truffle: src/share/vm/opto/memnode.cpp comparison

6892658: C2 should optimize some stringbuilder patterns Reviewed-by: kvn, twisti

comparison

equal deleted inserted replaced

-:8e7adf982378
+:7c57aead6d3e
 }
 return jt;
 }
 }
 } 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() ||
 // unsafe field access may not have a constant offset
 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
 tp->is_klassptr()->klass()->is_java_lang_Object() ||
 // also allow array-loading from the primary supertype

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