Simplified %StringEquals

src/runtime.cc

 // Copyright 2006-2008 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 2772 matching lines @@
 }
 
 
 static Object* Runtime_StringEquals(Arguments args) {
   NoHandleAllocation ha;
   ASSERT(args.length() == 2);
 
   CONVERT_CHECKED(String, x, args[0]);
   CONVERT_CHECKED(String, y, args[1]);
 
-  // This is very similar to String::Equals(String*) but that version
-  // requires flattened strings as input, whereas we flatten the
-  // strings only if the fast cases fail.  Note that this may fail,
-  // requiring a GC.  String::Equals(String*) returns a bool and has
-  // no way to signal a failure.
-  if (y == x) return Smi::FromInt(EQUAL);
-  if (x->IsSymbol() && y->IsSymbol()) return Smi::FromInt(NOT_EQUAL);
-  // Compare contents
-  int len = x->length();
-  if (len != y->length()) return Smi::FromInt(NOT_EQUAL);
-  if (len == 0) return Smi::FromInt(EQUAL);
-
-  // Handle one elment strings.
-  if (x->Get(0) != y->Get(0)) return Smi::FromInt(NOT_EQUAL);
-  if (len == 1) return Smi::FromInt(EQUAL);
-
-  // Fast case:  First, middle and last characters.
-  if (x->Get(len>>1) != y->Get(len>>1)) return Smi::FromInt(NOT_EQUAL);
-  if (x->Get(len - 1) != y->Get(len - 1)) return Smi::FromInt(NOT_EQUAL);
-
-  x->TryFlatten();
-  y->TryFlatten();
-
-  static StringInputBuffer buf1;
-  static StringInputBuffer buf2;
-  buf1.Reset(x);
-  buf2.Reset(y);
-  while (buf1.has_more()) {
-    if (buf1.GetNext() != buf2.GetNext())
-      return Smi::FromInt(NOT_EQUAL);
-  }
-  return Smi::FromInt(EQUAL);
+  bool not_equal = !x->Equals(y);
+  // This is slightly convoluted because the value that signifies
+  // equality is 0 and inequality is 1 so we have to negate the result
+  // from String::Equals.
+  ASSERT(not_equal == 0 || not_equal == 1);
+  STATIC_CHECK(EQUAL == 0);
+  STATIC_CHECK(NOT_EQUAL == 1);
+  return Smi::FromInt(not_equal);
 }
 
 
 static Object* Runtime_NumberCompare(Arguments args) {
   NoHandleAllocation ha;
   ASSERT(args.length() == 3);
 
   CONVERT_DOUBLE_CHECKED(x, args[0]);
   CONVERT_DOUBLE_CHECKED(y, args[1]);
   if (isnan(x) || isnan(y)) return args[2];
@@ skipping 2639 matching lines @@
 
 void Runtime::PerformGC(Object* result) {
   Failure* failure = Failure::cast(result);
   // Try to do a garbage collection; ignore it if it fails. The C
   // entry stub will throw an out-of-memory exception in that case.
   Heap::CollectGarbage(failure->requested(), failure->allocation_space());
 }
 
 
 } }  // namespace v8::internal