X86AsmParser: Do not process a non-existent token

[BrandonTJones]

Summary

This error can only happen if an unfinished operation is at Eof.

[BrandonTJones]

ping

[BrandonTJones]

ping

[craig.topper]

Can you write a test case?

[BrandonTJones]

added test case

[craig.topper]

LGTM

[BrandonTJones]

I do not have permissions to commit, can you do it for me? Thanks.

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

bool X86AsmParser::MatchAndEmitATTInstruction(SMLoc IDLoc, unsigned &Opcode,
   case Match_MissingFeature:
     return ErrorMissingFeature(IDLoc, ErrorInfo, MatchingInlineAsm);
   case Match_InvalidOperand:
     WasOriginallyInvalidOperand = true;
     break;
   case Match_MnemonicFail:
     break;
   }
+  if (Op.getToken().empty()) {
+    Error(IDLoc, "instruction must have size higher than 0", EmptyRange,
+          MatchingInlineAsm);
+    return true;
+  }
 
   // FIXME: Ideally, we would only attempt suffix matches for things which are
   // valid prefixes, and we could just infer the right unambiguous
   // type. However, that requires substantially more matcher support than the
   // following hack.
 
   // Change the operand to point to a temporary token.
   StringRef Base = Op.getToken();

llvm/test/MC/AsmParser/unfinished-op.s

+# RUN: not llvm-mc -triple i386-unknown-unknown %s 2>&1 > /dev/null| FileCheck %s --check-prefix=CHECK-ERROR
+
+#CHECK-ERROR: error: instruction must have size higher than 0
+    .byte 64;""

llvm/test/MC/X86/x86_operands.s

 // RUN: llvm-mc -triple i386-unknown-unknown %s | FileCheck %s
 
 # Immediates
 # CHECK: addl $1, %eax
         addl $1, %eax
 # CHECK: addl $3, %eax
         addl $(1+2), %eax
 # CHECK: addl $a, %eax
         addl $a, %eax
 # CHECK: addl $3, %eax
         addl $1 + 2, %eax
-        
 # Disambiguation
 
 # CHECK: addl $1, 8
         addl $1, 4+4
 # CHECK: addl $1, 8
         addl $1, (4+4)
 # CHECK: addl $1, 8(%eax)
         addl $1, 4+4(%eax)
 # CHECK: addl $1, 8(%eax)
         addl $1, (4+4)(%eax)
 # CHECK: addl $1, 8(%eax)
         addl $1, 8(%eax)
 # CHECK: addl $1, (%eax)
         addl $1, (%eax)
 # CHECK: addl $1, 8(,%eax)
         addl $1, (4+4)(,%eax)
-        
 # Indirect Memory Operands
 # CHECK: addl $1, 1(%eax)
         addl $1, 1(%eax)
 # CHECK: addl $1, 1(%eax,%ebx)
         addl $1, 1(%eax,%ebx)
 # CHECK: addl $1, 1(%eax,%ebx)
         addl $1, 1(%eax,%ebx,)
 # CHECK: addl $1, 1(%eax,%ebx,4)