add trivial support for passing label definitions through the MCStreamer.

This is suboptimal in several aspects, see the commented out assertion.
I need to talk to Daniel about this.

llvm-svn: 74057

include/llvm/MC/MCContext.h

@@ -56,6 +56,13 @@ namespace llvm {
     /// @param Name - The symbol name, which must be unique across all symbols.
     MCSymbol *CreateSymbol(MCAtom *Atom, const char *Name);
 
+    /// GetOrCreateSymbol - Lookup the symbol inside with the specified
+    /// @param Name.  If it exists, return it.  If not, create a forward
+    /// reference and return it.
+    ///
+    /// @param Name - The symbol name, which must be unique across all symbols.
+    MCSymbol *GetOrCreateSymbol(const char *Name);
+    
     /// CreateTemporarySymbol - Create a new temporary symbol inside @param Atom
     /// with the specified @param Name.
     ///

lib/MC/MCAsmStreamer.cpp

@@ -84,8 +84,8 @@ void MCAsmStreamer::SwitchSection(MCSection *Section) {
 void MCAsmStreamer::EmitLabel(MCSymbol *Symbol) {
   // FIXME: We need to enforce that we aren't printing atoms which are more
   // complicated than the assembler understands.
-  assert(Symbol->getAtom()->getSection() == CurSection && 
-         "The label for a symbol must match its section!");
+  //assert(Symbol->getAtom()->getSection() == CurSection && 
+  //       "The label for a symbol must match its section!");
   OS << Symbol->getName() << ":\n";
 }
 

lib/MC/MCContext.cpp

@@ -44,6 +44,20 @@ MCSymbol *MCContext::CreateSymbol(MCAtom *Atom, const char *Name) {
   return Entry = new (*this) MCSymbol(Atom, Name, false);
 }
 
+/// GetOrCreateSymbol - Lookup the symbol inside with the specified
+/// @param Name.  If it exists, return it.  If not, create a forward
+/// reference and return it.
+///
+/// @param Name - The symbol name, which must be unique across all symbols.
+MCSymbol *MCContext::GetOrCreateSymbol(const char *Name) {
+  MCSymbol *&Entry = Symbols[Name];
+  if (Entry) return Entry;
+
+  // FIXME: is a null atom the right way to make a forward ref?
+  return Entry = new (*this) MCSymbol(0, Name, false);
+}
+
+
 MCSymbol *MCContext::CreateTemporarySymbol(MCAtom *Atom, const char *Name) {
   // If unnamed, just create a symbol.
   if (Name[0] == '\0')

tools/llvm-mc/AsmParser.cpp

@@ -185,6 +185,12 @@ bool AsmParser::ParseStatement() {
   if (Lexer.Lex() == asmtok::Colon) {
     // identifier ':'   -> Label.
     Lexer.Lex();
+    
+    // Since we saw a label, create a symbol and emit it.
+    // FIXME: If the label starts with L it is an assembler temporary label.
+    // Why does the client of this api need to know this?
+    Out.EmitLabel(Ctx.GetOrCreateSymbol(IDVal));
+    
     return ParseStatement();
   }
   

tools/llvm-mc/AsmParser.h

@@ -17,17 +17,20 @@
 #include "AsmLexer.h"
 
 namespace llvm {
+class MCContext;
 class MCInst;
 class MCStreamer;
   
 class AsmParser {
   AsmLexer Lexer;
+  MCContext &Ctx;
   MCStreamer &Out;
   
   struct X86Operand;
   
 public:
-  AsmParser(SourceMgr &SM, MCStreamer &OutStr) : Lexer(SM), Out(OutStr) {}
+  AsmParser(SourceMgr &SM, MCContext &ctx, MCStreamer &OutStr)
+    : Lexer(SM), Ctx(ctx), Out(OutStr) {}
   ~AsmParser() {}
   
   bool Run();

tools/llvm-mc/llvm-mc.cpp

@@ -139,10 +139,9 @@ static int AssembleInput(const char *ProgName) {
   // it later.
   SrcMgr.setIncludeDirs(IncludeDirs);
   
-  // FIXME: don't leak streamer, own.
   MCContext Ctx;
   OwningPtr<MCStreamer> Str(createAsmStreamer(Ctx, outs()));
-  AsmParser Parser(SrcMgr, *Str.get());
+  AsmParser Parser(SrcMgr, Ctx, *Str.get());
   return Parser.Run();
 }