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comparison src/share/vm/opto/cfgnode.cpp @ 1542:eb79484f795f

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6937111: Restore optimization for Phi of AddP (6552204) Summary: Restored the original code which was removed by the fix for 6614100. Reviewed-by: never
author kvn
date Mon, 05 Apr 2010 10:17:15 -0700
parents ce590301ae2a
children 1a1603f975b5
comparison
equal deleted inserted replaced
1351:9bb91718aaf2 1542:eb79484f795f
1651 // This optimization only modifies phi - don't need to check for dead loop. 1651 // This optimization only modifies phi - don't need to check for dead loop.
1652 assert(opt == NULL || phase->eqv(opt, this), "do not elide phi"); 1652 assert(opt == NULL || phase->eqv(opt, this), "do not elide phi");
1653 if (opt != NULL) return opt; 1653 if (opt != NULL) return opt;
1654 } 1654 }
1655 1655
1656 if (in(1) != NULL && in(1)->Opcode() == Op_AddP && can_reshape) {
1657 // Try to undo Phi of AddP:
1658 // (Phi (AddP base base y) (AddP base2 base2 y))
1659 // becomes:
1660 // newbase := (Phi base base2)
1661 // (AddP newbase newbase y)
1662 //
1663 // This occurs as a result of unsuccessful split_thru_phi and
1664 // interferes with taking advantage of addressing modes. See the
1665 // clone_shift_expressions code in matcher.cpp
1666 Node* addp = in(1);
1667 const Type* type = addp->in(AddPNode::Base)->bottom_type();
1668 Node* y = addp->in(AddPNode::Offset);
1669 if (y != NULL && addp->in(AddPNode::Base) == addp->in(AddPNode::Address)) {
1670 // make sure that all the inputs are similar to the first one,
1671 // i.e. AddP with base == address and same offset as first AddP
1672 bool doit = true;
1673 for (uint i = 2; i < req(); i++) {
1674 if (in(i) == NULL ||
1675 in(i)->Opcode() != Op_AddP ||
1676 in(i)->in(AddPNode::Base) != in(i)->in(AddPNode::Address) ||
1677 in(i)->in(AddPNode::Offset) != y) {
1678 doit = false;
1679 break;
1680 }
1681 // Accumulate type for resulting Phi
1682 type = type->meet(in(i)->in(AddPNode::Base)->bottom_type());
1683 }
1684 Node* base = NULL;
1685 if (doit) {
1686 // Check for neighboring AddP nodes in a tree.
1687 // If they have a base, use that it.
1688 for (DUIterator_Fast kmax, k = this->fast_outs(kmax); k < kmax; k++) {
1689 Node* u = this->fast_out(k);
1690 if (u->is_AddP()) {
1691 Node* base2 = u->in(AddPNode::Base);
1692 if (base2 != NULL && !base2->is_top()) {
1693 if (base == NULL)
1694 base = base2;
1695 else if (base != base2)
1696 { doit = false; break; }
1697 }
1698 }
1699 }
1700 }
1701 if (doit) {
1702 if (base == NULL) {
1703 base = new (phase->C, in(0)->req()) PhiNode(in(0), type, NULL);
1704 for (uint i = 1; i < req(); i++) {
1705 base->init_req(i, in(i)->in(AddPNode::Base));
1706 }
1707 phase->is_IterGVN()->register_new_node_with_optimizer(base);
1708 }
1709 return new (phase->C, 4) AddPNode(base, base, y);
1710 }
1711 }
1712 }
1713
1656 // Split phis through memory merges, so that the memory merges will go away. 1714 // Split phis through memory merges, so that the memory merges will go away.
1657 // Piggy-back this transformation on the search for a unique input.... 1715 // Piggy-back this transformation on the search for a unique input....
1658 // It will be as if the merged memory is the unique value of the phi. 1716 // It will be as if the merged memory is the unique value of the phi.
1659 // (Do not attempt this optimization unless parsing is complete. 1717 // (Do not attempt this optimization unless parsing is complete.
1660 // It would make the parser's memory-merge logic sick.) 1718 // It would make the parser's memory-merge logic sick.)