8309266: C2: assert(final_con == (jlong)final_int) failed: final value should be integer

Reviewed-by: roland, chagedorn

Author: enothum

src/hotspot/share/opto/loopnode.cpp

@@ -2311,8 +2311,14 @@ const Type* LoopLimitNode::Value(PhaseGVN* phase) const {
     int final_int = (int)final_con;
     // The final value should be in integer range since the loop
     // is counted and the limit was checked for overflow.
-    assert(final_con == (jlong)final_int, "final value should be integer");
-    return TypeInt::make(final_int);
+    // Assert checks for overflow only if all input nodes are ConINodes, as during CCP
+    // there might be a temporary overflow from PhiNodes see JDK-8309266
+    assert((in(Init)->is_ConI() && in(Limit)->is_ConI() && in(Stride)->is_ConI()) ? final_con == (jlong)final_int : true, "final value should be integer");
+    if (final_con == (jlong)final_int) {
+      return TypeInt::make(final_int);
+    } else {
+      return bottom_type();
+    }
   }
 
   return bottom_type(); // TypeInt::INT

test/hotspot/jtreg/compiler/loopopts/TestLoopLimitOverflowDuringCCP.java

@@ -0,0 +1,53 @@
+/*
+ * 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 8309266
+ * @summary Integer overflow in LoopLimit::Value during PhaseCCP::analyze, triggered by the Phi Node from "flag ? Integer.MAX_VALUE : 1000"
+ * @run main/othervm -Xbatch -XX:CompileOnly=compiler.loopopts.TestLoopLimitOverflowDuringCCP::* compiler.loopopts.TestLoopLimitOverflowDuringCCP
+ */
+
+package compiler.loopopts;
+
+public class TestLoopLimitOverflowDuringCCP {
+    static boolean flag;
+
+    public static void main(String[] strArr) {
+        for (int i = 0; i < 10000; i++) {
+            flag = !flag;
+            test();
+        }
+    }
+
+    public static void test() {
+        int limit = flag ? Integer.MAX_VALUE : 1000;
+        int i = 0;
+        while (i < limit) {
+            i += 3;
+            if (flag) {
+                return;
+            }
+        }
+    }
+}