MC: Allow modifiers in MCSymbolRefExpr, and eliminate X86MCTargetExpr.

 - Although it would be nice to allow this decoupling, the assembler needs to be able to reason about MCSymbolRefExprs in too many places to make this viable. We can use a target specific encoding of the variant if this becomes an issue.
 - This patch also extends llvm-mc to support parsing of the modifiers, as opposed to lumping them in with the symbol.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@98592 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 12 insertions, 2 deletions

diff --git a/lib/MC/MCParser/AsmParser.cpp b/lib/MC/MCParser/AsmParser.cpp
index a241106..4ec5247 100644
--- a/lib/MC/MCParser/AsmParser.cpp
+++ b/lib/MC/MCParser/AsmParser.cpp
@@ -262,19 +262,29 @@ bool AsmParser::ParsePrimaryExpr(const MCExpr *&Res, SMLoc &EndLoc) {
   case AsmToken::String:
   case AsmToken::Identifier: {
     // This is a symbol reference.
-    MCSymbol *Sym = CreateSymbol(getTok().getIdentifier());
+    std::pair<StringRef, StringRef> Split = getTok().getIdentifier().split('@');
+    MCSymbol *Sym = CreateSymbol(Split.first);
+
+    // Lookup the symbol variant if used.
+    MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
+    if (Split.first.size() != getTok().getIdentifier().size())
+      Variant = MCSymbolRefExpr::getVariantKindForName(Split.second);
+
     EndLoc = Lexer.getLoc();
     Lex(); // Eat identifier.
 
     // If this is an absolute variable reference, substitute it now to preserve
     // semantics in the face of reassignment.
     if (Sym->getValue() && isa<MCConstantExpr>(Sym->getValue())) {
+      if (Variant)
+        return Error(EndLoc, "unexpected modified on variable reference");
+
       Res = Sym->getValue();
       return false;
     }
 
     // Otherwise create a symbol ref.
-    Res = MCSymbolRefExpr::Create(Sym, getContext());
+    Res = MCSymbolRefExpr::Create(Sym, Variant, getContext());
     return false;
   }
   case AsmToken::Integer: