Internalize strings in-place

src/mips64/codegen-mips64.cc

Index: src/mips64/codegen-mips64.cc
diff --git a/src/mips64/codegen-mips64.cc b/src/mips64/codegen-mips64.cc
index 134fe4dd8887cb00091df087a10435b196fc4ce2..78652846df91b81e6ae726a69249a189d31ee4b0 100644
--- a/src/mips64/codegen-mips64.cc
+++ b/src/mips64/codegen-mips64.cc
@@ -622,9 +622,10 @@ void StringCharLoadGenerator::Generate(MacroAssembler* masm,
   __ Branch(&check_sequential, eq, at, Operand(zero_reg));
 
   // Dispatch on the indirect string shape: slice or cons.
-  Label cons_string;
-  __ And(at, result, Operand(kSlicedNotConsMask));
-  __ Branch(&cons_string, eq, at, Operand(zero_reg));
+  Label cons_string, thin_string;
+  __ And(at, result, Operand(kStringRepresentationMask));
+  __ Branch(&cons_string, eq, at, Operand(kConsStringTag));
+  __ Branch(&thin_string, eq, at, Operand(kThinStringTag));
 
   // Handle slices.
   Label indirect_string_loaded;
@@ -634,6 +635,11 @@ void StringCharLoadGenerator::Generate(MacroAssembler* masm,
   __ Daddu(index, index, at);
   __ jmp(&indirect_string_loaded);
 
+  // Handle thin strings.
+  __ bind(&thin_string);
+  __ ld(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