| //===- MC-X86Specific.cpp - X86-Specific code for MC ----------------------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file implements X86-specific parsing, encoding and decoding stuff for |
| // MC. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "AsmParser.h" |
| #include "llvm/MC/MCInst.h" |
| using namespace llvm; |
| |
| /// X86Operand - Instances of this class represent one X86 machine instruction. |
| struct AsmParser::X86Operand { |
| enum { |
| Register, |
| Immediate, |
| Memory |
| } Kind; |
| |
| union { |
| struct { |
| unsigned RegNo; |
| } Reg; |
| |
| struct { |
| // FIXME: Should be a general expression. |
| int64_t Val; |
| } Imm; |
| |
| struct { |
| unsigned SegReg; |
| int64_t Disp; // FIXME: Should be a general expression. |
| unsigned BaseReg; |
| unsigned Scale; |
| unsigned ScaleReg; |
| } Mem; |
| }; |
| |
| static X86Operand CreateReg(unsigned RegNo) { |
| X86Operand Res; |
| Res.Kind = Register; |
| Res.Reg.RegNo = RegNo; |
| return Res; |
| } |
| static X86Operand CreateImm(int64_t Val) { |
| X86Operand Res; |
| Res.Kind = Immediate; |
| Res.Imm.Val = Val; |
| return Res; |
| } |
| static X86Operand CreateMem(unsigned SegReg, int64_t Disp, unsigned BaseReg, |
| unsigned Scale, unsigned ScaleReg) { |
| X86Operand Res; |
| Res.Kind = Memory; |
| Res.Mem.SegReg = SegReg; |
| Res.Mem.Disp = Disp; |
| Res.Mem.BaseReg = BaseReg; |
| Res.Mem.Scale = Scale; |
| Res.Mem.ScaleReg = ScaleReg; |
| return Res; |
| } |
| |
| void AddToMCInst(MCInst &I) { |
| // FIXME: Add in x86 order here. |
| } |
| }; |
| |
| bool AsmParser::ParseX86Operand(X86Operand &Op) { |
| switch (Lexer.getKind()) { |
| default: |
| return ParseX86MemOperand(Op); |
| case asmtok::Register: |
| // FIXME: Decode reg #. |
| // FIXME: if a segment register, this could either be just the seg reg, or |
| // the start of a memory operand. |
| Op = X86Operand::CreateReg(123); |
| Lexer.Lex(); // Eat register. |
| return false; |
| case asmtok::Dollar: { |
| // $42 -> immediate. |
| Lexer.Lex(); |
| int64_t Val; |
| if (ParseAbsoluteExpression(Val)) |
| return TokError("expected integer constant"); |
| Op = X86Operand::CreateReg(Val); |
| return false; |
| case asmtok::Star: |
| Lexer.Lex(); // Eat the star. |
| |
| if (Lexer.is(asmtok::Register)) { |
| Op = X86Operand::CreateReg(123); |
| Lexer.Lex(); // Eat register. |
| } else if (ParseX86MemOperand(Op)) |
| return true; |
| |
| // FIXME: Note that these are 'dereferenced' so that clients know the '*' is |
| // there. |
| return false; |
| } |
| } |
| } |
| |
| /// ParseX86MemOperand: segment: disp(basereg, indexreg, scale) |
| bool AsmParser::ParseX86MemOperand(X86Operand &Op) { |
| // FIXME: If SegReg ':' (e.g. %gs:), eat and remember. |
| unsigned SegReg = 0; |
| |
| // We have to disambiguate a parenthesized expression "(4+5)" from the start |
| // of a memory operand with a missing displacement "(%ebx)" or "(,%eax)". The |
| // only way to do this without lookahead is to eat the ( and see what is after |
| // it. |
| int64_t Disp = 0; |
| if (Lexer.isNot(asmtok::LParen)) { |
| if (ParseAbsoluteExpression(Disp)) return true; |
| |
| // After parsing the base expression we could either have a parenthesized |
| // memory address or not. If not, return now. If so, eat the (. |
| if (Lexer.isNot(asmtok::LParen)) { |
| Op = X86Operand::CreateMem(SegReg, Disp, 0, 0, 0); |
| return false; |
| } |
| |
| // Eat the '('. |
| Lexer.Lex(); |
| } else { |
| // Okay, we have a '('. We don't know if this is an expression or not, but |
| // so we have to eat the ( to see beyond it. |
| Lexer.Lex(); // Eat the '('. |
| |
| if (Lexer.is(asmtok::Register) || Lexer.is(asmtok::Comma)) { |
| // Nothing to do here, fall into the code below with the '(' part of the |
| // memory operand consumed. |
| } else { |
| // It must be an parenthesized expression, parse it now. |
| if (ParseAbsoluteExpression(Disp)) |
| return true; |
| |
| // After parsing the base expression we could either have a parenthesized |
| // memory address or not. If not, return now. If so, eat the (. |
| if (Lexer.isNot(asmtok::LParen)) { |
| Op = X86Operand::CreateMem(SegReg, Disp, 0, 0, 0); |
| return false; |
| } |
| |
| // Eat the '('. |
| Lexer.Lex(); |
| } |
| } |
| |
| // If we reached here, then we just ate the ( of the memory operand. Process |
| // the rest of the memory operand. |
| unsigned BaseReg = 0, ScaleReg = 0, Scale = 0; |
| |
| if (Lexer.is(asmtok::Register)) { |
| BaseReg = 123; // FIXME: decode reg # |
| Lexer.Lex(); // eat the register. |
| } |
| |
| if (Lexer.is(asmtok::Comma)) { |
| Lexer.Lex(); // eat the comma. |
| |
| if (Lexer.is(asmtok::Register)) { |
| ScaleReg = 123; // FIXME: decode reg # |
| Lexer.Lex(); // eat the register. |
| Scale = 1; // If not specified, the scale defaults to 1. |
| } |
| |
| if (Lexer.is(asmtok::Comma)) { |
| Lexer.Lex(); // eat the comma. |
| |
| // If present, get and validate scale amount. |
| if (Lexer.is(asmtok::IntVal)) { |
| int64_t ScaleVal = Lexer.getCurIntVal(); |
| if (ScaleVal != 1 && ScaleVal != 2 && ScaleVal != 4 && ScaleVal != 8) |
| return TokError("scale factor in address must be 1, 2, 4 or 8"); |
| Lexer.Lex(); // eat the scale. |
| Scale = (unsigned)ScaleVal; |
| } |
| } |
| } |
| |
| // Ok, we've eaten the memory operand, verify we have a ')' and eat it too. |
| if (Lexer.isNot(asmtok::RParen)) |
| return TokError("unexpected token in memory operand"); |
| Lexer.Lex(); // Eat the ')'. |
| |
| Op = X86Operand::CreateMem(SegReg, Disp, BaseReg, Scale, ScaleReg); |
| return false; |
| } |
| |
| /// ParseX86InstOperands - Parse the operands of an X86 instruction and return |
| /// them as the operands of an MCInst. |
| bool AsmParser::ParseX86InstOperands(MCInst &Inst) { |
| // If no operands are present, just return. |
| if (Lexer.is(asmtok::EndOfStatement)) |
| return false; |
| |
| // Read the first operand. |
| X86Operand Op; |
| if (ParseX86Operand(Op)) |
| return true; |
| Op.AddToMCInst(Inst); |
| |
| while (Lexer.is(asmtok::Comma)) { |
| Lexer.Lex(); // Eat the comma. |
| |
| // Parse and remember the operand. |
| Op = X86Operand(); |
| if (ParseX86Operand(Op)) |
| return true; |
| Op.AddToMCInst(Inst); |
| } |
| return false; |
| } |