1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
|
/*
* Copyright (c) 2022, 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 8288445
* @summary Test shift by 0
* @run main/othervm -Xbatch -XX:-TieredCompilation
* compiler.codegen.ShiftByZero
*/
package compiler.codegen;
public class ShiftByZero {
public static final int N = 64;
public static int[] i32 = new int[N];
public static void bMeth() {
int shift = i32[0];
// This loop is to confuse the optimizer, so that "shift" is
// optimized to 0 only after loop vectorization.
for (int i8 = 279; i8 > 1; --i8) {
shift <<= 6;
}
// low 6 bits of shift are 0, so shift can be
// simplified to constant 0
{
for (int i = 0; i < N; ++i) {
i32[i] += i32[i] >>= shift;
}
for (int i = 0; i < N; ++i) {
i32[i] += i32[i] >>>= shift;
}
for (int i = 0; i < N; ++i) {
i32[i] >>>= shift;
}
for (int i = 0; i < N; ++i) {
i32[i] >>= shift;
}
for (int i = 0; i < N; ++i) {
i32[i] <<= shift;
}
}
}
public static void main(String[] strArr) {
for (int i = 0; i < 20_000; i++) {
bMeth();
}
}
}
|
