Catch non-string subject in RegExpExecStub.

src/x64/code-stubs-x64.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 2645 matching lines @@
 
   // Check for flat cons string or sliced string.
   // A flat cons string is a cons string where the second part is the empty
   // string. In that case the subject string is just the first part of the cons
   // string. Also in this case the first part of the cons string is known to be
   // a sequential string or an external string.
   // In the case of a sliced string its offset has to be taken into account.
   Label cons_string, check_encoding;
   STATIC_ASSERT(kConsStringTag < kExternalStringTag);
   STATIC_ASSERT(kSlicedStringTag > kExternalStringTag);
+  STATIC_ASSERT(kIsNotStringMask > kExternalStringTag);
   __ cmpq(rbx, Immediate(kExternalStringTag));
   __ j(less, &cons_string, Label::kNear);
   __ j(equal, &runtime);
 
+  // Catch non-string subject (should already have been guarded against).
+  __ testb(ebx, Immediate(kIsNotStringMask));
+  __ j(zero, &runtime);
+
   // String is sliced.
   __ SmiToInteger32(r14, FieldOperand(rdi, SlicedString::kOffsetOffset));
   __ movq(rdi, FieldOperand(rdi, SlicedString::kParentOffset));
   // r14: slice offset
   // r15: original subject string
   // rdi: parent string
   __ jmp(&check_encoding, Label::kNear);
   // String is a cons string, check whether it is flat.
   __ bind(&cons_string);
   __ CompareRoot(FieldOperand(rdi, ConsString::kSecondOffset),
@@ skipping 3424 matching lines @@
                                  xmm0,
                                  &slow_elements);
   __ ret(0);
 }
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64