1 /*
2 * Copyright (c) 2016, 2023, 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 #include "precompiled.hpp"
26 #include "memory/resourceArea.hpp"
27 #include "opto/cfgnode.hpp"
28 #include "opto/phaseX.hpp"
29 #include "opto/replacednodes.hpp"
30
31 void ReplacedNodes::allocate_if_necessary() {
32 if (_replaced_nodes == nullptr) {
33 _replaced_nodes = new GrowableArray<ReplacedNode>();
34 }
35 }
36
37 bool ReplacedNodes::is_empty() const {
38 return _replaced_nodes == nullptr || _replaced_nodes->length() == 0;
39 }
40
41 bool ReplacedNodes::has_node(const ReplacedNode& r) const {
42 return _replaced_nodes->find(r) != -1;
43 }
44
45 bool ReplacedNodes::has_target_node(Node* n) const {
46 for (int i = 0; i < _replaced_nodes->length(); i++) {
47 if (_replaced_nodes->at(i).improved() == n) {
48 return true;
49 }
50 }
51 return false;
52 }
53
54 // Record replaced node if not seen before
55 void ReplacedNodes::record(Node* initial, Node* improved) {
56 allocate_if_necessary();
57 ReplacedNode r(initial, improved);
58 if (!has_node(r)) {
59 _replaced_nodes->push(r);
60 }
61 }
62
63 // Copy replaced nodes from one map to another. idx is used to
64 // identify nodes that are too new to be of interest in the target
65 // node list.
66 void ReplacedNodes::transfer_from(const ReplacedNodes& other, uint idx) {
67 if (other.is_empty()) {
68 return;
69 }
70 allocate_if_necessary();
71 for (int i = 0; i < other._replaced_nodes->length(); i++) {
72 ReplacedNode replaced = other._replaced_nodes->at(i);
73 // Only transfer the nodes that can actually be useful
74 if (!has_node(replaced) && (replaced.initial()->_idx < idx || has_target_node(replaced.initial()))) {
75 _replaced_nodes->push(replaced);
76 }
77 }
78 }
79
80 void ReplacedNodes::clone() {
81 if (_replaced_nodes != nullptr) {
82 GrowableArray<ReplacedNode>* replaced_nodes_clone = new GrowableArray<ReplacedNode>();
83 replaced_nodes_clone->appendAll(_replaced_nodes);
84 _replaced_nodes = replaced_nodes_clone;
85 }
86 }
87
88 void ReplacedNodes::reset() {
89 if (_replaced_nodes != nullptr) {
90 _replaced_nodes->clear();
91 }
92 }
93
94 // Perform node replacement (used when returning to caller)
95 void ReplacedNodes::apply(Node* n, uint idx) {
96 if (is_empty()) {
97 return;
98 }
99 for (int i = 0; i < _replaced_nodes->length(); i++) {
100 ReplacedNode replaced = _replaced_nodes->at(i);
101 // Only apply if improved node was created in a callee to avoid
102 // issues with irreducible loops in the caller
103 if (replaced.improved()->_idx >= idx) {
104 n->replace_edge(replaced.initial(), replaced.improved());
105 }
106 }
107 }
108
109 static void enqueue_use(Node* n, Node* use, Unique_Node_List& work) {
110 if (use->is_Phi()) {
111 Node* r = use->in(0);
112 assert(r->is_Region(), "Phi should have Region");
113 for (uint i = 1; i < use->req(); i++) {
114 if (use->in(i) == n) {
115 work.push(r->in(i));
116 }
117 }
118 } else {
119 work.push(use);
120 }
121 }
122
123 // Perform node replacement following late inlining.
124 void ReplacedNodes::apply(Compile* C, Node* ctl) {
125 // ctl is the control on exit of the method that was late inlined
126 if (is_empty()) {
127 return;
128 }
129 for (int i = 0; i < _replaced_nodes->length(); i++) {
130 ReplacedNode replaced = _replaced_nodes->at(i);
131 Node* initial = replaced.initial();
132 Node* improved = replaced.improved();
133 assert (ctl != nullptr && !ctl->is_top(), "replaced node should have actual control");
134
135 ResourceMark rm;
136 Unique_Node_List work;
137 // Go over all the uses of the node that is considered for replacement...
138 for (DUIterator j = initial->outs(); initial->has_out(j); j++) {
139 Node* use = initial->out(j);
140
141 if (use == improved || use->outcnt() == 0) {
142 continue;
143 }
144 work.clear();
145 enqueue_use(initial, use, work);
146 bool replace = true;
147 // Check that this use is dominated by ctl. Go ahead with the replacement if it is.
148 DEBUG_ONLY(uint loop_count = 0);
149 while (work.size() != 0 && replace) {
150 Node* n = work.pop();
151 if (use->outcnt() == 0) {
152 continue;
153 }
154 if (n->is_CFG() || (n->in(0) != nullptr && !n->in(0)->is_top())) {
155 // Skip projections, since some of the multi nodes aren't CFG (e.g., LoadStore and SCMemProj).
156 if (n->is_Proj()) {
157 n = n->in(0);
158 }
159 if (!n->is_CFG()) {
160 n = n->in(0);
161 }
162 assert(n->is_CFG(), "should be CFG now");
163 int depth = 0;
164 while(n != ctl) {
165 n = IfNode::up_one_dom(n);
166 depth++;
167 // limit search depth
168 if (depth >= 100 || n == nullptr) {
169 replace = false;
170 break;
171 }
172 }
173 } else {
174 for (DUIterator k = n->outs(); n->has_out(k); k++) {
175 enqueue_use(n, n->out(k), work);
176 }
177 }
178 assert(loop_count++ < K, "infinite loop in ReplacedNodes::apply");
179 }
180 if (replace) {
181 bool is_in_table = C->initial_gvn()->hash_delete(use);
182 int replaced = use->replace_edge(initial, improved);
183 if (is_in_table) {
184 C->initial_gvn()->hash_find_insert(use);
185 }
186 C->record_for_igvn(use);
187
188 assert(replaced > 0, "inconsistent");
189 --j;
190 }
191 }
192 }
193 }
194
195 void ReplacedNodes::dump(outputStream *st) const {
196 if (!is_empty()) {
197 st->print("replaced nodes: ");
198 for (int i = 0; i < _replaced_nodes->length(); i++) {
199 st->print("%d->%d", _replaced_nodes->at(i).initial()->_idx, _replaced_nodes->at(i).improved()->_idx);
200 if (i < _replaced_nodes->length()-1) {
201 st->print(",");
202 }
203 }
204 }
205 }
206
207 // Merge 2 list of replaced node at a point where control flow paths merge
208 void ReplacedNodes::merge_with(const ReplacedNodes& other) {
209 if (is_empty()) {
210 return;
211 }
212 if (other.is_empty()) {
213 reset();
214 return;
215 }
216 int shift = 0;
217 int len = _replaced_nodes->length();
218 for (int i = 0; i < len; i++) {
219 if (!other.has_node(_replaced_nodes->at(i))) {
220 shift++;
221 } else if (shift > 0) {
222 _replaced_nodes->at_put(i-shift, _replaced_nodes->at(i));
223 }
224 }
225 if (shift > 0) {
226 _replaced_nodes->trunc_to(len - shift);
227 }
228 }