) {
case 2:
insn->regBase = MODRM_REG_AX;
insn->eaRegBase = EA_REG_AX;
break;
case 4:
insn->regBase = MODRM_REG_EAX;
insn->eaRegBase = EA_REG_EAX;
break;
case 8:
insn->regBase = MODRM_REG_RAX;
insn->eaRegBase = EA_REG_RAX;
break;
}
reg |= rFromREX(insn->rexPrefix) << 3;
rm |= bFromREX(insn->rexPrefix) << 3;
evexrm = 0;
if (insn->vectorExtensionType == TYPE_EVEX && insn->mode == MODE_64BIT) {
reg |= r2FromEVEX2of4(insn->vectorExtensionPrefix[1]) << 4;
evexrm = xFromEVEX2of4(insn->vectorExtensionPrefix[1]) << 4;
}
insn->reg = (Reg)(insn->regBase + reg);
switch (insn->addressSize) {
case 2: {
EABase eaBaseBase = EA_BASE_BX_SI;
switch (mod) {
case 0x0:
if (rm == 0x6) {
insn->eaBase = EA_BASE_NONE;
insn->eaDisplacement = EA_DISP_16;
if (readDisplacement(insn))
return -1;
} else {
insn->eaBase = (EABase)(eaBaseBase + rm);
insn->eaDisplacement = EA_DISP_NONE;
}
break;
case 0x1:
insn->eaBase = (EABase)(eaBaseBase + rm);
insn->eaDisplacement = EA_DISP_8;
insn->displacementSize = 1;
if (readDisplacement(insn))
return -1;
break;
case 0x2:
insn->eaBase = (EABase)(eaBaseBase + rm);
insn->eaDisplacement = EA_DISP_16;
if (readDisplacement(insn))
return -1;
break;
case 0x3:
insn->eaBase = (EABase)(insn->eaRegBase + rm);
if (readDisplacement(insn))
return -1;
break;
}
break;
}
case 4:
case 8: {
EABase eaBaseBase = (insn->addressSize == 4 ? EA_BASE_EAX : EA_BASE_RAX);
switch (mod) {
case 0x0:
insn->eaDisplacement = EA_DISP_NONE; // readSIB may override this
// In determining whether RIP-relative mode is used (rm=5),
// or whether a SIB byte is present (rm=4),
// the extension bits (REX.b and EVEX.x) are ignored.
switch (rm & 7) {
case 0x4: // SIB byte is present
insn->eaBase = (insn->addressSize == 4 ? EA_BASE_sib : EA_BASE_sib64);
if (readSIB(insn) || readDisplacement(insn))
return -1;
break;
case 0x5: // RIP-relative
insn->eaBase = EA_BASE_NONE;
insn->eaDisplacement = EA_DISP_32;
if (readDisplacement(insn))
return -1;
break;
default:
insn->eaBase = (EABase)(eaBaseBase + rm);
break;
}
break;
case 0x1:
insn->displacementSize = 1;
LLVM_FALLTHROUGH;
case 0x2:
insn->eaDisplacement = (mod == 0x1 ? EA_DISP_8 : EA_DISP_32);
switch (rm & 7) {
case 0x4: // SIB byte is present
insn->eaBase = EA_BASE_sib;
if (readSIB(insn) || readDisplacement(insn))
return -1;
break;
default:
insn->eaBase = (EABase)(eaBaseBase + rm);
if (readDisplacement(insn))
return -1;
break;
}
break;
case 0x3:
insn->eaDisplacement = EA_DISP_NONE;
insn->eaBase = (EABase)(insn->eaRegBase + rm + evexrm);
break;
}
break;
}
} // switch (insn->addressSize)
return 0;
}
#define GENERIC_FIXUP_FUNC(name, base, prefix, mask) \
static uint16_t name(struct InternalInstruction *insn, OperandType type, \
uint8_t index, uint8_t *valid) { \
*valid = 1; \
switch (type) { \
default: \
debug("Unhandled register type"); \
*valid = 0; \
return 0; \
case TYPE_Rv: \
return base + index; \
case TYPE_R8: \
index &= mask; \
if (index > 0xf) \
*valid = 0; \
if (insn->rexPrefix && index >= 4 && index <= 7) { \
return prefix##_SPL + (index - 4); \
} else { \
return prefix##_AL + index; \
} \
case TYPE_R16: \
index &= mask; \
if (index > 0xf) \
*valid = 0; \
return prefix##_AX + index; \
case TYPE_R32: \
index &= mask; \
if (index > 0xf) \
*valid = 0; \
return prefix##_EAX + index; \
case TYPE_R64: \
index &= mask; \
if (index > 0xf) \
*valid = 0; \
return prefix##_RAX + index; \
case TYPE_ZMM: \
return prefix##_ZMM0 + index; \
case TYPE_YMM: \
return prefix##_YMM0 + index; \
case TYPE_XMM: \
return prefix##_XMM0 + index; \
case TYPE_TMM: \
if (index > 7) \
*valid = 0; \
return prefix##_TMM0 + index; \
case TYPE_VK: \
index &= 0xf; \
if (index > 7) \
*valid = 0; \
return prefix##_K0 + index; \
case TYPE_VK_PAIR: \
if (index > 7) \
*valid = 0; \
return prefix##_K0_K1 + (index / 2); \
case TYPE_MM64: \
return prefix##_MM0 + (index & 0x7); \
case TYPE_SEGMENTREG: \
if ((index & 7) > 5) \
*valid = 0; \
return prefix##_ES + (index & 7); \
case TYPE_DEBUGREG: \
return prefix##_DR0 + index; \
case TYPE_CONTROLREG: \
return prefix##_CR0 + index; \
case TYPE_MVSIBX: \
return prefix##_XMM0 + index; \
case TYPE_MVSIBY: \
return prefix##_YMM0 + index; \
case TYPE_MVSIBZ: \
return prefix##_ZMM0 + index; \
} \
}
// Consult an operand type to determine the meaning of the reg or R/M field. If
// the operand is an XMM operand, for example, an operand would be XMM0 instead
// of AX, which readModRM() would otherwise misinterpret it as.
//
// @param insn - The instruction containing the operand.
// @param type - The operand type.
// @param index - The existing value of the field as reported by readModRM().
// @param valid - The address of a uint8_t. The target is set to 1 if the
// field is valid for the register class; 0 if not.
// @return - The proper value.
GENERIC_FIXUP_FUNC(fixupRegValue, insn->regBase, MODRM_REG, 0x1f)
GENERIC_FIXUP_FUNC(fixupRMValue, insn->eaRegBase, EA_REG, 0xf)
// Consult an operand specifier to determine which of the fixup*Value functions
// to use in correcting readModRM()'ss interpretation.
//
// @param insn - See fixup*Value().
// @param op - The operand specifier.
// @return - 0 if fixup was successful; -1 if the register returned was
// invalid for its class.
static int fixupReg(struct InternalInstruction *insn,
const struct OperandSpecifier *op) {
uint8_t valid;
LLVM_DEBUG(dbgs() << "fixupReg()");
switch ((OperandEncoding)op->encoding) {
default:
debug("Expected a REG or R/M encoding in fixupReg");
return -1;
case ENCODING_VVVV:
insn->vvvv =
(Reg)fixupRegValue(insn, (OperandType)op->type, insn->vvvv, &valid);
if (!valid)
return -1;
break;
case ENCODING_REG:
insn->reg = (Reg)fixupRegValue(insn, (OperandType)op->type,
insn->reg - insn->regBase, &valid);
if (!valid)
return -1;
break;
case ENCODING_SIB:
CASE_ENCODING_RM:
if (insn->eaBase >= insn->eaRegBase) {
insn->eaBase = (EABase)fixupRMValue(
insn, (OperandType)op->type, insn->eaBase - insn->eaRegBase, &valid);
if (!valid)
return -1;
}
break;
}
return 0;
}
// Read the opcode (except the ModR/M byte in the case of extended or escape
// opcodes).
static bool readOpcode(struct InternalInstruction *insn) {
uint8_t current;
LLVM_DEBUG(dbgs() << "readOpcode()");
insn->opcodeType = ONEBYTE;
if (insn->vectorExtensionType == TYPE_EVEX) {
switch (mmmFromEVEX2of4(insn->vectorExtensionPrefix[1])) {
default:
LLVM_DEBUG(
dbgs() << format("Unhandled mmm field for instruction (0x%hhx)",
mmmFromEVEX2of4(insn->vectorExtensionPrefix[1])));
return true;
case VEX_LOB_0F:
insn->opcodeType = TWOBYTE;
return consume(insn, insn->opcode);
case VEX_LOB_0F38:
insn->opcodeType = THREEBYTE_38;
return consume(insn, insn->opcode);
case VEX_LOB_0F3A:
insn->opcodeType = THREEBYTE_3A;
return consume(insn, insn->opcode);
case VEX_LOB_MAP5:
insn->opcodeType = MAP5;
return consume(insn, insn->opcode);
case VEX_LOB_MAP6:
insn->opcodeType = MAP6;
return consume(insn, insn->opcode);
}
} else if (insn->vectorExtensionType == TYPE_VEX_3B) {
switch (mmmmmFromVEX2of3(insn->vectorExtensionPrefix[1])) {
default:
LLVM_DEBUG(
dbgs() << format("Unhandled m-mmmm field for instruction (0x%hhx)",
mmmmmFromVEX2of3(insn->vectorExtensionPrefix[1])));
return true;
case VEX_LOB_0F:
insn->opcodeType = TWOBYTE;
return consume(insn, insn->opcode);
case VEX_LOB_0F38:
insn->opcodeType = THREEBYTE_38;
return consume(insn, insn->opcode);
case VEX_LOB_0F3A:
insn->opcodeType = THREEBYTE_3A;
return consume(insn, insn->opcode);
case VEX_LOB_MAP5:
insn->opcodeType = MAP5;
return consume(insn, insn->opcode);
case VEX_LOB_MAP6:
insn->opcodeType = MAP6;
return consume(insn, insn->opcode);
}
} else if (insn->vectorExtensionType == TYPE_VEX_2B) {
insn->opcodeType = TWOBYTE;
return consume(insn, insn->opcode);
} else if (insn->vectorExtensionType == TYPE_XOP) {
switch (mmmmmFromXOP2of3(insn->vectorExtensionPrefix[1])) {
default:
LLVM_DEBUG(
dbgs() << format("Unhandled m-mmmm field for instruction (0x%hhx)",
mmmmmFromVEX2of3(insn->vectorExtensionPrefix[1])));
return true;
case XOP_MAP_SELECT_8:
insn->opcodeType = XOP8_MAP;
return consume(insn, insn->opcode);
case XOP_MAP_SELECT_9:
insn->opcodeType = XOP9_MAP;
return consume(insn, insn->opcode);
case XOP_MAP_SELECT_A:
insn->opcodeType = XOPA_MAP;
return consume(insn, insn->opcode);
}
}
if (consume(insn, current))
return true;
if (current == 0x0f) {
LLVM_DEBUG(
dbgs() << format("Found a two-byte escape prefix (0x%hhx)", current));
if (consume(insn, current))
return true;
if (current == 0x38) {
LLVM_DEBUG(dbgs() << format("Found a three-byte escape prefix (0x%hhx)",
current));
if (consume(insn, current))
return true;
insn->opcodeType = THREEBYTE_38;
} else if (current == 0x3a) {
LLVM_DEBUG(dbgs() << format("Found a three-byte escape prefix (0x%hhx)",
current));
if (consume(insn, current))
return true;
insn->opcodeType = THREEBYTE_3A;
} else if (current == 0x0f) {
LLVM_DEBUG(
dbgs() << format("Found a 3dnow escape prefix (0x%hhx)", current));
// Consume operands before the opcode to comply with the 3DNow encoding
if (readModRM(insn))
return true;
if (consume(insn, current))
return true;
insn->opcodeType = THREEDNOW_MAP;
} else {
LLVM_DEBUG(dbgs() << "Didn't find a three-byte escape prefix");
insn->opcodeType = TWOBYTE;
}
} else if (insn->mandatoryPrefix)
// The opcode with mandatory prefix must start with opcode escape.
// If not it's legacy repeat prefix
insn->mandatoryPrefix = 0;
// At this point we have consumed the full opcode.
// Anything we consume from here on must be unconsumed.
insn->opcode = current;
return false;
}
// Determine whether equiv is the 16-bit equivalent of orig (32-bit or 64-bit).
static bool is16BitEquivalent(const char *orig, const char *equiv) {
for (int i = 0;; i++) {
if (orig[i] == '\0' && equiv[i] == '\0')
return true;
if (orig[i] == '\0' || equiv[i] == '\0')
return false;
if (orig[i] != equiv[i]) {
if ((orig[i] == 'Q' || orig[i] == 'L') && equiv[i] == 'W')
continue;
if ((orig[i] == '6' || orig[i] == '3') && equiv[i] == '1')
continue;
if ((orig[i] == '4' || orig[i] == '2') && equiv[i] == '6')
continue;
return false;
}
}
}
// Determine whether this instruction is a 64-bit instruction.
static bool is64Bit(const char *name) {
for (int i = 0;; ++i) {
if (name[i] == '\0')
return false;
if (name[i] == '6' && name[i + 1] == '4')
return true;
}
}
// Determine the ID of an instruction, consuming the ModR/M byte as appropriate
// for extended and escape opcodes, and using a supplied attribute mask.
static int getInstructionIDWithAttrMask(uint16_t *instructionID,
struct InternalInstruction *insn,
uint16_t attrMask) {
auto insnCtx = InstructionContext(x86DisassemblerContexts[attrMask]);
const ContextDecision *decision;
switch (insn->opcodeType) {
case ONEBYTE:
decision = &ONEBYTE_SYM;
break;
case TWOBYTE:
decision = &TWOBYTE_SYM;
break;
case THREEBYTE_38:
decision = &THREEBYTE38_SYM;
break;
case THREEBYTE_3A:
decision = &THREEBYTE3A_SYM;
break;
case XOP8_MAP:
decision = &XOP8_MAP_SYM;
break;
case XOP9_MAP:
decision = &XOP9_MAP_SYM;
break;
case XOPA_MAP:
decision = &XOPA_MAP_SYM;
break;
case THREEDNOW_MAP:
decision = &THREEDNOW_MAP_SYM;
break;
case MAP5:
decision = &MAP5_SYM;
break;
case MAP6:
decision = &MAP6_SYM;
break;
}
if (decision->opcodeDecisions[insnCtx]
.modRMDecisions[insn->opcode]
.modrm_type != MODRM_ONEENTRY) {
if (readModRM(insn))
return -1;
*instructionID =
decode(insn->opcodeType, insnCtx, insn->opcode, insn->modRM);
} else {
*instructionID = decode(insn->opcodeType, insnCtx, insn->opcode, 0);
}
return 0;
}
// Determine the ID of an instruction, consuming the ModR/M byte as appropriate
// for extended and escape opcodes. Determines the attributes and context for
// the instruction before doing so.
static int getInstructionID(struct InternalInstruction *insn,
const MCInstrInfo *mii) {
uint16_t attrMask;
uint16_t instructionID;
LLVM_DEBUG(dbgs() << "getID()");
attrMask = ATTR_NONE;
if (insn->mode == MODE_64BIT)
attrMask |= ATTR_64BIT;
if (insn->vectorExtensionType != TYPE_NO_VEX_XOP) {
attrMask |= (insn->vectorExtensionType == TYPE_EVEX) ? ATTR_EVEX : ATTR_VEX;
if (insn->vectorExtensionType == TYPE_EVEX) {
switch (ppFromEVEX3of4(insn->vectorExtensionPrefix[2])) {
case VEX_PREFIX_66:
attrMask |= ATTR_OPSIZE;
break;
case VEX_PREFIX_F3:
attrMask |= ATTR_XS;
break;
case VEX_PREFIX_F2:
attrMask |= ATTR_XD;
break;
}
if (zFromEVEX4of4(insn->vectorExtensionPrefix[3]))
attrMask |= ATTR_EVEXKZ;
if (bFromEVEX4of4(insn->vectorExtensionPrefix[3]))
attrMask |= ATTR_EVEXB;
if (aaaFromEVEX4of4(insn->vectorExtensionPrefix[3]))
attrMask |= ATTR_EVEXK;
if (lFromEVEX4of4(insn->vectorExtensionPrefix[3]))
attrMask |= ATTR_VEXL;
if (l2FromEVEX4of4(insn->vectorExtensionPrefix[3]))
attrMask |= ATTR_EVEXL2;
} else if (insn->vectorExtensionType == TYPE_VEX_3B) {
switch (ppFromVEX3of3(insn->vectorExtensionPrefix[2])) {
case VEX_PREFIX_66:
attrMask |= ATTR_OPSIZE;
break;
case VEX_PREFIX_F3:
attrMask |= ATTR_XS;
break;
case VEX_PREFIX_F2:
attrMask |= ATTR_XD;
break;
}
if (lFromVEX3of3(insn->vectorExtensionPrefix[2]))
attrMask |= ATTR_VEXL;
} else if (insn->vectorExtensionType == TYPE_VEX_2B) {
switch (ppFromVEX2of2(insn->vectorExtensionPrefix[1])) {
case VEX_PREFIX_66:
attrMask |= ATTR_OPSIZE;
if (insn->hasAdSize)
attrMask |= ATTR_ADSIZE;
break;
case VEX_PREFIX_F3:
attrMask |= ATTR_XS;
break;
case VEX_PREFIX_F2:
attrMask |= ATTR_XD;
break;
}
if (lFromVEX2of2(insn->vectorExtensionPrefix[1]))
attrMask |= ATTR_VEXL;
} else if (insn->vectorExtensionType == TYPE_XOP) {
switch (ppFromXOP3of3(insn->vectorExtensionPrefix[2])) {
case VEX_PREFIX_66:
attrMask |= ATTR_OPSIZE;
break;
case VEX_PREFIX_F3:
attrMask |= ATTR_XS;
break;
case VEX_PREFIX_F2:
attrMask |= ATTR_XD;
break;
}
if (lFromXOP3of3(insn->vectorExtensionPrefix[2]))
attrMask |= ATTR_VEXL;
} else {
return -1;
}
} else if (!insn->mandatoryPrefix) {
// If we don't have mandatory prefix we should use legacy prefixes here
if (insn->hasOpSize && (insn->mode != MODE_16BIT))
attrMask |= ATTR_OPSIZE;
if (insn->hasAdSize)
attrMask |= ATTR_ADSIZE;
if (insn->opcodeType == ONEBYTE) {
if (insn->repeatPrefix == 0xf3 && (insn->opcode == 0x90))
// Special support for PAUSE
attrMask |= ATTR_XS;
} else {
if (insn->repeatPrefix == 0xf2)
attrMask |= ATTR_XD;
else if (insn->repeatPrefix == 0xf3)
attrMask |= ATTR_XS;
}
} else {
switch (insn->mandatoryPrefix) {
case 0xf2:
attrMask |= ATTR_XD;
break;
case 0xf3:
attrMask |= ATTR_XS;
break;
case 0x66:
if (insn->mode != MODE_16BIT)
attrMask |= ATTR_OPSIZE;
if (insn->hasAdSize)
attrMask |= ATTR_ADSIZE;
break;
case 0x67:
attrMask |= ATTR_ADSIZE;
break;
}
}
if (insn->rexPrefix & 0x08) {
attrMask |= ATTR_REXW;
attrMask &= ~ATTR_ADSIZE;
}
if (insn->mode == MODE_16BIT) {
// JCXZ/JECXZ need special handling for 16-bit mode because the meaning
// of the AdSize prefix is inverted w.r.t. 32-bit mode.
if (insn->opcodeType == ONEBYTE && insn->opcode == 0xE3)
attrMask ^= ATTR_ADSIZE;
// If we're in 16-bit mode and this is one of the relative jumps and opsize
// prefix isn't present, we need to force the opsize attribute since the
// prefix is inverted relative to 32-bit mode.
if (!insn->hasOpSize && insn->opcodeType == ONEBYTE &&
(insn->opcode == 0xE8 || insn->opcode == 0xE9))
attrMask |= ATTR_OPSIZE;
if (!insn->hasOpSize && insn->opcodeType == TWOBYTE &&
insn->opcode >= 0x80 && insn->opcode <= 0x8F)
attrMask |= ATTR_OPSIZE;
}
if (getInstructionIDWithAttrMask(&instructionID, insn, attrMask))
return -1;
// The following clauses compensate for limitations of the tables.
if (insn->mode != MODE_64BIT &&
insn->vectorExtensionType != TYPE_NO_VEX_XOP) {
// The tables can't distinquish between cases where the W-bit is used to
// select register size and cases where its a required part of the opcode.
if ((insn->vectorExtensionType == TYPE_EVEX &&
wFromEVEX3of4(insn->vectorExtensionPrefix[2])) ||
(insn->vectorExtensionType == TYPE_VEX_3B &&
wFromVEX3of3(insn->vectorExtensionPrefix[2])) ||
(insn->vectorExtensionType == TYPE_XOP &&
wFromXOP3of3(insn->vectorExtensionPrefix[2]))) {
uint16_t instructionIDWithREXW;
if (getInstructionIDWithAttrMask(&instructionIDWithREXW, insn,
attrMask | ATTR_REXW)) {
insn->instructionID = instructionID;
insn->spec = &INSTRUCTIONS_SYM[instructionID];
return 0;
}
auto SpecName = mii->getName(instructionIDWithREXW);
// If not a 64-bit instruction. Switch the opcode.
if (!is64Bit(SpecName.data())) {
insn->instructionID = instructionIDWithREXW;
insn->spec = &INSTRUCTIONS_SYM[instructionIDWithREXW];
return 0;
}
}
}
// Absolute moves, umonitor, and movdir64b need special handling.
// -For 16-bit mode because the meaning of the AdSize and OpSize prefixes are
// inverted w.r.t.
// -For 32-bit mode we need to ensure the ADSIZE prefix is observed in
// any position.
if ((insn->opcodeType == ONEBYTE && ((insn->opcode & 0xFC) == 0xA0)) ||
(insn->opcodeType == TWOBYTE && (insn->opcode == 0xAE)) ||
(insn->opcodeType == THREEBYTE_38 && insn->opcode == 0xF8)) {
// Make sure we observed the prefixes in any position.
if (insn->hasAdSize)
attrMask |= ATTR_ADSIZE;
if (insn->hasOpSize)
attrMask |= ATTR_OPSIZE;
// In 16-bit, invert the attributes.
if (insn->mode == MODE_16BIT) {
attrMask ^= ATTR_ADSIZE;
// The OpSize attribute is only valid with the absolute moves.
if (insn->opcodeType == ONEBYTE && ((insn->opcode & 0xFC) == 0xA0))
attrMask ^= ATTR_OPSIZE;
}
if (getInstructionIDWithAttrMask(&instructionID, insn, attrMask))
return -1;
insn->instructionID = instructionID;
insn->spec = &INSTRUCTIONS_SYM[instructionID];
return 0;
}
if ((insn->mode == MODE_16BIT || insn->hasOpSize) &&
!(attrMask & ATTR_OPSIZE)) {
// The instruction tables make no distinction between instructions that
// allow OpSize anywhere (i.e., 16-bit operations) and that need it in a
// particular spot (i.e., many MMX operations). In general we're
// conservative, but in the specific case where OpSize is present but not in
// the right place we check if there's a 16-bit operation.
const struct InstructionSpecifier *spec;
uint16_t instructionIDWithOpsize;
llvm::StringRef specName, specWithOpSizeName;
spec = &INSTRUCTIONS_SYM[instructionID];
if (getInstructionIDWithAttrMask(&instructionIDWithOpsize, insn,
attrMask | ATTR_OPSIZE)) {
// ModRM required with OpSize but not present. Give up and return the
// version without OpSize set.
insn->instructionID = instructionID;
insn->spec = spec;
return 0;
}
specName = mii->getName(instructionID);
specWithOpSizeName = mii->getName(instructionIDWithOpsize);
if (is16BitEquivalent(specName.data(), specWithOpSizeName.data()) &&
(insn->mode == MODE_16BIT) ^ insn->hasOpSize) {
insn->instructionID = instructionIDWithOpsize;
insn->spec = &INSTRUCTIONS_SYM[instructionIDWithOpsize];
} else {
insn->instructionID = instructionID;
insn->spec = spec;
}
return 0;
}
if (insn->opcodeType == ONEBYTE && insn->opcode == 0x90 &&
insn->rexPrefix & 0x01) {
// NOOP shouldn't decode as NOOP if REX.b is set. Instead it should decode
// as XCHG %r8, %eax.
const struct InstructionSpecifier *spec;
uint16_t instructionIDWithNewOpcode;
const struct InstructionSpecifier *specWithNewOpcode;
spec = &INSTRUCTIONS_SYM[instructionID];
// Borrow opcode from one of the other XCHGar opcodes
insn->opcode = 0x91;
if (getInstructionIDWithAttrMask(&instructionIDWithNewOpcode, insn,
attrMask)) {
insn->opcode = 0x90;
insn->instructionID = instructionID;
insn->spec = spec;
return 0;
}
specWithNewOpcode = &INSTRUCTIONS_SYM[instructionIDWithNewOpcode];
// Change back
insn->opcode = 0x90;
insn->instructionID = instructionIDWithNewOpcode;
insn->spec = specWithNewOpcode;
return 0;
}
insn->instructionID = instructionID;
insn->spec = &INSTRUCTIONS_SYM[insn->instructionID];
return 0;
}
// Read an operand from the opcode field of an instruction and interprets it
// appropriately given the operand width. Handles AddRegFrm instructions.
//
// @param insn - the instruction whose opcode field is to be read.
// @param size - The width (in bytes) of the register being specified.
// 1 means AL and friends, 2 means AX, 4 means EAX, and 8 means
// RAX.
// @return - 0 on success; nonzero otherwise.
static int readOpcodeRegister(struct InternalInstruction *insn, uint8_t size) {
LLVM_DEBUG(dbgs() << "readOpcodeRegister()");
if (size == 0)
size = insn->registerSize;
switch (size) {
case 1:
insn->opcodeRegister = (Reg)(
MODRM_REG_AL + ((bFromREX(insn->rexPrefix) << 3) | (insn->opcode & 7)));
if (insn->rexPrefix && insn->opcodeRegister >= MODRM_REG_AL + 0x4 &&
insn->opcodeRegister < MODRM_REG_AL + 0x8) {
insn->opcodeRegister =
(Reg)(MODRM_REG_SPL + (insn->opcodeRegister - MODRM_REG_AL - 4));
}
break;
case 2:
insn->opcodeRegister = (Reg)(
MODRM_REG_AX + ((bFromREX(insn->rexPrefix) << 3) | (insn->opcode & 7)));
break;
case 4:
insn->opcodeRegister =
(Reg)(MODRM_REG_EAX +
((bFromREX(insn->rexPrefix) << 3) | (insn->opcode & 7)));
break;
case 8:
insn->opcodeRegister =
(Reg)(MODRM_REG_RAX +
((bFromREX(insn->rexPrefix) << 3) | (insn->opcode & 7)));
break;
}
return 0;
}
// Consume an immediate operand from an instruction, given the desired operand
// size.
//
// @param insn - The instruction whose operand is to be read.
// @param size - The width (in bytes) of the operand.
// @return - 0 if the immediate was successfully consumed; nonzero
// otherwise.
static int readImmediate(struct InternalInstruction *insn, uint8_t size) {
uint8_t imm8;
uint16_t imm16;
uint32_t imm32;
uint64_t imm64;
LLVM_DEBUG(dbgs() << "readImmediate()");
assert(insn->numImmediatesConsumed < 2 && "Already consumed two immediates");
insn->immediateSize = size;
insn->immediateOffset = insn->readerCursor - insn->startLocation;
switch (size) {
case 1:
if (consume(insn, imm8))
return -1;
insn->immediates[insn->numImmediatesConsumed] = imm8;
break;
case 2:
if (consume(insn, imm16))
return -1;
insn->immediates[insn->numImmediatesConsumed] = imm16;
break;
case 4:
if (consume(insn, imm32))
return -1;
insn->immediates[insn->numImmediatesConsumed] = imm32;
break;
case 8:
if (consume(insn, imm64))
return -1;
insn->immediates[insn->numImmediatesConsumed] = imm64;
break;
default:
llvm_unreachable("invalid size");
}
insn->numImmediatesConsumed++;
return 0;
}
// Consume vvvv from an instruction if it has a VEX prefix.
static int readVVVV(struct InternalInstruction *insn) {
LLVM_DEBUG(dbgs() << "readVVVV()");
int vvvv;
if (insn->vectorExtensionType == TYPE_EVEX)
vvvv = (v2FromEVEX4of4(insn->vectorExtensionPrefix[3]) << 4 |
vvvvFromEVEX3of4(insn->vectorExtensionPrefix[2]));
else if (insn->vectorExtensionType == TYPE_VEX_3B)
vvvv = vvvvFromVEX3of3(insn->vectorExtensionPrefix[2]);
else if (insn->vectorExtensionType == TYPE_VEX_2B)
vvvv = vvvvFromVEX2of2(insn->vectorExtensionPrefix[1]);
else if (insn->vectorExtensionType == TYPE_XOP)
vvvv = vvvvFromXOP3of3(insn->vectorExtensionPrefix[2]);
else
return -1;
if (insn->mode != MODE_64BIT)
vvvv &= 0xf; // Can only clear bit 4. Bit 3 must be cleared later.
insn->vvvv = static_cast<Reg>(vvvv);
return 0;
}
// Read an mask register from the opcode field of an instruction.
//
// @param insn - The instruction whose opcode field is to be read.
// @return - 0 on success; nonzero otherwise.
static int readMaskRegister(struct InternalInstruction *insn) {
LLVM_DEBUG(dbgs() << "readMaskRegister()");
if (insn->vectorExtensionType != TYPE_EVEX)
return -1;
insn->writemask =
static_cast<Reg>(aaaFromEVEX4of4(insn->vectorExtensionPrefix[3]));
return 0;
}
// Consults the specifier for an instruction and consumes all
// operands for that instruction, interpreting them as it goes.
static int readOperands(struct InternalInstruction *insn) {
int hasVVVV, needVVVV;
int sawRegImm = 0;
LLVM_DEBUG(dbgs() << "readOperands()");
// If non-zero vvvv specified, make sure one of the operands uses it.
hasVVVV = !readVVVV(insn);
needVVVV = hasVVVV && (insn->vvvv != 0);
for (const auto &Op : x86OperandSets[insn->spec->operands]) {
switch (Op.encoding) {
case ENCODING_NONE:
case ENCODING_SI:
case ENCODING_DI:
break;
CASE_ENCODING_VSIB:
// VSIB can use the V2 bit so check only the other bits.
if (needVVVV)
needVVVV = hasVVVV & ((insn->vvvv & 0xf) != 0);
if (readModRM(insn))
return -1;
// Reject if SIB wasn't used.
if (insn->eaBase != EA_BASE_sib && insn->eaBase != EA_BASE_sib64)
return -1;
// If sibIndex was set to SIB_INDEX_NONE, index offset is 4.
if (insn->sibIndex == SIB_INDEX_NONE)
insn->sibIndex = (SIBIndex)(insn->sibIndexBase + 4);
// If EVEX.v2 is set this is one of the 16-31 registers.
if (insn->vectorExtensionType == TYPE_EVEX && insn->mode == MODE_64BIT &&
v2FromEVEX4of4(insn->vectorExtensionPrefix[3]))
insn->sibIndex = (SIBIndex)(insn->sibIndex + 16);
// Adjust the index register to the correct size.
switch ((OperandType)Op.type) {
default:
debug("Unhandled VSIB index type");
return -1;
case TYPE_MVSIBX:
insn->sibIndex =
(SIBIndex)(SIB_INDEX_XMM0 + (insn->sibIndex - insn->sibIndexBase));
break;
case TYPE_MVSIBY:
insn->sibIndex =
(SIBIndex)(SIB_INDEX_YMM0 + (insn->sibIndex - insn->sibIndexBase));
break;
case TYPE_MVSIBZ:
insn->sibIndex =
(SIBIndex)(SIB_INDEX_ZMM0 + (insn->sibIndex - insn->sibIndexBase));
break;
}
// Apply the AVX512 compressed displacement scaling factor.
if (Op.encoding != ENCODING_REG && insn->eaDisplacement == EA_DISP_8)
insn->displacement *= 1 << (Op.encoding - ENCODING_VSIB);
break;
case ENCODING_SIB:
// Reject if SIB wasn't used.
if (insn->eaBase != EA_BASE_sib && insn->eaBase != EA_BASE_sib64)
return -1;
if (readModRM(insn))
return -1;
if (fixupReg(insn, &Op))
return -1;
break;
case ENCODING_REG:
CASE_ENCODING_RM:
if (readModRM(insn))
return -1;
if (fixupReg(insn, &Op))
return -1;
// Apply the AVX512 compressed displacement scaling factor.
if (Op.encoding != ENCODING_REG && insn->eaDisplacement == EA_DISP_8)
insn->displacement *= 1 << (Op.encoding - ENCODING_RM);
break;
case ENCODING_IB:
if (sawRegImm) {
// Saw a register immediate so don't read again and instead split the
// previous immediate. FIXME: This is a hack.
insn->immediates[insn->numImmediatesConsumed] =
insn->immediates[insn->numImmediatesConsumed - 1] & 0xf;
++insn->numImmediatesConsumed;
break;
}
if (readImmediate(insn, 1))
return -1;
if (Op.type == TYPE_XMM || Op.type == TYPE_YMM)
sawRegImm = 1;
break;
case ENCODING_IW:
if (readImmediate(insn, 2))
return -1;
break;
case ENCODING_ID:
if (readImmediate(insn, 4))
return -1;
break;
case ENCODING_IO:
if (readImmediate(insn, 8))
return -1;
break;
case ENCODING_Iv:
if (readImmediate(insn, insn->immediateSize))
return -1;
break;
case ENCODING_Ia:
if (readImmediate(insn, insn->addressSize))
return -1;
break;
case ENCODING_IRC:
insn->RC = (l2FromEVEX4of4(insn->vectorExtensionPrefix[3]) << 1) |
lFromEVEX4of4(insn->vectorExtensionPrefix[3]);
break;
case ENCODING_RB:
if (readOpcodeRegister(insn, 1))
return -1;
break;
case ENCODING_RW:
if (readOpcodeRegister(insn, 2))
return -1;
break;
case ENCODING_RD:
if (readOpcodeRegister(insn, 4))
return -1;
break;
case ENCODING_RO:
if (readOpcodeRegister(insn, 8))
return -1;
break;
case ENCODING_Rv:
if (readOpcodeRegister(insn, 0))
return -1;
break;
case ENCODING_CC:
insn->immediates[1] = insn->opcode & 0xf;
break;
case ENCODING_FP:
break;
case ENCODING_VVVV:
needVVVV = 0; // Mark that we have found a VVVV operand.
if (!hasVVVV)
return -1;
if (insn->mode != MODE_64BIT)
insn->vvvv = static_cast<Reg>(insn->vvvv & 0x7);
if (fixupReg(insn, &Op))
return -1;
break;
case ENCODING_WRITEMASK:
if (readMaskRegister(insn))
return -1;
break;
case ENCODING_DUP:
break;
default:
LLVM_DEBUG(dbgs() << "Encountered an operand with an unknown encoding.");
return -1;
}
}
// If we didn't find ENCODING_VVVV operand, but non-zero vvvv present, fail
if (needVVVV)
return -1;
return 0;
}
namespace llvm {
// Fill-ins to make the compiler happy. These constants are never actually
// assigned; they are just filler to make an automatically-generated switch
// statement work.
namespace X86 {
enum {
BX_SI = 500,
BX_DI = 501,
BP_SI = 502,
BP_DI = 503,
sib = 504,
sib64 = 505
};
} // namespace X86
} // namespace llvm
static bool translateInstruction(MCInst &target,
InternalInstruction &source,
const MCDisassembler *Dis);
namespace {
/// Generic disassembler for all X86 platforms. All each platform class should
/// have to do is subclass the constructor, and provide a different
/// disassemblerMode value.
class X86GenericDisassembler : public MCDisassembler {
std::unique_ptr<const MCInstrInfo> MII;
public:
X86GenericDisassembler(const MCSubtargetInfo &STI, MCContext &Ctx,
std::unique_ptr<const MCInstrInfo> MII);
public:
DecodeStatus getInstruction(MCInst &instr, uint64_t &size,
ArrayRef<uint8_t> Bytes, uint64_t Address,
raw_ostream &cStream) const override;
private:
DisassemblerMode fMode;
};
} // namespace
X86GenericDisassembler::X86GenericDisassembler(
const MCSubtargetInfo &STI,
MCContext &Ctx,
std::unique_ptr<const MCInstrInfo> MII)
: MCDisassembler(STI, Ctx), MII(std::move(MII)) {
const FeatureBitset &FB = STI.getFeatureBits();
if (FB[X86::Mode16Bit]) {
fMode = MODE_16BIT;
return;
} else if (FB[X86::Mode32Bit]) {
fMode = MODE_32BIT;
return;
} else if (FB[X86::Mode64Bit]) {
fMode = MODE_64BIT;
return;
}
llvm_unreachable("Invalid CPU mode");
}
MCDisassembler::DecodeStatus X86GenericDisassembler::getInstruction(
MCInst &Instr, uint64_t &Size, ArrayRef<uint8_t> Bytes, uint64_t Address,
raw_ostream &CStream) const {
CommentStream = &CStream;
InternalInstruction Insn;
memset(&Insn, 0, sizeof(InternalInstruction));
Insn.bytes = Bytes;
Insn.startLocation = Address;
Insn.readerCursor = Address;
Insn.mode = fMode;
if (Bytes.empty() || readPrefixes(&Insn) || readOpcode(&Insn) ||
getInstructionID(&Insn, MII.get()) || Insn.instructionID == 0 ||
readOperands(&Insn)) {
Size = Insn.readerCursor - Address;
return Fail;
}
Insn.operands = x86OperandSets[Insn.spec->operands];
Insn.length = Insn.readerCursor - Insn.startLocation;
Size = Insn.length;
if (Size > 15)
LLVM_DEBUG(dbgs() << "Instruction exceeds 15-byte limit");
bool Ret = translateInstruction(Instr, Insn, this);
if (!Ret) {
unsigned Flags = X86::IP_NO_PREFIX;
if (Insn.hasAdSize)
Flags |= X86::IP_HAS_AD_SIZE;
if (!Insn.mandatoryPrefix) {
if (Insn.hasOpSize)
Flags |= X86::IP_HAS_OP_SIZE;
if (Insn.repeatPrefix == 0xf2)
Flags |= X86::IP_HAS_REPEAT_NE;
else if (Insn.repeatPrefix == 0xf3 &&
// It should not be 'pause' f3 90
Insn.opcode != 0x90)
Flags |= X86::IP_HAS_REPEAT;
if (Insn.hasLockPrefix)
Flags |= X86::IP_HAS_LOCK;
}
Instr.setFlags(Flags);
}
return (!Ret) ? Success : Fail;
}
//
// Private code that translates from struct InternalInstructions to MCInsts.
//
/// translateRegister - Translates an internal register to the appropriate LLVM
/// register, and appends it as an operand to an MCInst.
///
/// @param mcInst - The MCInst to append to.
/// @param reg - The Reg to append.
static void translateRegister(MCInst &mcInst, Reg reg) {
#define ENTRY(x) X86::x,
static constexpr MCPhysReg llvmRegnums[] = {ALL_REGS};
#undef ENTRY
MCPhysReg llvmRegnum = llvmRegnums[reg];
mcInst.addOperand(MCOperand::createReg(llvmRegnum));
}
/// tryAddingSymbolicOperand - trys to add a symbolic operand in place of the
/// immediate Value in the MCInst.
///
/// @param Value - The immediate Value, has had any PC adjustment made by
/// the caller.
/// @param isBranch - If the instruction is a branch instruction
/// @param Address - The starting address of the instruction
/// @param Offset - The byte offset to this immediate in the instruction
/// @param Width - The byte width of this immediate in the instruction
///
/// If the getOpInfo() function was set when setupForSymbolicDisassembly() was
/// called then that function is called to get any symbolic information for the
/// immediate in the instruction using the Address, Offset and Width. If that
/// returns non-zero then the symbolic information it returns is used to create
/// an MCExpr and that is added as an operand to the MCInst. If getOpInfo()
/// returns zero and isBranch is true then a symbol look up for immediate Value
/// is done and if a symbol is found an MCExpr is created with that, else
/// an MCExpr with the immediate Value is created. This function returns true
/// if it adds an operand to the MCInst and false otherwise.
static bool tryAddingSymbolicOperand(int64_t Value, bool isBranch,
uint64_t Address, uint64_t Offset,
uint64_t Width, MCInst &MI,
const MCDisassembler *Dis) {
return Dis->tryAddingSymbolicOperand(MI, Value, Address, isBranch,
Offset, Width);
}
/// tryAddingPcLoadReferenceComment - trys to add a comment as to what is being
/// referenced by a load instruction with the base register that is the rip.
/// These can often be addresses in a literal pool. The Address of the
/// instruction and its immediate Value are used to determine the address
/// being referenced in the literal pool entry. The SymbolLookUp call back will
/// return a pointer to a literal 'C' string if the referenced address is an
/// address into a section with 'C' string literals.
static void tryAddingPcLoadReferenceComment(uint64_t Address, uint64_t Value,
const void *Decoder) {
const MCDisassembler *Dis = static_cast<const MCDisassembler*>(Decoder);
Dis->tryAddingPcLoadReferenceComment(Value, Address);
}
static const uint8_t segmentRegnums[SEG_OVERRIDE_max] = {
0, // SEG_OVERRIDE_NONE
X86::CS,
X86::SS,
X86::DS,
X86::ES,
X86::FS,
X86::GS
};
/// translateSrcIndex - Appends a source index operand to an MCInst.
///
/// @param mcInst - The MCInst to append to.
/// @param insn - The internal instruction.
static bool translateSrcIndex(MCInst &mcInst, InternalInstruction &insn) {
unsigned baseRegNo;
if (insn.mode == MODE_64BIT)
baseRegNo = insn.hasAdSize ? X86::ESI : X86::RSI;
else if (insn.mode == MODE_32BIT)
baseRegNo = insn.hasAdSize ? X86::SI : X86::ESI;
else {
assert(insn.mode == MODE_16BIT);
baseRegNo = insn.hasAdSize ? X86::ESI : X86::SI;
}
MCOperand baseReg = MCOperand::createReg(baseRegNo);
mcInst.addOperand(baseReg);
MCOperand segmentReg;
segmentReg = MCOperand::createReg(segmentRegnums[insn.segmentOverride]);
mcInst.addOperand(segmentReg);
return false;
}
/// translateDstIndex - Appends a destination index operand to an MCInst.
///
/// @param mcInst - The MCInst to append to.
/// @param insn - The internal instruction.
static bool translateDstIndex(MCInst &mcInst, InternalInstruction &insn) {
unsigned baseRegNo;
if (insn.mode == MODE_64BIT)
baseRegNo = insn.hasAdSize ? X86::EDI : X86::RDI;
else if (insn.mode == MODE_32BIT)
baseRegNo = insn.hasAdSize ? X86::DI : X86::EDI;
else {
assert(insn.mode == MODE_16BIT);
baseRegNo = insn.hasAdSize ? X86::EDI : X86::DI;
}
MCOperand baseReg = MCOperand::createReg(baseRegNo);
mcInst.addOperand(baseReg);
return false;
}
/// translateImmediate - Appends an immediate operand to an MCInst.
///
/// @param mcInst - The MCInst to append to.
/// @param immediate - The immediate value to append.
/// @param operand - The operand, as stored in the descriptor table.
/// @param insn - The internal instruction.
static void translateImmediate(MCInst &mcInst, uint64_t immediate,
const OperandSpecifier &operand,
InternalInstruction &insn,
const MCDisassembler *Dis) {
// Sign-extend the immediate if necessary.
OperandType type = (OperandType)operand.type;
bool isBranch = false;
uint64_t pcrel = 0;
if (type == TYPE_REL) {
isBranch = true;
pcrel = insn.startLocation +
insn.immediateOffset + insn.immediateSize;
switch (operand.encoding) {
default:
break;
case ENCODING_Iv:
switch (insn.displacementSize) {
default:
break;
case 1:
if(immediate & 0x80)
immediate |= ~(0xffull);
break;
case 2:
if(immediate & 0x8000)
immediate |= ~(0xffffull);
break;
case 4:
if(immediate & 0x80000000)
immediate |= ~(0xffffffffull);
break;
case 8:
break;
}
break;
case ENCODING_IB:
if(immediate & 0x80)
immediate |= ~(0xffull);
break;
case ENCODING_IW:
if(immediate & 0x8000)
immediate |= ~(0xffffull);
break;
case ENCODING_ID:
if(immediate & 0x80000000)
immediate |= ~(0xffffffffull);
break;
}
}
// By default sign-extend all X86 immediates based on their encoding.
else if (type == TYPE_IMM) {
switch (operand.encoding) {
default:
break;
case ENCODING_IB:
if(immediate & 0x80)
immediate |= ~(0xffull);
break;
case ENCODING_IW:
if(immediate & 0x8000)
immediate |= ~(0xffffull);
break;
case ENCODING_ID:
if(immediate & 0x80000000)
immediate |= ~(0xffffffffull);
break;
case ENCODING_IO:
break;
}
}
switch (type) {
case TYPE_XMM:
mcInst.addOperand(MCOperand::createReg(X86::XMM0 + (immediate >> 4)));
return;
case TYPE_YMM:
mcInst.addOperand(MCOperand::createReg(X86::YMM0 + (immediate >> 4)));
return;
case TYPE_ZMM:
mcInst.addOperand(MCOperand::createReg(X86::ZMM0 + (immediate >> 4)));
return;
default:
// operand is 64 bits wide. Do nothing.
break;
}
if(!tryAddingSymbolicOperand(immediate + pcrel, isBranch, insn.startLocation,
insn.immediateOffset, insn.immediateSize,
mcInst, Dis))
mcInst.addOperand(MCOperand::createImm(immediate));
if (type == TYPE_MOFFS) {
MCOperand segmentReg;
segmentReg = MCOperand::createReg(segmentRegnums[insn.segmentOverride]);
mcInst.addOperand(segmentReg);
}
}
/// translateRMRegister - Translates a register stored in the R/M field of the
/// ModR/M byte to its LLVM equivalent and appends it to an MCInst.
/// @param mcInst - The MCInst to append to.
/// @param insn - The internal instruction to extract the R/M field
/// from.
/// @return - 0 on success; -1 otherwise
static bool translateRMRegister(MCInst &mcInst,
InternalInstruction &insn) {
if (insn.eaBase == EA_BASE_sib || insn.eaBase == EA_BASE_sib64) {
debug("A R/M register operand may not have a SIB byte");
return true;
}
switch (insn.eaBase) {
default:
debug("Unexpected EA base register");
return true;
case EA_BASE_NONE:
debug("EA_BASE_NONE for ModR/M base");
return true;
#define ENTRY(x) case EA_BASE_##x:
ALL_EA_BASES
#undef ENTRY
debug("A R/M register operand may not have a base; "
"the operand must be a register.");
return true;
#define ENTRY(x) \
case EA_REG_##x: \
mcInst.addOperand(MCOperand::createReg(X86::x)); break;
ALL_REGS
#undef ENTRY
}
return false;
}
/// translateRMMemory - Translates a memory operand stored in the Mod and R/M
/// fields of an internal instruction (and possibly its SIB byte) to a memory
/// operand in LLVM's format, and appends it to an MCInst.
///
/// @param mcInst - The MCInst to append to.
/// @param insn - The instruction to extract Mod, R/M, and SIB fields
/// from.
/// @param ForceSIB - The instruction must use SIB.
/// @return - 0 on success; nonzero otherwise
static bool translateRMMemory(MCInst &mcInst, InternalInstruction &insn,
const MCDisassembler *Dis,
bool ForceSIB = false) {
// Addresses in an MCInst are represented as five operands:
// 1. basereg (register) The R/M base, or (if there is a SIB) the
// SIB base
// 2. scaleamount (immediate) 1, or (if there is a SIB) the specified
// scale amount
// 3. indexreg (register) x86_registerNONE, or (if there is a SIB)
// the index (which is multiplied by the
// scale amount)
// 4. displacement (immediate) 0, or the displacement if there is one
// 5. segmentreg (register) x86_registerNONE for now, but could be set
// if we have segment overrides
MCOperand baseReg;
MCOperand scaleAmount;
MCOperand indexReg;
MCOperand displacement;
MCOperand segmentReg;
uint64_t pcrel = 0;
if (insn.eaBase == EA_BASE_sib || insn.eaBase == EA_BASE_sib64) {
if (insn.sibBase != SIB_BASE_NONE) {
switch (insn.sibBase) {
default:
debug("Unexpected sibBase");
return true;
#define ENTRY(x) \
case SIB_BASE_##x: \
baseReg = MCOperand::createReg(X86::x); break;
ALL_SIB_BASES
#undef ENTRY
}
} else {
baseReg = MCOperand::createReg(X86::NoRegister);
}
if (insn.sibIndex != SIB_INDEX_NONE) {
switch (insn.sibIndex) {
default:
debug("Unexpected sibIndex");
return true;
#define ENTRY(x) \
case SIB_INDEX_##x: \
indexReg = MCOperand::createReg(X86::x); break;
EA_BASES_32BIT
EA_BASES_64BIT
REGS_XMM
REGS_YMM
REGS_ZMM
#undef ENTRY
}
} else {
// Use EIZ/RIZ for a few ambiguous cases where the SIB byte is present,
// but no index is used and modrm alone should have been enough.
// -No base register in 32-bit mode. In 64-bit mode this is used to
// avoid rip-relative addressing.
// -Any base register used other than ESP/RSP/R12D/R12. Using these as a
// base always requires a SIB byte.
// -A scale other than 1 is used.
if (!ForceSIB &&
(insn.sibScale != 1 ||
(insn.sibBase == SIB_BASE_NONE && insn.mode != MODE_64BIT) ||
(insn.sibBase != SIB_BASE_NONE &&
insn.sibBase != SIB_BASE_ESP && insn.sibBase != SIB_BASE_RSP &&
insn.sibBase != SIB_BASE_R12D && insn.sibBase != SIB_BASE_R12))) {
indexReg = MCOperand::createReg(insn.addressSize == 4 ? X86::EIZ :
X86::RIZ);
} else
indexReg = MCOperand::createReg(X86::NoRegister);
}
scaleAmount = MCOperand::createImm(insn.sibScale);
} else {
switch (insn.eaBase) {
case EA_BASE_NONE:
if (insn.eaDisplacement == EA_DISP_NONE) {
debug("EA_BASE_NONE and EA_DISP_NONE for ModR/M base");
return true;
}
if (insn.mode == MODE_64BIT){
pcrel = insn.startLocation +
insn.displacementOffset + insn.displacementSize;
tryAddingPcLoadReferenceComment(insn.startLocation +
insn.displacementOffset,
insn.displacement + pcrel, Dis);
// Section 2.2.1.6
baseReg = MCOperand::createReg(insn.addressSize == 4 ? X86::EIP :
X86::RIP);
}
else
baseReg = MCOperand::createReg(X86::NoRegister);
indexReg = MCOperand::createReg(X86::NoRegister);
break;
case EA_BASE_BX_SI:
baseReg = MCOperand::createReg(X86::BX);
indexReg = MCOperand::createReg(X86::SI);
break;
case EA_BASE_BX_DI:
baseReg = MCOperand::createReg(X86::BX);
indexReg = MCOperand::createReg(X86::DI);
break;
case EA_BASE_BP_SI:
baseReg = MCOperand::createReg(X86::BP);
indexReg = MCOperand::createReg(X86::SI);
break;
case EA_BASE_BP_DI:
baseReg = MCOperand::createReg(X86::BP);
indexReg = MCOperand::createReg(X86::DI);
break;
default:
indexReg = MCOperand::createReg(X86::NoRegister);
switch (insn.eaBase) {
default:
debug("Unexpected eaBase");
return true;
// Here, we will use the fill-ins defined above. However,
// BX_SI, BX_DI, BP_SI, and BP_DI are all handled above and
// sib and sib64 were handled in the top-level if, so they're only
// placeholders to keep the compiler happy.
#define ENTRY(x) \
case EA_BASE_##x: \
baseReg = MCOperand::createReg(X86::x); break;
ALL_EA_BASES
#undef ENTRY
#define ENTRY(x) case EA_REG_##x:
ALL_REGS
#undef ENTRY
debug("A R/M memory operand may not be a register; "
"the base field must be a base.");
return true;
}
}
scaleAmount = MCOperand::createImm(1);
}
displacement = MCOperand::createImm(insn.displacement);
segmentReg = MCOperand::createReg(segmentRegnums[insn.segmentOverride]);
mcInst.addOperand(baseReg);
mcInst.addOperand(scaleAmount);
mcInst.addOperand(indexReg);
if(!tryAddingSymbolicOperand(insn.displacement + pcrel, false,
insn.startLocation, insn.displacementOffset,
insn.displacementSize, mcInst, Dis))
mcInst.addOperand(displacement);
mcInst.addOperand(segmentReg);
return false;
}
/// translateRM - Translates an operand stored in the R/M (and possibly SIB)
/// byte of an instruction to LLVM form, and appends it to an MCInst.
///
/// @param mcInst - The MCInst to append to.
/// @param operand - The operand, as stored in the descriptor table.
/// @param insn - The instruction to extract Mod, R/M, and SIB fields
/// from.
/// @return - 0 on success; nonzero otherwise
static bool translateRM(MCInst &mcInst, const OperandSpecifier &operand,
InternalInstruction &insn, const MCDisassembler *Dis) {
switch (operand.type) {
default:
debug("Unexpected type for a R/M operand");
return true;
case TYPE_R8:
case TYPE_R16:
case TYPE_R32:
case TYPE_R64:
case TYPE_Rv:
case TYPE_MM64:
case TYPE_XMM:
case TYPE_YMM:
case TYPE_ZMM:
case TYPE_TMM:
case TYPE_VK_PAIR:
case TYPE_VK:
case TYPE_DEBUGREG:
case TYPE_CONTROLREG:
case TYPE_BNDR:
return translateRMRegister(mcInst, insn);
case TYPE_M:
case TYPE_MVSIBX:
case TYPE_MVSIBY:
case TYPE_MVSIBZ:
return translateRMMemory(mcInst, insn, Dis);
case TYPE_MSIB:
return translateRMMemory(mcInst, insn, Dis, true);
}
}
/// translateFPRegister - Translates a stack position on the FPU stack to its
/// LLVM form, and appends it to an MCInst.
///
/// @param mcInst - The MCInst to append to.
/// @param stackPos - The stack position to translate.
static void translateFPRegister(MCInst &mcInst,
uint8_t stackPos) {
mcInst.addOperand(MCOperand::createReg(X86::ST0 + stackPos));
}
/// translateMaskRegister - Translates a 3-bit mask register number to
/// LLVM form, and appends it to an MCInst.
///
/// @param mcInst - The MCInst to append to.
/// @param maskRegNum - Number of mask register from 0 to 7.
/// @return - false on success; true otherwise.
static bool translateMaskRegister(MCInst &mcInst,
uint8_t maskRegNum) {
if (maskRegNum >= 8) {
debug("Invalid mask register number");
return true;
}
mcInst.addOperand(MCOperand::createReg(X86::K0 + maskRegNum));
return false;
}
/// translateOperand - Translates an operand stored in an internal instruction
/// to LLVM's format and appends it to an MCInst.
///
/// @param mcInst - The MCInst to append to.
/// @param operand - The operand, as stored in the descriptor table.
/// @param insn - The internal instruction.
/// @return - false on success; true otherwise.
static bool translateOperand(MCInst &mcInst, const OperandSpecifier &operand,
InternalInstruction &insn,
const MCDisassembler *Dis) {
switch (operand.encoding) {
default:
debug("Unhandled operand encoding during translation");
return true;
case ENCODING_REG:
translateRegister(mcInst, insn.reg);
return false;
case ENCODING_WRITEMASK:
return translateMaskRegister(mcInst, insn.writemask);
case ENCODING_SIB:
CASE_ENCODING_RM:
CASE_ENCODING_VSIB:
return translateRM(mcInst, operand, insn, Dis);
case ENCODING_IB:
case ENCODING_IW:
case ENCODING_ID:
case ENCODING_IO:
case ENCODING_Iv:
case ENCODING_Ia:
translateImmediate(mcInst,
insn.immediates[insn.numImmediatesTranslated++],
operand,
insn,
Dis);
return false;
case ENCODING_IRC:
mcInst.addOperand(MCOperand::createImm(insn.RC));
return false;
case ENCODING_SI:
return translateSrcIndex(mcInst, insn);
case ENCODING_DI:
return translateDstIndex(mcInst, insn);
case ENCODING_RB:
case ENCODING_RW:
case ENCODING_RD:
case ENCODING_RO:
case ENCODING_Rv:
translateRegister(mcInst, insn.opcodeRegister);
return false;
case ENCODING_CC:
mcInst.addOperand(MCOperand::createImm(insn.immediates[1]));
return false;
case ENCODING_FP:
translateFPRegister(mcInst, insn.modRM & 7);
return false;
case ENCODING_VVVV:
translateRegister(mcInst, insn.vvvv);
return false;
case ENCODING_DUP:
return translateOperand(mcInst, insn.operands[operand.type - TYPE_DUP0],
insn, Dis);
}
}
/// translateInstruction - Translates an internal instruction and all its
/// operands to an MCInst.
///
/// @param mcInst - The MCInst to populate with the instruction's data.
/// @param insn - The internal instruction.
/// @return - false on success; true otherwise.
static bool translateInstruction(MCInst &mcInst,
InternalInstruction &insn,
const MCDisassembler *Dis) {
if (!insn.spec) {
debug("Instruction has no specification");
return true;
}
mcInst.clear();
mcInst.setOpcode(insn.instructionID);
// If when reading the prefix bytes we determined the overlapping 0xf2 or 0xf3
// prefix bytes should be disassembled as xrelease and xacquire then set the
// opcode to those instead of the rep and repne opcodes.
if (insn.xAcquireRelease) {
if(mcInst.getOpcode() == X86::REP_PREFIX)
mcInst.setOpcode(X86::XRELEASE_PREFIX);
else if(mcInst.getOpcode() == X86::REPNE_PREFIX)
mcInst.setOpcode(X86::XACQUIRE_PREFIX);
}
insn.numImmediatesTranslated = 0;
for (const auto &Op : insn.operands) {
if (Op.encoding != ENCODING_NONE) {
if (translateOperand(mcInst, Op, insn, Dis)) {
return true;
}
}
}
return false;
}
static MCDisassembler *createX86Disassembler(const Target &T,
const MCSubtargetInfo &STI,
MCContext &Ctx) {
std::unique_ptr<const MCInstrInfo> MII(T.createMCInstrInfo());
return new X86GenericDisassembler(STI, Ctx, std::move(MII));
}
extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeX86Disassembler() {
// Register the disassembler.
TargetRegistry::RegisterMCDisassembler(getTheX86_32Target(),
createX86Disassembler);
TargetRegistry::RegisterMCDisassembler(getTheX86_64Target(),
createX86Disassembler);
}