6889300: assert(i != k || is_new || i->outcnt() > 0, "don't return dead nodes")
Summary: PhiNode::Ideal() should return TOP for Phi node with no users.
Reviewed-by: never, jrose
--- a/hotspot/src/share/vm/opto/cfgnode.cpp Tue Oct 13 20:54:13 2009 -0700
+++ b/hotspot/src/share/vm/opto/cfgnode.cpp Tue Oct 13 22:32:31 2009 -0700
@@ -1531,6 +1531,8 @@
return NULL; // No change
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
// (in addition to Region input).
@@ -1550,6 +1552,12 @@
}
}
+ 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);
if (uin == top) { // Simplest case: no alive inputs.
if (can_reshape) // IGVN transformation
@@ -1684,8 +1692,7 @@
// Equivalent code is in MemNode::Ideal_common
Node *m = phase->transform(n);
if (outcnt() == 0) { // Above transform() may kill us!
- progress = phase->C->top();
- break;
+ return top;
}
// If transformed to a MergeMem, get the desired slice
// Otherwise the returned node represents memory for every slice
--- a/hotspot/src/share/vm/opto/ifnode.cpp Tue Oct 13 20:54:13 2009 -0700
+++ b/hotspot/src/share/vm/opto/ifnode.cpp Tue Oct 13 22:32:31 2009 -0700
@@ -240,13 +240,13 @@
// as a single huge transform.
igvn->register_new_node_with_optimizer( region_c );
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
// 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.
Node *hook = new (igvn->C, 4) Node(4);
hook->init_req(0, phi_x);
hook->init_req(1, phi_c);
+ phi_x = phase->transform( phi_x );
// Make the compare
Node *cmp_c = phase->makecon(t);
@@ -322,6 +322,7 @@
phi_s = PhiNode::make_blank(region_s,phi);
phi_s->init_req( 1, phi_c );
phi_s->init_req( 2, phi_x );
+ hook->add_req(phi_s);
phi_s = phase->transform(phi_s);
}
proj_path_data = phi_s;
@@ -333,6 +334,7 @@
phi_f = PhiNode::make_blank(region_f,phi);
phi_f->init_req( 1, phi_c );
phi_f->init_req( 2, phi_x );
+ hook->add_req(phi_f);
phi_f = phase->transform(phi_f);
}
proj_path_data = phi_f;