6910484: incorrect integer optimization (loosing and op-r in a given example)

Summary: Remove AND operation only if mask is equal to shift.
Reviewed-by: never

src/share/vm/opto/divnode.cpp

@@ -114,7 +114,8 @@ static Node *transform_int_divide( PhaseGVN *phase, Node *dividend, jint divisor
       if( andconi_t && andconi_t->is_con() ) {
         jint andconi = andconi_t->get_con();
         if( andconi < 0 && is_power_of_2(-andconi) && (-andconi) >= d ) {
-          dividend = dividend->in(1);
+          if( (-andconi) == d ) // Remove AND if it clears bits which will be shifted
+            dividend = dividend->in(1);
           needs_rounding = false;
         }
       }
@@ -356,7 +357,8 @@ static Node *transform_long_divide( PhaseGVN *phase, Node *dividend, jlong divis
       if( andconl_t && andconl_t->is_con() ) {
         jlong andconl = andconl_t->get_con();
         if( andconl < 0 && is_power_of_2_long(-andconl) && (-andconl) >= d ) {
-          dividend = dividend->in(1);
+          if( (-andconl) == d ) // Remove AND if it clears bits which will be shifted
+            dividend = dividend->in(1);
           needs_rounding = false;
         }
       }

test/compiler/6910484/Test.java

+/*
+ * Copyright 2009 SAP.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+/**
+ * @test
+ * @bug 6910484
+ * @summary incorrect integer optimization (loosing and op-r in a given example)
+ *
+ * @run main/othervm -Xbatch Test
+ */
+
+public class Test {
+
+    public static void main(String[] args) {
+        long iteration = 0;
+        for(int i = 0; i <11000; i++) {
+            iteration++;
+            int result = test(255);
+            if (result != 112) {
+                System.out.println("expected 112, but got " + result + " after iteration " + iteration);
+                System.exit(97);
+            }
+        }
+    }
+
+    private static int test(int x) {
+        return (x & -32) / 2;
+    }
+
+}