Mercurial > hg > truffle
annotate src/share/vm/opto/loopUnswitch.cpp @ 2474:1dac0f3af89f
7019210: Fix misc references to /bugreport websites
Reviewed-by: skannan
author | ohair |
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date | Thu, 07 Apr 2011 20:26:41 -0700 |
parents | 9dc311b8473e |
children | 1d1603768966 08eb13460b3a |
rev | line source |
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0 | 1 /* |
1972 | 2 * Copyright (c) 2006, 2010, Oracle and/or its affiliates. All rights reserved. |
0 | 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 * | |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
0 | 22 * |
23 */ | |
24 | |
1972 | 25 #include "precompiled.hpp" |
26 #include "memory/allocation.inline.hpp" | |
27 #include "opto/connode.hpp" | |
28 #include "opto/loopnode.hpp" | |
29 #include "opto/rootnode.hpp" | |
0 | 30 |
31 //================= Loop Unswitching ===================== | |
32 // | |
33 // orig: transformed: | |
34 // if (invariant-test) then | |
35 // loop loop | |
36 // stmt1 stmt1 | |
37 // if (invariant-test) then stmt2 | |
38 // stmt2 stmt4 | |
39 // else endloop | |
40 // stmt3 else | |
41 // endif loop [clone] | |
42 // stmt4 stmt1 [clone] | |
43 // endloop stmt3 | |
44 // stmt4 [clone] | |
45 // endloop | |
46 // endif | |
47 // | |
48 // Note: the "else" clause may be empty | |
49 | |
50 //------------------------------policy_unswitching----------------------------- | |
51 // Return TRUE or FALSE if the loop should be unswitched | |
52 // (ie. clone loop with an invariant test that does not exit the loop) | |
53 bool IdealLoopTree::policy_unswitching( PhaseIdealLoop *phase ) const { | |
54 if( !LoopUnswitching ) { | |
55 return false; | |
56 } | |
108 | 57 if (!_head->is_Loop()) { |
58 return false; | |
59 } | |
0 | 60 uint nodes_left = MaxNodeLimit - phase->C->unique(); |
61 if (2 * _body.size() > nodes_left) { | |
62 return false; // Too speculative if running low on nodes. | |
63 } | |
64 LoopNode* head = _head->as_Loop(); | |
65 if (head->unswitch_count() + 1 > head->unswitch_max()) { | |
66 return false; | |
67 } | |
68 return phase->find_unswitching_candidate(this) != NULL; | |
69 } | |
70 | |
71 //------------------------------find_unswitching_candidate----------------------------- | |
72 // Find candidate "if" for unswitching | |
73 IfNode* PhaseIdealLoop::find_unswitching_candidate(const IdealLoopTree *loop) const { | |
74 | |
75 // Find first invariant test that doesn't exit the loop | |
76 LoopNode *head = loop->_head->as_Loop(); | |
77 IfNode* unswitch_iff = NULL; | |
78 Node* n = head->in(LoopNode::LoopBackControl); | |
79 while (n != head) { | |
80 Node* n_dom = idom(n); | |
81 if (n->is_Region()) { | |
82 if (n_dom->is_If()) { | |
83 IfNode* iff = n_dom->as_If(); | |
84 if (iff->in(1)->is_Bool()) { | |
85 BoolNode* bol = iff->in(1)->as_Bool(); | |
86 if (bol->in(1)->is_Cmp()) { | |
87 // If condition is invariant and not a loop exit, | |
88 // then found reason to unswitch. | |
89 if (loop->is_invariant(bol) && !loop->is_loop_exit(iff)) { | |
90 unswitch_iff = iff; | |
91 } | |
92 } | |
93 } | |
94 } | |
95 } | |
96 n = n_dom; | |
97 } | |
98 return unswitch_iff; | |
99 } | |
100 | |
101 //------------------------------do_unswitching----------------------------- | |
102 // Clone loop with an invariant test (that does not exit) and | |
103 // insert a clone of the test that selects which version to | |
104 // execute. | |
105 void PhaseIdealLoop::do_unswitching (IdealLoopTree *loop, Node_List &old_new) { | |
106 | |
107 // Find first invariant test that doesn't exit the loop | |
108 LoopNode *head = loop->_head->as_Loop(); | |
109 | |
110 IfNode* unswitch_iff = find_unswitching_candidate((const IdealLoopTree *)loop); | |
111 assert(unswitch_iff != NULL, "should be at least one"); | |
112 | |
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113 #ifndef PRODUCT |
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114 if (TraceLoopOpts) { |
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115 tty->print("Unswitch %d ", head->unswitch_count()+1); |
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116 loop->dump_head(); |
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117 } |
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118 #endif |
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119 |
0 | 120 // Need to revert back to normal loop |
121 if (head->is_CountedLoop() && !head->as_CountedLoop()->is_normal_loop()) { | |
122 head->as_CountedLoop()->set_normal_loop(); | |
123 } | |
124 | |
125 ProjNode* proj_true = create_slow_version_of_loop(loop, old_new); | |
126 | |
127 assert(proj_true->is_IfTrue() && proj_true->unique_ctrl_out() == head, "by construction"); | |
128 | |
129 // Increment unswitch count | |
130 LoopNode* head_clone = old_new[head->_idx]->as_Loop(); | |
131 int nct = head->unswitch_count() + 1; | |
132 head->set_unswitch_count(nct); | |
133 head_clone->set_unswitch_count(nct); | |
134 | |
135 // Add test to new "if" outside of loop | |
136 IfNode* invar_iff = proj_true->in(0)->as_If(); | |
137 Node* invar_iff_c = invar_iff->in(0); | |
138 BoolNode* bol = unswitch_iff->in(1)->as_Bool(); | |
139 invar_iff->set_req(1, bol); | |
140 invar_iff->_prob = unswitch_iff->_prob; | |
141 | |
142 ProjNode* proj_false = invar_iff->proj_out(0)->as_Proj(); | |
143 | |
605 | 144 // Hoist invariant casts out of each loop to the appropriate |
0 | 145 // control projection. |
146 | |
147 Node_List worklist; | |
148 | |
149 for (DUIterator_Fast imax, i = unswitch_iff->fast_outs(imax); i < imax; i++) { | |
150 ProjNode* proj= unswitch_iff->fast_out(i)->as_Proj(); | |
151 // Copy to a worklist for easier manipulation | |
152 for (DUIterator_Fast jmax, j = proj->fast_outs(jmax); j < jmax; j++) { | |
153 Node* use = proj->fast_out(j); | |
154 if (use->Opcode() == Op_CheckCastPP && loop->is_invariant(use->in(1))) { | |
155 worklist.push(use); | |
156 } | |
157 } | |
158 ProjNode* invar_proj = invar_iff->proj_out(proj->_con)->as_Proj(); | |
159 while (worklist.size() > 0) { | |
160 Node* use = worklist.pop(); | |
161 Node* nuse = use->clone(); | |
162 nuse->set_req(0, invar_proj); | |
163 _igvn.hash_delete(use); | |
164 use->set_req(1, nuse); | |
165 _igvn._worklist.push(use); | |
166 register_new_node(nuse, invar_proj); | |
167 // Same for the clone | |
168 Node* use_clone = old_new[use->_idx]; | |
169 _igvn.hash_delete(use_clone); | |
170 use_clone->set_req(1, nuse); | |
171 _igvn._worklist.push(use_clone); | |
172 } | |
173 } | |
174 | |
175 // Hardwire the control paths in the loops into if(true) and if(false) | |
176 _igvn.hash_delete(unswitch_iff); | |
177 short_circuit_if(unswitch_iff, proj_true); | |
178 _igvn._worklist.push(unswitch_iff); | |
179 | |
180 IfNode* unswitch_iff_clone = old_new[unswitch_iff->_idx]->as_If(); | |
181 _igvn.hash_delete(unswitch_iff_clone); | |
182 short_circuit_if(unswitch_iff_clone, proj_false); | |
183 _igvn._worklist.push(unswitch_iff_clone); | |
184 | |
185 // Reoptimize loops | |
186 loop->record_for_igvn(); | |
187 for(int i = loop->_body.size() - 1; i >= 0 ; i--) { | |
188 Node *n = loop->_body[i]; | |
189 Node *n_clone = old_new[n->_idx]; | |
190 _igvn._worklist.push(n_clone); | |
191 } | |
192 | |
193 #ifndef PRODUCT | |
194 if (TraceLoopUnswitching) { | |
195 tty->print_cr("Loop unswitching orig: %d @ %d new: %d @ %d", | |
196 head->_idx, unswitch_iff->_idx, | |
197 old_new[head->_idx]->_idx, unswitch_iff_clone->_idx); | |
198 } | |
199 #endif | |
200 | |
201 C->set_major_progress(); | |
202 } | |
203 | |
204 //-------------------------create_slow_version_of_loop------------------------ | |
205 // Create a slow version of the loop by cloning the loop | |
206 // and inserting an if to select fast-slow versions. | |
207 // Return control projection of the entry to the fast version. | |
208 ProjNode* PhaseIdealLoop::create_slow_version_of_loop(IdealLoopTree *loop, | |
209 Node_List &old_new) { | |
210 LoopNode* head = loop->_head->as_Loop(); | |
211 Node* entry = head->in(LoopNode::EntryControl); | |
212 _igvn.hash_delete(entry); | |
213 _igvn._worklist.push(entry); | |
214 IdealLoopTree* outer_loop = loop->_parent; | |
215 | |
216 Node *cont = _igvn.intcon(1); | |
217 set_ctrl(cont, C->root()); | |
216
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218 Node* opq = new (C, 2) Opaque1Node(C, cont); |
0 | 219 register_node(opq, outer_loop, entry, dom_depth(entry)); |
220 Node *bol = new (C, 2) Conv2BNode(opq); | |
221 register_node(bol, outer_loop, entry, dom_depth(entry)); | |
222 IfNode* iff = new (C, 2) IfNode(entry, bol, PROB_MAX, COUNT_UNKNOWN); | |
223 register_node(iff, outer_loop, entry, dom_depth(entry)); | |
224 ProjNode* iffast = new (C, 1) IfTrueNode(iff); | |
225 register_node(iffast, outer_loop, iff, dom_depth(iff)); | |
226 ProjNode* ifslow = new (C, 1) IfFalseNode(iff); | |
227 register_node(ifslow, outer_loop, iff, dom_depth(iff)); | |
228 | |
229 // Clone the loop body. The clone becomes the fast loop. The | |
230 // original pre-header will (illegally) have 2 control users (old & new loops). | |
231 clone_loop(loop, old_new, dom_depth(head), iff); | |
232 assert(old_new[head->_idx]->is_Loop(), "" ); | |
233 | |
234 // Fast (true) control | |
235 _igvn.hash_delete(head); | |
236 head->set_req(LoopNode::EntryControl, iffast); | |
237 set_idom(head, iffast, dom_depth(head)); | |
238 _igvn._worklist.push(head); | |
239 | |
240 // Slow (false) control | |
241 LoopNode* slow_head = old_new[head->_idx]->as_Loop(); | |
242 _igvn.hash_delete(slow_head); | |
243 slow_head->set_req(LoopNode::EntryControl, ifslow); | |
244 set_idom(slow_head, ifslow, dom_depth(slow_head)); | |
245 _igvn._worklist.push(slow_head); | |
246 | |
247 recompute_dom_depth(); | |
248 | |
249 return iffast; | |
250 } |