8342330: C2: "node pinned on loop exit test?" assert failure

Backport-of: 004aaea76db091569aa88eeb6b08db3408f288cd

Author: Satyen Subramaniam

src/hotspot/share/opto/loopopts.cpp

@@ -1849,10 +1849,11 @@ bool PhaseIdealLoop::ctrl_of_use_out_of_loop(const Node* n, Node* n_ctrl, IdealL
   // Sinking a node from a pre loop to its main loop pins the node between the pre and main loops. If that node is input
   // to a check that's eliminated by range check elimination, it becomes input to an expression that feeds into the exit
   // test of the pre loop above the point in the graph where it's pinned.
-  if (n_loop->_head->is_CountedLoop() && n_loop->_head->as_CountedLoop()->is_pre_loop() &&
-      u_loop->_head->is_CountedLoop() && u_loop->_head->as_CountedLoop()->is_main_loop() &&
-      n_loop->_next == get_loop(u_loop->_head->as_CountedLoop()->skip_strip_mined())) {
-    return false;
+  if (n_loop->_head->is_CountedLoop() && n_loop->_head->as_CountedLoop()->is_pre_loop()) {
+    CountedLoopNode* pre_loop = n_loop->_head->as_CountedLoop();
+    if (is_dominator(pre_loop->loopexit(), ctrl)) {
+      return false;
+    }
   }
   return true;
 }

test/hotspot/jtreg/compiler/rangechecks/TestSunkRangeFromPreLoopRCE.java

@@ -0,0 +1,81 @@
+/*
+ * Copyright (c) 2024, Red Hat, Inc. 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 8342330
+ * @summary C2: "node pinned on loop exit test?" assert failure
+ * @requires vm.flavor == "server"
+  *
+ * @run main/othervm -XX:-BackgroundCompilation -XX:-UseOnStackReplacement -XX:-TieredCompilation
+ *                   -XX:-UseLoopPredicate -XX:LoopMaxUnroll=0 TestSunkRangeFromPreLoopRCE
+ *
+ */
+
+
+import java.util.Arrays;
+
+public class TestSunkRangeFromPreLoopRCE {
+    private static int[] array = new int[1000];
+    private static A objectField = new A(42);
+
+    public static void main(String[] args) {
+        boolean[] allTrue = new boolean[1000];
+        Arrays.fill(allTrue, true);
+        boolean[] allFalse = new boolean[1000];
+        for (int i = 0; i < 20_000; i++) {
+            test1(array.length/4, allTrue, 1, 0);
+            test1(array.length/4, allFalse, 1, 0);
+        }
+    }
+
+    private static int test1(int stop, boolean[] flags, int otherScale, int x) {
+        int scale;
+        for (scale = 0; scale < 4; scale++) {
+            for (int i = 0; i < 10; i++) {
+
+            }
+        }
+        if (array == null) {
+        }
+        int v = 0;
+        for (int i = 0; i < stop; i++) {
+            v += array[i];
+            v += array[scale * i];
+            if (i * scale + (objectField.intField + 1) == x) {
+            }
+            v += (scale - 4) * (x-objectField.intField);
+            if (flags[i]) {
+                return (x-objectField.intField);
+            }
+        }
+        return v;
+    }
+
+    private static class A {
+        A(int field) {
+            intField = field;
+        }
+        public int intField;
+    }
+}