8017243: 8001345 is incomplete
Summary: Replaces unused decodeN at MemBarAcquire with its corresponding loadN if loadN is used at more than one place.
Reviewed-by: kvn, twisti
--- a/hotspot/src/share/vm/opto/memnode.cpp Mon Jun 24 18:23:45 2013 -0700
+++ b/hotspot/src/share/vm/opto/memnode.cpp Tue Jun 25 12:07:07 2013 -0700
@@ -2943,11 +2943,19 @@
Node* my_mem = in(MemBarNode::Precedent);
// The MembarAquire may keep an unused LoadNode alive through the Precedent edge
if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
- assert(my_mem->unique_out() == this, "sanity");
- phase->hash_delete(this);
- del_req(Precedent);
- phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
- my_mem = NULL;
+ // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
+ // replace this Precedent (decodeN) with the Load instead.
+ if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
+ Node* load_node = my_mem->in(1);
+ set_req(MemBarNode::Precedent, load_node);
+ phase->is_IterGVN()->_worklist.push(my_mem);
+ my_mem = load_node;
+ } else {
+ assert(my_mem->unique_out() == this, "sanity");
+ del_req(Precedent);
+ phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
+ my_mem = NULL;
+ }
}
if (my_mem != NULL && my_mem->is_Mem()) {
const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();