Skip to content

Commit 1ef45c5

Browse files
rwestrelrwestrel
committedFeb 14, 2022
8280799: С2: assert(false) failed: cyclic dependency prevents range check elimination
Reviewed-by: thartmann, kvn
1 parent 483d4b9 commit 1ef45c5

File tree

3 files changed

+319
-26
lines changed

3 files changed

+319
-26
lines changed
 

‎src/hotspot/share/opto/loopnode.cpp

+33-26
Original file line numberDiff line numberDiff line change
@@ -5725,38 +5725,45 @@ void PhaseIdealLoop::build_loop_late_post_work(Node *n, bool pinned) {
57255725
}
57265726
assert(early == legal || legal != C->root(), "bad dominance of inputs");
57275727

5728+
if (least != early) {
5729+
// Move the node above predicates as far up as possible so a
5730+
// following pass of loop predication doesn't hoist a predicate
5731+
// that depends on it above that node.
5732+
Node* new_ctrl = least;
5733+
for (;;) {
5734+
if (!new_ctrl->is_Proj()) {
5735+
break;
5736+
}
5737+
CallStaticJavaNode* call = new_ctrl->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none);
5738+
if (call == NULL) {
5739+
break;
5740+
}
5741+
int req = call->uncommon_trap_request();
5742+
Deoptimization::DeoptReason trap_reason = Deoptimization::trap_request_reason(req);
5743+
if (trap_reason != Deoptimization::Reason_loop_limit_check &&
5744+
trap_reason != Deoptimization::Reason_predicate &&
5745+
trap_reason != Deoptimization::Reason_profile_predicate) {
5746+
break;
5747+
}
5748+
Node* c = new_ctrl->in(0)->in(0);
5749+
if (is_dominator(c, early) && c != early) {
5750+
break;
5751+
}
5752+
new_ctrl = c;
5753+
}
5754+
least = new_ctrl;
5755+
}
57285756
// Try not to place code on a loop entry projection
57295757
// which can inhibit range check elimination.
57305758
if (least != early) {
57315759
Node* ctrl_out = least->unique_ctrl_out();
57325760
if (ctrl_out && ctrl_out->is_Loop() &&
5733-
least == ctrl_out->in(LoopNode::EntryControl)) {
5734-
// Move the node above predicates as far up as possible so a
5735-
// following pass of loop predication doesn't hoist a predicate
5736-
// that depends on it above that node.
5737-
Node* new_ctrl = least;
5738-
for (;;) {
5739-
if (!new_ctrl->is_Proj()) {
5740-
break;
5741-
}
5742-
CallStaticJavaNode* call = new_ctrl->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none);
5743-
if (call == NULL) {
5744-
break;
5745-
}
5746-
int req = call->uncommon_trap_request();
5747-
Deoptimization::DeoptReason trap_reason = Deoptimization::trap_request_reason(req);
5748-
if (trap_reason != Deoptimization::Reason_loop_limit_check &&
5749-
trap_reason != Deoptimization::Reason_predicate &&
5750-
trap_reason != Deoptimization::Reason_profile_predicate) {
5751-
break;
5752-
}
5753-
Node* c = new_ctrl->in(0)->in(0);
5754-
if (is_dominator(c, early) && c != early) {
5755-
break;
5756-
}
5757-
new_ctrl = c;
5761+
least == ctrl_out->in(LoopNode::EntryControl) &&
5762+
(ctrl_out->is_CountedLoop() || ctrl_out->is_OuterStripMinedLoop())) {
5763+
Node* least_dom = idom(least);
5764+
if (get_loop(least_dom)->is_member(get_loop(least))) {
5765+
least = least_dom;
57585766
}
5759-
least = new_ctrl;
57605767
}
57615768
}
57625769

‎src/hotspot/share/opto/split_if.cpp

+18
Original file line numberDiff line numberDiff line change
@@ -201,6 +201,24 @@ bool PhaseIdealLoop::split_up( Node *n, Node *blk1, Node *blk2 ) {
201201
return true;
202202
}
203203
}
204+
if (n->Opcode() == Op_OpaqueLoopStride || n->Opcode() == Op_OpaqueLoopInit) {
205+
Unique_Node_List wq;
206+
wq.push(n);
207+
for (uint i = 0; i < wq.size(); i++) {
208+
Node* m = wq.at(i);
209+
if (m->is_If()) {
210+
assert(skeleton_predicate_has_opaque(m->as_If()), "opaque node not reachable from if?");
211+
Node* bol = clone_skeleton_predicate_bool(m, NULL, NULL, m->in(0));
212+
_igvn.replace_input_of(m, 1, bol);
213+
} else {
214+
assert(!m->is_CFG(), "not CFG expected");
215+
for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
216+
Node* u = m->fast_out(j);
217+
wq.push(u);
218+
}
219+
}
220+
}
221+
}
204222

205223
// See if splitting-up a Store. Any anti-dep loads must go up as
206224
// well. An anti-dep load might be in the wrong block, because in

‎test/hotspot/jtreg/compiler/loopopts/TestPredicateInputBelowLoopPredicate.java

+268
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,268 @@
1+
/*
2+
* Copyright (c) 2022, Red Hat, Inc. 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 8280799
27+
* @summary С2: assert(false) failed: cyclic dependency prevents range check elimination
28+
* @run main/othervm -XX:-BackgroundCompilation -XX:-UseCountedLoopSafepoints TestPredicateInputBelowLoopPredicate
29+
*/
30+
31+
public class TestPredicateInputBelowLoopPredicate {
32+
private static final Object object = new Object();
33+
private static int fieldStop = 100;
34+
private static int[] array = new int[200];
35+
private static int[] array2 = new int[200];
36+
private static int fieldStart = 0;
37+
38+
public static void main(String[] args) {
39+
for (int i = 0; i < 20_000; i++) {
40+
test(true);
41+
test(false);
42+
}
43+
}
44+
45+
private static void test(boolean flag) {
46+
if (array == null) {
47+
}
48+
int start = fieldStart;
49+
int i = start;
50+
for(;;) {
51+
int j;
52+
for (j = -10; j < 0; j++) {
53+
}
54+
int stop = fieldStop;
55+
// bound check becomes candidate for predication once
56+
// loop above is optimized out
57+
array[stop - i + j] = 0;
58+
59+
// A bunch of stuff to grow loop body size and prevent peeling:
60+
array2[0] = 0;
61+
array2[1] = 0;
62+
array2[2] = 0;
63+
array2[3] = 0;
64+
array2[4] = 0;
65+
array2[5] = 0;
66+
array2[6] = 0;
67+
array2[7] = 0;
68+
array2[8] = 0;
69+
array2[9] = 0;
70+
array2[10] = 0;
71+
array2[11] = 0;
72+
array2[12] = 0;
73+
array2[13] = 0;
74+
array2[14] = 0;
75+
array2[15] = 0;
76+
array2[16] = 0;
77+
array2[17] = 0;
78+
array2[18] = 0;
79+
array2[19] = 0;
80+
array2[20] = 0;
81+
array2[21] = 0;
82+
array2[22] = 0;
83+
array2[23] = 0;
84+
array2[24] = 0;
85+
array2[25] = 0;
86+
array2[26] = 0;
87+
array2[27] = 0;
88+
array2[28] = 0;
89+
array2[29] = 0;
90+
array2[30] = 0;
91+
array2[31] = 0;
92+
array2[32] = 0;
93+
array2[33] = 0;
94+
array2[34] = 0;
95+
array2[35] = 0;
96+
array2[36] = 0;
97+
array2[37] = 0;
98+
array2[38] = 0;
99+
array2[39] = 0;
100+
array2[40] = 0;
101+
array2[41] = 0;
102+
array2[42] = 0;
103+
array2[43] = 0;
104+
array2[44] = 0;
105+
array2[45] = 0;
106+
array2[46] = 0;
107+
array2[47] = 0;
108+
array2[48] = 0;
109+
array2[49] = 0;
110+
array2[50] = 0;
111+
array2[51] = 0;
112+
array2[52] = 0;
113+
array2[53] = 0;
114+
array2[54] = 0;
115+
array2[55] = 0;
116+
array2[56] = 0;
117+
array2[57] = 0;
118+
array2[58] = 0;
119+
array2[59] = 0;
120+
array2[60] = 0;
121+
array2[61] = 0;
122+
array2[62] = 0;
123+
array2[63] = 0;
124+
array2[64] = 0;
125+
array2[65] = 0;
126+
array2[66] = 0;
127+
array2[67] = 0;
128+
array2[68] = 0;
129+
array2[69] = 0;
130+
array2[70] = 0;
131+
array2[71] = 0;
132+
array2[72] = 0;
133+
array2[73] = 0;
134+
array2[74] = 0;
135+
array2[75] = 0;
136+
array2[76] = 0;
137+
array2[77] = 0;
138+
array2[78] = 0;
139+
array2[79] = 0;
140+
array2[80] = 0;
141+
array2[81] = 0;
142+
array2[82] = 0;
143+
array2[83] = 0;
144+
array2[84] = 0;
145+
array2[85] = 0;
146+
array2[86] = 0;
147+
array2[87] = 0;
148+
array2[88] = 0;
149+
array2[89] = 0;
150+
array2[90] = 0;
151+
array2[91] = 0;
152+
array2[92] = 0;
153+
array2[93] = 0;
154+
array2[94] = 0;
155+
array2[95] = 0;
156+
array2[96] = 0;
157+
array2[97] = 0;
158+
array2[98] = 0;
159+
array2[99] = 0;
160+
161+
array2[100] = 0;
162+
array2[101] = 0;
163+
array2[102] = 0;
164+
array2[103] = 0;
165+
array2[104] = 0;
166+
array2[105] = 0;
167+
array2[106] = 0;
168+
array2[107] = 0;
169+
array2[108] = 0;
170+
array2[109] = 0;
171+
array2[110] = 0;
172+
array2[111] = 0;
173+
array2[112] = 0;
174+
array2[113] = 0;
175+
array2[114] = 0;
176+
array2[115] = 0;
177+
array2[116] = 0;
178+
array2[117] = 0;
179+
array2[118] = 0;
180+
array2[119] = 0;
181+
array2[120] = 0;
182+
array2[121] = 0;
183+
array2[122] = 0;
184+
array2[123] = 0;
185+
array2[124] = 0;
186+
array2[125] = 0;
187+
array2[126] = 0;
188+
array2[127] = 0;
189+
array2[128] = 0;
190+
array2[129] = 0;
191+
array2[130] = 0;
192+
array2[131] = 0;
193+
array2[132] = 0;
194+
array2[133] = 0;
195+
array2[134] = 0;
196+
array2[135] = 0;
197+
array2[136] = 0;
198+
array2[137] = 0;
199+
array2[138] = 0;
200+
array2[139] = 0;
201+
array2[140] = 0;
202+
array2[141] = 0;
203+
array2[142] = 0;
204+
array2[143] = 0;
205+
array2[144] = 0;
206+
array2[145] = 0;
207+
array2[146] = 0;
208+
array2[147] = 0;
209+
array2[148] = 0;
210+
array2[149] = 0;
211+
array2[150] = 0;
212+
array2[151] = 0;
213+
array2[152] = 0;
214+
array2[153] = 0;
215+
array2[154] = 0;
216+
array2[155] = 0;
217+
array2[156] = 0;
218+
array2[157] = 0;
219+
array2[158] = 0;
220+
array2[159] = 0;
221+
array2[160] = 0;
222+
array2[161] = 0;
223+
array2[162] = 0;
224+
array2[163] = 0;
225+
array2[164] = 0;
226+
array2[165] = 0;
227+
array2[166] = 0;
228+
array2[167] = 0;
229+
array2[168] = 0;
230+
array2[169] = 0;
231+
array2[170] = 0;
232+
array2[171] = 0;
233+
array2[172] = 0;
234+
array2[173] = 0;
235+
array2[174] = 0;
236+
array2[175] = 0;
237+
array2[176] = 0;
238+
array2[177] = 0;
239+
array2[178] = 0;
240+
array2[179] = 0;
241+
array2[180] = 0;
242+
array2[181] = 0;
243+
array2[182] = 0;
244+
array2[183] = 0;
245+
array2[184] = 0;
246+
array2[185] = 0;
247+
array2[186] = 0;
248+
array2[187] = 0;
249+
array2[188] = 0;
250+
array2[189] = 0;
251+
array2[190] = 0;
252+
array2[191] = 0;
253+
array2[192] = 0;
254+
array2[193] = 0;
255+
array2[194] = 0;
256+
array2[195] = 0;
257+
array2[196] = 0;
258+
array2[197] = 0;
259+
array2[198] = 0;
260+
array2[199] = 0;
261+
i++;
262+
263+
if (i == stop) { // requires a loop limit predicate
264+
break;
265+
}
266+
}
267+
}
268+
}

0 commit comments

Comments
 (0)
Please sign in to comment.