some baby steps.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@73848 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 201 insertions, 2 deletions

diff --git a/tools/llvm-mc/AsmLexer.cpp b/tools/llvm-mc/AsmLexer.cpp
new file mode 100644
index 0000000..da86465
--- /dev/null
+++ b/tools/llvm-mc/AsmLexer.cpp
@@ -0,0 +1,87 @@
+//===- AsmLexer.cpp - Lexer 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 lexer for assembly files.
+//
+//===----------------------------------------------------------------------===//
+
+#include "AsmLexer.h"
+#include "llvm/Support/SourceMgr.h"
+#include "llvm/Support/MemoryBuffer.h"
+using namespace llvm;
+
+AsmLexer::AsmLexer(SourceMgr &SM) : SrcMgr(SM) {
+  CurBuffer = 0;
+  CurBuf = SrcMgr.getMemoryBuffer(CurBuffer);
+  CurPtr = CurBuf->getBufferStart();
+  TokStart = 0;
+}
+
+void AsmLexer::PrintError(const char *Loc, const std::string &Msg) const {
+  SrcMgr.PrintError(SMLoc::getFromPointer(Loc), Msg);
+}
+
+void AsmLexer::PrintError(SMLoc Loc, const std::string &Msg) const {
+  SrcMgr.PrintError(Loc, Msg);
+}
+
+int AsmLexer::getNextChar() {
+  char CurChar = *CurPtr++;
+  switch (CurChar) {
+  default:
+    return (unsigned char)CurChar;
+  case 0: {
+    // A nul character in the stream is either the end of the current buffer or
+    // a random nul in the file.  Disambiguate that here.
+    if (CurPtr-1 != CurBuf->getBufferEnd())
+      return 0;  // Just whitespace.
+    
+    // If this is the end of an included file, pop the parent file off the
+    // include stack.
+    SMLoc ParentIncludeLoc = SrcMgr.getParentIncludeLoc(CurBuffer);
+    if (ParentIncludeLoc != SMLoc()) {
+      CurBuffer = SrcMgr.FindBufferContainingLoc(ParentIncludeLoc);
+      CurBuf = SrcMgr.getMemoryBuffer(CurBuffer);
+      CurPtr = ParentIncludeLoc.getPointer();
+      return getNextChar();
+    }
+    
+    // Otherwise, return end of file.
+    --CurPtr;  // Another call to lex will return EOF again.  
+    return EOF;
+  }
+  }
+}
+
+asmtok::TokKind AsmLexer::LexToken() {
+  TokStart = CurPtr;
+  // This always consumes at least one character.
+  int CurChar = getNextChar();
+  
+  switch (CurChar) {
+  default:
+    // Handle letters: [a-zA-Z_]
+//    if (isalpha(CurChar) || CurChar == '_' || CurChar == '#')
+//      return LexIdentifier();
+    
+    // Unknown character, emit an error.
+    return asmtok::Error;
+  case EOF: return asmtok::Eof;
+  case 0:
+  case ' ':
+  case '\t':
+  case '\n':
+  case '\r':
+    // Ignore whitespace.
+    return LexToken();
+  case ':': return asmtok::Colon;
+  case '+': return asmtok::Plus;
+  case '-': return asmtok::Minus;
+  }
+}
\ No newline at end of file
diff --git a/tools/llvm-mc/AsmLexer.h b/tools/llvm-mc/AsmLexer.h
new file mode 100644
index 0000000..08e6f9c
--- /dev/null
+++ b/tools/llvm-mc/AsmLexer.h
@@ -0,0 +1,92 @@
+//===- AsmLexer.h - Lexer for Assembly Files --------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This class declares the lexer for assembly files.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef ASMLEXER_H
+#define ASMLEXER_H
+
+#include "llvm/Support/DataTypes.h"
+#include <string>
+#include <cassert>
+
+namespace llvm {
+class MemoryBuffer;
+class SourceMgr;
+class SMLoc;
+
+namespace asmtok {
+  enum TokKind {
+    // Markers
+    Eof, Error,
+
+    Identifier,
+    IntVal,
+    
+    
+    Colon,
+    Plus,
+    Minus
+  };
+}
+
+/// AsmLexer - Lexer class for assembly files.
+class AsmLexer {
+  SourceMgr &SrcMgr;
+  
+  const char *CurPtr;
+  const MemoryBuffer *CurBuf;
+  
+  // Information about the current token.
+  const char *TokStart;
+  asmtok::TokKind CurKind;
+  std::string CurStrVal;  // This is valid for Identifier.
+  int64_t CurIntVal;
+  
+  /// CurBuffer - This is the current buffer index we're lexing from as managed
+  /// by the SourceMgr object.
+  int CurBuffer;
+  
+public:
+  AsmLexer(SourceMgr &SrcMgr);
+  ~AsmLexer() {}
+  
+  asmtok::TokKind Lex() {
+    return CurKind = LexToken();
+  }
+  
+  asmtok::TokKind getKind() const { return CurKind; }
+  
+  const std::string &getCurStrVal() const {
+    assert(CurKind == asmtok::Identifier &&
+           "This token doesn't have a string value");
+    return CurStrVal;
+  }
+  int64_t getCurIntVal() const {
+    assert(CurKind == asmtok::IntVal && "This token isn't an integer");
+    return CurIntVal;
+  }
+  
+  SMLoc getLoc() const;
+  
+  void PrintError(const char *Loc, const std::string &Msg) const;
+  void PrintError(SMLoc Loc, const std::string &Msg) const;
+  
+private:
+  int getNextChar();
+
+  /// LexToken - Read the next token and return its code.
+  asmtok::TokKind LexToken();
+};
+  
+} // end namespace llvm
+
+#endif
diff --git a/tools/llvm-mc/llvm-mc.cpp b/tools/llvm-mc/llvm-mc.cpp
index 74e419c..8364298 100644
--- a/tools/llvm-mc/llvm-mc.cpp
+++ b/tools/llvm-mc/llvm-mc.cpp
@@ -19,6 +19,7 @@
 #include "llvm/Support/SourceMgr.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/System/Signals.h"
+#include "AsmLexer.h"
 using namespace llvm;
 
 static cl::opt<std::string>
@@ -63,10 +64,29 @@ static int AssembleInput(const char *ProgName) {
   // Record the location of the include directories so that the lexer can find
   // it later.
   SrcMgr.setIncludeDirs(IncludeDirs);
+
+  
   
-  //TGParser Parser(SrcMgr);
-  //return Parser.ParseFile();
+  AsmLexer Lexer(SrcMgr);
   
+  asmtok::TokKind Tok = Lexer.Lex();
+  while (Tok != asmtok::Eof) {
+    switch (Tok) {
+    default: outs() << "<<unknown token>>\n"; break;
+    case asmtok::Error: outs() << "<<error>>\n"; break;
+    case asmtok::Identifier:
+      outs() << "identifier: " << Lexer.getCurStrVal() << '\n';
+      break;
+    case asmtok::IntVal:
+      outs() << "int: " << Lexer.getCurIntVal() << '\n';
+      break;
+    case asmtok::Colon:  outs() << "Colon\n"; break;
+    case asmtok::Plus:   outs() << "Plus\n"; break;
+    case asmtok::Minus:  outs() << "Minus\n"; break;
+    }
+    
+    Tok = Lexer.Lex();
+  }
   
   return 1;
 }