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, uint idx) {
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 // Only apply if improved node was created in a callee to avoid
101 // issues with irreducible loops in the caller
102 if (replaced.improved()->_idx >= idx) {
103 n->replace_edge(replaced.initial(), replaced.improved());
104 }
105 }
106 }
107
108 static void enqueue_use(Node* n, Node* use, Unique_Node_List& work) {
109 if (use->is_Phi()) {
110 Node* r = use->in(0);
111 assert(r->is_Region(), "Phi should have Region");
112 for (uint i = 1; i < use->req(); i++) {
113 if (use->in(i) == n) {
114 work.push(r->in(i));
115 }
116 }
117 } else {
118 work.push(use);
119 }
120 }
121
122 // Perfom node replacement following late inlining
123 void ReplacedNodes::apply(Compile* C, Node* ctl) {
124 // ctl is the control on exit of the method that was late inlined
125 if (is_empty()) {
126 return;
127 }
128 for (int i = 0; i < _replaced_nodes->length(); i++) {
129 ReplacedNode replaced = _replaced_nodes->at(i);
130 Node* initial = replaced.initial();
131 Node* improved = replaced.improved();
132 assert (ctl != NULL && !ctl->is_top(), "replaced node should have actual control");
133
134 ResourceMark rm;
135 Unique_Node_List work;
136 // Go over all the uses of the node that is considered for replacement...
137 for (DUIterator j = initial->outs(); initial->has_out(j); j++) {
138 Node* use = initial->out(j);
139
140 if (use == improved || use->outcnt() == 0) {
141 continue;
142 }
143 work.clear();
144 enqueue_use(initial, use, work);
145 bool replace = true;
146 // Check that this use is dominated by ctl. Go ahead with the
147 // replacement if it is.
148 while (work.size() != 0 && replace) {
149 Node* n = work.pop();
150 if (use->outcnt() == 0) {
151 continue;
152 }
153 if (n->is_CFG() || (n->in(0) != NULL && !n->in(0)->is_top())) {
154 int depth = 0;
155 Node *m = n;
156 if (!n->is_CFG()) {
157 n = n->in(0);
158 }
159 assert(n->is_CFG(), "should be CFG now");
160 while(n != ctl) {
161 n = IfNode::up_one_dom(n);
162 depth++;
163 // limit search depth
164 if (depth >= 100 || n == NULL) {
165 replace = false;
166 break;
167 }
168 }
169 } else {
170 for (DUIterator k = n->outs(); n->has_out(k); k++) {
171 enqueue_use(n, n->out(k), work);
172 }
173 }
174 }
175 if (replace) {
176 bool is_in_table = C->initial_gvn()->hash_delete(use);
177 int replaced = use->replace_edge(initial, improved);
178 if (is_in_table) {
179 C->initial_gvn()->hash_find_insert(use);
180 }
181 C->record_for_igvn(use);
182
183 assert(replaced > 0, "inconsistent");
184 --j;
185 }
186 }
187 }
188 }
189
190 void ReplacedNodes::dump(outputStream *st) const {
191 if (!is_empty()) {
192 st->print("replaced nodes: ");
193 for (int i = 0; i < _replaced_nodes->length(); i++) {
194 st->print("%d->%d", _replaced_nodes->at(i).initial()->_idx, _replaced_nodes->at(i).improved()->_idx);
195 if (i < _replaced_nodes->length()-1) {
196 st->print(",");
197 }
198 }
199 }
200 }
201
202 // Merge 2 list of replaced node at a point where control flow paths merge
203 void ReplacedNodes::merge_with(const ReplacedNodes& other) {
204 if (is_empty()) {
205 return;
206 }
207 if (other.is_empty()) {
208 reset();
209 return;
210 }
211 int shift = 0;
212 int len = _replaced_nodes->length();
213 for (int i = 0; i < len; i++) {
214 if (!other.has_node(_replaced_nodes->at(i))) {
215 shift++;
216 } else if (shift > 0) {
217 _replaced_nodes->at_put(i-shift, _replaced_nodes->at(i));
218 }
219 }
220 if (shift > 0) {
221 _replaced_nodes->trunc_to(len - shift);
222 }
223 }