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// Copyright 2016 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef V8_COMPILER_MEMORY_OPTIMIZER_H_
#define V8_COMPILER_MEMORY_OPTIMIZER_H_
#include "src/compiler/graph-assembler.h"
#include "src/zone/zone-containers.h"
namespace v8 {
namespace internal {
class TickCounter;
namespace compiler {
// Forward declarations.
class CommonOperatorBuilder;
struct ElementAccess;
class Graph;
class JSGraph;
class MachineOperatorBuilder;
class Node;
class Operator;
// NodeIds are identifying numbers for nodes that can be used to index auxiliary
// out-of-line data associated with each node.
using NodeId = uint32_t;
// Lowers all simplified memory access and allocation related nodes (i.e.
// Allocate, LoadField, StoreField and friends) to machine operators.
// Performs allocation folding and store write barrier elimination
// implicitly.
class MemoryOptimizer final {
public:
enum class AllocationFolding { kDoAllocationFolding, kDontAllocationFolding };
MemoryOptimizer(JSGraph* jsgraph, Zone* zone,
PoisoningMitigationLevel poisoning_level,
AllocationFolding allocation_folding,
const char* function_debug_name, TickCounter* tick_counter);
~MemoryOptimizer() = default;
void Optimize();
private:
// An allocation group represents a set of allocations that have been folded
// together.
class AllocationGroup final : public ZoneObject {
public:
AllocationGroup(Node* node, AllocationType allocation, Zone* zone);
AllocationGroup(Node* node, AllocationType allocation, Node* size,
Zone* zone);
~AllocationGroup() = default;
void Add(Node* object);
bool Contains(Node* object) const;
bool IsYoungGenerationAllocation() const {
return allocation() == AllocationType::kYoung;
}
AllocationType allocation() const { return allocation_; }
Node* size() const { return size_; }
private:
ZoneSet<NodeId> node_ids_;
AllocationType const allocation_;
Node* const size_;
DISALLOW_IMPLICIT_CONSTRUCTORS(AllocationGroup);
};
// An allocation state is propagated on the effect paths through the graph.
class AllocationState final : public ZoneObject {
public:
static AllocationState const* Empty(Zone* zone) {
return new (zone) AllocationState();
}
static AllocationState const* Closed(AllocationGroup* group, Zone* zone) {
return new (zone) AllocationState(group);
}
static AllocationState const* Open(AllocationGroup* group, intptr_t size,
Node* top, Zone* zone) {
return new (zone) AllocationState(group, size, top);
}
bool IsYoungGenerationAllocation() const;
AllocationGroup* group() const { return group_; }
Node* top() const { return top_; }
intptr_t size() const { return size_; }
private:
AllocationState();
explicit AllocationState(AllocationGroup* group);
AllocationState(AllocationGroup* group, intptr_t size, Node* top);
AllocationGroup* const group_;
// The upper bound of the combined allocated object size on the current path
// (max int if allocation folding is impossible on this path).
intptr_t const size_;
Node* const top_;
DISALLOW_COPY_AND_ASSIGN(AllocationState);
};
// An array of allocation states used to collect states on merges.
using AllocationStates = ZoneVector<AllocationState const*>;
// We thread through tokens to represent the current state on a given effect
// path through the graph.
struct Token {
Node* node;
AllocationState const* state;
};
void VisitNode(Node*, AllocationState const*);
void VisitAllocateRaw(Node*, AllocationState const*);
void VisitCall(Node*, AllocationState const*);
void VisitLoadFromObject(Node*, AllocationState const*);
void VisitLoadElement(Node*, AllocationState const*);
void VisitLoadField(Node*, AllocationState const*);
void VisitStoreToObject(Node*, AllocationState const*);
void VisitStoreElement(Node*, AllocationState const*);
void VisitStoreField(Node*, AllocationState const*);
void VisitStore(Node*, AllocationState const*);
void VisitOtherEffect(Node*, AllocationState const*);
Node* ComputeIndex(ElementAccess const&, Node*);
WriteBarrierKind ComputeWriteBarrierKind(Node* node, Node* object,
Node* value,
AllocationState const* state,
WriteBarrierKind);
AllocationState const* MergeStates(AllocationStates const& states);
void EnqueueMerge(Node*, int, AllocationState const*);
void EnqueueUses(Node*, AllocationState const*);
void EnqueueUse(Node*, int, AllocationState const*);
bool NeedsPoisoning(LoadSensitivity load_sensitivity) const;
// Returns true if the AllocationType of the current AllocateRaw node that we
// are visiting needs to be updated to kOld, due to propagation of tenuring
// from outer to inner allocations.
bool AllocationTypeNeedsUpdateToOld(Node* const user, const Edge edge);
AllocationState const* empty_state() const { return empty_state_; }
Graph* graph() const;
Isolate* isolate() const;
JSGraph* jsgraph() const { return jsgraph_; }
CommonOperatorBuilder* common() const;
MachineOperatorBuilder* machine() const;
Zone* zone() const { return zone_; }
GraphAssembler* gasm() { return &graph_assembler_; }
SetOncePointer<const Operator> allocate_operator_;
JSGraph* const jsgraph_;
AllocationState const* const empty_state_;
ZoneMap<NodeId, AllocationStates> pending_;
ZoneQueue<Token> tokens_;
Zone* const zone_;
GraphAssembler graph_assembler_;
PoisoningMitigationLevel poisoning_level_;
AllocationFolding allocation_folding_;
const char* function_debug_name_;
TickCounter* const tick_counter_;
DISALLOW_IMPLICIT_CONSTRUCTORS(MemoryOptimizer);
};
} // namespace compiler
} // namespace internal
} // namespace v8
#endif // V8_COMPILER_MEMORY_OPTIMIZER_H_