MIPS: Make kAsciiDataHintTag have correct semantics for all both 1 and 2 byte string types.

Port r12966 (ec963fe0)

BUG=
TEST=

Review URL: https://chromiumcodereview.appspot.com/11316091
Patch from Akos Palfi <palfia@homejinni.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13021 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/mips/code-stubs-mips.cc

@@ -6600,12 +6600,6 @@ void StringAddStub::Generate(MacroAssembler* masm) {
   __ and_(at, at, t1);
   __ Branch(&ascii_data, ne, at, Operand(zero_reg));
 
-  __ xor_(t0, t0, 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);
   __ Branch(&allocated);

src/mips/macro-assembler-mips.cc

@@ -4896,8 +4896,10 @@ void MacroAssembler::JumpIfBothInstanceTypesAreNotSequentialAscii(
     Register scratch2,
     Label* failure) {
   int kFlatAsciiStringMask =
-      kIsNotStringMask | kStringEncodingMask | kStringRepresentationMask;
+      kIsNotStringMask | kStringEncodingMask | kAsciiDataHintMask |
+      kStringRepresentationMask;
   int kFlatAsciiStringTag = ASCII_STRING_TYPE;
+  ASSERT_EQ(ASCII_STRING_TYPE, ASCII_STRING_TYPE & kFlatAsciiStringMask);
   ASSERT(kFlatAsciiStringTag <= 0xffff);  // Ensure this fits 16-bit immed.
   andi(scratch1, first, kFlatAsciiStringMask);
   Branch(failure, ne, scratch1, Operand(kFlatAsciiStringTag));
@@ -4910,8 +4912,10 @@ void MacroAssembler::JumpIfInstanceTypeIsNotSequentialAscii(Register type,
                                                             Register scratch,
                                                             Label* failure) {
   int kFlatAsciiStringMask =
-      kIsNotStringMask | kStringEncodingMask | kStringRepresentationMask;
+      kIsNotStringMask | kStringEncodingMask | kAsciiDataHintMask |
+      kStringRepresentationMask;
   int kFlatAsciiStringTag = ASCII_STRING_TYPE;
+  ASSERT_EQ(ASCII_STRING_TYPE, ASCII_STRING_TYPE & kFlatAsciiStringMask);
   And(scratch, type, Operand(kFlatAsciiStringMask));
   Branch(failure, ne, scratch, Operand(kFlatAsciiStringTag));
 }