Ben Murdoch | c561043 | 2016-08-08 18:44:38 +0100 | [diff] [blame] | 1 | // Copyright 2016 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_MEMORY_OPTIMIZER_H_ |
| 6 | #define V8_COMPILER_MEMORY_OPTIMIZER_H_ |
| 7 | |
| 8 | #include "src/zone-containers.h" |
| 9 | |
| 10 | namespace v8 { |
| 11 | namespace internal { |
| 12 | namespace compiler { |
| 13 | |
| 14 | // Forward declarations. |
| 15 | class CommonOperatorBuilder; |
| 16 | struct ElementAccess; |
| 17 | class Graph; |
| 18 | class JSGraph; |
| 19 | class MachineOperatorBuilder; |
| 20 | class Node; |
| 21 | class Operator; |
| 22 | |
| 23 | // NodeIds are identifying numbers for nodes that can be used to index auxiliary |
| 24 | // out-of-line data associated with each node. |
| 25 | typedef uint32_t NodeId; |
| 26 | |
| 27 | // Lowers all simplified memory access and allocation related nodes (i.e. |
| 28 | // Allocate, LoadField, StoreField and friends) to machine operators. |
| 29 | // Performs allocation folding and store write barrier elimination |
| 30 | // implicitly. |
| 31 | class MemoryOptimizer final { |
| 32 | public: |
| 33 | MemoryOptimizer(JSGraph* jsgraph, Zone* zone); |
| 34 | ~MemoryOptimizer() {} |
| 35 | |
| 36 | void Optimize(); |
| 37 | |
| 38 | private: |
| 39 | // An allocation group represents a set of allocations that have been folded |
| 40 | // together. |
| 41 | class AllocationGroup final : public ZoneObject { |
| 42 | public: |
| 43 | AllocationGroup(Node* node, PretenureFlag pretenure, Zone* zone); |
| 44 | AllocationGroup(Node* node, PretenureFlag pretenure, Node* size, |
| 45 | Zone* zone); |
| 46 | ~AllocationGroup() {} |
| 47 | |
| 48 | void Add(Node* object); |
| 49 | bool Contains(Node* object) const; |
| 50 | bool IsNewSpaceAllocation() const { return pretenure() == NOT_TENURED; } |
| 51 | |
| 52 | PretenureFlag pretenure() const { return pretenure_; } |
| 53 | Node* size() const { return size_; } |
| 54 | |
| 55 | private: |
| 56 | ZoneSet<NodeId> node_ids_; |
| 57 | PretenureFlag const pretenure_; |
| 58 | Node* const size_; |
| 59 | |
| 60 | DISALLOW_IMPLICIT_CONSTRUCTORS(AllocationGroup); |
| 61 | }; |
| 62 | |
| 63 | // An allocation state is propagated on the effect paths through the graph. |
| 64 | class AllocationState final : public ZoneObject { |
| 65 | public: |
| 66 | static AllocationState const* Empty(Zone* zone) { |
| 67 | return new (zone) AllocationState(); |
| 68 | } |
| 69 | static AllocationState const* Closed(AllocationGroup* group, Zone* zone) { |
| 70 | return new (zone) AllocationState(group); |
| 71 | } |
| 72 | static AllocationState const* Open(AllocationGroup* group, int size, |
| 73 | Node* top, Zone* zone) { |
| 74 | return new (zone) AllocationState(group, size, top); |
| 75 | } |
| 76 | |
| 77 | bool IsNewSpaceAllocation() const; |
| 78 | |
| 79 | AllocationGroup* group() const { return group_; } |
| 80 | Node* top() const { return top_; } |
| 81 | int size() const { return size_; } |
| 82 | |
| 83 | private: |
| 84 | AllocationState(); |
| 85 | explicit AllocationState(AllocationGroup* group); |
| 86 | AllocationState(AllocationGroup* group, int size, Node* top); |
| 87 | |
| 88 | AllocationGroup* const group_; |
| 89 | // The upper bound of the combined allocated object size on the current path |
| 90 | // (max int if allocation folding is impossible on this path). |
| 91 | int const size_; |
| 92 | Node* const top_; |
| 93 | |
| 94 | DISALLOW_COPY_AND_ASSIGN(AllocationState); |
| 95 | }; |
| 96 | |
| 97 | // An array of allocation states used to collect states on merges. |
| 98 | typedef ZoneVector<AllocationState const*> AllocationStates; |
| 99 | |
| 100 | // We thread through tokens to represent the current state on a given effect |
| 101 | // path through the graph. |
| 102 | struct Token { |
| 103 | Node* node; |
| 104 | AllocationState const* state; |
| 105 | }; |
| 106 | |
| 107 | void VisitNode(Node*, AllocationState const*); |
| 108 | void VisitAllocate(Node*, AllocationState const*); |
| 109 | void VisitCall(Node*, AllocationState const*); |
| 110 | void VisitLoadElement(Node*, AllocationState const*); |
| 111 | void VisitLoadField(Node*, AllocationState const*); |
| 112 | void VisitStoreElement(Node*, AllocationState const*); |
| 113 | void VisitStoreField(Node*, AllocationState const*); |
| 114 | void VisitOtherEffect(Node*, AllocationState const*); |
| 115 | |
| 116 | Node* ComputeIndex(ElementAccess const&, Node*); |
| 117 | WriteBarrierKind ComputeWriteBarrierKind(Node* object, |
| 118 | AllocationState const* state, |
| 119 | WriteBarrierKind); |
| 120 | |
| 121 | AllocationState const* MergeStates(AllocationStates const& states); |
| 122 | |
| 123 | void EnqueueMerge(Node*, int, AllocationState const*); |
| 124 | void EnqueueUses(Node*, AllocationState const*); |
| 125 | void EnqueueUse(Node*, int, AllocationState const*); |
| 126 | |
| 127 | AllocationState const* empty_state() const { return empty_state_; } |
| 128 | Graph* graph() const; |
| 129 | Isolate* isolate() const; |
| 130 | JSGraph* jsgraph() const { return jsgraph_; } |
| 131 | CommonOperatorBuilder* common() const; |
| 132 | MachineOperatorBuilder* machine() const; |
| 133 | Zone* zone() const { return zone_; } |
| 134 | |
| 135 | SetOncePointer<const Operator> allocate_operator_; |
| 136 | JSGraph* const jsgraph_; |
| 137 | AllocationState const* const empty_state_; |
| 138 | ZoneMap<NodeId, AllocationStates> pending_; |
| 139 | ZoneQueue<Token> tokens_; |
| 140 | Zone* const zone_; |
| 141 | |
| 142 | DISALLOW_IMPLICIT_CONSTRUCTORS(MemoryOptimizer); |
| 143 | }; |
| 144 | |
| 145 | } // namespace compiler |
| 146 | } // namespace internal |
| 147 | } // namespace v8 |
| 148 | |
| 149 | #endif // V8_COMPILER_MEMORY_OPTIMIZER_H_ |