1 /*
2 * Copyright (c) 2014, 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 "opto/cfgnode.hpp"
27 #include "opto/phaseX.hpp"
28 #include "opto/replacednodes.hpp"
29
30 void ReplacedNodes::allocate_if_necessary() {
31 if (_replaced_nodes == NULL) {
32 _replaced_nodes = new GrowableArray<ReplacedNode>();
33 }
34 }
35
36 bool ReplacedNodes::is_empty() const {
37 return _replaced_nodes == NULL || _replaced_nodes->length() == 0;
38 }
39
40 bool ReplacedNodes::has_node(const ReplacedNode& r) const {
41 return _replaced_nodes->find(r) != -1;
42 }
43
44 bool ReplacedNodes::has_target_node(Node* n) const {
45 for (int i = 0; i < _replaced_nodes->length(); i++) {
46 if (_replaced_nodes->at(i).improved() == n) {
47 return true;
48 }
49 }
50 return false;
51 }
52
53 // Record replaced node if not seen before
54 void ReplacedNodes::record(Node* initial, Node* improved) {
55 allocate_if_necessary();
56 ReplacedNode r(initial, improved);
57 if (!has_node(r)) {
58 _replaced_nodes->push(r);
59 }
60 }
61
62 // Copy replaced nodes from one map to another. idx is used to
63 // identify nodes that are too new to be of interest in the target
64 // node list.
65 void ReplacedNodes::transfer_from(const ReplacedNodes& other, uint idx) {
66 if (other.is_empty()) {
67 return;
68 }
69 allocate_if_necessary();
70 for (int i = 0; i < other._replaced_nodes->length(); i++) {
71 ReplacedNode replaced = other._replaced_nodes->at(i);
72 // Only transfer the nodes that can actually be useful
73 if (!has_node(replaced) && (replaced.initial()->_idx < idx || has_target_node(replaced.initial()))) {
74 _replaced_nodes->push(replaced);
75 }
76 }
77 }
78
79 void ReplacedNodes::clone() {
80 if (_replaced_nodes != NULL) {
81 GrowableArray<ReplacedNode>* replaced_nodes_clone = new GrowableArray<ReplacedNode>();
82 replaced_nodes_clone->appendAll(_replaced_nodes);
83 _replaced_nodes = replaced_nodes_clone;
84 }
85 }
86
87 void ReplacedNodes::reset() {
88 if (_replaced_nodes != NULL) {
89 _replaced_nodes->clear();
90 }
91 }
92
93 // Perfom node replacement (used when returning to caller)
94 void ReplacedNodes::apply(Node* n) {
95 if (is_empty()) {
96 return;
97 }
98 for (int i = 0; i < _replaced_nodes->length(); i++) {
99 ReplacedNode replaced = _replaced_nodes->at(i);
100 n->replace_edge(replaced.initial(), replaced.improved());
101 }
102 }
103
104 static void enqueue_use(Node* n, Node* use, Unique_Node_List& work) {
105 if (use->is_Phi()) {
106 Node* r = use->in(0);
107 assert(r->is_Region(), "Phi should have Region");
108 for (uint i = 1; i < use->req(); i++) {
109 if (use->in(i) == n) {
110 work.push(r->in(i));
111 }
112 }
113 } else {
114 work.push(use);
115 }
116 }
117
118 // Perfom node replacement following late inlining
119 void ReplacedNodes::apply(Compile* C, Node* ctl) {
120 // ctl is the control on exit of the method that was late inlined
121 if (is_empty()) {
122 return;
123 }
124 for (int i = 0; i < _replaced_nodes->length(); i++) {
125 ReplacedNode replaced = _replaced_nodes->at(i);
126 Node* initial = replaced.initial();
127 Node* improved = replaced.improved();
128 assert (ctl != NULL && !ctl->is_top(), "replaced node should have actual control");
129
130 ResourceMark rm;
131 Unique_Node_List work;
132 // Go over all the uses of the node that is considered for replacement...
133 for (DUIterator j = initial->outs(); initial->has_out(j); j++) {
134 Node* use = initial->out(j);
135
136 if (use == improved || use->outcnt() == 0) {
137 continue;
138 }
139 work.clear();
140 enqueue_use(initial, use, work);
141 bool replace = true;
142 // Check that this use is dominated by ctl. Go ahead with the
143 // replacement if it is.
144 while (work.size() != 0 && replace) {
145 Node* n = work.pop();
146 if (use->outcnt() == 0) {
147 continue;
148 }
149 if (n->is_CFG() || (n->in(0) != NULL && !n->in(0)->is_top())) {
150 int depth = 0;
151 Node *m = n;
152 if (!n->is_CFG()) {
153 n = n->in(0);
154 }
155 assert(n->is_CFG(), "should be CFG now");
156 while(n != ctl) {
157 n = IfNode::up_one_dom(n);
158 depth++;
159 // limit search depth
160 if (depth >= 100 || n == NULL) {
161 replace = false;
162 break;
163 }
164 }
165 } else {
166 for (DUIterator k = n->outs(); n->has_out(k); k++) {
167 enqueue_use(n, n->out(k), work);
168 }
169 }
170 }
171 if (replace) {
172 bool is_in_table = C->initial_gvn()->hash_delete(use);
173 int replaced = use->replace_edge(initial, improved);
174 if (is_in_table) {
175 C->initial_gvn()->hash_find_insert(use);
176 }
177 C->record_for_igvn(use);
178
179 assert(replaced > 0, "inconsistent");
180 --j;
181 }
182 }
183 }
184 }
185
186 void ReplacedNodes::dump(outputStream *st) const {
187 if (!is_empty()) {
188 st->print("replaced nodes: ");
189 for (int i = 0; i < _replaced_nodes->length(); i++) {
190 st->print("%d->%d", _replaced_nodes->at(i).initial()->_idx, _replaced_nodes->at(i).improved()->_idx);
191 if (i < _replaced_nodes->length()-1) {
192 st->print(",");
193 }
194 }
195 }
196 }
197
198 // Merge 2 list of replaced node at a point where control flow paths merge
199 void ReplacedNodes::merge_with(const ReplacedNodes& other) {
200 if (is_empty()) {
201 return;
202 }
203 if (other.is_empty()) {
204 reset();
205 return;
206 }
207 int shift = 0;
208 int len = _replaced_nodes->length();
209 for (int i = 0; i < len; i++) {
210 if (!other.has_node(_replaced_nodes->at(i))) {
211 shift++;
212 } else if (shift > 0) {
213 _replaced_nodes->at_put(i-shift, _replaced_nodes->at(i));
214 }
215 }
216 if (shift > 0) {
217 _replaced_nodes->trunc_to(len - shift);
218 }
219 }