Revert of Internalize strings in-place

src/arm/code-stubs-arm.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_ARM
 
 #include "src/code-stubs.h"
 #include "src/api-arguments.h"
 #include "src/base/bits.h"
 #include "src/bootstrapper.h"
@@ skipping 1280 matching lines @@
   //     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 or thin string.  Replace subject with parent.  Go to (1).
+  // (8) Sliced string.  Replace subject with parent.  Go to (1).
 
   Label seq_string /* 4 */, external_string /* 6 */, check_underlying /* 1 */,
       not_seq_nor_cons /* 5 */, not_long_external /* 7 */;
 
   __ bind(&check_underlying);
   __ ldr(r0, FieldMemOperand(subject, HeapObject::kMapOffset));
   __ ldrb(r0, FieldMemOperand(r0, Map::kInstanceTypeOffset));
 
   // (1) Sequential string?  If yes, go to (4).
   __ and_(r1,
           r0,
           Operand(kIsNotStringMask |
                   kStringRepresentationMask |
                   kShortExternalStringMask),
           SetCC);
   STATIC_ASSERT((kStringTag | kSeqStringTag) == 0);
   __ b(eq, &seq_string);  // Go to (4).
 
   // (2) Sequential or cons?  If not, go to (5).
   STATIC_ASSERT(kConsStringTag < kExternalStringTag);
   STATIC_ASSERT(kSlicedStringTag > kExternalStringTag);
-  STATIC_ASSERT(kThinStringTag > kExternalStringTag);
   STATIC_ASSERT(kIsNotStringMask > kExternalStringTag);
   STATIC_ASSERT(kShortExternalStringTag > kExternalStringTag);
   __ cmp(r1, Operand(kExternalStringTag));
   __ b(ge, &not_seq_nor_cons);  // Go to (5).
 
   // (3) Cons string.  Check that it's flat.
   // Replace subject with first string and reload instance type.
   __ ldr(r0, FieldMemOperand(subject, ConsString::kSecondOffset));
   __ CompareRoot(r0, Heap::kempty_stringRootIndex);
   __ b(ne, &runtime);
   __ ldr(subject, FieldMemOperand(subject, ConsString::kFirstOffset));
   __ jmp(&check_underlying);
 
   // (4) Sequential string.  Load regexp code according to encoding.
   __ bind(&seq_string);
   // subject: sequential subject string (or look-alike, external string)
   // r3: original subject string
   // Load previous index and check range before r3 is overwritten.  We have to
   // use r3 instead of subject here because subject might have been only made
   // to look like a sequential string when it actually is an external string.
   __ ldr(r1, MemOperand(sp, kPreviousIndexOffset));
   __ JumpIfNotSmi(r1, &runtime);
   __ ldr(r3, FieldMemOperand(r3, String::kLengthOffset));
   __ cmp(r3, Operand(r1));
   __ b(ls, &runtime);
   __ SmiUntag(r1);
 
-  STATIC_ASSERT(8 == kOneByteStringTag);
+  STATIC_ASSERT(4 == kOneByteStringTag);
   STATIC_ASSERT(kTwoByteStringTag == 0);
   __ and_(r0, r0, Operand(kStringEncodingMask));
-  __ mov(r3, Operand(r0, ASR, 3), SetCC);
+  __ mov(r3, Operand(r0, ASR, 2), SetCC);
   __ ldr(r6, FieldMemOperand(regexp_data, JSRegExp::kDataOneByteCodeOffset),
          ne);
   __ ldr(r6, FieldMemOperand(regexp_data, JSRegExp::kDataUC16CodeOffset), eq);
 
   // (E) Carry on.  String handling is done.
   // r6: irregexp code
   // Check that the irregexp code has been generated for the actual string
   // encoding. If it has, the field contains a code object otherwise it contains
   // a smi (code flushing support).
   __ JumpIfSmi(r6, &runtime);
@@ skipping 213 matching lines @@
          subject,
          Operand(SeqTwoByteString::kHeaderSize - kHeapObjectTag));
   __ jmp(&seq_string);  // Go to (4).
 
   // (7) Short external string or not a string?  If yes, bail out to runtime.
   __ bind(&not_long_external);
   STATIC_ASSERT(kNotStringTag != 0 && kShortExternalStringTag !=0);
   __ tst(r1, Operand(kIsNotStringMask | kShortExternalStringMask));
   __ b(ne, &runtime);
 
-  // (8) Sliced or thin string.  Replace subject with parent.  Go to (4).
-  Label thin_string;
-  __ cmp(r1, Operand(kThinStringTag));
-  __ b(eq, &thin_string);
+  // (8) Sliced string.  Replace subject with parent.  Go to (4).
   // Load offset into r9 and replace subject string with parent.
   __ ldr(r9, FieldMemOperand(subject, SlicedString::kOffsetOffset));
   __ SmiUntag(r9);
   __ ldr(subject, FieldMemOperand(subject, SlicedString::kParentOffset));
   __ jmp(&check_underlying);  // Go to (4).
-
-  __ bind(&thin_string);
-  __ ldr(subject, FieldMemOperand(subject, ThinString::kActualOffset));
-  __ jmp(&check_underlying);  // Go to (4).
 #endif  // V8_INTERPRETED_REGEXP
 }
 
 
 static void CallStubInRecordCallTarget(MacroAssembler* masm, CodeStub* stub) {
   // r0 : number of arguments to the construct function
   // r1 : the function to call
   // r2 : feedback vector
   // r3 : slot in feedback vector (Smi)
   FrameAndConstantPoolScope scope(masm, StackFrame::INTERNAL);
@@ skipping 2561 matching lines @@
   CallApiFunctionAndReturn(masm, api_function_address, thunk_ref,
                            kStackUnwindSpace, NULL, return_value_operand, NULL);
 }
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_ARM