1 files changed, 351 insertions, 0 deletions
diff --git a/tools/llvm-mc/AsmParser.cpp b/tools/llvm-mc/AsmParser.cpp
new file mode 100644
index 0000000..715ff39
--- /dev/null
+++ b/tools/llvm-mc/AsmParser.cpp
@@ -0,0 +1,351 @@
+//===- AsmParser.cpp - Parser for Assembly Files --------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This class implements the parser for assembly files.
+//
+//===----------------------------------------------------------------------===//
+
+#include "AsmParser.h"
+#include "llvm/Support/SourceMgr.h"
+#include "llvm/Support/raw_ostream.h"
+using namespace llvm;
+
+bool AsmParser::Error(SMLoc L, const char *Msg) {
+  Lexer.PrintMessage(L, Msg);
+  return true;
+}
+
+bool AsmParser::TokError(const char *Msg) {
+  Lexer.PrintMessage(Lexer.getLoc(), Msg);
+  return true;
+}
+
+bool AsmParser::Run() {
+  // Prime the lexer.
+  Lexer.Lex();
+  
+  while (Lexer.isNot(asmtok::Eof))
+    if (ParseStatement())
+      return true;
+  
+  return false;
+}
+
+/// EatToEndOfStatement - Throw away the rest of the line for testing purposes.
+void AsmParser::EatToEndOfStatement() {
+  while (Lexer.isNot(asmtok::EndOfStatement) &&
+         Lexer.isNot(asmtok::Eof))
+    Lexer.Lex();
+  
+  // Eat EOL.
+  if (Lexer.is(asmtok::EndOfStatement))
+    Lexer.Lex();
+}
+
+
+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;
+  }
+};
+
+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 (ParseExpression(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 (ParseExpression(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 (ParseParenExpr(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;
+}
+
+/// ParseParenExpr - Parse a paren expression and return it.
+/// NOTE: This assumes the leading '(' has already been consumed.
+///
+/// parenexpr ::= expr)
+///
+bool AsmParser::ParseParenExpr(int64_t &Res) {
+  if (ParseExpression(Res)) return true;
+  if (Lexer.isNot(asmtok::RParen))
+    return TokError("expected ')' in parentheses expression");
+  Lexer.Lex();
+  return false;
+}
+
+/// ParsePrimaryExpr - Parse a primary expression and return it.
+///  primaryexpr ::= (parenexpr
+///  primaryexpr ::= symbol
+///  primaryexpr ::= number
+///  primaryexpr ::= ~,+,- primaryexpr
+bool AsmParser::ParsePrimaryExpr(int64_t &Res) {
+  switch (Lexer.getKind()) {
+  default:
+    return TokError("unknown token in expression");
+  case asmtok::Identifier:
+    // This is a label, this should be parsed as part of an expression, to
+    // handle things like LFOO+4
+    Res = 0; // FIXME.
+    Lexer.Lex(); // Eat identifier.
+    return false;
+  case asmtok::IntVal:
+    Res = Lexer.getCurIntVal();
+    Lexer.Lex(); // Eat identifier.
+    return false;
+  case asmtok::LParen:
+    Lexer.Lex(); // Eat the '('.
+    return ParseParenExpr(Res);
+  case asmtok::Tilde:
+  case asmtok::Plus:
+  case asmtok::Minus:
+    Lexer.Lex(); // Eat the operator.
+    return ParsePrimaryExpr(Res);
+  }
+}
+
+/// ParseExpression - Parse an expression and return it.
+/// 
+///  expr ::= expr +,- expr          -> lowest.
+///  expr ::= expr |,^,&,! expr      -> middle.
+///  expr ::= expr *,/,%,<<,>> expr  -> highest.
+///  expr ::= primaryexpr
+///
+bool AsmParser::ParseExpression(int64_t &Res) {
+  return ParsePrimaryExpr(Res);
+}
+  
+  
+  
+  
+/// ParseStatement:
+///   ::= EndOfStatement
+///   ::= Label* Directive ...Operands... EndOfStatement
+///   ::= Label* Identifier OperandList* EndOfStatement
+bool AsmParser::ParseStatement() {
+  switch (Lexer.getKind()) {
+  default:
+    return TokError("unexpected token at start of statement");
+  case asmtok::EndOfStatement:
+    Lexer.Lex();
+    return false;
+  case asmtok::Identifier:
+    break;
+  // TODO: Recurse on local labels etc.
+  }
+  
+  // If we have an identifier, handle it as the key symbol.
+  SMLoc IDLoc = Lexer.getLoc();
+  std::string IDVal = Lexer.getCurStrVal();
+  
+  // Consume the identifier, see what is after it.
+  if (Lexer.Lex() == asmtok::Colon) {
+    // identifier ':'   -> Label.
+    Lexer.Lex();
+    return ParseStatement();
+  }
+  
+  // Otherwise, we have a normal instruction or directive.  
+  if (IDVal[0] == '.') {
+    Lexer.PrintMessage(IDLoc, "warning: ignoring directive for now");
+    EatToEndOfStatement();
+    return false;
+  }
+
+  // If it's an instruction, parse an operand list.
+  std::vector<X86Operand> Operands;
+  
+  // Read the first operand, if present.  Note that we require a newline at the
+  // end of file, so we don't have to worry about Eof here.
+  if (Lexer.isNot(asmtok::EndOfStatement)) {
+    X86Operand Op;
+    if (ParseX86Operand(Op))
+      return true;
+    Operands.push_back(Op);
+  }
+
+  while (Lexer.is(asmtok::Comma)) {
+    Lexer.Lex();  // Eat the comma.
+    
+    // Parse and remember the operand.
+    X86Operand Op;
+    if (ParseX86Operand(Op))
+      return true;
+    Operands.push_back(Op);
+  }
+  
+  if (Lexer.isNot(asmtok::EndOfStatement))
+    return TokError("unexpected token in operand list");
+
+  // Eat the end of statement marker.
+  Lexer.Lex();
+  
+  // Instruction is good, process it.
+  outs() << "Found instruction: " << IDVal << " with " << Operands.size()
+         << " operands.\n";
+  
+  // Skip to end of line for now.
+  return false;
+}