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/allocation.inline.hpp"
27 #include "opto/connode.hpp"
28 #include "opto/convertnode.hpp"
29 #include "opto/loopnode.hpp"
30 #include "opto/opaquenode.hpp"
31 #include "opto/rootnode.hpp"
32
33 //================= Loop Unswitching =====================
34 //
35 // orig: transformed:
36 // if (invariant-test) then
37 // predicate predicate
38 // loop loop
39 // stmt1 stmt1
40 // if (invariant-test) then stmt2
41 // stmt2 stmt4
42 // else endloop
43 // stmt3 else
44 // endif predicate [clone]
45 // stmt4 loop [clone]
46 // endloop stmt1 [clone]
47 // stmt3
48 // stmt4 [clone]
49 // endloop
50 // endif
51 //
52 // Note: the "else" clause may be empty
53
54 //------------------------------policy_unswitching-----------------------------
55 // Return TRUE or FALSE if the loop should be unswitched
56 // (ie. clone loop with an invariant test that does not exit the loop)
57 bool IdealLoopTree::policy_unswitching( PhaseIdealLoop *phase ) const {
58 if (!LoopUnswitching) {
59 return false;
60 }
61 if (!_head->is_Loop()) {
62 return false;
63 }
64
65 // If nodes are depleted, some transform has miscalculated its needs.
66 assert(!phase->exceeding_node_budget(), "sanity");
67
68 // check for vectorized loops, any unswitching was already applied
69 if (_head->is_CountedLoop() && _head->as_CountedLoop()->is_unroll_only()) {
70 return false;
71 }
72
73 LoopNode* head = _head->as_Loop();
74 if (head->unswitch_count() + 1 > head->unswitch_max()) {
75 return false;
76 }
77 if (phase->find_unswitching_candidate(this) == NULL) {
78 return false;
79 }
80
81 // Too speculative if running low on nodes.
82 return phase->may_require_nodes(est_loop_clone_sz(3, _body.size()));
83 }
84
85 //------------------------------find_unswitching_candidate-----------------------------
86 // Find candidate "if" for unswitching
87 IfNode* PhaseIdealLoop::find_unswitching_candidate(const IdealLoopTree *loop) const {
88
89 // Find first invariant test that doesn't exit the loop
90 LoopNode *head = loop->_head->as_Loop();
91 IfNode* unswitch_iff = NULL;
92 Node* n = head->in(LoopNode::LoopBackControl);
93 while (n != head) {
94 Node* n_dom = idom(n);
95 if (n->is_Region()) {
96 if (n_dom->is_If()) {
97 IfNode* iff = n_dom->as_If();
98 if (iff->in(1)->is_Bool()) {
99 BoolNode* bol = iff->in(1)->as_Bool();
100 if (bol->in(1)->is_Cmp()) {
101 // If condition is invariant and not a loop exit,
102 // then found reason to unswitch.
103 if (loop->is_invariant(bol) && !loop->is_loop_exit(iff)) {
104 unswitch_iff = iff;
105 }
106 }
107 }
108 }
109 }
110 n = n_dom;
111 }
112 return unswitch_iff;
113 }
114
115 //------------------------------do_unswitching-----------------------------
116 // Clone loop with an invariant test (that does not exit) and
117 // insert a clone of the test that selects which version to
118 // execute.
119 void PhaseIdealLoop::do_unswitching (IdealLoopTree *loop, Node_List &old_new) {
120
121 // Find first invariant test that doesn't exit the loop
122 LoopNode *head = loop->_head->as_Loop();
123
124 IfNode* unswitch_iff = find_unswitching_candidate((const IdealLoopTree *)loop);
125 assert(unswitch_iff != NULL, "should be at least one");
126
127 #ifndef PRODUCT
128 if (TraceLoopOpts) {
129 tty->print("Unswitch %d ", head->unswitch_count()+1);
130 loop->dump_head();
131 }
132 #endif
133
134 // Need to revert back to normal loop
135 if (head->is_CountedLoop() && !head->as_CountedLoop()->is_normal_loop()) {
136 head->as_CountedLoop()->set_normal_loop();
137 }
138
139 ProjNode* proj_true = create_slow_version_of_loop(loop, old_new, unswitch_iff->Opcode(), CloneIncludesStripMined);
140
141 #ifdef ASSERT
142 Node* uniqc = proj_true->unique_ctrl_out();
143 Node* entry = head->skip_strip_mined()->in(LoopNode::EntryControl);
144 Node* predicate = find_predicate(entry);
145 if (predicate != NULL) {
151 if (n != NULL) {
152 predicate = n;
153 entry = skip_loop_predicates(entry);
154 }
155 }
156 if (predicate != NULL && UseProfiledLoopPredicate) {
157 entry = find_predicate(entry);
158 if (entry != NULL) predicate = entry;
159 }
160 if (predicate != NULL) predicate = predicate->in(0);
161 assert(proj_true->is_IfTrue() &&
162 (predicate == NULL && uniqc == head && !head->is_strip_mined() ||
163 predicate == NULL && uniqc == head->in(LoopNode::EntryControl) && head->is_strip_mined() ||
164 predicate != NULL && uniqc == predicate), "by construction");
165 #endif
166 // Increment unswitch count
167 LoopNode* head_clone = old_new[head->_idx]->as_Loop();
168 int nct = head->unswitch_count() + 1;
169 head->set_unswitch_count(nct);
170 head_clone->set_unswitch_count(nct);
171
172 // Add test to new "if" outside of loop
173 IfNode* invar_iff = proj_true->in(0)->as_If();
174 Node* invar_iff_c = invar_iff->in(0);
175 BoolNode* bol = unswitch_iff->in(1)->as_Bool();
176 invar_iff->set_req(1, bol);
177 invar_iff->_prob = unswitch_iff->_prob;
178
179 ProjNode* proj_false = invar_iff->proj_out(0)->as_Proj();
180
181 // Hoist invariant casts out of each loop to the appropriate
182 // control projection.
183
184 Node_List worklist;
185
186 for (DUIterator_Fast imax, i = unswitch_iff->fast_outs(imax); i < imax; i++) {
187 ProjNode* proj= unswitch_iff->fast_out(i)->as_Proj();
188 // Copy to a worklist for easier manipulation
189 for (DUIterator_Fast jmax, j = proj->fast_outs(jmax); j < jmax; j++) {
190 Node* use = proj->fast_out(j);
191 if (use->Opcode() == Op_CheckCastPP && loop->is_invariant(use->in(1))) {
192 worklist.push(use);
193 }
194 }
195 ProjNode* invar_proj = invar_iff->proj_out(proj->_con)->as_Proj();
196 while (worklist.size() > 0) {
197 Node* use = worklist.pop();
198 Node* nuse = use->clone();
199 nuse->set_req(0, invar_proj);
200 _igvn.replace_input_of(use, 1, nuse);
201 register_new_node(nuse, invar_proj);
202 // Same for the clone
203 Node* use_clone = old_new[use->_idx];
204 _igvn.replace_input_of(use_clone, 1, nuse);
205 }
206 }
207
208 // Hardwire the control paths in the loops into if(true) and if(false)
209 _igvn.rehash_node_delayed(unswitch_iff);
210 short_circuit_if(unswitch_iff, proj_true);
211
212 IfNode* unswitch_iff_clone = old_new[unswitch_iff->_idx]->as_If();
213 _igvn.rehash_node_delayed(unswitch_iff_clone);
214 short_circuit_if(unswitch_iff_clone, proj_false);
215
216 // Reoptimize loops
217 loop->record_for_igvn();
218 for(int i = loop->_body.size() - 1; i >= 0 ; i--) {
219 Node *n = loop->_body[i];
220 Node *n_clone = old_new[n->_idx];
221 _igvn._worklist.push(n_clone);
222 }
223
224 #ifndef PRODUCT
225 if (TraceLoopUnswitching) {
226 tty->print_cr("Loop unswitching orig: %d @ %d new: %d @ %d",
227 head->_idx, unswitch_iff->_idx,
228 old_new[head->_idx]->_idx, unswitch_iff_clone->_idx);
229 }
230 #endif
231
232 C->set_major_progress();
233 }
234
|
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/allocation.inline.hpp"
27 #include "opto/mulnode.hpp"
28 #include "opto/addnode.hpp"
29 #include "opto/connode.hpp"
30 #include "opto/convertnode.hpp"
31 #include "opto/loopnode.hpp"
32 #include "opto/opaquenode.hpp"
33 #include "opto/rootnode.hpp"
34
35 //================= Loop Unswitching =====================
36 //
37 // orig: transformed:
38 // if (invariant-test) then
39 // predicate predicate
40 // loop loop
41 // stmt1 stmt1
42 // if (invariant-test) then stmt2
43 // stmt2 stmt4
44 // else endloop
45 // stmt3 else
46 // endif predicate [clone]
47 // stmt4 loop [clone]
48 // endloop stmt1 [clone]
49 // stmt3
50 // stmt4 [clone]
51 // endloop
52 // endif
53 //
54 // Note: the "else" clause may be empty
55
56 static bool is_flattened_array_check(Node* iff, PhaseTransform* phase) {
57 if (iff->Opcode() != Op_If) {
58 return false;
59 }
60 Node* bol = iff->in(1);
61 if (!bol->is_Bool() || bol->as_Bool()->_test._test != BoolTest::ne) {
62 return false;
63 }
64 Node* cmp = bol->in(1);
65 if (cmp->Opcode() != Op_CmpI) {
66 return false;
67 }
68 Node* cmp_in1 = cmp->in(1);
69 Node* cmp_in2 = cmp->in(2);
70 if ((unsigned int)cmp_in2->find_int_con(0) != Klass::_lh_array_tag_vt_value) {
71 return false;
72 }
73 if (cmp_in1->Opcode() != Op_RShiftI) {
74 return false;
75 }
76 Node* shift_in1 = cmp_in1->in(1);
77 Node* shift_in2 = cmp_in1->in(2);
78 if ((unsigned int)shift_in2->find_int_con(0) != Klass::_lh_array_tag_shift) {
79 return false;
80 }
81 if (shift_in1->Opcode() != Op_LoadI) {
82 return false;
83 }
84 intptr_t offset;
85 Node* addr = AddPNode::Ideal_base_and_offset(shift_in1->in(MemNode::Address), phase, offset);
86 if (addr == NULL || offset != in_bytes(Klass::layout_helper_offset())) {
87 return false;
88 }
89 if (!phase->type(addr)->isa_klassptr()) {
90 return false;
91 }
92
93 return true;
94 }
95
96 //------------------------------policy_unswitching-----------------------------
97 // Return TRUE or FALSE if the loop should be unswitched
98 // (ie. clone loop with an invariant test that does not exit the loop)
99 bool IdealLoopTree::policy_unswitching( PhaseIdealLoop *phase ) const {
100 if (!LoopUnswitching) {
101 return false;
102 }
103 if (!_head->is_Loop()) {
104 return false;
105 }
106
107 // If nodes are depleted, some transform has miscalculated its needs.
108 assert(!phase->exceeding_node_budget(), "sanity");
109
110 // check for vectorized loops, any unswitching was already applied
111 if (_head->is_CountedLoop() && _head->as_CountedLoop()->is_unroll_only()) {
112 return false;
113 }
114
115 LoopNode* head = _head->as_Loop();
116 if (head->unswitch_count() + 1 > head->unswitch_max()) {
117 return false;
118 }
119
120 if (head->is_flattened_arrays()) {
121 return false;
122 }
123
124 Node_List flattened_checks;
125 if (phase->find_unswitching_candidate(this, flattened_checks) == NULL && flattened_checks.size() == 0) {
126 return false;
127 }
128
129 // Too speculative if running low on nodes.
130 return phase->may_require_nodes(est_loop_clone_sz(3, _body.size()));
131 }
132
133 //------------------------------find_unswitching_candidate-----------------------------
134 // Find candidate "if" for unswitching
135 IfNode* PhaseIdealLoop::find_unswitching_candidate(const IdealLoopTree *loop, Node_List& flattened_checks) const {
136
137 // Find first invariant test that doesn't exit the loop
138 LoopNode *head = loop->_head->as_Loop();
139 IfNode* unswitch_iff = NULL;
140 Node* n = head->in(LoopNode::LoopBackControl);
141 while (n != head) {
142 Node* n_dom = idom(n);
143 if (n->is_Region()) {
144 if (n_dom->is_If()) {
145 IfNode* iff = n_dom->as_If();
146 if (iff->in(1)->is_Bool()) {
147 BoolNode* bol = iff->in(1)->as_Bool();
148 if (bol->in(1)->is_Cmp()) {
149 // If condition is invariant and not a loop exit,
150 // then found reason to unswitch.
151 if (loop->is_invariant(bol) && !loop->is_loop_exit(iff)) {
152 unswitch_iff = iff;
153 }
154 }
155 }
156 }
157 }
158 n = n_dom;
159 }
160
161 if (unswitch_iff == NULL || is_flattened_array_check(unswitch_iff, &_igvn)) {
162 // collect all flattened array checks
163 for (uint i = 0; i < loop->_body.size(); i++) {
164 Node* n = loop->_body.at(i);
165 if (is_flattened_array_check(n, &_igvn) &&
166 loop->is_invariant(n->in(1)) &&
167 !loop->is_loop_exit(n)) {
168 flattened_checks.push(n);
169 }
170 }
171 unswitch_iff = NULL;
172 }
173
174 return unswitch_iff;
175 }
176
177 //------------------------------do_unswitching-----------------------------
178 // Clone loop with an invariant test (that does not exit) and
179 // insert a clone of the test that selects which version to
180 // execute.
181 void PhaseIdealLoop::do_unswitching (IdealLoopTree *loop, Node_List &old_new) {
182
183 // Find first invariant test that doesn't exit the loop
184 LoopNode *head = loop->_head->as_Loop();
185
186 Node_List flattened_checks;
187 IfNode* unswitch_iff = find_unswitching_candidate((const IdealLoopTree *)loop, flattened_checks);
188 assert(unswitch_iff != NULL || flattened_checks.size() > 0, "should be at least one");
189 if (unswitch_iff == NULL) {
190 unswitch_iff = flattened_checks.at(0)->as_If();
191 }
192
193 #ifndef PRODUCT
194 if (TraceLoopOpts) {
195 tty->print("Unswitch %d ", head->unswitch_count()+1);
196 loop->dump_head();
197 }
198 #endif
199
200 // Need to revert back to normal loop
201 if (head->is_CountedLoop() && !head->as_CountedLoop()->is_normal_loop()) {
202 head->as_CountedLoop()->set_normal_loop();
203 }
204
205 ProjNode* proj_true = create_slow_version_of_loop(loop, old_new, unswitch_iff->Opcode(), CloneIncludesStripMined);
206
207 #ifdef ASSERT
208 Node* uniqc = proj_true->unique_ctrl_out();
209 Node* entry = head->skip_strip_mined()->in(LoopNode::EntryControl);
210 Node* predicate = find_predicate(entry);
211 if (predicate != NULL) {
217 if (n != NULL) {
218 predicate = n;
219 entry = skip_loop_predicates(entry);
220 }
221 }
222 if (predicate != NULL && UseProfiledLoopPredicate) {
223 entry = find_predicate(entry);
224 if (entry != NULL) predicate = entry;
225 }
226 if (predicate != NULL) predicate = predicate->in(0);
227 assert(proj_true->is_IfTrue() &&
228 (predicate == NULL && uniqc == head && !head->is_strip_mined() ||
229 predicate == NULL && uniqc == head->in(LoopNode::EntryControl) && head->is_strip_mined() ||
230 predicate != NULL && uniqc == predicate), "by construction");
231 #endif
232 // Increment unswitch count
233 LoopNode* head_clone = old_new[head->_idx]->as_Loop();
234 int nct = head->unswitch_count() + 1;
235 head->set_unswitch_count(nct);
236 head_clone->set_unswitch_count(nct);
237 head_clone->mark_flattened_arrays();
238
239 // Add test to new "if" outside of loop
240 IfNode* invar_iff = proj_true->in(0)->as_If();
241 Node* invar_iff_c = invar_iff->in(0);
242 invar_iff->_prob = unswitch_iff->_prob;
243 if (flattened_checks.size() > 0) {
244 // Flattened array checks are used in
245 // Parse::array_store()/Parse::array_load() to switch between a
246 // legacy object array access and a flattened value array
247 // access. We want the performance impact on legacy accesses to be
248 // as small as possible so we make 2 copies of the loops: a fast
249 // one where all accesses are known to be legacy, a slow one where
250 // some accesses are to flattened arrays. Flattened array checks
251 // can be removed from the first one but not from the second one
252 // as it can have a mix of flattened/legacy accesses.
253 BoolNode* bol = unswitch_iff->in(1)->clone()->as_Bool();
254 register_new_node(bol, invar_iff->in(0));
255 Node* cmp = bol->in(1)->clone();
256 register_new_node(cmp, invar_iff->in(0));
257 bol->set_req(1, cmp);
258 Node* in1 = NULL;
259 for (uint i = 0; i < flattened_checks.size(); i++) {
260 Node* v = flattened_checks.at(i)->in(1)->in(1)->in(1);
261 v = new AndINode(v, _igvn.intcon(Klass::_lh_array_tag_vt_value));
262 register_new_node(v, invar_iff->in(0));
263 if (in1 == NULL) {
264 in1 = v;
265 } else {
266 in1 = new OrINode(in1, v);
267 register_new_node(in1, invar_iff->in(0));
268 }
269 }
270 cmp->set_req(1, in1);
271 invar_iff->set_req(1, bol);
272 } else {
273 BoolNode* bol = unswitch_iff->in(1)->as_Bool();
274 invar_iff->set_req(1, bol);
275 }
276
277 ProjNode* proj_false = invar_iff->proj_out(0)->as_Proj();
278
279 // Hoist invariant casts out of each loop to the appropriate
280 // control projection.
281
282 Node_List worklist;
283
284 for (DUIterator_Fast imax, i = unswitch_iff->fast_outs(imax); i < imax; i++) {
285 ProjNode* proj= unswitch_iff->fast_out(i)->as_Proj();
286 // Copy to a worklist for easier manipulation
287 for (DUIterator_Fast jmax, j = proj->fast_outs(jmax); j < jmax; j++) {
288 Node* use = proj->fast_out(j);
289 if (use->Opcode() == Op_CheckCastPP && loop->is_invariant(use->in(1))) {
290 worklist.push(use);
291 }
292 }
293 ProjNode* invar_proj = invar_iff->proj_out(proj->_con)->as_Proj();
294 while (worklist.size() > 0) {
295 Node* use = worklist.pop();
296 Node* nuse = use->clone();
297 nuse->set_req(0, invar_proj);
298 _igvn.replace_input_of(use, 1, nuse);
299 register_new_node(nuse, invar_proj);
300 // Same for the clone
301 Node* use_clone = old_new[use->_idx];
302 _igvn.replace_input_of(use_clone, 1, nuse);
303 }
304 }
305
306 IfNode* unswitch_iff_clone = old_new[unswitch_iff->_idx]->as_If();
307 if (flattened_checks.size() > 0) {
308 for (uint i = 0; i < flattened_checks.size(); i++) {
309 IfNode* iff = flattened_checks.at(i)->as_If();
310 _igvn.rehash_node_delayed(iff);
311 short_circuit_if(iff, proj_true);
312 }
313 } else {
314 // Hardwire the control paths in the loops into if(true) and if(false)
315 _igvn.rehash_node_delayed(unswitch_iff);
316 short_circuit_if(unswitch_iff, proj_true);
317
318 _igvn.rehash_node_delayed(unswitch_iff_clone);
319 short_circuit_if(unswitch_iff_clone, proj_false);
320 }
321
322 // Reoptimize loops
323 loop->record_for_igvn();
324 for(int i = loop->_body.size() - 1; i >= 0 ; i--) {
325 Node *n = loop->_body[i];
326 Node *n_clone = old_new[n->_idx];
327 _igvn._worklist.push(n_clone);
328 }
329
330 #ifndef PRODUCT
331 if (TraceLoopUnswitching) {
332 tty->print_cr("Loop unswitching orig: %d @ %d new: %d @ %d",
333 head->_idx, unswitch_iff->_idx,
334 old_new[head->_idx]->_idx, unswitch_iff_clone->_idx);
335 }
336 #endif
337
338 C->set_major_progress();
339 }
340
|