8274060: C2: Incorrect computation after JDK-8273454

Reviewed-by: thartmann, neliasso, chagedorn

Author: shipilev

src/hotspot/share/opto/mulnode.cpp

@@ -63,10 +63,16 @@ Node *MulNode::Ideal(PhaseGVN *phase, bool can_reshape) {
   const Type *t2 = phase->type( in(2) );
   Node *progress = NULL;        // Progress flag
 
-  // convert "(-a)*(-b)" into "a*b"
+  // This code is used by And nodes too, but some conversions are
+  // only valid for the actual Mul nodes.
+  uint op = Opcode();
+  bool real_mul = (op == Op_MulI) || (op == Op_MulL) ||
+                  (op == Op_MulF) || (op == Op_MulD);
+
+  // Convert "(-a)*(-b)" into "a*b".
   Node *in1 = in(1);
   Node *in2 = in(2);
-  if (in1->is_Sub() && in2->is_Sub()) {
+  if (real_mul && in1->is_Sub() && in2->is_Sub()) {
     if (phase->type(in1->in(1))->is_zero_type() &&
         phase->type(in2->in(1))->is_zero_type()) {
       set_req(1, in1->in(2));
@@ -119,7 +125,6 @@ Node *MulNode::Ideal(PhaseGVN *phase, bool can_reshape) {
 
   // If the right input is a constant, and the left input is a product of a
   // constant, flatten the expression tree.
-  uint op = Opcode();
   if( t2->singleton() &&        // Right input is a constant?
       op != Op_MulF &&          // Float & double cannot reassociate
       op != Op_MulD ) {

test/hotspot/jtreg/compiler/integerArithmetic/TestNegAnd.java

@@ -0,0 +1,76 @@
+/*
+ * Copyright (c) 2021, 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
+ * @key randomness
+ * @bug 8274060
+ * @summary Test broken transformation (-a) & (-b) = a & b does not happen
+ *
+ * @library /test/lib
+ *
+ * @run main/othervm -XX:-TieredCompilation -XX:-BackgroundCompilation -XX:-UseOnStackReplacement -XX:CompileCommand="dontinline,TestNegAnd::test*" TestNegAnd
+ *
+ */
+
+import java.util.Random;
+import jdk.test.lib.Utils;
+import jdk.test.lib.Asserts;
+
+public class TestNegAnd {
+    private static final Random random = Utils.getRandomInstance();
+    // Enough cycles to ensure test methods are JIT-ed
+    private static final int TEST_COUNT = 20_000;
+
+    private static int testInt(int a, int b) {
+        return (-a) & (-b);
+    }
+    private static long testLong(long a, long b) {
+        return (-a) & (-b);
+    }
+
+    private static void runIntTests() {
+        for (int index = 0; index < TEST_COUNT; index ++) {
+            int a = random.nextInt();
+            int b = random.nextInt();
+            int expected = (-a) & (-b);
+            int res = testInt(a, b);
+            Asserts.assertEQ(res, expected);
+        }
+    }
+
+    private static void runLongTests() {
+        for (int index = 0; index < TEST_COUNT; index ++) {
+            long a = random.nextLong();
+            long b = random.nextLong();
+            long expected = (-a) & (-b);
+            long res = testLong(a, b);
+            Asserts.assertEQ(res, expected);
+        }
+    }
+
+    public static void main(String[] args) {
+        runIntTests();
+        runLongTests();
+    }
+}