8259641: C2: assert(early->dominates(LCA)) failed: early is high enough

Reviewed-by: chagedorn, thartmann

src/hotspot/share/opto/loopnode.cpp

@@ -5020,7 +5020,7 @@ Node *PhaseIdealLoop::get_late_ctrl( Node *n, Node *early ) {
             for (uint j = 1; j < s->req(); j++) {
               Node* in = s->in(j);
               Node* r_in = r->in(j);
-              if (worklist.member(in) && is_dominator(early, r_in)) {
+              if ((worklist.member(in) || in == mem) && is_dominator(early, r_in)) {
                 LCA = dom_lca_for_get_late_ctrl(LCA, r_in, n);
               }
             }

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

@@ -0,0 +1,95 @@
+/*
+ * Copyright (c) 2021, 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 8259641
+ * @summary C2: assert(early->dominates(LCA)) failed: early is high enough
+ *
+ * @run main/othervm -Xcomp -XX:CompileOnly=TestBrokenAntiDependenceWithPhi TestBrokenAntiDependenceWithPhi
+ *
+ */
+
+public class TestBrokenAntiDependenceWithPhi {
+
+    int a;
+    int b;
+    byte c;
+
+    long e(int f, int g, long h) {
+        int i[] = new int[a];
+        double j = 2.74886;
+        long k[][] = new long[a][a];
+        long l = checkSum(k);
+        return l;
+    }
+
+    void m() {
+        int s, o, p[] = new int[a];
+        double d;
+        for (d = 5; d < 388; d++) {
+            e(b, b, 40418347472393L);
+            for (s = 3; s < 66; ++s)
+                int1array(a, 9);
+        }
+        for (o = 6; o > 2; o--)
+            p[o] = c;
+    }
+
+    public static void main(String[] q) {
+        TestBrokenAntiDependenceWithPhi r = new TestBrokenAntiDependenceWithPhi();
+        try {
+            r.m();
+        } catch (ArrayIndexOutOfBoundsException aioobe) {
+        }
+    }
+
+    public static long checkSum(long[] a) {
+        long sum = 0;
+        for (int j = 0; j < a.length; j++) {
+            sum += (a[j] / (j + 1) + a[j] % (j + 1));
+        }
+        return sum;
+    }
+
+    public static long checkSum(long[][] a) {
+        long sum = 0;
+        for (int j = 0; j < a.length; j++) {
+            sum += checkSum(a[j]);
+        }
+        return sum;
+    }
+
+    public static int[] int1array(int sz, int seed) {
+        int[] ret = new int[sz];
+        init(ret, seed);
+        return ret;
+    }
+
+    public static void init(int[] a, int seed) {
+        for (int j = 0; j < a.length; j++) {
+            a[j] = (j % 2 == 0) ? seed + j : seed - j;
+        }
+    }
+
+}