llvm-mc/Mach-O: Don't put assembler temporary labels in the symbol table.

- I moved section creation back into AsmParser. I think policy decisions like
   this should be pushed higher, not lower, when possible (in addition the
   assembler has flags which change this behavior, for example).


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@80162 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/MC/MCContext.h

@@ -57,6 +57,8 @@ namespace llvm {
     /// reference and return it.
     ///
     /// @param Name - The symbol name, which must be unique across all symbols.
+    /// @param IsTemporary - Whether this symbol is an assembler temporary,
+    /// which should not survive into the symbol table for the translation unit.
     MCSymbol *GetOrCreateSymbol(const StringRef &Name);
     
     /// CreateTemporarySymbol - Create a new temporary symbol with the specified

include/llvm/MC/MCSymbol.h

@@ -63,6 +63,11 @@ namespace llvm {
     /// @name Symbol Type
     /// @{
 
+    /// isTemporary - Check if this is an assembler temporary symbol.
+    bool isTemporary() const {
+      return IsTemporary;
+    }
+
     /// isDefined - Check if this symbol is defined (i.e., it has an address).
     ///
     /// Defined symbols are either absolute or in some section.

lib/MC/MCAssembler.cpp

@@ -557,6 +557,10 @@ public:
            ie = Asm.symbol_end(); it != ie; ++it) {
       MCSymbol &Symbol = it->getSymbol();
 
+      // Ignore assembler temporaries.
+      if (it->getSymbol().isTemporary())
+        continue;
+
       if (!it->isExternal() && !Symbol.isUndefined())
         continue;
 
@@ -589,6 +593,10 @@ public:
            ie = Asm.symbol_end(); it != ie; ++it) {
       MCSymbol &Symbol = it->getSymbol();
 
+      // Ignore assembler temporaries.
+      if (it->getSymbol().isTemporary())
+        continue;
+
       if (it->isExternal() || Symbol.isUndefined())
         continue;
 

lib/MC/MCContext.cpp

@@ -38,7 +38,6 @@ MCSymbol *MCContext::GetOrCreateSymbol(const StringRef &Name) {
   return Entry = new (*this) MCSymbol(Name, false);
 }
 
-
 MCSymbol *MCContext::CreateTemporarySymbol(const StringRef &Name) {
   // If unnamed, just create a symbol.
   if (Name.empty())

test/MC/MachO/symbols-1.s

@@ -13,8 +13,9 @@ sym_local_C:
 sym_globl_def_A: 
 sym_globl_def_B: 
 sym_globl_def_C: 
+Lsym_asm_temp:
         .long 0
-
+        
 // CHECK: ('cputype', 7)
 // CHECK: ('cpusubtype', 3)
 // CHECK: ('filetype', 1)

tools/llvm-mc/AsmParser.cpp

@@ -129,6 +129,17 @@ bool AsmParser::ParseParenExpr(AsmExpr *&Res) {
   return false;
 }
 
+MCSymbol *AsmParser::CreateSymbol(StringRef Name) {
+  if (MCSymbol *S = Ctx.LookupSymbol(Name))
+    return S;
+
+  // If the label starts with L it is an assembler temporary label.
+  if (Name.startswith("L"))
+    return Ctx.CreateTemporarySymbol(Name);
+
+  return Ctx.CreateSymbol(Name);
+}
+
 /// ParsePrimaryExpr - Parse a primary expression and return it.
 ///  primaryexpr ::= (parenexpr
 ///  primaryexpr ::= symbol
@@ -148,7 +159,7 @@ bool AsmParser::ParsePrimaryExpr(AsmExpr *&Res) {
   case AsmToken::Identifier: {
     // This is a label, this should be parsed as part of an expression, to
     // handle things like LFOO+4.
-    MCSymbol *Sym = Ctx.GetOrCreateSymbol(Lexer.getTok().getIdentifier());
+    MCSymbol *Sym = CreateSymbol(Lexer.getTok().getIdentifier());
     
     Res = new AsmSymbolRefExpr(Sym);
     Lexer.Lex(); // Eat identifier.
@@ -371,13 +382,11 @@ bool AsmParser::ParseStatement() {
     // FIXME: Diagnostics. Note the location of the definition as a label.
     // FIXME: This doesn't diagnose assignment to a symbol which has been
     // implicitly marked as external.
-    MCSymbol *Sym = Ctx.GetOrCreateSymbol(IDVal);
+    MCSymbol *Sym = CreateSymbol(IDVal);
     if (!Sym->isUndefined())
       return Error(IDLoc, "invalid symbol redefinition");
     
-    // 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?
+    // Emit the label.
     Out.EmitLabel(Sym);
    
     return ParseStatement();
@@ -683,7 +692,7 @@ bool AsmParser::ParseAssignment(const StringRef &Name, bool IsDotSet) {
   // FIXME: Diagnostics. Note the location of the definition as a label.
   // FIXME: Handle '.'.
   // FIXME: Diagnose assignment to protected identifier (e.g., register name).
-  MCSymbol *Sym = Ctx.GetOrCreateSymbol(Name);
+  MCSymbol *Sym = CreateSymbol(Name);
   if (!Sym->isUndefined() && !Sym->isAbsolute())
     return Error(EqualLoc, "symbol has already been defined");
 
@@ -1110,7 +1119,7 @@ bool AsmParser::ParseDirectiveSymbolAttribute(MCStreamer::SymbolAttr Attr) {
       if (ParseIdentifier(Name))
         return TokError("expected identifier in directive");
       
-      MCSymbol *Sym = Ctx.GetOrCreateSymbol(Name);
+      MCSymbol *Sym = CreateSymbol(Name);
 
       Out.EmitSymbolAttribute(Sym, Attr);
 
@@ -1135,7 +1144,7 @@ bool AsmParser::ParseDirectiveDarwinSymbolDesc() {
     return TokError("expected identifier in directive");
   
   // Handle the identifier as the key symbol.
-  MCSymbol *Sym = Ctx.GetOrCreateSymbol(Name);
+  MCSymbol *Sym = CreateSymbol(Name);
 
   if (Lexer.isNot(AsmToken::Comma))
     return TokError("unexpected token in '.desc' directive");
@@ -1166,7 +1175,7 @@ bool AsmParser::ParseDirectiveComm(bool IsLocal) {
     return TokError("expected identifier in directive");
   
   // Handle the identifier as the key symbol.
-  MCSymbol *Sym = Ctx.GetOrCreateSymbol(Name);
+  MCSymbol *Sym = CreateSymbol(Name);
 
   if (Lexer.isNot(AsmToken::Comma))
     return TokError("unexpected token in directive");
@@ -1258,7 +1267,7 @@ bool AsmParser::ParseDirectiveDarwinZerofill() {
   
   // handle the identifier as the key symbol.
   SMLoc IDLoc = Lexer.getLoc();
-  MCSymbol *Sym = Ctx.GetOrCreateSymbol(Lexer.getTok().getString());
+  MCSymbol *Sym = CreateSymbol(Lexer.getTok().getString());
   Lexer.Lex();
 
   if (Lexer.isNot(AsmToken::Comma))
@@ -1363,7 +1372,7 @@ bool AsmParser::ParseDirectiveDarwinLsym() {
     return TokError("expected identifier in directive");
   
   // Handle the identifier as the key symbol.
-  MCSymbol *Sym = Ctx.GetOrCreateSymbol(Name);
+  MCSymbol *Sym = CreateSymbol(Name);
 
   if (Lexer.isNot(AsmToken::Comma))
     return TokError("unexpected token in '.lsym' directive");

tools/llvm-mc/AsmParser.h

@@ -69,6 +69,8 @@ public:
   /// }
 
 private:
+  MCSymbol *CreateSymbol(StringRef Name);
+
   bool ParseStatement();
 
   bool TokError(const char *Msg);