Internalize strings in-place

src/arm/codegen-arm.cc

Index: src/arm/codegen-arm.cc
diff --git a/src/arm/codegen-arm.cc b/src/arm/codegen-arm.cc
index 06e92168b6f7c1a2e6966d0e8af408de9ef936a9..2152d6837a09dcef23c172f09baa69716082fdd1 100644
--- a/src/arm/codegen-arm.cc
+++ b/src/arm/codegen-arm.cc
@@ -332,9 +332,12 @@ void StringCharLoadGenerator::Generate(MacroAssembler* masm,
   __ b(eq, &check_sequential);
 
   // Dispatch on the indirect string shape: slice or cons.
-  Label cons_string;
-  __ tst(result, Operand(kSlicedNotConsMask));
+  Label cons_string, thin_string;
+  __ and_(result, result, Operand(kStringRepresentationMask));
+  __ cmp(result, Operand(kConsStringTag));
   __ b(eq, &cons_string);
+  __ cmp(result, Operand(kThinStringTag));
+  __ b(eq, &thin_string);
 
   // Handle slices.
   Label indirect_string_loaded;
@@ -343,6 +346,11 @@ void StringCharLoadGenerator::Generate(MacroAssembler* masm,
   __ add(index, index, Operand::SmiUntag(result));
   __ jmp(&indirect_string_loaded);
 
+  // Handle thin strings.
+  __ bind(&thin_string);
+  __ ldr(string, FieldMemOperand(string, ThinString::kActualOffset));
+  __ jmp(&indirect_string_loaded);
+
   // 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