MIPS: Remove move ascii data hint for one byte strings

src/mips/code-stubs-mips.cc

Index: src/mips/code-stubs-mips.cc
diff --git a/src/mips/code-stubs-mips.cc b/src/mips/code-stubs-mips.cc
index 3d01be6064b13dbbf4370ef38bf39a629b5e5543..fb853d83414f67639753ca77ab29d7f6c4117fa8 100644
--- a/src/mips/code-stubs-mips.cc
+++ b/src/mips/code-stubs-mips.cc
@@ -6684,6 +6684,11 @@ void StringAddStub::Generate(MacroAssembler* masm) {
   __ And(at, t0, Operand(kAsciiDataHintMask));
   __ and_(at, at, t1);
   __ Branch(&ascii_data, ne, at, Operand(zero_reg));
+  __ Xor(t0, t0, Operand(t1));
+  STATIC_ASSERT(kOneByteStringTag != 0 && kAsciiDataHintTag != 0);
+  __ And(t0, t0, Operand(kOneByteStringTag | kAsciiDataHintTag));
+  __ Branch(&ascii_data, eq, t0,
+      Operand(kOneByteStringTag | kAsciiDataHintTag));
 
   // Allocate a two byte cons string.
   __ AllocateTwoByteConsString(v0, t2, t0, t1, &call_runtime);