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8017243: 8001345 is incomplete

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Replaces unused decodeN at MemBarAcquire with its corresponding loadN if loadN is used at more than one place.

Reviewed-by: kvn, twisti
This commit is contained in:
Niclas Adlertz 2013-06-25 12:07:07 -07:00
parent d5d79568d0
commit 19d56715fa
1 changed files with 13 additions and 5 deletions
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18
hotspot/src/share/vm/opto/memnode.cpp
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@ -2943,11 +2943,19 @@ Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
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();