# HG changeset patch
# User neliasso
# Date 1551359038 -3600
#      Thu Feb 28 14:03:58 2019 +0100
# Node ID 36dd0b27bf57695c2c0a258ff91fc1ee5af08204
# Parent  56089cf6152c41cbca3848bcb8796fcccbbe8c3a
8219448: split-if update_uses accesses stale idom data
Reviewed-by:

diff --git a/src/hotspot/share/opto/split_if.cpp b/src/hotspot/share/opto/split_if.cpp
--- a/src/hotspot/share/opto/split_if.cpp
+++ b/src/hotspot/share/opto/split_if.cpp
@@ -523,7 +523,9 @@
   }
   _igvn.remove_dead_node(new_iff);
   // Lazy replace IDOM info with the region's dominator
-  lazy_replace( iff, region_dom );
+  lazy_replace(iff, region_dom);
+  lazy_update(region, region_dom); // idom must be update before handle_uses, the replacement is done after
+  region->set_req(0, NULL);        // Break the self-cycle. Required for lazy_update to work on region
 
   // Now make the original merge point go dead, by handling all its uses.
   small_cache region_cache;
@@ -566,8 +568,7 @@
     --k;
   } // End of while merge point has phis
 
-  assert(region->outcnt() == 1, "Only self reference should remain"); // Just Self on the Region
-  region->set_req(0, NULL);       // Break the self-cycle
+  assert(region->outcnt() == 0, "Should be empty now");
 
   // Any leftover bits in the splitting block must not have depended on local
   // Phi inputs (these have already been split-up).  Hence it's safe to hoist