Offheap Adjustments for Unsafe calls that are converted to atomic

intrinsics during unsafeFastPath

During unsafeFastPath, some UnsafeAPI calls (such as Unsafe.getAndAdd())
are converted to atomic intrinsics (such as atomicFetchAndAdd). When
this occurs with offheap allocation enabled, and the object is an array,
load dataAddr.

Signed-off-by: midronij <[email protected]>

runtime/compiler/optimizer/UnsafeFastPath.cpp

@@ -326,10 +326,19 @@ bool TR_UnsafeFastPath::tryTransformUnsafeAtomicCallInVarHandleAccessMethod(TR::
       }
    else
       {
-      TR::Node* object = node->getChild(1);
-      TR::Node* offset = node->getChild(2);
-      unsafeAddress = comp()->target().is32Bit() ? TR::Node::create(node, TR::aiadd, 2, object, TR::Node::create(node, TR::l2i, 1, offset)) :
-                                                       TR::Node::create(node, TR::aladd, 2, object, offset);
+      TR::Node *object = node->getChild(1);
+      TR::Node *offset = node->getChild(2);
+
+      TR::Node *baseAddr = object;
+
+      //load dataAddr only if offheap is enabled and object is array
+#if defined(J9VM_GC_ENABLE_SPARSE_HEAP_ALLOCATION)
+      if (isUnsafeCallerAccessingArrayElement(callerMethod) && TR::Compiler->om.isOffHeapAllocationEnabled() && comp()->target().is64Bit())
+         baseAddr = TR::TransformUtil::generateDataAddrLoadTrees(comp(), object);
+#endif /* J9VM_GC_ENABLE_SPARSE_HEAP_ALLOCATION */
+
+      unsafeAddress = comp()->target().is32Bit() ? TR::Node::create(node, TR::aiadd, 2, baseAddr, TR::Node::create(node, TR::l2i, 1, offset)) :
+                                                   TR::Node::create(node, TR::aladd, 2, baseAddr, offset);
       unsafeAddress->setIsInternalPointer(true);
       }