8134031: Incorrect JIT compilation of complex code with inlining and escape analysis

Summary: Bad rewiring of memory edges when we split unique types during EA
Reviewed-by: kvn

src/share/vm/opto/escape.cpp

@@ -3183,7 +3183,7 @@ void ConnectionGraph::split_unique_types(GrowableArray<Node *>  &alloc_worklist)
     // Note 2: MergeMem may already contains instance memory slices added
     // during find_inst_mem() call when memory nodes were processed above.
     igvn->hash_delete(nmm);
-    uint nslices = nmm->req();
+    uint nslices = MIN2(nmm->req(), new_index_start);
     for (uint i = Compile::AliasIdxRaw+1; i < nslices; i++) {
       Node* mem = nmm->in(i);
       Node* cur = NULL;

test/compiler/escapeAnalysis/TestEABadMergeMem.java

+/*
+ * Copyright (c) 2015, 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 8134031
+ * @summary Bad rewiring of memory edges when we split unique types during EA
+ * @run main/othervm -XX:-BackgroundCompilation -XX:-UseOnStackReplacement -XX:CompileCommand=dontinline,TestEABadMergeMem::m_notinlined TestEABadMergeMem
+ *
+ */
+
+public class TestEABadMergeMem {
+
+    static class Box {
+        int i;
+    }
+
+    static void m_notinlined() {
+    }
+
+    static float dummy1;
+    static float dummy2;
+
+    static int test(Box a, Box c, int i, int j, int k, boolean flag1, boolean flag2) {
+        Box b = new Box(); // non escaping
+        a.i = i;
+        b.i = j;
+        c.i = k;
+
+        m_notinlined();
+
+        boolean flag3 = false;
+        if (flag1) {
+            for (int ii = 0; ii < 100; ii++) {
+                if (flag2) {
+                    dummy1 = (float)ii;
+                } else {
+                    dummy2 = (float)ii;
+                }
+            }
+            flag3 = true;
+        }
+        // Memory Phi here with projection of not inlined call as one edge, MergeMem as other
+
+        if (flag3) { // will split through Phi during loopopts
+            int res = c.i + b.i;
+            m_notinlined(); // prevents split through phi during igvn
+            return res;
+        } else {
+            return 44 + 43;
+        }
+    }
+
+    static public void main(String[] args) {
+        for (int i = 0; i < 20000; i++) {
+            // m(2);
+            Box a = new Box();
+            Box c = new Box();
+            int res = test(a, c, 42, 43, 44, (i%2) == 0, (i%3) == 0);
+            if (res != 44 + 43) {
+                throw new RuntimeException("Bad result " + res);
+            }
+        }
+    }
+
+}