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1 // Copyright 2013 the V8 project authors. All rights reserved. | 1 // Copyright 2013 the V8 project authors. All rights reserved. |
2 // Redistribution and use in source and binary forms, with or without | 2 // Redistribution and use in source and binary forms, with or without |
3 // modification, are permitted provided that the following conditions are | 3 // modification, are permitted provided that the following conditions are |
4 // met: | 4 // met: |
5 // | 5 // |
6 // * Redistributions of source code must retain the above copyright | 6 // * Redistributions of source code must retain the above copyright |
7 // notice, this list of conditions and the following disclaimer. | 7 // notice, this list of conditions and the following disclaimer. |
8 // * Redistributions in binary form must reproduce the above | 8 // * Redistributions in binary form must reproduce the above |
9 // copyright notice, this list of conditions and the following | 9 // copyright notice, this list of conditions and the following |
10 // disclaimer in the documentation and/or other materials provided | 10 // disclaimer in the documentation and/or other materials provided |
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110 } | 110 } |
111 // Improvements possible: | 111 // Improvements possible: |
112 // - eliminate redundant HCheckSmi, HCheckInstanceType instructions | 112 // - eliminate redundant HCheckSmi, HCheckInstanceType instructions |
113 // - track which values have been HCheckHeapObject'd | 113 // - track which values have been HCheckHeapObject'd |
114 } | 114 } |
115 | 115 |
116 return this; | 116 return this; |
117 } | 117 } |
118 | 118 |
119 // Global analysis: Copy state to successor block. | 119 // Global analysis: Copy state to successor block. |
120 HCheckTable* Copy(HBasicBlock* succ, Zone* zone) { | 120 HCheckTable* Copy(HBasicBlock* succ, HBasicBlock* from_block, Zone* zone) { |
121 HCheckTable* copy = new(phase_->zone()) HCheckTable(phase_); | 121 HCheckTable* copy = new(phase_->zone()) HCheckTable(phase_); |
122 for (int i = 0; i < size_; i++) { | 122 for (int i = 0; i < size_; i++) { |
123 HCheckTableEntry* old_entry = &entries_[i]; | 123 HCheckTableEntry* old_entry = &entries_[i]; |
124 HCheckTableEntry* new_entry = ©->entries_[i]; | 124 HCheckTableEntry* new_entry = ©->entries_[i]; |
125 // TODO(titzer): keep the check if this block dominates the successor? | 125 // TODO(titzer): keep the check if this block dominates the successor? |
126 new_entry->object_ = old_entry->object_; | 126 new_entry->object_ = old_entry->object_; |
127 new_entry->check_ = NULL; | 127 new_entry->check_ = NULL; |
128 new_entry->maps_ = old_entry->maps_->Copy(phase_->zone()); | 128 new_entry->maps_ = old_entry->maps_->Copy(phase_->zone()); |
129 } | 129 } |
130 copy->cursor_ = cursor_; | 130 copy->cursor_ = cursor_; |
131 copy->size_ = size_; | 131 copy->size_ = size_; |
132 | 132 |
133 copy->InheritPhiOperands(succ, this, from_block, COPY, zone); | |
134 | |
133 // Branch-sensitive analysis for certain comparisons may add more facts | 135 // Branch-sensitive analysis for certain comparisons may add more facts |
134 // to the state for the successor on the true branch. | 136 // to the state for the successor on the true branch. |
137 bool learned = false; | |
135 HControlInstruction* end = succ->predecessors()->at(0)->end(); | 138 HControlInstruction* end = succ->predecessors()->at(0)->end(); |
136 if (succ->predecessors()->length() == 1 && end->SuccessorAt(0) == succ) { | 139 if (succ->predecessors()->length() == 1 && end->SuccessorAt(0) == succ) { |
137 if (end->IsCompareMap()) { | 140 if (end->IsCompareMap()) { |
138 // Learn on the true branch of if(CompareMap(x)). | 141 // Learn on the true branch of if(CompareMap(x)). |
139 HCompareMap* cmp = HCompareMap::cast(end); | 142 HCompareMap* cmp = HCompareMap::cast(end); |
140 HValue* object = cmp->value()->ActualValue(); | 143 HValue* object = cmp->value()->ActualValue(); |
141 HCheckTableEntry* entry = copy->Find(object); | 144 HCheckTableEntry* entry = copy->Find(object); |
142 if (entry == NULL) { | 145 if (entry == NULL) { |
143 copy->Insert(object, cmp->map()); | 146 copy->Insert(object, cmp->map()); |
144 } else { | 147 } else { |
145 MapSet list = new(phase_->zone()) UniqueSet<Map>(); | 148 MapSet list = new(phase_->zone()) UniqueSet<Map>(); |
146 list->Add(cmp->map(), phase_->zone()); | 149 list->Add(cmp->map(), phase_->zone()); |
147 entry->maps_ = list; | 150 entry->maps_ = list; |
148 } | 151 } |
152 learned = true; | |
149 } else if (end->IsCompareObjectEqAndBranch()) { | 153 } else if (end->IsCompareObjectEqAndBranch()) { |
150 // Learn on the true branch of if(CmpObjectEq(x, y)). | 154 // Learn on the true branch of if(CmpObjectEq(x, y)). |
151 HCompareObjectEqAndBranch* cmp = | 155 HCompareObjectEqAndBranch* cmp = |
152 HCompareObjectEqAndBranch::cast(end); | 156 HCompareObjectEqAndBranch::cast(end); |
153 HValue* left = cmp->left()->ActualValue(); | 157 HValue* left = cmp->left()->ActualValue(); |
154 HValue* right = cmp->right()->ActualValue(); | 158 HValue* right = cmp->right()->ActualValue(); |
155 HCheckTableEntry* le = copy->Find(left); | 159 HCheckTableEntry* le = copy->Find(left); |
156 HCheckTableEntry* re = copy->Find(right); | 160 HCheckTableEntry* re = copy->Find(right); |
157 if (le == NULL) { | 161 if (le == NULL) { |
158 if (re != NULL) { | 162 if (re != NULL) { |
159 copy->Insert(left, NULL, re->maps_->Copy(zone)); | 163 copy->Insert(left, NULL, re->maps_->Copy(zone)); |
160 } | 164 } |
161 } else if (re == NULL) { | 165 } else if (re == NULL) { |
162 copy->Insert(right, NULL, le->maps_->Copy(zone)); | 166 copy->Insert(right, NULL, le->maps_->Copy(zone)); |
163 } else { | 167 } else { |
164 MapSet intersect = le->maps_->Intersect(re->maps_, zone); | 168 MapSet intersect = le->maps_->Intersect(re->maps_, zone); |
165 le->maps_ = intersect; | 169 le->maps_ = intersect; |
166 re->maps_ = intersect->Copy(zone); | 170 re->maps_ = intersect->Copy(zone); |
167 } | 171 } |
172 learned = true; | |
168 } | 173 } |
169 // Learning on false branches requires storing negative facts. | 174 // Learning on false branches requires storing negative facts. |
170 } | 175 } |
171 | 176 |
177 if (FLAG_trace_check_elimination) { | |
178 PrintF("B%d checkmaps-table %s from B%d:\n", | |
179 succ->block_id(), | |
180 learned ? "learned" : "copied", | |
181 from_block->block_id()); | |
182 copy->Print(); | |
183 } | |
184 | |
172 return copy; | 185 return copy; |
173 } | 186 } |
174 | 187 |
175 // Global analysis: Merge this state with the other incoming state. | 188 // Global analysis: Merge this state with the other incoming state. |
176 HCheckTable* Merge(HBasicBlock* succ, HCheckTable* that, Zone* zone) { | 189 void Merge(HBasicBlock* succ, HCheckTable* that, |
177 if (that->size_ == 0) { | 190 HBasicBlock* that_block, Zone* zone) { |
178 // If the other state is empty, simply reset. | 191 if (that_block->IsReachable()) { |
179 size_ = 0; | 192 if (that->size_ == 0) { |
180 cursor_ = 0; | 193 // If the other state is empty, simply reset. |
181 return this; | 194 size_ = 0; |
182 } | 195 cursor_ = 0; |
183 bool compact = false; | |
184 for (int i = 0; i < size_; i++) { | |
185 HCheckTableEntry* this_entry = &entries_[i]; | |
186 HCheckTableEntry* that_entry = that->Find(this_entry->object_); | |
187 if (that_entry == NULL) { | |
188 this_entry->object_ = NULL; | |
189 compact = true; | |
190 } else { | 196 } else { |
191 this_entry->maps_ = this_entry->maps_->Union( | 197 InheritPhiOperands(succ, that, that_block, MERGE, zone); |
192 that_entry->maps_, phase_->zone()); | 198 |
193 if (this_entry->check_ != that_entry->check_) this_entry->check_ = NULL; | 199 bool compact = false; |
194 ASSERT(this_entry->maps_->size() > 0); | 200 for (int i = 0; i < size_; i++) { |
201 HCheckTableEntry* this_entry = &entries_[i]; | |
202 HCheckTableEntry* that_entry = that->Find(this_entry->object_); | |
203 // Keep those phis in the table that dominate succ block. | |
204 if (that_entry == NULL) { | |
205 if (!this_entry->object_->IsPhi() || | |
206 !this_entry->object_->block()->EqualToOrDominates(succ)) { | |
207 this_entry->object_ = NULL; | |
208 compact = true; | |
209 } | |
210 } else { | |
211 this_entry->maps_ = | |
212 this_entry->maps_->Union(that_entry->maps_, phase_->zone()); | |
213 if (this_entry->check_ != that_entry->check_) { | |
214 this_entry->check_ = NULL; | |
215 } | |
216 ASSERT(this_entry->maps_->size() > 0); | |
217 } | |
218 } | |
219 if (compact) Compact(); | |
195 } | 220 } |
196 } | 221 } |
197 if (compact) Compact(); | 222 |
198 return this; | 223 if (FLAG_trace_check_elimination) { |
224 PrintF("B%d checkmaps-table merged with B%d table:\n", | |
225 succ->block_id(), that_block->block_id()); | |
226 Print(); | |
227 } | |
228 } | |
229 | |
230 enum InheritPhiOperandsMode { COPY, MERGE }; | |
231 void InheritPhiOperands(HBasicBlock* succ, HCheckTable* that, | |
232 HBasicBlock* that_block, InheritPhiOperandsMode mode, | |
233 Zone* zone) { | |
234 if (succ->predecessors()->length() == 1) return; | |
235 | |
236 int pred_index = succ->PredecessorIndexOf(that_block); | |
237 | |
238 for (int i = 0; i < that->size_; i++) { | |
239 HCheckTableEntry* that_entry = &that->entries_[i]; | |
240 if (that_entry->object_ != NULL) { | |
241 HPhi* phi = NULL; | |
242 for (int phi_index = 0; | |
243 phi_index < succ->phis()->length(); | |
244 ++phi_index) { | |
245 HPhi* tmp_phi = succ->phis()->at(phi_index); | |
246 if (tmp_phi->OperandAt(pred_index) == that_entry->object_) { | |
247 phi = tmp_phi; | |
248 break; | |
249 } | |
250 } | |
251 | |
252 if (phi != NULL) { | |
253 // Found a |phi| with operand equal to |that_entry->object_|. | |
254 HCheckTableEntry* phi_entry = (mode == MERGE) ? Find(phi) : NULL; | |
255 if (phi_entry == NULL) { | |
256 // Create an entry for a phi in the table. | |
257 Insert(phi, NULL, that_entry->maps_); | |
258 } else { | |
259 phi_entry->maps_ = | |
260 phi_entry->maps_->Union(that_entry->maps_, phase_->zone()); | |
261 } | |
262 } | |
263 } | |
264 } | |
199 } | 265 } |
200 | 266 |
201 void ReduceCheckMaps(HCheckMaps* instr) { | 267 void ReduceCheckMaps(HCheckMaps* instr) { |
202 HValue* object = instr->value()->ActualValue(); | 268 HValue* object = instr->value()->ActualValue(); |
203 HCheckTableEntry* entry = Find(object); | 269 HCheckTableEntry* entry = Find(object); |
204 if (entry != NULL) { | 270 if (entry != NULL) { |
205 // entry found; | 271 // entry found; |
206 MapSet a = entry->maps_; | 272 MapSet a = entry->maps_; |
207 MapSet i = instr->map_set().Copy(phase_->zone()); | 273 MapSet i = instr->map_set().Copy(phase_->zone()); |
208 if (a->IsSubset(i)) { | 274 if (a->IsSubset(i)) { |
209 // The first check is more strict; the second is redundant. | 275 // The first check is more strict; the second is redundant. |
210 if (entry->check_ != NULL) { | 276 if (entry->check_ != NULL) { |
277 TRACE(("Replacing redundant CheckMaps #%d at B%d with #%d\n", | |
278 instr->id(), instr->block()->block_id(), entry->check_->id())); | |
211 instr->DeleteAndReplaceWith(entry->check_); | 279 instr->DeleteAndReplaceWith(entry->check_); |
212 INC_STAT(redundant_); | 280 INC_STAT(redundant_); |
213 } else { | 281 } else { |
214 instr->DeleteAndReplaceWith(instr->value()); | 282 TRACE(("Marking redundant CheckMaps #%d at B%d as dead\n", |
283 instr->id(), instr->block()->block_id())); | |
284 // Mark check as dead but leave it in the graph as a checkpoint for | |
285 // subsequent checks. | |
286 instr->SetFlag(HValue::kIsDead); | |
287 entry->check_ = instr; | |
215 INC_STAT(removed_); | 288 INC_STAT(removed_); |
216 } | 289 } |
217 return; | 290 return; |
218 } | 291 } |
219 i = i->Intersect(a, phase_->zone()); | 292 MapSet narrowed_maps = i->Intersect(a, phase_->zone()); |
titzer
2014/01/23 18:40:55
Would prefer the name "intersection" instead of na
Igor Sheludko
2014/01/29 12:27:13
Done.
| |
220 if (i->size() == 0) { | 293 if (narrowed_maps->size() == 0) { |
221 // Intersection is empty; probably megamorphic, which is likely to | 294 // Intersection is empty; probably megamorphic, which is likely to |
222 // deopt anyway, so just leave things as they are. | 295 // deopt anyway, so just leave things as they are. |
223 INC_STAT(empty_); | 296 INC_STAT(empty_); |
224 } else { | 297 } else { |
225 // TODO(titzer): replace the first check with a more strict check | 298 // Narrow set of maps in the second check and replace the first |
299 // check with a more strict one. | |
300 entry->maps_ = narrowed_maps; | |
301 if (narrowed_maps->size() != i->size()) { | |
302 // Narrow set of maps in the second check maps instruction. | |
303 HGraph* graph = instr->block()->graph(); | |
304 HCheckMaps* new_check_maps = | |
305 HCheckMaps::New(graph->zone(), NULL, instr->value(), | |
306 narrowed_maps, instr->typecheck()); | |
307 new_check_maps->InsertBefore(instr); | |
308 TRACE(("CheckMaps #%d for #%d narrowed to #%d:\n", | |
309 instr->id(), instr->value()->id(), new_check_maps->id())); | |
310 instr->DeleteAndReplaceWith(new_check_maps); | |
titzer
2014/01/23 18:40:55
I think you want to replace both entry->check_ (if
Igor Sheludko
2014/01/29 12:27:13
Done.
| |
311 entry->check_ = new_check_maps; | |
312 } else { | |
313 TRACE(("CheckMaps #%d for #%d narrowed:\n", | |
314 instr->id(), instr->value()->id())); | |
titzer
2014/01/23 18:40:55
In this case, you haven't actually changed anythin
Igor Sheludko
2014/01/29 12:27:13
Done.
| |
315 entry->check_ = instr; | |
316 } | |
317 if (FLAG_trace_check_elimination) { | |
318 Print(); | |
319 } | |
226 INC_STAT(narrowed_); | 320 INC_STAT(narrowed_); |
227 } | 321 } |
228 } else { | 322 } else { |
229 // No entry; insert a new one. | 323 // No entry; insert a new one. |
230 Insert(object, instr, instr->map_set().Copy(phase_->zone())); | 324 Insert(object, instr, instr->map_set().Copy(phase_->zone())); |
231 } | 325 } |
232 } | 326 } |
233 | 327 |
234 void ReduceCheckValue(HCheckValue* instr) { | 328 void ReduceCheckValue(HCheckValue* instr) { |
235 // Canonicalize HCheckValues; they might have their values load-eliminated. | 329 // Canonicalize HCheckValues; they might have their values load-eliminated. |
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552 PRINT_STAT(removed_cho); | 646 PRINT_STAT(removed_cho); |
553 PRINT_STAT(narrowed); | 647 PRINT_STAT(narrowed); |
554 PRINT_STAT(loads); | 648 PRINT_STAT(loads); |
555 PRINT_STAT(empty); | 649 PRINT_STAT(empty); |
556 PRINT_STAT(compares_true); | 650 PRINT_STAT(compares_true); |
557 PRINT_STAT(compares_false); | 651 PRINT_STAT(compares_false); |
558 PRINT_STAT(transitions); | 652 PRINT_STAT(transitions); |
559 } | 653 } |
560 | 654 |
561 } } // namespace v8::internal | 655 } } // namespace v8::internal |
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