MIPS: port RegExpMacroAssembler::CheckStackGuardState should update input string pointer...

src/mips/regexp-macro-assembler-mips.cc

Index: src/mips/regexp-macro-assembler-mips.cc
diff --git a/src/mips/regexp-macro-assembler-mips.cc b/src/mips/regexp-macro-assembler-mips.cc
index 9db5c5bed210732fdd1a072cd2c83ab1ba7e45a5..cb210fed04fc88233af4e8d2e23751b813248014 100644
--- a/src/mips/regexp-macro-assembler-mips.cc
+++ b/src/mips/regexp-macro-assembler-mips.cc
@@ -1112,6 +1112,11 @@ int RegExpMacroAssemblerMIPS::CheckStackGuardState(Address* return_address,
     frame_entry<const String*>(re_frame, kInputString) = *subject;
     frame_entry<const byte*>(re_frame, kInputStart) = new_address;
     frame_entry<const byte*>(re_frame, kInputEnd) = new_address + byte_length;
+  } else if (frame_entry<const String*>(re_frame, kInputString) != *subject) {
+    // Subject string might have been a ConsString that underwent
+    // short-circuiting during GC. That will not change start_address but
+    // will change pointer inside the subject handle.
+    frame_entry<const String*>(re_frame, kInputString) = *subject;
   }
 
   return 0;