1 //===- MC-X86Specific.cpp - X86-Specific code for MC ----------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements X86-specific parsing, encoding and decoding stuff for
13 //===----------------------------------------------------------------------===//
15 #include "AsmParser.h"
16 #include "llvm/MC/MCInst.h"
17 #include "llvm/Support/SourceMgr.h"
20 /// X86Operand - Instances of this class represent one X86 machine instruction.
21 struct AsmParser::X86Operand {
46 unsigned getReg() const {
47 assert(Kind == Register && "Invalid access!");
51 static X86Operand CreateReg(unsigned RegNo) {
54 Res.Reg.RegNo = RegNo;
57 static X86Operand CreateImm(MCValue Val) {
63 static X86Operand CreateMem(unsigned SegReg, MCValue Disp, unsigned BaseReg,
64 unsigned IndexReg, unsigned Scale) {
65 // If there is no index register, we should never have a scale, and we
66 // should always have a scale (in {1,2,4,8}) if we do.
67 assert(((Scale == 0 && !IndexReg) ||
68 (IndexReg && (Scale == 1 || Scale == 2 ||
69 Scale == 4 || Scale == 8))) &&
73 Res.Mem.SegReg = SegReg;
75 Res.Mem.BaseReg = BaseReg;
76 Res.Mem.IndexReg = IndexReg;
77 Res.Mem.Scale = Scale;
82 bool AsmParser::ParseX86Register(X86Operand &Op) {
83 assert(Lexer.getKind() == asmtok::Register && "Invalid token kind!");
85 // FIXME: Decode register number.
86 Op = X86Operand::CreateReg(123);
87 Lexer.Lex(); // Eat register token.
92 bool AsmParser::ParseX86Operand(X86Operand &Op) {
93 switch (Lexer.getKind()) {
95 return ParseX86MemOperand(Op);
96 case asmtok::Register:
97 // FIXME: if a segment register, this could either be just the seg reg, or
98 // the start of a memory operand.
99 return ParseX86Register(Op);
100 case asmtok::Dollar: {
104 if (ParseRelocatableExpression(Val))
106 Op = X86Operand::CreateImm(Val);
110 Lexer.Lex(); // Eat the star.
112 if (Lexer.is(asmtok::Register)) {
113 if (ParseX86Register(Op))
115 } else if (ParseX86MemOperand(Op))
118 // FIXME: Note the '*' in the operand for use by the matcher.
124 /// ParseX86MemOperand: segment: disp(basereg, indexreg, scale)
125 bool AsmParser::ParseX86MemOperand(X86Operand &Op) {
126 // FIXME: If SegReg ':' (e.g. %gs:), eat and remember.
129 // We have to disambiguate a parenthesized expression "(4+5)" from the start
130 // of a memory operand with a missing displacement "(%ebx)" or "(,%eax)". The
131 // only way to do this without lookahead is to eat the ( and see what is after
133 MCValue Disp = MCValue::get(0, 0, 0);
134 if (Lexer.isNot(asmtok::LParen)) {
135 if (ParseRelocatableExpression(Disp)) return true;
137 // After parsing the base expression we could either have a parenthesized
138 // memory address or not. If not, return now. If so, eat the (.
139 if (Lexer.isNot(asmtok::LParen)) {
140 Op = X86Operand::CreateMem(SegReg, Disp, 0, 0, 0);
147 // Okay, we have a '('. We don't know if this is an expression or not, but
148 // so we have to eat the ( to see beyond it.
149 Lexer.Lex(); // Eat the '('.
151 if (Lexer.is(asmtok::Register) || Lexer.is(asmtok::Comma)) {
152 // Nothing to do here, fall into the code below with the '(' part of the
153 // memory operand consumed.
155 // It must be an parenthesized expression, parse it now.
156 if (ParseParenRelocatableExpression(Disp))
159 // After parsing the base expression we could either have a parenthesized
160 // memory address or not. If not, return now. If so, eat the (.
161 if (Lexer.isNot(asmtok::LParen)) {
162 Op = X86Operand::CreateMem(SegReg, Disp, 0, 0, 0);
171 // If we reached here, then we just ate the ( of the memory operand. Process
172 // the rest of the memory operand.
173 unsigned BaseReg = 0, IndexReg = 0, Scale = 0;
175 if (Lexer.is(asmtok::Register)) {
176 if (ParseX86Register(Op))
178 BaseReg = Op.getReg();
181 if (Lexer.is(asmtok::Comma)) {
182 Lexer.Lex(); // Eat the comma.
184 // Following the comma we should have either an index register, or a scale
185 // value. We don't support the later form, but we want to parse it
188 // Not that even though it would be completely consistent to support syntax
189 // like "1(%eax,,1)", the assembler doesn't.
190 if (Lexer.is(asmtok::Register)) {
191 if (ParseX86Register(Op))
193 IndexReg = Op.getReg();
194 Scale = 1; // If not specified, the scale defaults to 1.
196 if (Lexer.isNot(asmtok::RParen)) {
197 // Parse the scale amount:
198 // ::= ',' [scale-expression]
199 if (Lexer.isNot(asmtok::Comma))
201 Lexer.Lex(); // Eat the comma.
203 if (Lexer.isNot(asmtok::RParen)) {
205 if (ParseAbsoluteExpression(ScaleVal))
208 // Validate the scale amount.
209 if (ScaleVal != 1 && ScaleVal != 2 && ScaleVal != 4 && ScaleVal != 8)
210 return TokError("scale factor in address must be 1, 2, 4 or 8");
211 Scale = (unsigned)ScaleVal;
214 } else if (Lexer.isNot(asmtok::RParen)) {
215 // Otherwise we have the unsupported form of a scale amount without an
217 SMLoc Loc = Lexer.getLoc();
220 if (ParseAbsoluteExpression(Value))
223 return Error(Loc, "cannot have scale factor without index register");
227 // Ok, we've eaten the memory operand, verify we have a ')' and eat it too.
228 if (Lexer.isNot(asmtok::RParen))
229 return TokError("unexpected token in memory operand");
230 Lexer.Lex(); // Eat the ')'.
232 Op = X86Operand::CreateMem(SegReg, Disp, BaseReg, IndexReg, Scale);
236 /// MatchX86Inst - Convert a parsed instruction name and operand list into a
237 /// concrete instruction.
238 static bool MatchX86Inst(const StringRef &Name,
239 llvm::SmallVector<AsmParser::X86Operand, 3> &Operands,
244 /// ParseX86InstOperands - Parse the operands of an X86 instruction and return
245 /// them as the operands of an MCInst.
246 bool AsmParser::ParseX86InstOperands(const StringRef &InstName, MCInst &Inst) {
247 llvm::SmallVector<X86Operand, 3> Operands;
249 if (Lexer.isNot(asmtok::EndOfStatement)) {
250 // Read the first operand.
251 Operands.push_back(X86Operand());
252 if (ParseX86Operand(Operands.back()))
255 while (Lexer.is(asmtok::Comma)) {
256 Lexer.Lex(); // Eat the comma.
258 // Parse and remember the operand.
259 Operands.push_back(X86Operand());
260 if (ParseX86Operand(Operands.back()))
265 return MatchX86Inst(InstName, Operands, Inst);