Prevent compacting NULLCHKs into computed call trees

Compacting NULLCHK into computed calls will result in the NULLCHK notbeing performed before dispatching into the call target if there is no need for dereferencing of the reference child to dispatch. Also includes some formatting fixes. Signed-off-by: Nazim Bhuiyan <nubhuiyan@ibm.com>
eclipse · Aug 20, 2021 · 2805e95 · 2805e95
1 parent 61f1845
commit 2805e95
Showing 1 changed file with 39 additions and 36 deletions.
diff --git a/compiler/optimizer/LocalOpts.cpp b/compiler/optimizer/LocalOpts.cpp
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2000, 2020 IBM Corp. and others
+ * Copyright (c) 2000, 2021 IBM Corp. and others
  *
  * This program and the accompanying materials are made available under
  * the terms of the Eclipse Public License 2.0 which accompanies this
@@ -2199,44 +2199,47 @@ bool TR_CompactNullChecks::replacePassThroughIfPossible(TR::Node *currentNode, T
            (opCode.isCallIndirect() && (i==1))) &&
           (currentParent == NULL || !currentParent->getOpCode().isResolveCheck())
           )
-          {
-          bool canCompact = false;
-          if (_isNextTree ||
-              (opCode.isArrayLength()) ||
-              (opCode.isLoadVar() && !writtenSymbols->get(currentNode->getSymbolReference()->getReferenceNumber())))
-             canCompact = true;
-
-          if (canCompact &&
-              performTransformation(comp(), "%sCompact null check %p with node %p in next tree\n", optDetailString(), prevNode, currentNode))
-             {
-               //if (!_isNextTree)
-               // printf("Found a new opportunity in %s\n", comp()->signature());
+         {
+         bool canCompact = false;
+         if (_isNextTree ||
+            (opCode.isArrayLength()) ||
+            (opCode.isLoadVar() && !writtenSymbols->get(currentNode->getSymbolReference()->getReferenceNumber())))
+            canCompact = true;
 
-             if (opCode.isTreeTop())
-                {
-                if (!(comp()->useAnchors() && currentTree->getNode()->getOpCode().isAnchor()))
-                   (*isTreeTopNode) = true;
-                }
+         // compacting null check into computed calls will result in the null check not being performed before dispatching into the
+         // call target if there is no need for dereferencing the reference child for the dispatch
+         if (opCode.isCallIndirect() && opCode.hasSymbolReference() && currentNode->getSymbol()->castToMethodSymbol()->isComputed())
+            canCompact = false;
 
-             prevNode->getFirstChild()->recursivelyDecReferenceCount();
-             prevNode->setAndIncChild(0, currentNode);
-             if (child->getOpCodeValue() != TR::loadaddr) //For loadaddr, IsNonNull is always true
-                child->setIsNonNull(false); // it is no longer known that the reference is non null
+         if (canCompact &&
+            performTransformation(comp(), "%sCompact null check %p with node %p in next tree\n", optDetailString(), prevNode, currentNode))
+            {
 
-             if (0 && comp()->useAnchors() &&
-                   currentTree->getNode()->getOpCode().isAnchor())
-                {
-                TR::TreeTop *prevTree = currentTree;
-                while (prevTree->getNode() != prevNode)
-                   prevTree = prevTree->getPrevTreeTop();
-                TR::TreeTop *preceedingTree = currentTree->getPrevTreeTop();
-                preceedingTree->join(currentTree->getNextTreeTop());
-                prevTree->getPrevTreeTop()->join(currentTree);
-                currentTree->join(prevTree);
-                }
-             return true;
-             }
-          }
+            if (opCode.isTreeTop())
+               {
+               if (!(comp()->useAnchors() && currentTree->getNode()->getOpCode().isAnchor()))
+                  (*isTreeTopNode) = true;
+               }
+
+            prevNode->getFirstChild()->recursivelyDecReferenceCount();
+            prevNode->setAndIncChild(0, currentNode);
+            if (child->getOpCodeValue() != TR::loadaddr) //For loadaddr, IsNonNull is always true
+               child->setIsNonNull(false); // it is no longer known that the reference is non null
+
+            if (0 && comp()->useAnchors() &&
+                  currentTree->getNode()->getOpCode().isAnchor())
+               {
+               TR::TreeTop *prevTree = currentTree;
+               while (prevTree->getNode() != prevNode)
+                  prevTree = prevTree->getPrevTreeTop();
+               TR::TreeTop *preceedingTree = currentTree->getPrevTreeTop();
+               preceedingTree->join(currentTree->getNextTreeTop());
+               prevTree->getPrevTreeTop()->join(currentTree);
+               currentTree->join(prevTree);
+               }
+            return true;
+            }
+         }
       }
 
    return false;