Use regular map-checks to guard string-length loading.

src/mips/stub-cache-mips.cc

 // Copyright 2012 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 356 matching lines @@
 
 
 // Generate code to load the length from a string object and return the length.
 // If the receiver object is not a string or a wrapped string object the
 // execution continues at the miss label. The register containing the
 // receiver is potentially clobbered.
 void StubCompiler::GenerateLoadStringLength(MacroAssembler* masm,
                                             Register receiver,
                                             Register scratch1,
                                             Register scratch2,
-                                            Label* miss,
-                                            bool support_wrappers) {
+                                            Label* miss) {
   Label check_wrapper;
 
   // Check if the object is a string leaving the instance type in the
   // scratch1 register.
-  GenerateStringCheck(masm, receiver, scratch1, scratch2, miss,
-                      support_wrappers ? &check_wrapper : miss);
+  GenerateStringCheck(masm, receiver, scratch1, scratch2, miss, &check_wrapper);
 
   // Load length directly from the string.
   __ Ret(USE_DELAY_SLOT);
   __ lw(v0, FieldMemOperand(receiver, String::kLengthOffset));
 
-  if (support_wrappers) {
-    // Check if the object is a JSValue wrapper.
-    __ bind(&check_wrapper);
-    __ Branch(miss, ne, scratch1, Operand(JS_VALUE_TYPE));
+  // Check if the object is a JSValue wrapper.
+  __ bind(&check_wrapper);
+  __ Branch(miss, ne, scratch1, Operand(JS_VALUE_TYPE));
 
-    // Unwrap the value and check if the wrapped value is a string.
-    __ lw(scratch1, FieldMemOperand(receiver, JSValue::kValueOffset));
-    GenerateStringCheck(masm, scratch1, scratch2, scratch2, miss, miss);
-    __ Ret(USE_DELAY_SLOT);
-    __ lw(v0, FieldMemOperand(scratch1, String::kLengthOffset));
-  }
+  // Unwrap the value and check if the wrapped value is a string.
+  __ lw(scratch1, FieldMemOperand(receiver, JSValue::kValueOffset));
+  GenerateStringCheck(masm, scratch1, scratch2, scratch2, miss, miss);
+  __ Ret(USE_DELAY_SLOT);
+  __ lw(v0, FieldMemOperand(scratch1, String::kLengthOffset));
 }
 
 
 void StubCompiler::GenerateLoadFunctionPrototype(MacroAssembler* masm,
                                                  Register receiver,
                                                  Register scratch1,
                                                  Register scratch2,
                                                  Label* miss_label) {
   __ TryGetFunctionPrototype(receiver, scratch1, scratch2, miss_label);
   __ Ret(USE_DELAY_SLOT);
@@ skipping 2783 matching lines @@
   // -----------------------------------
   TailCallBuiltin(masm, Builtins::kKeyedLoadIC_MissForceGeneric);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_MIPS