8209639: assert failure in coalesce.cpp: attempted to spill a non-spillable item

Reviewed-by: neliasso, kvn

src/share/vm/opto/coalesce.cpp

@@ -25,6 +25,7 @@
 #include "precompiled.hpp"
 #include "memory/allocation.inline.hpp"
 #include "opto/block.hpp"
+#include "opto/c2compiler.hpp"
 #include "opto/cfgnode.hpp"
 #include "opto/chaitin.hpp"
 #include "opto/coalesce.hpp"
@@ -294,9 +295,13 @@ void PhaseAggressiveCoalesce::insert_copies( Matcher &matcher ) {
             } else {
               int ireg = m->ideal_reg();
               if (ireg == 0 || ireg == Op_RegFlags) {
+                if (C->subsume_loads()) {
+                  C->record_failure(C2Compiler::retry_no_subsuming_loads());
+                } else {
                   assert(false, err_msg("attempted to spill a non-spillable item: %d: %s, ireg = %d",
                                         m->_idx, m->Name(), ireg));
                   C->record_method_not_compilable("attempted to spill a non-spillable item");
+                }
                 return;
               }
               const RegMask *rm = C->matcher()->idealreg2spillmask[ireg];

test/compiler/c2/SubsumingLoadsCauseFlagSpill.java

+/*
+ * Copyright (c) 2018, 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 8209639
+ * @summary assert failure in coalesce.cpp: attempted to spill a non-spillable item
+ *
+ * @run main/othervm -XX:-BackgroundCompilation -XX:CompileCommand=dontinline,SubsumingLoadsCauseFlagSpill::not_inlined -Xmx1024m SubsumingLoadsCauseFlagSpill
+ *
+ */
+
+public class SubsumingLoadsCauseFlagSpill {
+    private static Object field;
+    private static boolean do_throw;
+    private static volatile boolean barrier;
+
+    public static void main(String[] args) {
+        for (int i = 0; i < 20_000; i++) {
+            do_throw = true;
+            field = null;
+            test(0);
+            do_throw = false;
+            field = new Object();
+            test(0);
+        }
+    }
+
+    private static float test(float f) {
+        Object v = null;
+        try {
+            not_inlined();
+            v = field;
+        } catch (MyException me) {
+            v = field;
+            barrier = true;
+        }
+        if (v == null) {
+            return f * f;
+        }
+        return f;
+    }
+
+    private static void not_inlined() throws MyException{
+        if (do_throw) {
+            throw new MyException();
+        }
+    }
+
+    private static class MyException extends Throwable {
+    }
+}