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1 // Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file | 1 // Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file |
2 // for details. All rights reserved. Use of this source code is governed by a | 2 // for details. All rights reserved. Use of this source code is governed by a |
3 // BSD-style license that can be found in the LICENSE file. | 3 // BSD-style license that can be found in the LICENSE file. |
4 | 4 |
5 #ifndef VM_FLOW_GRAPH_OPTIMIZER_H_ | 5 #ifndef VM_FLOW_GRAPH_OPTIMIZER_H_ |
6 #define VM_FLOW_GRAPH_OPTIMIZER_H_ | 6 #define VM_FLOW_GRAPH_OPTIMIZER_H_ |
7 | 7 |
8 #include "vm/intermediate_language.h" | 8 #include "vm/intermediate_language.h" |
9 #include "vm/flow_graph.h" | 9 #include "vm/flow_graph.h" |
10 | 10 |
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290 | 290 |
291 // Sparse conditional constant propagation and unreachable code elimination. | 291 // Sparse conditional constant propagation and unreachable code elimination. |
292 // Assumes that use lists are computed and preserves them. | 292 // Assumes that use lists are computed and preserves them. |
293 class ConstantPropagator : public FlowGraphVisitor { | 293 class ConstantPropagator : public FlowGraphVisitor { |
294 public: | 294 public: |
295 ConstantPropagator(FlowGraph* graph, | 295 ConstantPropagator(FlowGraph* graph, |
296 const GrowableArray<BlockEntryInstr*>& ignored); | 296 const GrowableArray<BlockEntryInstr*>& ignored); |
297 | 297 |
298 static void Optimize(FlowGraph* graph); | 298 static void Optimize(FlowGraph* graph); |
299 | 299 |
300 // Only visit branches to optimize away unreachable blocks discovered | 300 // (1) Visit branches to optimize away unreachable blocks discovered by range |
301 // by range analysis. | 301 // analysis. |
| 302 // (2) Eliminate branches that have the same true- and false-target: For |
| 303 // example, this occurs after expressions like |
| 304 // |
| 305 // if (a == null || b == null) { |
| 306 // ... |
| 307 // } |
| 308 // |
| 309 // where b is known to be null. |
302 static void OptimizeBranches(FlowGraph* graph); | 310 static void OptimizeBranches(FlowGraph* graph); |
303 | 311 |
304 // Used to initialize the abstract value of definitions. | 312 // Used to initialize the abstract value of definitions. |
305 static RawObject* Unknown() { return Object::unknown_constant().raw(); } | 313 static RawObject* Unknown() { return Object::unknown_constant().raw(); } |
306 | 314 |
307 private: | 315 private: |
308 void Analyze(); | 316 void Analyze(); |
309 void VisitBranches(); | 317 void VisitBranches(); |
310 void Transform(); | 318 void Transform(); |
| 319 void EliminateRedundantBranches(); |
311 | 320 |
312 void SetReachable(BlockEntryInstr* block); | 321 void SetReachable(BlockEntryInstr* block); |
313 void SetValue(Definition* definition, const Object& value); | 322 void SetValue(Definition* definition, const Object& value); |
314 | 323 |
315 // Assign the join (least upper bound) of a pair of abstract values to the | 324 // Assign the join (least upper bound) of a pair of abstract values to the |
316 // first one. | 325 // first one. |
317 void Join(Object* left, const Object& right); | 326 void Join(Object* left, const Object& right); |
318 | 327 |
319 bool IsUnknown(const Object& value) { | 328 bool IsUnknown(const Object& value) { |
320 return value.raw() == unknown_.raw(); | 329 return value.raw() == unknown_.raw(); |
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420 // Optimize spill stores inside try-blocks by identifying values that always | 429 // Optimize spill stores inside try-blocks by identifying values that always |
421 // contain a single known constant at catch block entry. | 430 // contain a single known constant at catch block entry. |
422 class TryCatchAnalyzer : public AllStatic { | 431 class TryCatchAnalyzer : public AllStatic { |
423 public: | 432 public: |
424 static void Optimize(FlowGraph* flow_graph); | 433 static void Optimize(FlowGraph* flow_graph); |
425 }; | 434 }; |
426 | 435 |
427 } // namespace dart | 436 } // namespace dart |
428 | 437 |
429 #endif // VM_FLOW_GRAPH_OPTIMIZER_H_ | 438 #endif // VM_FLOW_GRAPH_OPTIMIZER_H_ |
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