8144484: assert(no_dead_loop) failed: dead loop detected
Summary: Bailout early without splitting Phi through memory merges if TOP inputs present for Phi Nodes
Reviewed-by: thartmann, kvn
--- a/hotspot/src/share/vm/opto/cfgnode.cpp Fri Feb 03 08:17:35 2017 +0100
+++ b/hotspot/src/share/vm/opto/cfgnode.cpp Fri Feb 03 00:46:58 2017 -0800
@@ -1889,6 +1889,12 @@
bool saw_self = false;
for( uint i=1; i<req(); ++i ) {// For all paths in
Node *ii = in(i);
+ // TOP inputs should not be counted as safe inputs because if the
+ // Phi references itself through all other inputs then splitting the
+ // Phi through memory merges would create dead loop at later stage.
+ if (ii == top) {
+ return NULL; // Delay optimization until graph is cleaned.
+ }
if (ii->is_MergeMem()) {
MergeMemNode* n = ii->as_MergeMem();
merge_width = MAX2(merge_width, n->req());