MIPS64: [regexp] do not assume short external strings have a minimum size.

src/mips64/code-stubs-mips64.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #if V8_TARGET_ARCH_MIPS64
 
 #include "src/code-stubs.h"
 #include "src/api-arguments.h"
 #include "src/bootstrapper.h"
 #include "src/codegen.h"
@@ skipping 1665 matching lines @@
   // Multiplying by 2 comes for free since a2 is smi-tagged.
   STATIC_ASSERT(Isolate::kJSRegexpStaticOffsetsVectorSize >= 2);
   int temp = Isolate::kJSRegexpStaticOffsetsVectorSize / 2 - 1;
   __ Branch(&runtime, hi, a2, Operand(Smi::FromInt(temp)));
 
   // Reset offset for possibly sliced string.
   __ mov(t0, zero_reg);
   __ ld(subject, MemOperand(sp, kSubjectOffset));
   __ JumpIfSmi(subject, &runtime);
   __ mov(a3, subject);  // Make a copy of the original subject string.
-  __ ld(a0, FieldMemOperand(subject, HeapObject::kMapOffset));
-  __ lbu(a0, FieldMemOperand(a0, Map::kInstanceTypeOffset));
 
   // subject: subject string
-  // a0: subject string instance type
   // a3: subject string
   // regexp_data: RegExp data (FixedArray)
   // Handle subject string according to its encoding and representation:
   // (1) Sequential string?  If yes, go to (4).
   // (2) Sequential or cons?  If not, go to (5).
   // (3) Cons string.  If the string is flat, replace subject with first string
   //     and go to (1). Otherwise bail out to runtime.
   // (4) Sequential string.  Load regexp code according to encoding.
   // (E) Carry on.
   /// [...]
 
   // Deferred code at the end of the stub:
   // (5) Long external string?  If not, go to (7).
   // (6) External string.  Make it, offset-wise, look like a sequential string.
   //     Go to (4).
   // (7) Short external string or not a string?  If yes, bail out to runtime.
   // (8) Sliced string.  Replace subject with parent.  Go to (1).
 
   Label check_underlying;   // (1)
   Label seq_string;         // (4)
   Label not_seq_nor_cons;   // (5)
   Label external_string;    // (6)
   Label not_long_external;  // (7)
 
   __ bind(&check_underlying);
   __ ld(a2, FieldMemOperand(subject, HeapObject::kMapOffset));
-  __ Daddu(a0, a2, Map::kInstanceTypeOffset);
-  __ lbu(a0, MemOperand(a0));
+  __ lbu(a0, FieldMemOperand(a2, Map::kInstanceTypeOffset));
 
   // (1) Sequential string?  If yes, go to (4).
   __ And(a1,
          a0,
          Operand(kIsNotStringMask |
                  kStringRepresentationMask |
                  kShortExternalStringMask));
   STATIC_ASSERT((kStringTag | kSeqStringTag) == 0);
   __ Branch(&seq_string, eq, a1, Operand(zero_reg));  // Go to (4).
 
@@ skipping 4044 matching lines @@
                            kStackUnwindSpace, kInvalidStackOffset,
                            return_value_operand, NULL);
 }
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_MIPS64