MIPS: The check for internalized strings relied on the fact that we had less than 64 distinct InstanceTypes.

Port r15358 (3af77be)

Original commit message:
The check for internalized strings relied on the fact that we had less
than 64 distinct InstanceTypes. We are hitting that boundary, so this
check needs to be more comprehensive. In fact, two bits need to be
tested: verify that kNotStringTag isn't set, and that kInternalizedTag
is set.

BUG=

Review URL: https://codereview.chromium.org/18083004
Patch from Balazs Kilvady <kilvadyb@homejinni.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15368 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/mips/code-stubs-mips.cc

@@ -1181,12 +1181,17 @@ static void EmitStrictTwoHeapObjectCompare(MacroAssembler* masm,
 
     // Now that we have the types we might as well check for
     // internalized-internalized.
-    // Ensure that no non-strings have the internalized bit set.
-    STATIC_ASSERT(LAST_TYPE < kNotStringTag + kIsInternalizedMask);
+    Label not_internalized;
     STATIC_ASSERT(kInternalizedTag != 0);
-    __ And(t2, a2, Operand(a3));
-    __ And(t0, t2, Operand(kIsInternalizedMask));
-    __ Branch(&return_not_equal, ne, t0, Operand(zero_reg));
+    __ And(t2, a2, Operand(kIsNotStringMask | kIsInternalizedMask));
+    __ Branch(&not_internalized, ne, t2,
+        Operand(kInternalizedTag | kStringTag));
+
+    __ And(a3, a3, Operand(kIsNotStringMask | kIsInternalizedMask));
+    __ Branch(&return_not_equal, eq, a3,
+        Operand(kInternalizedTag | kStringTag));
+
+    __ bind(&not_internalized);
 }
 
 
@@ -1220,8 +1225,7 @@ static void EmitCheckForInternalizedStringsOrObjects(MacroAssembler* masm,
   ASSERT((lhs.is(a0) && rhs.is(a1)) ||
          (lhs.is(a1) && rhs.is(a0)));
 
-  // a2 is object type of lhs.
-  // Ensure that no non-strings have the internalized bit set.
+  // a2 is object type of rhs.
   Label object_test;
   STATIC_ASSERT(kInternalizedTag != 0);
   __ And(at, a2, Operand(kIsNotStringMask));
@@ -6612,9 +6616,13 @@ void ICCompareStub::GenerateInternalizedStrings(MacroAssembler* masm) {
   __ lbu(tmp1, FieldMemOperand(tmp1, Map::kInstanceTypeOffset));
   __ lbu(tmp2, FieldMemOperand(tmp2, Map::kInstanceTypeOffset));
   STATIC_ASSERT(kInternalizedTag != 0);
-  __ And(tmp1, tmp1, Operand(tmp2));
-  __ And(tmp1, tmp1, kIsInternalizedMask);
-  __ Branch(&miss, eq, tmp1, Operand(zero_reg));
+
+  __ And(tmp1, tmp1, Operand(kIsNotStringMask | kIsInternalizedMask));
+  __ Branch(&miss, ne, tmp1, Operand(kInternalizedTag | kStringTag));
+
+  __ And(tmp2, tmp2, Operand(kIsNotStringMask | kIsInternalizedMask));
+  __ Branch(&miss, ne, tmp2, Operand(kInternalizedTag | kStringTag));
+
   // Make sure a0 is non-zero. At this point input operands are
   // guaranteed to be non-zero.
   ASSERT(right.is(a0));
@@ -6654,17 +6662,8 @@ void ICCompareStub::GenerateUniqueNames(MacroAssembler* masm) {
   __ lbu(tmp1, FieldMemOperand(tmp1, Map::kInstanceTypeOffset));
   __ lbu(tmp2, FieldMemOperand(tmp2, Map::kInstanceTypeOffset));
 
-  Label succeed1;
-  __ And(at, tmp1, Operand(kIsInternalizedMask));
-  __ Branch(&succeed1, ne, at, Operand(zero_reg));
-  __ Branch(&miss, ne, tmp1, Operand(SYMBOL_TYPE));
-  __ bind(&succeed1);
-
-  Label succeed2;
-  __ And(at, tmp2, Operand(kIsInternalizedMask));
-  __ Branch(&succeed2, ne, at, Operand(zero_reg));
-  __ Branch(&miss, ne, tmp2, Operand(SYMBOL_TYPE));
-  __ bind(&succeed2);
+  __ JumpIfNotUniqueName(tmp1, &miss);
+  __ JumpIfNotUniqueName(tmp2, &miss);
 
   // Use a0 as result
   __ mov(v0, a0);
@@ -6727,7 +6726,8 @@ void ICCompareStub::GenerateStrings(MacroAssembler* masm) {
   // Handle not identical strings.
 
   // Check that both strings are internalized strings. If they are, we're done
-  // because we already know they are not identical.
+  // because we already know they are not identical. We know they are both
+  // strings.
   if (equality) {
     ASSERT(GetCondition() == eq);
     STATIC_ASSERT(kInternalizedTag != 0);
@@ -6932,10 +6932,7 @@ void NameDictionaryLookupStub::GenerateNegativeLookup(MacroAssembler* masm,
     __ lw(entity_name, FieldMemOperand(entity_name, HeapObject::kMapOffset));
     __ lbu(entity_name,
            FieldMemOperand(entity_name, Map::kInstanceTypeOffset));
-    __ And(scratch0, entity_name, Operand(kIsInternalizedMask));
-    __ Branch(&good, ne, scratch0, Operand(zero_reg));
-    __ Branch(miss, ne, entity_name, Operand(SYMBOL_TYPE));
-
+    __ JumpIfNotUniqueName(entity_name, miss);
     __ bind(&good);
 
     // Restore the properties.
@@ -7109,14 +7106,10 @@ void NameDictionaryLookupStub::Generate(MacroAssembler* masm) {
 
     if (i != kTotalProbes - 1 && mode_ == NEGATIVE_LOOKUP) {
       // Check if the entry name is not a unique name.
-      Label cont;
       __ lw(entry_key, FieldMemOperand(entry_key, HeapObject::kMapOffset));
       __ lbu(entry_key,
              FieldMemOperand(entry_key, Map::kInstanceTypeOffset));
-      __ And(result, entry_key, Operand(kIsInternalizedMask));
-      __ Branch(&cont, ne, result, Operand(zero_reg));
-      __ Branch(&maybe_in_dictionary, ne, entry_key, Operand(SYMBOL_TYPE));
-      __ bind(&cont);
+      __ JumpIfNotUniqueName(entry_key, &maybe_in_dictionary);
     }
   }
 

src/mips/ic-mips.cc

@@ -326,7 +326,8 @@ static void GenerateKeyNameCheck(MacroAssembler* masm,
   __ And(at, hash, Operand(Name::kContainsCachedArrayIndexMask));
   __ Branch(index_string, eq, at, Operand(zero_reg));
 
-  // Is the string internalized?
+  // Is the string internalized? We know it's a string, so a single
+  // bit test is enough.
   // map: key map
   __ lbu(hash, FieldMemOperand(map, Map::kInstanceTypeOffset));
   STATIC_ASSERT(kInternalizedTag != 0);

src/mips/macro-assembler-mips.cc

@@ -3202,6 +3202,14 @@ void MacroAssembler::AllocateAsciiSlicedString(Register result,
 }
 
 
+void MacroAssembler::JumpIfNotUniqueName(Register reg,
+                                         Label* not_unique_name) {
+  STATIC_ASSERT(((SYMBOL_TYPE - 1) & kIsInternalizedMask) == kInternalizedTag);
+  Branch(not_unique_name, lt, reg, Operand(kIsInternalizedMask));
+  Branch(not_unique_name, gt, reg, Operand(SYMBOL_TYPE));
+}
+
+
 // Allocates a heap number or jumps to the label if the young space is full and
 // a scavenge is needed.
 void MacroAssembler::AllocateHeapNumber(Register result,

src/mips/macro-assembler-mips.h

@@ -1406,6 +1406,8 @@ class MacroAssembler: public Assembler {
                                               Register scratch,
                                               Label* failure);
 
+  void JumpIfNotUniqueName(Register reg, Label* not_unique_name);
+
   // Test that both first and second are sequential ASCII strings.
   // Assume that they are non-smis.
   void JumpIfNonSmisNotBothSequentialAsciiStrings(Register first,