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6937111: Restore optimization for Phi of AddP (6552204)

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Restored the original code which was removed by the fix for 6614100.

Reviewed-by: never
This commit is contained in:
Vladimir Kozlov 2010-04-05 10:17:15 -07:00
parent 6f0a3e4a80
commit d72f8abedf
1 changed files with 58 additions and 0 deletions
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58
hotspot/src/share/vm/opto/cfgnode.cpp
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@ -1653,6 +1653,64 @@ Node *PhiNode::Ideal(PhaseGVN *phase, bool can_reshape) {
if (opt != NULL) return opt; if (opt != NULL) return opt;
} }
if (in(1) != NULL && in(1)->Opcode() == Op_AddP && can_reshape) {
// Try to undo Phi of AddP:
// (Phi (AddP base base y) (AddP base2 base2 y))
// becomes:
// newbase := (Phi base base2)
// (AddP newbase newbase y)
//
// This occurs as a result of unsuccessful split_thru_phi and
// interferes with taking advantage of addressing modes. See the
// clone_shift_expressions code in matcher.cpp
Node* addp = in(1);
const Type* type = addp->in(AddPNode::Base)->bottom_type();
Node* y = addp->in(AddPNode::Offset);
if (y != NULL && addp->in(AddPNode::Base) == addp->in(AddPNode::Address)) {
// make sure that all the inputs are similar to the first one,
// i.e. AddP with base == address and same offset as first AddP
bool doit = true;
for (uint i = 2; i < req(); i++) {
if (in(i) == NULL ||
in(i)->Opcode() != Op_AddP ||
in(i)->in(AddPNode::Base) != in(i)->in(AddPNode::Address) ||
in(i)->in(AddPNode::Offset) != y) {
doit = false;
break;
}
// Accumulate type for resulting Phi
type = type->meet(in(i)->in(AddPNode::Base)->bottom_type());
}
Node* base = NULL;
if (doit) {
// Check for neighboring AddP nodes in a tree.
// If they have a base, use that it.
for (DUIterator_Fast kmax, k = this->fast_outs(kmax); k < kmax; k++) {
Node* u = this->fast_out(k);
if (u->is_AddP()) {
Node* base2 = u->in(AddPNode::Base);
if (base2 != NULL && !base2->is_top()) {
if (base == NULL)
base = base2;
else if (base != base2)
{ doit = false; break; }
}
}
}
}
if (doit) {
if (base == NULL) {
base = new (phase->C, in(0)->req()) PhiNode(in(0), type, NULL);
for (uint i = 1; i < req(); i++) {
base->init_req(i, in(i)->in(AddPNode::Base));
}
phase->is_IterGVN()->register_new_node_with_optimizer(base);
}
return new (phase->C, 4) AddPNode(base, base, y);
}
}
}
// Split phis through memory merges, so that the memory merges will go away. // Split phis through memory merges, so that the memory merges will go away.
// Piggy-back this transformation on the search for a unique input.... // Piggy-back this transformation on the search for a unique input....
// It will be as if the merged memory is the unique value of the phi. // It will be as if the merged memory is the unique value of the phi.