Internalize strings in-place

src/arm/code-stubs-arm.cc

Index: src/arm/code-stubs-arm.cc
diff --git a/src/arm/code-stubs-arm.cc b/src/arm/code-stubs-arm.cc
index 08b31ea907368d61621a0b3242354ff58cf29368..7c3ce3a242f2555fccde85f631717e89acef46c6 100644
--- a/src/arm/code-stubs-arm.cc
+++ b/src/arm/code-stubs-arm.cc
@@ -1295,7 +1295,7 @@ void RegExpExecStub::Generate(MacroAssembler* masm) {
   // (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).
+  // (8) Sliced or thin 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 */;
@@ -1344,10 +1344,10 @@ void RegExpExecStub::Generate(MacroAssembler* masm) {
   __ b(ls, &runtime);
   __ SmiUntag(r1);
 
-  STATIC_ASSERT(4 == kOneByteStringTag);
+  STATIC_ASSERT(8 == kOneByteStringTag);
   STATIC_ASSERT(kTwoByteStringTag == 0);
   __ and_(r0, r0, Operand(kStringEncodingMask));
-  __ mov(r3, Operand(r0, ASR, 2), SetCC);
+  __ mov(r3, Operand(r0, ASR, 3), SetCC);
   __ ldr(r6, FieldMemOperand(regexp_data, JSRegExp::kDataOneByteCodeOffset),
          ne);
   __ ldr(r6, FieldMemOperand(regexp_data, JSRegExp::kDataUC16CodeOffset), eq);
@@ -1581,12 +1581,19 @@ void RegExpExecStub::Generate(MacroAssembler* masm) {
   __ tst(r1, Operand(kIsNotStringMask | kShortExternalStringMask));
   __ b(ne, &runtime);
 
-  // (8) Sliced string.  Replace subject with parent.  Go to (4).
+  // (8) Sliced or thin string.  Replace subject with parent.  Go to (4).
+  Label thin_string;
+  __ cmp(r1, Operand(kThinStringTag));
+  __ b(eq, &thin_string);
   // 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
 }