8251458: Parse::do_lookupswitch fails with "assert(_cnt >= 0) failed"

Limit the counter value to max_jint.

Reviewed-by: kvn, vlivanov, chagedorn

src/hotspot/share/opto/parse2.cpp

@@ -528,7 +528,8 @@ void Parse::do_lookupswitch() {
     for (int j = 0; j < len; j++) {
       table[3*j+0] = iter().get_int_table(2+2*j);
       table[3*j+1] = iter().get_dest_table(2+2*j+1);
-      table[3*j+2] = profile == NULL ? 1 : profile->count_at(j);
+      // Handle overflow when converting from uint to jint
+      table[3*j+2] = (profile == NULL) ? 1 : MIN2<uint>(max_jint, profile->count_at(j));
     }
     qsort(table, len, 3*sizeof(table[0]), jint_cmp);
   }

test/hotspot/jtreg/compiler/profiling/TestMultiBranchDataOverflow.java

@@ -0,0 +1,62 @@
+/*
+ * Copyright (c) 2020, 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 8251458
+ * @summary Test int range overflow of MultiBranchData counter.
+ * @run main/othervm -XX:CompileCommand=dontinline,compiler.profiling.TestMultiBranchDataOverflow::test
+ *                   -Xbatch -XX:Tier4BackEdgeThreshold=2147483647
+ *                   compiler.profiling.TestMultiBranchDataOverflow
+ */
+
+package compiler.profiling;
+
+public class TestMultiBranchDataOverflow {
+
+    public static int test(int val, long max) {
+        int res = 0;
+        for (long l = 0; l < max; ++l) {
+            switch (val) {
+            case 0:
+                return 0;
+            case 42:
+                res++;
+                break;
+            }
+        }
+        return res;
+    }
+
+    public static void main(String[] args) {
+        // Warmup to generate profile information that has a MultiBranchData
+        // counter > Integer.MAX_VALUE for the i == 42 lookupswitch branch.
+        long max = Integer.MAX_VALUE + 100_000L;
+        test(42, max);
+
+        // Trigger C2 compilation
+        for (int i = 0; i < 10_000; ++i) {
+            test(42, 1);
+        }
+    }
+}