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6889300: assert(i != k || is_new || i->outcnt() > 0, "don't return dead nodes")

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PhiNode::Ideal() should return TOP for Phi node with no users.

Reviewed-by: never, jrose
This commit is contained in:
Vladimir Kozlov 2009-10-13 22:32:31 -07:00
parent 9a22acef05
commit 998bcbaf4b
2 changed files with 12 additions and 3 deletions
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11
hotspot/src/share/vm/opto/cfgnode.cpp
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@ -1531,6 +1531,8 @@ Node *PhiNode::Ideal(PhaseGVN *phase, bool can_reshape) {
return NULL; // No change return NULL; // No change
Node *top = phase->C->top(); Node *top = phase->C->top();
bool new_phi = (outcnt() == 0); // transforming new Phi
assert(!can_reshape || !new_phi, "for igvn new phi should be hooked");
// The are 2 situations when only one valid phi's input is left // The are 2 situations when only one valid phi's input is left
// (in addition to Region input). // (in addition to Region input).
@ -1550,6 +1552,12 @@ Node *PhiNode::Ideal(PhaseGVN *phase, bool can_reshape) {
} }
} }
if (can_reshape && outcnt() == 0) {
// set_req() above may kill outputs if Phi is referenced
// only by itself on the dead (top) control path.
return top;
}
Node* uin = unique_input(phase); Node* uin = unique_input(phase);
if (uin == top) { // Simplest case: no alive inputs. if (uin == top) { // Simplest case: no alive inputs.
if (can_reshape) // IGVN transformation if (can_reshape) // IGVN transformation
@ -1684,8 +1692,7 @@ Node *PhiNode::Ideal(PhaseGVN *phase, bool can_reshape) {
// Equivalent code is in MemNode::Ideal_common // Equivalent code is in MemNode::Ideal_common
Node *m = phase->transform(n); Node *m = phase->transform(n);
if (outcnt() == 0) { // Above transform() may kill us! if (outcnt() == 0) { // Above transform() may kill us!
progress = phase->C->top(); return top;
break;
} }
// If transformed to a MergeMem, get the desired slice // If transformed to a MergeMem, get the desired slice
// Otherwise the returned node represents memory for every slice // Otherwise the returned node represents memory for every slice

4
hotspot/src/share/vm/opto/ifnode.cpp
View File

@ -240,13 +240,13 @@ static Node* split_if(IfNode *iff, PhaseIterGVN *igvn) {
// as a single huge transform. // as a single huge transform.
igvn->register_new_node_with_optimizer( region_c ); igvn->register_new_node_with_optimizer( region_c );
igvn->register_new_node_with_optimizer( region_x ); igvn->register_new_node_with_optimizer( region_x );
phi_x = phase->transform( phi_x );
// Prevent the untimely death of phi_x. Currently he has no uses. He is // Prevent the untimely death of phi_x. Currently he has no uses. He is
// about to get one. If this only use goes away, then phi_x will look dead. // about to get one. If this only use goes away, then phi_x will look dead.
// However, he will be picking up some more uses down below. // However, he will be picking up some more uses down below.
Node *hook = new (igvn->C, 4) Node(4); Node *hook = new (igvn->C, 4) Node(4);
hook->init_req(0, phi_x); hook->init_req(0, phi_x);
hook->init_req(1, phi_c); hook->init_req(1, phi_c);
phi_x = phase->transform( phi_x );
// Make the compare // Make the compare
Node *cmp_c = phase->makecon(t); Node *cmp_c = phase->makecon(t);
@ -322,6 +322,7 @@ static Node* split_if(IfNode *iff, PhaseIterGVN *igvn) {
phi_s = PhiNode::make_blank(region_s,phi); phi_s = PhiNode::make_blank(region_s,phi);
phi_s->init_req( 1, phi_c ); phi_s->init_req( 1, phi_c );
phi_s->init_req( 2, phi_x ); phi_s->init_req( 2, phi_x );
hook->add_req(phi_s);
phi_s = phase->transform(phi_s); phi_s = phase->transform(phi_s);
} }
proj_path_data = phi_s; proj_path_data = phi_s;
@ -333,6 +334,7 @@ static Node* split_if(IfNode *iff, PhaseIterGVN *igvn) {
phi_f = PhiNode::make_blank(region_f,phi); phi_f = PhiNode::make_blank(region_f,phi);
phi_f->init_req( 1, phi_c ); phi_f->init_req( 1, phi_c );
phi_f->init_req( 2, phi_x ); phi_f->init_req( 2, phi_x );
hook->add_req(phi_f);
phi_f = phase->transform(phi_f); phi_f = phase->transform(phi_f);
} }
proj_path_data = phi_f; proj_path_data = phi_f;