Re-commit r192758 - MC: quote tricky symbol names in asm output

The reason this got reverted was that the @feat.00 symbol which was emitted
for every TU became quoted, and on cygwin/mingw we use the gas assembler which
couldn't handle the quotes.

This commit fixes the problem by only emitting @feat.00 for win32, where we use
clang -cc1as to assemble. gas would just drop this symbol anyway, so there is no
loss there.

With @feat.00 gone, there shouldn't be quoted symbols showing up on cygwin since
it uses the Itanium ABI, which doesn't put these funny characters in symbols.

> Because of win32 mangling, we produce symbol and section names with
> funny characters in them, most notably @ characters.
>
> MC would choke on trying to parse its own assembly output. This patch addresses
> that by:
>
> - Making @ trigger quoting of symbol names
> - Also quote section names in the same way
> - Just parse section names like other identifiers (to allow for quotes)
> - Don't assume @ signifies a symbol variant if it is in a string.

llvm-svn: 192859

1 files changed, 12 insertions, 6 deletions

diff --git a/llvm/lib/MC/MCParser/AsmParser.cpp b/llvm/lib/MC/MCParser/AsmParser.cpp
index 9a362563a7e..75f5c78b70b 100644
--- a/llvm/lib/MC/MCParser/AsmParser.cpp
+++ b/llvm/lib/MC/MCParser/AsmParser.cpp
@@ -792,19 +792,25 @@ bool AsmParser::parsePrimaryExpr(const MCExpr *&Res, SMLoc &EndLoc) {
     EndLoc = SMLoc::getFromPointer(Identifier.end());
 
     // This is a symbol reference.
+    StringRef SymbolName = Identifier;
+    MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
     std::pair<StringRef, StringRef> Split = Identifier.split('@');
-    MCSymbol *Sym = getContext().GetOrCreateSymbol(Split.first);
 
-    // Lookup the symbol variant if used.
-    MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
-    if (Split.first.size() != Identifier.size()) {
-      Variant = MCSymbolRefExpr::getVariantKindForName(Split.second);
+    if (Split.first.size() != Identifier.size() &&
+        FirstTokenKind != AsmToken::String) {
+      SymbolName = Split.first;
+      StringRef VariantName = Split.second;
+
+      // Lookup the symbol variant.
+      Variant = MCSymbolRefExpr::getVariantKindForName(VariantName);
       if (Variant == MCSymbolRefExpr::VK_Invalid) {
         Variant = MCSymbolRefExpr::VK_None;
-        return TokError("invalid variant '" + Split.second + "'");
+        return TokError("invalid variant '" + VariantName + "'");
       }
     }
 
+    MCSymbol *Sym = getContext().GetOrCreateSymbol(SymbolName);
+
     // If this is an absolute variable reference, substitute it now to preserve
     // semantics in the face of reassignment.
     if (Sym->isVariable() && isa<MCConstantExpr>(Sym->getVariableValue())) {