8308892: Bad graph detected in build_loop_late after JDK-8305635

Reviewed-by: rcastanedalo, roland, thartmann

Author: chhagedorn

src/hotspot/share/opto/loopPredicate.cpp

@@ -1835,6 +1835,9 @@ ParsePredicateNode* ParsePredicates::get_parse_predicate_or_null(Node* parse_pre
 }
 
 // Initialize the Parse Predicate projection field that matches the kind of the parent of `parse_predicate_proj`.
+// Only initialize if Parse Predicate projection itself or any of the Parse Predicate projections coming further up
+// in the graph are not already initialized (this would be a sign of repeated Parse Predicates which are not cleaned up,
+// yet).
 bool ParsePredicates::assign_predicate_proj(ParsePredicateSuccessProj* parse_predicate_proj) {
   ParsePredicateNode* parse_predicate = get_parse_predicate_or_null(parse_predicate_proj);
   assert(parse_predicate != nullptr, "must exist");
@@ -1847,13 +1850,16 @@ bool ParsePredicates::assign_predicate_proj(ParsePredicateSuccessProj* parse_pre
       _loop_predicate_proj = parse_predicate_proj;
       break;
     case Deoptimization::DeoptReason::Reason_profile_predicate:
-      if (_profiled_loop_predicate_proj != nullptr) {
+      if (_profiled_loop_predicate_proj != nullptr ||
+          _loop_predicate_proj != nullptr) {
         return false;
       }
       _profiled_loop_predicate_proj = parse_predicate_proj;
       break;
     case Deoptimization::DeoptReason::Reason_loop_limit_check:
-      if (_loop_limit_check_predicate_proj != nullptr) {
+      if (_loop_limit_check_predicate_proj != nullptr ||
+          _loop_predicate_proj != nullptr ||
+          _profiled_loop_predicate_proj != nullptr) {
         return false;
       }
       _loop_limit_check_predicate_proj = parse_predicate_proj;

test/hotspot/jtreg/compiler/predicates/TestWrongPredicateOrder.java

@@ -0,0 +1,89 @@
+/*
+ * Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+/*
+ * @test
+ * @bug 8308892
+ * @summary Test that Parse Predicates immediately following other Parse Predicates
+            are cleaned up properly.
+ * @run main/othervm -Xbatch compiler.predicates.TestWrongPredicateOrder
+ */
+
+package compiler.predicates;
+
+public class TestWrongPredicateOrder {
+    static boolean flag;
+    static int iFld = 0;
+    static int iFld2 = 34;
+    static int iArr[] = new int[1005];
+    static int iArr2[] = new int[2];
+
+
+    public static void main(String[] strArr) {
+        // We will keep hitting the Profiled Loop Predicate for RC1 (Integer.MAX_VALUE - 1 - 3 > 1005) such that we will
+        // not emit the Profile Loop Parse Predicate anymore. After that, we will also keep hitting the Loop Limit Check
+        // Predicate (Interger.MAX_VALUE - 1 > Integer.MAX_VALUE - 2) such that we will also not emit the Loop Limit Check
+        // Parse Predicate anymore. As a result, we'll only emit the Loop Parse Predicate in the next re-compilation.
+        // In the next re-compilation, we'll hoist IC1 as Loop Predicate and IC2 as Profiled Loop Predicate.
+        // They have a data dependency between them but this is normally okay because Profiled Loop Predicates are below
+        // Loop Predicates in the graph. But due to the flipped order of Parse Predicates in this bug, we create the
+        // Hoisted Predicates in the wrong order and we end up with a bad graph and assert.
+        for (int i = 0; i < 10000; i++) {
+            flag = !flag;
+            test();
+        }
+    }
+
+    public static void test() {
+        // Ensure to emit Loop Limit Check Predicate which is hit too often
+        // -> no Loop Limit Check Parse Predicate is added in re-compilation anymore
+        int limit = flag ? Integer.MAX_VALUE - 1 : 1000;
+
+        int i = 0;
+        // Loop Limit Check Predicate: limit <= Integer.MAX_VALUE - stride + 1 = Integer.MAX_VALUE - 2
+        while (i < limit) {
+            i += 3;
+            // Invariant check hoisted as Loop Predicate
+            iArr2[iFld] = 1; // (IC1)
+
+            if (flag) {
+                // Early exit -> enables Profiled Loop Predicate creation below
+                return;
+            }
+
+            // Invariant check hoisted as Profiled Loop Predicate
+            // Data dependency on Loop Predicate for "iArr2[0] = 1"
+            iArr2[1] = 5; // (IC2)
+
+            // Profiled Loop Predicate for range check hit too much -> no Profiled Loop Parse Predicate is added in
+            // re-compilation anymore
+            iArr[i] = 34; // (RC1)
+
+            if (iFld2 == 5555) {
+                i++; // UCT -> ensures to emit Parse Predicates twice with an If in between that is folded after parsing
+            }
+        }
+    }
+}
+