src/share/vm/opto/ifnode.cpp

@@ -21,10 +21,11 @@
  * questions.
  *
  */
 
 #include "precompiled.hpp"
+#include "ci/ciTypeFlow.hpp"
 #include "memory/allocation.inline.hpp"
 #include "opto/addnode.hpp"
 #include "opto/castnode.hpp"
 #include "opto/cfgnode.hpp"
 #include "opto/connode.hpp"

@@ -766,11 +767,17 @@
 }
 
 // Do this If and the dominating If both branch out to an uncommon trap
 bool IfNode::has_only_uncommon_traps(ProjNode* proj, ProjNode*& success, ProjNode*& fail, PhaseIterGVN* igvn) {
   ProjNode* otherproj = proj->other_if_proj();
-  CallStaticJavaNode* dom_unc = otherproj->is_uncommon_trap_proj(Deoptimization::Reason_none);
+  // Dominating uncommon trap must have 'Reason_unstable_if' to ensure re-execution of folded Ifs
+  CallStaticJavaNode* dom_unc = otherproj->is_uncommon_trap_proj(Deoptimization::Reason_unstable_if);
+
+  // We need to re-execute the check after deoptimization
+  if (!dom_unc->jvms()->should_reexecute()) {
+    return false;
+  }
 
   if (otherproj->outcnt() == 1 && dom_unc != NULL) {
     CallStaticJavaNode* unc = NULL;
     ProjNode* unc_proj = uncommon_trap_proj(unc);
     if (unc_proj != NULL && unc_proj->outcnt() == 1) {

@@ -782,16 +789,32 @@
         }
         assert(r->has_phi() == NULL, "simple region shouldn't have a phi");
       } else if (dom_unc->in(0) != otherproj || unc->in(0) != unc_proj) {
         return false;
       }
+
+      // Check if the bci of the dominating uncommon trap dominates the bci
+      // of the dominated uncommon trap. Otherwise we may not re-execute
+      // the dominated check after deoptimization from the merged uncommon trap.
+      ciMethod* method = unc->jvms()->method();
+      ciMethod* dom_method = dom_unc->jvms()->method();
+      if (method != dom_method) {
+        return false;
+      }
+      ciTypeFlow* flow = dom_method->get_flow_analysis();
+      int bci = unc->jvms()->bci();
+      int dom_bci = dom_unc->jvms()->bci();
+      if (!flow->is_dominated_by(bci, dom_bci)) {
+        return false;
+      }
+
       // See merge_uncommon_traps: the reason of the uncommon trap
       // will be changed and the state of the dominating If will be
       // used. Checked that we didn't apply this transformation in a
       // previous compilation and it didn't cause too many traps
-      if (!igvn->C->too_many_traps(dom_unc->jvms()->method(), dom_unc->jvms()->bci(), Deoptimization::Reason_unstable_fused_if) &&
-          !igvn->C->too_many_traps(dom_unc->jvms()->method(), dom_unc->jvms()->bci(), Deoptimization::Reason_range_check)) {
+      if (!igvn->C->too_many_traps(dom_method, dom_bci, Deoptimization::Reason_unstable_fused_if) &&
+          !igvn->C->too_many_traps(dom_method, dom_bci, Deoptimization::Reason_range_check)) {
         success = unc_proj;
         fail = unc_proj->other_if_proj();
         return true;
       }
     }