MIPS: Catch non-string subject in RegExpExecStub.

src/mips/code-stubs-mips.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 4728 matching lines @@
   __ Branch(&runtime, gt, a2, Operand(at));
 
   // Reset offset for possibly sliced string.
   __ mov(t0, zero_reg);
   // subject: Subject string
   // regexp_data: RegExp data (FixedArray)
   // Check the representation and encoding of the subject string.
   Label seq_string;
   __ lw(a0, FieldMemOperand(subject, HeapObject::kMapOffset));
   __ lbu(a0, FieldMemOperand(a0, Map::kInstanceTypeOffset));
-  // First check for flat string.
+  // First check for flat string.  None of the following string type tests will
+  // succeed if kIsNotStringTag is set.
   __ And(a1, a0, Operand(kIsNotStringMask | kStringRepresentationMask));
   STATIC_ASSERT((kStringTag | kSeqStringTag) == 0);
   __ Branch(&seq_string, eq, a1, Operand(zero_reg));
 
   // subject: Subject string
   // a0: instance type if Subject string
   // regexp_data: RegExp data (FixedArray)
+  // a1: whether subject is a string and if yes, its string representation
   // 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);
   __ Branch(&cons_string, lt, a1, Operand(kExternalStringTag));
   __ Branch(&runtime, eq, a1, Operand(kExternalStringTag));
 
+  // Catch non-string subject (should already have been guarded against).
+  STATIC_ASSERT(kNotStringTag != 0);
+  __ And(at, a1, Operand(kIsNotStringMask));
+  __ Branch(&runtime, ne, at, Operand(zero_reg));
+
   // String is sliced.
   __ lw(t0, FieldMemOperand(subject, SlicedString::kOffsetOffset));
   __ sra(t0, t0, kSmiTagSize);
   __ lw(subject, FieldMemOperand(subject, SlicedString::kParentOffset));
   // t5: offset of sliced string, smi-tagged.
   __ jmp(&check_encoding);
   // String is a cons string, check whether it is flat.
   __ bind(&cons_string);
   __ lw(a0, FieldMemOperand(subject, ConsString::kSecondOffset));
   __ LoadRoot(a1, Heap::kEmptyStringRootIndex);
@@ skipping 2682 matching lines @@
                                  &slow_elements);
   __ Ret();
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_MIPS