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

src/arm/code-stubs-arm.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 874 matching lines @@
 
     __ CompareObjectType(lhs, r3, r3, FIRST_SPEC_OBJECT_TYPE);
     __ b(ge, &return_not_equal);
 
     // Check for oddballs: true, false, null, undefined.
     __ cmp(r3, Operand(ODDBALL_TYPE));
     __ b(eq, &return_not_equal);
 
     // 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_(r2, r2, Operand(r3));
-    __ tst(r2, Operand(kIsInternalizedMask));
-    __ b(ne, &return_not_equal);
+    __ and_(r2, r2, Operand(kIsNotStringMask | kIsInternalizedMask));
+    __ cmp(r2, Operand(kInternalizedTag | kStringTag));
+    __ b(ne, &not_internalized);  // r2 (rhs) is not an internalized string
+
+    __ and_(r3, r3, Operand(kIsNotStringMask | kIsInternalizedMask));
+    __ cmp(r3, Operand(kInternalizedTag | kStringTag));
+    __ b(eq, &return_not_equal);  // both rhs and lhs are internalized strings
+
+    __ bind(&not_internalized);
 }
 
 
 // See comment at call site.
 static void EmitCheckForTwoHeapNumbers(MacroAssembler* masm,
                                        Register lhs,
                                        Register rhs,
                                        Label* both_loaded_as_doubles,
                                        Label* not_heap_numbers,
                                        Label* slow) {
@@ skipping 19 matching lines @@
 // Fast negative check for internalized-to-internalized equality.
 static void EmitCheckForInternalizedStringsOrObjects(MacroAssembler* masm,
                                                      Register lhs,
                                                      Register rhs,
                                                      Label* possible_strings,
                                                      Label* not_both_strings) {
   ASSERT((lhs.is(r0) && rhs.is(r1)) ||
          (lhs.is(r1) && rhs.is(r0)));
 
   // r2 is object type of rhs.
-  // Ensure that no non-strings have the internalized bit set.
   Label object_test;
   STATIC_ASSERT(kInternalizedTag != 0);
   __ tst(r2, Operand(kIsNotStringMask));
   __ b(ne, &object_test);
   __ tst(r2, Operand(kIsInternalizedMask));
   __ b(eq, possible_strings);
   __ CompareObjectType(lhs, r3, r3, FIRST_NONSTRING_TYPE);
   __ b(ge, not_both_strings);
   __ tst(r3, Operand(kIsInternalizedMask));
   __ b(eq, possible_strings);
@@ skipping 5255 matching lines @@
 
   // Check that both operands are heap objects.
   __ JumpIfEitherSmi(left, right, &miss);
 
   // Check that both operands are internalized strings.
   __ ldr(tmp1, FieldMemOperand(left, HeapObject::kMapOffset));
   __ ldr(tmp2, FieldMemOperand(right, HeapObject::kMapOffset));
   __ ldrb(tmp1, FieldMemOperand(tmp1, Map::kInstanceTypeOffset));
   __ ldrb(tmp2, FieldMemOperand(tmp2, Map::kInstanceTypeOffset));
   STATIC_ASSERT(kInternalizedTag != 0);
-  __ and_(tmp1, tmp1, Operand(tmp2));
-  __ tst(tmp1, Operand(kIsInternalizedMask));
-  __ b(eq, &miss);
+
+  __ and_(tmp1, tmp1, Operand(kIsNotStringMask | kIsInternalizedMask));
+  __ cmp(tmp1, Operand(kInternalizedTag | kStringTag));
+  __ b(ne, &miss);
+
+  __ and_(tmp2, tmp2, Operand(kIsNotStringMask | kIsInternalizedMask));
+  __ cmp(tmp2, Operand(kInternalizedTag | kStringTag));
+  __ b(ne, &miss);
 
   // Internalized strings are compared by identity.
   __ cmp(left, right);
   // Make sure r0 is non-zero. At this point input operands are
   // guaranteed to be non-zero.
   ASSERT(right.is(r0));
   STATIC_ASSERT(EQUAL == 0);
   STATIC_ASSERT(kSmiTag == 0);
   __ mov(r0, Operand(Smi::FromInt(EQUAL)), LeaveCC, eq);
   __ Ret();
@@ skipping 18 matching lines @@
   __ JumpIfEitherSmi(left, right, &miss);
 
   // Check that both operands are unique names. This leaves the instance
   // types loaded in tmp1 and tmp2.
   STATIC_ASSERT(kInternalizedTag != 0);
   __ ldr(tmp1, FieldMemOperand(left, HeapObject::kMapOffset));
   __ ldr(tmp2, FieldMemOperand(right, HeapObject::kMapOffset));
   __ ldrb(tmp1, FieldMemOperand(tmp1, Map::kInstanceTypeOffset));
   __ ldrb(tmp2, FieldMemOperand(tmp2, Map::kInstanceTypeOffset));
 
-  Label succeed1;
-  __ tst(tmp1, Operand(kIsInternalizedMask));
-  __ b(ne, &succeed1);
-  __ cmp(tmp1, Operand(SYMBOL_TYPE));
-  __ b(ne, &miss);
-  __ bind(&succeed1);
-
-  Label succeed2;
-  __ tst(tmp2, Operand(kIsInternalizedMask));
-  __ b(ne, &succeed2);
-  __ cmp(tmp2, Operand(SYMBOL_TYPE));
-  __ b(ne, &miss);
-  __ bind(&succeed2);
+  __ JumpIfNotUniqueName(tmp1, &miss);
+  __ JumpIfNotUniqueName(tmp2, &miss);
 
   // Unique names are compared by identity.
   __ cmp(left, right);
   // Make sure r0 is non-zero. At this point input operands are
   // guaranteed to be non-zero.
   ASSERT(right.is(r0));
   STATIC_ASSERT(EQUAL == 0);
   STATIC_ASSERT(kSmiTag == 0);
   __ mov(r0, Operand(Smi::FromInt(EQUAL)), LeaveCC, eq);
   __ Ret();
@@ skipping 34 matching lines @@
   // Fast check for identical strings.
   __ cmp(left, right);
   STATIC_ASSERT(EQUAL == 0);
   STATIC_ASSERT(kSmiTag == 0);
   __ mov(r0, Operand(Smi::FromInt(EQUAL)), LeaveCC, eq);
   __ Ret(eq);
 
   // 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);
     __ and_(tmp3, tmp1, Operand(tmp2));
     __ tst(tmp3, Operand(kIsInternalizedMask));
     // Make sure r0 is non-zero. At this point input operands are
     // guaranteed to be non-zero.
     ASSERT(right.is(r0));
     __ Ret(ne);
   }
@@ skipping 165 matching lines @@
     __ b(eq, miss);
 
     Label good;
     __ cmp(entity_name, tmp);
     __ b(eq, &good);
 
     // Check if the entry name is not a unique name.
     __ ldr(entity_name, FieldMemOperand(entity_name, HeapObject::kMapOffset));
     __ ldrb(entity_name,
             FieldMemOperand(entity_name, Map::kInstanceTypeOffset));
-    __ tst(entity_name, Operand(kIsInternalizedMask));
-    __ b(ne, &good);
-    __ cmp(entity_name, Operand(SYMBOL_TYPE));
-    __ b(ne, miss);
-
+    __ JumpIfNotUniqueName(entity_name, miss);
     __ bind(&good);
 
     // Restore the properties.
     __ ldr(properties,
            FieldMemOperand(receiver, JSObject::kPropertiesOffset));
   }
 
   const int spill_mask =
       (lr.bit() | r6.bit() | r5.bit() | r4.bit() | r3.bit() |
        r2.bit() | r1.bit() | r0.bit());
@@ skipping 146 matching lines @@
     // Having undefined at this place means the name is not contained.
     __ cmp(entry_key, Operand(undefined));
     __ b(eq, &not_in_dictionary);
 
     // Stop if found the property.
     __ cmp(entry_key, Operand(key));
     __ b(eq, &in_dictionary);
 
     if (i != kTotalProbes - 1 && mode_ == NEGATIVE_LOOKUP) {
       // Check if the entry name is not a unique name.
-      Label cont;
       __ ldr(entry_key, FieldMemOperand(entry_key, HeapObject::kMapOffset));
       __ ldrb(entry_key,
               FieldMemOperand(entry_key, Map::kInstanceTypeOffset));
-      __ tst(entry_key, Operand(kIsInternalizedMask));
-      __ b(ne, &cont);
-      __ cmp(entry_key, Operand(SYMBOL_TYPE));
-      __ b(ne, &maybe_in_dictionary);
-      __ bind(&cont);
+      __ JumpIfNotUniqueName(entry_key, &maybe_in_dictionary);
     }
   }
 
   __ 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, Operand::Zero());
     __ Ret();
@@ skipping 711 matching lines @@
   __ bind(&fast_elements_case);
   GenerateCase(masm, FAST_ELEMENTS);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM