--- a/hotspot/src/share/vm/opto/memnode.cpp Fri Nov 27 07:56:58 2009 -0800
+++ b/hotspot/src/share/vm/opto/memnode.cpp Thu Nov 12 09:24:21 2009 -0800
@@ -1503,6 +1503,8 @@
}
}
} else if (tp->base() == Type::InstPtr) {
+ const TypeInstPtr* tinst = tp->is_instptr();
+ ciKlass* klass = tinst->klass();
assert( off != Type::OffsetBot ||
// arrays can be cast to Objects
tp->is_oopptr()->klass()->is_java_lang_Object() ||
@@ -1510,6 +1512,25 @@
phase->C->has_unsafe_access(),
"Field accesses must be precise" );
// For oop loads, we expect the _type to be precise
+ if (OptimizeStringConcat && klass == phase->C->env()->String_klass() &&
+ adr->is_AddP() && off != Type::OffsetBot) {
+ // For constant Strings treat the fields as compile time constants.
+ Node* base = adr->in(AddPNode::Base);
+ if (base->Opcode() == Op_ConP) {
+ const TypeOopPtr* t = phase->type(base)->isa_oopptr();
+ ciObject* string = t->const_oop();
+ ciConstant constant = string->as_instance()->field_value_by_offset(off);
+ if (constant.basic_type() == T_INT) {
+ return TypeInt::make(constant.as_int());
+ } else if (constant.basic_type() == T_ARRAY) {
+ if (adr->bottom_type()->is_ptr_to_narrowoop()) {
+ return TypeNarrowOop::make_from_constant(constant.as_object());
+ } else {
+ return TypeOopPtr::make_from_constant(constant.as_object());
+ }
+ }
+ }
+ }
} else if (tp->base() == Type::KlassPtr) {
assert( off != Type::OffsetBot ||
// arrays can be cast to Objects