X86AsmParser AVX-512: Return error instead of hitting assert

When parsing a sequence of tokens beginning with {, it will hit an assert and crash if the token afterwards is not an identifier. Instead of this, return a more verbose error as seen elsewhere in the function.

Patch by Brandon Jones (BrandonTJones)

Differential Revision: https://reviews.llvm.org/D57375

llvm-svn: 354356

llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp

@@ -1654,6 +1654,8 @@ X86AsmParser::ParseRoundingModeOp(SMLoc Start) {
   const AsmToken &Tok = Parser.getTok();
   // Eat "{" and mark the current place.
   const SMLoc consumedToken = consumeToken();
+  if (Tok.isNot(AsmToken::Identifier))
+    return ErrorOperand(Tok.getLoc(), "Expected an identifier after {");
   if (Tok.getIdentifier().startswith("r")){
     int rndMode = StringSwitch<int>(Tok.getIdentifier())
       .Case("rn", X86::STATIC_ROUNDING::TO_NEAREST_INT)

llvm/test/MC/X86/avx512-err.s

@@ -11,3 +11,6 @@ vfmsub213ps %zmm8, %zmm8, %zmm8 {rn-sae}
 
 // ERR: invalid operand for instruction
 cvtsd2sil  {rn-sae}, %xmm1, %eax
+
+// ERR: Expected an identifier after {
+cvtsd2sil  {{sae}, %xmm1, %eax