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1 // Copyright (c) 2014, the Dart project authors. Please see the AUTHORS file | 1 // Copyright (c) 2014, 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 library dart2js.cps_ir.redundant_phi_elimination; | 5 library dart2js.cps_ir.redundant_phi_elimination; |
6 | 6 |
7 import 'cps_ir_nodes.dart'; | 7 import 'cps_ir_nodes.dart'; |
8 import 'optimizers.dart'; | 8 import 'optimizers.dart'; |
9 | 9 |
10 /// Eliminate redundant phis from the given [FunctionDefinition]. | 10 /// Eliminate redundant phis from the given [FunctionDefinition]. |
11 /// | 11 /// |
12 /// Phis in this case are [Continuations] together with corresponding | 12 /// Phis in this case are [Continuations] together with corresponding |
13 /// [InvokeContinuation]s. A [Continuation] parameter at position i is redundant | 13 /// [InvokeContinuation]s. A [Continuation] parameter at position i is redundant |
14 /// if for all [InvokeContinuation]s, the parameter at position i is identical | 14 /// if for all [InvokeContinuation]s, the parameter at position i is identical |
15 /// (except for feedback). Redundant parameters are removed from the | 15 /// (except for feedback). Redundant parameters are removed from the |
16 /// continuation signature, all invocations, and replaced within the | 16 /// continuation signature, all invocations, and replaced within the |
17 /// continuation body. | 17 /// continuation body. |
18 class RedundantPhiEliminator extends TrampolineRecursiveVisitor implements Pass
{ | 18 class RedundantPhiEliminator extends TrampolineRecursiveVisitor |
| 19 implements Pass { |
19 String get passName => 'Redundant phi elimination'; | 20 String get passName => 'Redundant phi elimination'; |
20 | 21 |
21 final Set<Continuation> workSet = new Set<Continuation>(); | 22 final Set<Continuation> workSet = new Set<Continuation>(); |
22 | 23 |
23 @override | 24 @override |
24 void rewrite(FunctionDefinition root) { | 25 void rewrite(FunctionDefinition root) { |
25 // Traverse the tree once to build the work set. | 26 // Traverse the tree once to build the work set. |
26 visit(root); | 27 visit(root); |
27 | 28 |
28 // Process each continuation one-by-one. | 29 // Process each continuation one-by-one. |
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115 } | 116 } |
116 dst++; | 117 dst++; |
117 continue; | 118 continue; |
118 } | 119 } |
119 | 120 |
120 Primitive oldDefinition = cont.parameters[src]; | 121 Primitive oldDefinition = cont.parameters[src]; |
121 | 122 |
122 // Add continuations of about-to-be modified invokes to worklist since | 123 // Add continuations of about-to-be modified invokes to worklist since |
123 // we might introduce new optimization opportunities. | 124 // we might introduce new optimization opportunities. |
124 for (Reference ref = oldDefinition.firstRef; | 125 for (Reference ref = oldDefinition.firstRef; |
125 ref != null; | 126 ref != null; |
126 ref = ref.next) { | 127 ref = ref.next) { |
127 Node parent = ref.parent; | 128 Node parent = ref.parent; |
128 if (parent is InvokeContinuation) { | 129 if (parent is InvokeContinuation) { |
129 Continuation thatCont = parent.continuation; | 130 Continuation thatCont = parent.continuation; |
130 if (thatCont != cont) { | 131 if (thatCont != cont) { |
131 workSet.add(thatCont); | 132 workSet.add(thatCont); |
132 } | 133 } |
133 } | 134 } |
134 } | 135 } |
135 | 136 |
136 // Replace individual parameters: | 137 // Replace individual parameters: |
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195 /// Returns the LetCont that now binds [continuation]. | 196 /// Returns the LetCont that now binds [continuation]. |
196 LetCont _makeUniqueBinding(Continuation continuation) { | 197 LetCont _makeUniqueBinding(Continuation continuation) { |
197 LetCont letCont = continuation.parent; | 198 LetCont letCont = continuation.parent; |
198 if (letCont.continuations.length == 1) return letCont; | 199 if (letCont.continuations.length == 1) return letCont; |
199 letCont.continuations.remove(continuation); | 200 letCont.continuations.remove(continuation); |
200 LetCont newBinding = new LetCont(continuation, null); | 201 LetCont newBinding = new LetCont(continuation, null); |
201 continuation.parent = newBinding; | 202 continuation.parent = newBinding; |
202 newBinding.insertBelow(letCont); | 203 newBinding.insertBelow(letCont); |
203 return newBinding; | 204 return newBinding; |
204 } | 205 } |
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