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1 // Copyright 2014 the V8 project authors. All rights reserved. | 1 // Copyright 2014 the V8 project authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 #ifndef V8_AST_AST_NUMBERING_H_ | 5 #ifndef V8_AST_AST_NUMBERING_H_ |
6 #define V8_AST_AST_NUMBERING_H_ | 6 #define V8_AST_AST_NUMBERING_H_ |
7 | 7 |
8 namespace v8 { | 8 namespace v8 { |
9 namespace internal { | 9 namespace internal { |
10 | 10 |
11 // Forward declarations. | 11 // Forward declarations. |
12 class FunctionLiteral; | 12 class FunctionLiteral; |
13 class Isolate; | 13 class Isolate; |
14 class Zone; | 14 class Zone; |
15 | 15 |
16 namespace AstNumbering { | 16 namespace AstNumbering { |
17 // Assign type feedback IDs, bailout IDs, and generator yield IDs to an AST node | 17 // Assign type feedback IDs, bailout IDs, and generator yield IDs to an AST node |
18 // tree. | 18 // tree; perform catch prediction for TryStatements. |
19 bool Renumber(Isolate* isolate, Zone* zone, FunctionLiteral* function); | 19 bool Renumber(Isolate* isolate, Zone* zone, FunctionLiteral* function); |
20 } | 20 } |
21 | 21 |
22 // Some details on yield IDs | 22 // Some details on yield IDs |
23 // ------------------------- | 23 // ------------------------- |
24 // | 24 // |
25 // In order to assist Ignition in generating bytecode for a generator function, | 25 // In order to assist Ignition in generating bytecode for a generator function, |
26 // we assign a unique number (the yield ID) to each Yield node in its AST. We | 26 // we assign a unique number (the yield ID) to each Yield node in its AST. We |
27 // also annotate loops with the number of yields they contain (loop.yield_count) | 27 // also annotate loops with the number of yields they contain (loop.yield_count) |
28 // and the smallest ID of those (loop.first_yield_id), and we annotate the | 28 // and the smallest ID of those (loop.first_yield_id), and we annotate the |
29 // function itself with the number of yields it contains (function.yield_count). | 29 // function itself with the number of yields it contains (function.yield_count). |
30 // | 30 // |
31 // The way in which we choose the IDs is simply by enumerating the Yield nodes. | 31 // The way in which we choose the IDs is simply by enumerating the Yield nodes. |
32 // Ignition relies on the following properties: | 32 // Ignition relies on the following properties: |
33 // - For each loop l and each yield y of l: | 33 // - For each loop l and each yield y of l: |
34 // l.first_yield_id <= y.yield_id < l.first_yield_id + l.yield_count | 34 // l.first_yield_id <= y.yield_id < l.first_yield_id + l.yield_count |
35 // - For the generator function f itself and each yield y of f: | 35 // - For the generator function f itself and each yield y of f: |
36 // 0 <= y.yield_id < f.yield_count | 36 // 0 <= y.yield_id < f.yield_count |
37 | 37 |
38 } // namespace internal | 38 } // namespace internal |
39 } // namespace v8 | 39 } // namespace v8 |
40 | 40 |
41 #endif // V8_AST_AST_NUMBERING_H_ | 41 #endif // V8_AST_AST_NUMBERING_H_ |
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