8231223: C2's conditional move optimization fails with assert(bol->Opcode() == Op_Bool) failed

Bail out if the range check If has an Opaque4Node input instead of a BoolNode.

Reviewed-by: roland, kvn

src/hotspot/share/opto/loopPredicate.cpp

@@ -1381,7 +1381,6 @@ bool PhaseIdealLoop::loop_predication_impl(IdealLoopTree *loop) {
     } // end while
   }
 
-  Node_List if_proj_list_freq(area);
   if (follow_branches) {
     PathFrequency pf(loop->_head, this);
 
@@ -1399,6 +1398,7 @@ bool PhaseIdealLoop::loop_predication_impl(IdealLoopTree *loop) {
     // And look into all branches
     Node_Stack stack(0);
     VectorSet seen(Thread::current()->resource_area());
+    Node_List if_proj_list_freq(area);
     while (regions.size() > 0) {
       Node* c = regions.pop();
       loop_predication_follow_branches(c, loop, loop_trip_cnt, pf, stack, seen, if_proj_list_freq);

src/hotspot/share/opto/loopopts.cpp

@@ -653,7 +653,10 @@ Node *PhaseIdealLoop::conditional_move( Node *region ) {
     }
   }//for
   Node* bol = iff->in(1);
-  assert(bol->Opcode() == Op_Bool, "");
+  if (bol->Opcode() == Op_Opaque4) {
+    return NULL; // Ignore loop predicate checks (the Opaque4 ensures they will go away)
+  }
+  assert(bol->Opcode() == Op_Bool, "Unexpected node");
   int cmp_op = bol->in(1)->Opcode();
   // It is expensive to generate flags from a float compare.
   // Avoid duplicated float compare.

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

@@ -0,0 +1,62 @@
+/*
+ * Copyright (c) 2019, 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 8231223
+ * @summary Test conditional move optimization encountering an Opaque4Node.
+ * @run main/othervm -Xbatch -XX:-TieredCompilation
+ *                   -XX:CompileCommand=inline,compiler.loopopts.TestCMovWithOpaque::test
+ *                   compiler.loopopts.TestCMovWithOpaque
+ */
+
+package compiler.loopopts;
+
+public class TestCMovWithOpaque {
+
+    public static void test(int array[]) {
+        for (int i = 1; i < 8; i += 3) {
+            for (int j = 0; j < 4; ++j) {
+                switch (i % 4) {
+                case 0:
+                    break;
+                case 1:
+                    break;
+                case 2:
+                    break;
+                case 3:
+                    array[j] += 42;
+                    break;
+                }
+            }
+        }
+    }
+
+    public static void main(String[] args) {
+        int[] array = new int[4];
+        for (int i = 0; i < 20_000; ++i) {
+            test(array);
+        }
+    }
+}