Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 1 | // Copyright 2015 the V8 project authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style license that can be |
| 3 | // found in the LICENSE file. |
| 4 | |
| 5 | #ifndef V8_COMPILER_BRANCH_CONDITION_ELIMINATION_H_ |
| 6 | #define V8_COMPILER_BRANCH_CONDITION_ELIMINATION_H_ |
| 7 | |
| 8 | #include "src/compiler/graph-reducer.h" |
| 9 | |
| 10 | namespace v8 { |
| 11 | namespace internal { |
| 12 | namespace compiler { |
| 13 | |
Ben Murdoch | da12d29 | 2016-06-02 14:46:10 +0100 | [diff] [blame] | 14 | // Forward declarations. |
| 15 | class CommonOperatorBuilder; |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 16 | class JSGraph; |
| 17 | |
| 18 | |
| 19 | class BranchElimination final : public AdvancedReducer { |
| 20 | public: |
| 21 | BranchElimination(Editor* editor, JSGraph* js_graph, Zone* zone); |
| 22 | ~BranchElimination() final; |
| 23 | |
| 24 | Reduction Reduce(Node* node) final; |
| 25 | |
| 26 | private: |
| 27 | struct BranchCondition { |
| 28 | Node* condition; |
| 29 | bool is_true; |
| 30 | BranchCondition* next; |
| 31 | |
| 32 | BranchCondition(Node* condition, bool is_true, BranchCondition* next) |
| 33 | : condition(condition), is_true(is_true), next(next) {} |
| 34 | }; |
| 35 | |
| 36 | // Class for tracking information about branch conditions. |
| 37 | // At the moment it is a linked list of conditions and their values |
| 38 | // (true or false). |
| 39 | class ControlPathConditions { |
| 40 | public: |
| 41 | Maybe<bool> LookupCondition(Node* condition) const; |
| 42 | |
| 43 | const ControlPathConditions* AddCondition(Zone* zone, Node* condition, |
| 44 | bool is_true) const; |
| 45 | static const ControlPathConditions* Empty(Zone* zone); |
| 46 | void Merge(const ControlPathConditions& other); |
| 47 | |
| 48 | bool operator==(const ControlPathConditions& other) const; |
| 49 | bool operator!=(const ControlPathConditions& other) const { |
| 50 | return !(*this == other); |
| 51 | } |
| 52 | |
| 53 | private: |
| 54 | ControlPathConditions(BranchCondition* head, size_t condition_count) |
| 55 | : head_(head), condition_count_(condition_count) {} |
| 56 | |
| 57 | BranchCondition* head_; |
| 58 | // We keep track of the list length so that we can find the longest |
| 59 | // common tail easily. |
| 60 | size_t condition_count_; |
| 61 | }; |
| 62 | |
| 63 | // Maps each control node to the condition information known about the node. |
| 64 | // If the information is nullptr, then we have not calculated the information |
| 65 | // yet. |
| 66 | class PathConditionsForControlNodes { |
| 67 | public: |
| 68 | PathConditionsForControlNodes(Zone* zone, size_t size_hint) |
| 69 | : info_for_node_(size_hint, nullptr, zone) {} |
| 70 | const ControlPathConditions* Get(Node* node); |
| 71 | void Set(Node* node, const ControlPathConditions* conditions); |
| 72 | |
| 73 | private: |
| 74 | ZoneVector<const ControlPathConditions*> info_for_node_; |
| 75 | }; |
| 76 | |
| 77 | Reduction ReduceBranch(Node* node); |
Ben Murdoch | da12d29 | 2016-06-02 14:46:10 +0100 | [diff] [blame] | 78 | Reduction ReduceDeoptimizeConditional(Node* node); |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 79 | Reduction ReduceIf(Node* node, bool is_true_branch); |
| 80 | Reduction ReduceLoop(Node* node); |
| 81 | Reduction ReduceMerge(Node* node); |
| 82 | Reduction ReduceStart(Node* node); |
| 83 | Reduction ReduceOtherControl(Node* node); |
| 84 | |
| 85 | Reduction TakeConditionsFromFirstControl(Node* node); |
| 86 | Reduction UpdateConditions(Node* node, |
| 87 | const ControlPathConditions* conditions); |
| 88 | |
| 89 | Node* dead() const { return dead_; } |
Ben Murdoch | da12d29 | 2016-06-02 14:46:10 +0100 | [diff] [blame] | 90 | Graph* graph() const; |
| 91 | JSGraph* jsgraph() const { return jsgraph_; } |
| 92 | CommonOperatorBuilder* common() const; |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 93 | |
Ben Murdoch | da12d29 | 2016-06-02 14:46:10 +0100 | [diff] [blame] | 94 | JSGraph* const jsgraph_; |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 95 | PathConditionsForControlNodes node_conditions_; |
| 96 | Zone* zone_; |
| 97 | Node* dead_; |
| 98 | }; |
| 99 | |
| 100 | } // namespace compiler |
| 101 | } // namespace internal |
| 102 | } // namespace v8 |
| 103 | |
| 104 | #endif // V8_COMPILER_BRANCH_CONDITION_ELIMINATION_H_ |