Using array index hash code for string-to-number conversion.

src/ia32/full-codegen-ia32.cc

Index: src/ia32/full-codegen-ia32.cc
===================================================================
--- src/ia32/full-codegen-ia32.cc	(revision 5357)
+++ src/ia32/full-codegen-ia32.cc	(working copy)
@@ -2848,6 +2848,46 @@
 }
 
 
+void FullCodeGenerator::EmitHasCachedArrayIndex(ZoneList<Expression*>* args) {
+  ASSERT(args->length() == 1);
+
+  VisitForValue(args->at(0), kAccumulator);
+
+  if (FLAG_debug_code) {
+    __ AbortIfNotString(eax);
+  }
+
+  Label materialize_true, materialize_false;
+  Label* if_true = NULL;
+  Label* if_false = NULL;
+  Label* fall_through = NULL;
+  PrepareTest(&materialize_true, &materialize_false,
+              &if_true, &if_false, &fall_through);
+
+  __ test(FieldOperand(eax, String::kHashFieldOffset),
+          Immediate(String::kContainsCachedArrayIndexMask));
+  Split(zero, if_true, if_false, fall_through);
+
+  Apply(context_, if_true, if_false);
+}
+
+
+void FullCodeGenerator::EmitGetCachedArrayIndex(ZoneList<Expression*>* args) {
+  ASSERT(args->length() == 1);
+
+  VisitForValue(args->at(0), kAccumulator);
+
+  if (FLAG_debug_code) {
+    __ AbortIfNotString(eax);
+  }
+
+  __ mov(eax, FieldOperand(eax, String::kHashFieldOffset));
+  __ IndexFromHash(eax, eax);
+
+  Apply(context_, eax);
+}
+
+
 void FullCodeGenerator::VisitCallRuntime(CallRuntime* expr) {
   Handle<String> name = expr->name();
   if (name->length() > 0 && name->Get(0) == '_') {