1 /*
2 * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 */
23
24 /*
25 * @test
26 * @bug 8078262 8177095
27 * @summary Tests correct dominator information after loop peeling.
28 *
29 * @run main/othervm -Xcomp
30 * -XX:CompileCommand=compileonly,compiler.loopopts.TestLoopPeeling::test*
31 * compiler.loopopts.TestLoopPeeling
32 */
33
34 package compiler.loopopts;
35
36 public class TestLoopPeeling {
37
38 public int[] array = new int[100];
39
40 public static void main(String args[]) {
41 TestLoopPeeling test = new TestLoopPeeling();
42 try {
43 test.testArrayAccess1(0, 1);
44 test.testArrayAccess2(0);
45 test.testArrayAccess3(0, false);
46 test.testArrayAllocation(0, 1);
47 } catch (Exception e) {
48 // Ignore exceptions
49 }
50 }
51
52 public void testArrayAccess1(int index, int inc) {
53 int storeIndex = -1;
54
55 for (; index < 10; index += inc) {
56 // This loop invariant check triggers loop peeling because it can
57 // be moved out of the loop (see 'IdealLoopTree::policy_peeling').
58 if (inc == 42) return;
59
60 // This loop variant usage of LShiftL( ConvI2L( Phi(storeIndex) ) )
61 // prevents the split if optimization that would otherwise clone the
62 // LShiftL and ConvI2L nodes and assign them to their corresponding array
63 // address computation (see 'PhaseIdealLoop::split_if_with_blocks_post').
64 if (storeIndex > 0 && array[storeIndex] == 42) return;
65
66 if (index == 42) {
67 // This store and the corresponding range check are moved out of the
68 // loop and both used after main loop and the peeled iteration exit.
69 // For the peeled iteration, storeIndex is always -1 and the ConvI2L
70 // is replaced by TOP. However, the range check is not folded because
71 // we don't do the split if optimization in PhaseIdealLoop2.
72 // As a result, we have a (dead) control path from the peeled iteration
73 // to the StoreI but the data path is removed.
74 array[storeIndex] = 1;
75 return;
76 }
77
78 storeIndex++;
79 }
80 }
81
82 public int testArrayAccess2(int index) {
83 // Load1 and the corresponding range check are moved out of the loop
84 // and both are used after the main loop and the peeled iteration exit.
85 // For the peeled iteration, storeIndex is always Integer.MIN_VALUE and
86 // for the main loop it is 0. Hence, the merging phi has type int:<=0.
87 // Load1 reads the array at index ConvI2L(CastII(AddI(storeIndex, -1)))
88 // where the CastII is range check dependent and has type int:>=0.
89 // The CastII gets pushed through the AddI and its type is changed to int:>=1
90 // which does not overlap with the input type of storeIndex (int:<=0).
91 // The CastII is replaced by TOP causing a cascade of other eliminations.
92 // Since the control path through the range check CmpU(AddI(storeIndex, -1))
93 // is not eliminated, the graph is in a corrupted state. We fail once we merge
94 // with the result of Load2 because we get data from a non-dominating region.
95 int storeIndex = Integer.MIN_VALUE;
96 for (; index < 10; ++index) {
97 if (index == 42) {
98 return array[storeIndex-1]; // Load1
99 }
100 storeIndex = 0;
101 }
102 return array[42]; // Load2
103 }
104
105 public int testArrayAccess3(int index, boolean b) {
106 // Same as testArrayAccess2 but manifests as crash in register allocator.
107 int storeIndex = Integer.MIN_VALUE;
108 for (; index < 10; ++index) {
109 if (b) {
110 return 0;
111 }
112 if (index == 42) {
113 return array[storeIndex-1]; // Load1
114 }
115 storeIndex = 0;
116 }
117 return array[42]; // Load2
118 }
119
120 public byte[] testArrayAllocation(int index, int inc) {
121 int allocationCount = -1;
122 byte[] result;
123
124 for (; index < 10; index += inc) {
125 // This loop invariant check triggers loop peeling because it can
126 // be moved out of the loop (see 'IdealLoopTree::policy_peeling').
127 if (inc == 42) return null;
128
129 if (index == 42) {
130 // This allocation and the corresponding size check are moved out of the
131 // loop and both used after main loop and the peeled iteration exit.
132 // For the peeled iteration, allocationCount is always -1 and the ConvI2L
133 // is replaced by TOP. However, the size check is not folded because
134 // we don't do the split if optimization in PhaseIdealLoop2.
135 // As a result, we have a (dead) control path from the peeled iteration
136 // to the allocation but the data path is removed.
137 result = new byte[allocationCount];
138 return result;
139 }
140
141 allocationCount++;
142 }
143 return null;
144 }
145 }
146