3 files changed, 21 insertions, 13 deletions

diff --git a/lib/MC/MCAsmInfo.cpp b/lib/MC/MCAsmInfo.cpp
index 6112ad1fca..0eea75ef04 100644
--- a/lib/MC/MCAsmInfo.cpp
+++ b/lib/MC/MCAsmInfo.cpp
@@ -53,6 +53,7 @@ MCAsmInfo::MCAsmInfo() {
   AllowQuotesInName = false;
   AllowNameToStartWithDigit = false;
   AllowPeriodsInName = true;
+  AllowAtInName = false;
   AllowUTF8 = true;
   UseDataRegionDirectives = false;
   ZeroDirective = "\t.zero\t";
diff --git a/lib/MC/MCParser/AsmLexer.cpp b/lib/MC/MCParser/AsmLexer.cpp
index 1ce0cc2a1d..b49dd01047 100644
--- a/lib/MC/MCParser/AsmLexer.cpp
+++ b/lib/MC/MCParser/AsmLexer.cpp
@@ -138,9 +138,9 @@ AsmToken AsmLexer::LexHexFloatLiteral(bool NoIntDigits) {
   return AsmToken(AsmToken::Real, StringRef(TokStart, CurPtr - TokStart));
 }
 
-/// LexIdentifier: [a-zA-Z_.][a-zA-Z0-9_$.@]*
+/// LexIdentifier: [a-zA-Z_.][a-zA-Z0-9_$.@?]*
 static bool IsIdentifierChar(char c) {
-  return isalnum(c) || c == '_' || c == '$' || c == '.' || c == '@';
+  return isalnum(c) || c == '_' || c == '$' || c == '.' || c == '@' || c == '?';
 }
 AsmToken AsmLexer::LexIdentifier() {
   // Check for floating point literals.
diff --git a/lib/MC/MCParser/AsmParser.cpp b/lib/MC/MCParser/AsmParser.cpp
index 9a362563a7..1fb8480b05 100644
--- a/lib/MC/MCParser/AsmParser.cpp
+++ b/lib/MC/MCParser/AsmParser.cpp
@@ -769,6 +769,7 @@ bool AsmParser::parsePrimaryExpr(const MCExpr *&Res, SMLoc &EndLoc) {
     Res = MCUnaryExpr::CreateLNot(Res, getContext());
     return false;
   case AsmToken::Dollar:
+  case AsmToken::At:
   case AsmToken::String:
   case AsmToken::Identifier: {
     StringRef Identifier;
@@ -792,19 +793,25 @@ 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 (Variant == MCSymbolRefExpr::VK_Invalid) {
+      if (Variant != MCSymbolRefExpr::VK_Invalid) {
+        SymbolName = Split.first;
+      } else if (MAI.doesAllowAtInName()) {
+        Variant = MCSymbolRefExpr::VK_None;
+      } else {
         Variant = MCSymbolRefExpr::VK_None;
         return TokError("invalid variant '" + Split.second + "'");
       }
     }
 
+    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())) {
@@ -2105,25 +2112,25 @@ bool AsmParser::parseAssignment(StringRef Name, bool allow_redef,
 ///   ::= string
 bool AsmParser::parseIdentifier(StringRef &Res) {
   // The assembler has relaxed rules for accepting identifiers, in particular we
-  // allow things like '.globl $foo', which would normally be separate
-  // tokens. At this level, we have already lexed so we cannot (currently)
+  // allow things like '.globl $foo' and '.def @feat.00', which would normally be
+  // separate tokens. At this level, we have already lexed so we cannot (currently)
   // handle this as a context dependent token, instead we detect adjacent tokens
   // and return the combined identifier.
-  if (Lexer.is(AsmToken::Dollar)) {
-    SMLoc DollarLoc = getLexer().getLoc();
+  if (Lexer.is(AsmToken::Dollar) || Lexer.is(AsmToken::At)) {
+    SMLoc PrefixLoc = getLexer().getLoc();
 
-    // Consume the dollar sign, and check for a following identifier.
+    // Consume the prefix character, and check for a following identifier.
     Lex();
     if (Lexer.isNot(AsmToken::Identifier))
       return true;
 
-    // We have a '$' followed by an identifier, make sure they are adjacent.
-    if (DollarLoc.getPointer() + 1 != getTok().getLoc().getPointer())
+    // We have a '$' or '@' followed by an identifier, make sure they are adjacent.
+    if (PrefixLoc.getPointer() + 1 != getTok().getLoc().getPointer())
       return true;
 
     // Construct the joined identifier and consume the token.
     Res =
-        StringRef(DollarLoc.getPointer(), getTok().getIdentifier().size() + 1);
+        StringRef(PrefixLoc.getPointer(), getTok().getIdentifier().size() + 1);
     Lex();
     return false;
   }