The check for internalized strings relied on the fact that we had less

src/ia32/code-stubs-ia32.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 6835 matching lines @@
   STATIC_ASSERT(kSmiTag == 0);
   __ and_(tmp1, right);
   __ JumpIfSmi(tmp1, &miss, Label::kNear);
 
   // Check that both operands are internalized strings.
   __ mov(tmp1, FieldOperand(left, HeapObject::kMapOffset));
   __ mov(tmp2, FieldOperand(right, HeapObject::kMapOffset));
   __ movzx_b(tmp1, FieldOperand(tmp1, Map::kInstanceTypeOffset));
   __ movzx_b(tmp2, FieldOperand(tmp2, Map::kInstanceTypeOffset));
   STATIC_ASSERT(kInternalizedTag != 0);
-  __ and_(tmp1, tmp2);
-  __ test(tmp1, Immediate(kIsInternalizedMask));
-  __ j(zero, &miss, Label::kNear);
+  __ and_(tmp1, Immediate(kIsNotStringMask | kIsInternalizedMask));
+  __ cmpb(tmp1, kInternalizedTag | kStringTag);
+  __ j(not_equal, &miss, Label::kNear);
+
+  __ and_(tmp2, Immediate(kIsNotStringMask | kIsInternalizedMask));
+  __ cmpb(tmp2, kInternalizedTag | kStringTag);
+  __ j(not_equal, &miss, Label::kNear);
 
   // Internalized strings are compared by identity.
   Label done;
   __ cmp(left, right);
   // Make sure eax is non-zero. At this point input operands are
   // guaranteed to be non-zero.
   ASSERT(right.is(eax));
   __ j(not_equal, &done, Label::kNear);
   STATIC_ASSERT(EQUAL == 0);
   STATIC_ASSERT(kSmiTag == 0);
@@ skipping 25 matching lines @@
 
   // Check that both operands are unique names. This leaves the instance
   // types loaded in tmp1 and tmp2.
   STATIC_ASSERT(kInternalizedTag != 0);
   __ mov(tmp1, FieldOperand(left, HeapObject::kMapOffset));
   __ mov(tmp2, FieldOperand(right, HeapObject::kMapOffset));
   __ movzx_b(tmp1, FieldOperand(tmp1, Map::kInstanceTypeOffset));
   __ movzx_b(tmp2, FieldOperand(tmp2, Map::kInstanceTypeOffset));
 
   Label succeed1;
-  __ test(tmp1, Immediate(kIsInternalizedMask));
-  __ j(not_zero, &succeed1);
   __ cmpb(tmp1, static_cast<uint8_t>(SYMBOL_TYPE));
-  __ j(not_equal, &miss);
+  __ j(equal, &succeed1);
+  __ and_(tmp1, Immediate(kIsNotStringMask | kIsInternalizedMask));
+  __ cmpb(tmp1, kIsInternalizedMask | kStringTag);
+  __ j(not_equal, &miss, Label::kNear);
   __ bind(&succeed1);
 
   Label succeed2;
-  __ test(tmp2, Immediate(kIsInternalizedMask));
-  __ j(not_zero, &succeed2);
   __ cmpb(tmp2, static_cast<uint8_t>(SYMBOL_TYPE));
-  __ j(not_equal, &miss);
+  __ j(equal, &succeed2);
+  __ and_(tmp2, Immediate(kIsNotStringMask | kIsInternalizedMask));
+  __ cmpb(tmp2, kIsInternalizedMask | kStringTag);
+  __ j(not_equal, &miss, Label::kNear);
   __ bind(&succeed2);
 
   // Unique names are compared by identity.
   Label done;
   __ cmp(left, right);
   // Make sure eax is non-zero. At this point input operands are
   // guaranteed to be non-zero.
   ASSERT(right.is(eax));
   __ j(not_equal, &done, Label::kNear);
   STATIC_ASSERT(EQUAL == 0);
@@ skipping 45 matching lines @@
   STATIC_ASSERT(EQUAL == 0);
   STATIC_ASSERT(kSmiTag == 0);
   __ Set(eax, Immediate(Smi::FromInt(EQUAL)));
   __ ret(0);
 
   // Handle not identical strings.
   __ bind(&not_same);
 
   // Check that both strings are internalized. If they are, we're done
   // because we already know they are not identical.  But in the case of
-  // non-equality compare, we still need to determine the order.
+  // non-equality compare, we still need to determine the order. We
+  // also know they are both strings.
   if (equality) {
     Label do_compare;
     STATIC_ASSERT(kInternalizedTag != 0);
     __ and_(tmp1, tmp2);
     __ test(tmp1, Immediate(kIsInternalizedMask));
     __ j(zero, &do_compare, Label::kNear);
     // Make sure eax is non-zero. At this point input operands are
     // guaranteed to be non-zero.
     ASSERT(right.is(eax));
     __ ret(0);
@@ skipping 138 matching lines @@
     __ cmp(entity_name, Handle<Name>(name));
     __ j(equal, miss);
 
     Label good;
     // Check for the hole and skip.
     __ cmp(entity_name, masm->isolate()->factory()->the_hole_value());
     __ j(equal, &good, Label::kNear);
 
     // Check if the entry name is not a unique name.
     __ mov(entity_name, FieldOperand(entity_name, HeapObject::kMapOffset));
+    __ cmpb(FieldOperand(entity_name, Map::kInstanceTypeOffset),
+            static_cast<uint8_t>(SYMBOL_TYPE));
+    __ j(equal, &good);
+    __ test_b(FieldOperand(entity_name, Map::kInstanceTypeOffset),
+              kIsNotStringMask);
+    __ j(not_zero, miss);
     __ test_b(FieldOperand(entity_name, Map::kInstanceTypeOffset),
               kIsInternalizedMask);
-    __ j(not_zero, &good);
-    __ cmpb(FieldOperand(entity_name, Map::kInstanceTypeOffset),
-            static_cast<uint8_t>(SYMBOL_TYPE));
-    __ j(not_equal, miss);
+    __ j(zero, miss);
     __ bind(&good);
   }
 
   NameDictionaryLookupStub stub(properties, r0, r0, NEGATIVE_LOOKUP);
   __ push(Immediate(Handle<Object>(name)));
   __ push(Immediate(name->Hash()));
   __ CallStub(&stub);
   __ test(r0, r0);
   __ j(not_zero, miss);
   __ jmp(done);
@@ skipping 114 matching lines @@
     __ j(equal, &in_dictionary);
 
     if (i != kTotalProbes - 1 && mode_ == NEGATIVE_LOOKUP) {
       // If we hit a key that is not a unique name during negative
       // lookup we have to bailout as this key might be equal to the
       // key we are looking for.
 
       // Check if the entry name is not a unique name.
       Label cont;
       __ mov(scratch, FieldOperand(scratch, HeapObject::kMapOffset));
+      __ cmpb(FieldOperand(scratch, Map::kInstanceTypeOffset),
+              static_cast<uint8_t>(SYMBOL_TYPE));
+      __ j(equal, &cont);
+      __ test_b(FieldOperand(scratch, Map::kInstanceTypeOffset),
+                kIsNotStringMask);
+      __ j(not_zero, &maybe_in_dictionary);
       __ test_b(FieldOperand(scratch, Map::kInstanceTypeOffset),
                 kIsInternalizedMask);
-      __ j(not_zero, &cont);
-      __ cmpb(FieldOperand(scratch, Map::kInstanceTypeOffset),
-              static_cast<uint8_t>(SYMBOL_TYPE));
-      __ j(not_equal, &maybe_in_dictionary);
+      __ j(zero, &maybe_in_dictionary);
       __ bind(&cont);
     }
   }
 
   __ bind(&maybe_in_dictionary);
   // If we are doing negative lookup then probing failure should be
   // treated as a lookup success. For positive lookup probing failure
   // should be treated as lookup failure.
   if (mode_ == POSITIVE_LOOKUP) {
     __ mov(result_, Immediate(0));
@@ skipping 719 matching lines @@
   __ bind(&fast_elements_case);
   GenerateCase(masm, FAST_ELEMENTS);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32