Implement parsing support for the .comm directive. Patch by

Kevin Enderby!

llvm-svn: 74944

1 files changed, 59 insertions, 0 deletions

diff --git a/llvm/tools/llvm-mc/AsmParser.cpp b/llvm/tools/llvm-mc/AsmParser.cpp
index f5bf5892012..1a3543aac77 100644
--- a/llvm/tools/llvm-mc/AsmParser.cpp
+++ b/llvm/tools/llvm-mc/AsmParser.cpp
@@ -520,6 +520,9 @@ bool AsmParser::ParseStatement() {
     if (!strcmp(IDVal, ".weak_reference"))
       return ParseDirectiveSymbolAttribute(MCStreamer::WeakReference);
 
+    if (!strcmp(IDVal, ".comm"))
+      return ParseDirectiveComm();
+
     Warning(IDLoc, "ignoring directive for now");
     EatToEndOfStatement();
     return false;
@@ -896,3 +899,59 @@ bool AsmParser::ParseDirectiveSymbolAttribute(MCStreamer::SymbolAttr Attr) {
   Lexer.Lex();
   return false;  
 }
+
+/// ParseDirectiveComm
+///  ::= .comm identifier , size_expression [ , align_expression ]
+bool AsmParser::ParseDirectiveComm() {
+  if (Lexer.isNot(asmtok::Identifier))
+    return TokError("expected identifier in directive");
+  
+  // handle the identifier as the key symbol.
+  SMLoc IDLoc = Lexer.getLoc();
+  MCSymbol *Sym = Ctx.GetOrCreateSymbol(Lexer.getCurStrVal());
+  Lexer.Lex();
+
+  if (Lexer.isNot(asmtok::Comma))
+    return TokError("unexpected token in directive");
+  Lexer.Lex();
+
+  int64_t Size;
+  SMLoc SizeLoc = Lexer.getLoc();
+  if (ParseAbsoluteExpression(Size))
+    return true;
+
+  int64_t Pow2Alignment = 0;
+  SMLoc Pow2AlignmentLoc;
+  if (Lexer.is(asmtok::Comma)) {
+    Lexer.Lex();
+    Pow2AlignmentLoc = Lexer.getLoc();
+    if (ParseAbsoluteExpression(Pow2Alignment))
+      return true;
+  }
+  
+  if (Lexer.isNot(asmtok::EndOfStatement))
+    return TokError("unexpected token in '.comm' directive");
+  
+  Lexer.Lex();
+
+  // NOTE: a size of zero should create a undefined symbol
+  if (Size < 0)
+    return Error(SizeLoc, "invalid '.comm' size, can't be less than zero");
+
+  // NOTE: The alignment in the directive is a power of 2 value, the assember
+  // may internally end up wanting an alignment in bytes.
+  // FIXME: Diagnose overflow.
+  if (Pow2Alignment < 0)
+    return Error(Pow2AlignmentLoc, "invalid '.comm' alignment, can't be less "
+                 "than zero");
+
+  // TODO: Symbol must be undefined or it is a error to re-defined the symbol
+  if (Sym->getSection() || Ctx.GetSymbolValue(Sym))
+    return Error(IDLoc, "invalid symbol redefinition");
+
+  // TODO: Symbol to be made into a common with this Size and Pow2Alignment
+
+  Out.EmitCommonSymbol(Sym, Size, Pow2Alignment);
+
+  return false;
+}