Revert of Internalize strings in-place

src/x87/codegen-x87.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.
 
 #include "src/x87/codegen-x87.h"
 
 #if V8_TARGET_ARCH_X87
 
 #include "src/codegen.h"
 #include "src/heap/heap.h"
@@ skipping 210 matching lines @@
   // Fetch the instance type of the receiver into result register.
   __ mov(result, FieldOperand(string, HeapObject::kMapOffset));
   __ movzx_b(result, FieldOperand(result, Map::kInstanceTypeOffset));
 
   // We need special handling for indirect strings.
   Label check_sequential;
   __ test(result, Immediate(kIsIndirectStringMask));
   __ j(zero, &check_sequential, Label::kNear);
 
   // Dispatch on the indirect string shape: slice or cons.
-  Label cons_string, thin_string;
-  __ and_(result, Immediate(kStringRepresentationMask));
-  __ cmp(result, Immediate(kConsStringTag));
-  __ j(equal, &cons_string, Label::kNear);
-  __ cmp(result, Immediate(kThinStringTag));
-  __ j(equal, &thin_string, Label::kNear);
+  Label cons_string;
+  __ test(result, Immediate(kSlicedNotConsMask));
+  __ j(zero, &cons_string, Label::kNear);
 
   // Handle slices.
   Label indirect_string_loaded;
   __ mov(result, FieldOperand(string, SlicedString::kOffsetOffset));
   __ SmiUntag(result);
   __ add(index, result);
   __ mov(string, FieldOperand(string, SlicedString::kParentOffset));
   __ jmp(&indirect_string_loaded, Label::kNear);
 
-  // Handle thin strings.
-  __ bind(&thin_string);
-  __ mov(string, FieldOperand(string, ThinString::kActualOffset));
-  __ jmp(&indirect_string_loaded, Label::kNear);
-
   // Handle cons strings.
   // Check whether the right hand side is the empty string (i.e. if
   // this is really a flat string in a cons string). If that is not
   // the case we would rather go to the runtime system now to flatten
   // the string.
   __ bind(&cons_string);
   __ cmp(FieldOperand(string, ConsString::kSecondOffset),
          Immediate(factory->empty_string()));
   __ j(not_equal, call_runtime);
   __ mov(string, FieldOperand(string, ConsString::kFirstOffset));
@@ skipping 112 matching lines @@
     CodePatcher patcher(isolate, sequence, young_length);
     patcher.masm()->call(stub->instruction_start(), RelocInfo::NONE32);
   }
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_X87