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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef jit_StupidAllocator_h
#define jit_StupidAllocator_h
#include "jit/RegisterAllocator.h"
// Simple register allocator that only carries registers within basic blocks.
namespace js {
namespace jit {
class StupidAllocator : public RegisterAllocator
{
static const uint32_t MAX_REGISTERS = AnyRegister::Total;
static const uint32_t MISSING_ALLOCATION = UINT32_MAX;
struct AllocatedRegister {
AnyRegister reg;
// The type of the value in the register.
LDefinition::Type type;
// Virtual register this physical reg backs, or MISSING_ALLOCATION.
uint32_t vreg;
// id of the instruction which most recently used this register.
uint32_t age;
// Whether the physical register is not synced with the backing stack slot.
bool dirty;
void set(uint32_t vreg, LInstruction* ins = nullptr, bool dirty = false) {
this->vreg = vreg;
this->age = ins ? ins->id() : 0;
this->dirty = dirty;
}
};
// Active allocation for the current code position.
mozilla::Array<AllocatedRegister, MAX_REGISTERS> registers;
uint32_t registerCount;
// Type indicating an index into registers.
typedef uint32_t RegisterIndex;
// Information about each virtual register.
Vector<LDefinition*, 0, SystemAllocPolicy> virtualRegisters;
public:
StupidAllocator(MIRGenerator* mir, LIRGenerator* lir, LIRGraph& graph)
: RegisterAllocator(mir, lir, graph)
{
}
[[nodiscard]] bool go();
private:
[[nodiscard]] bool init();
void syncForBlockEnd(LBlock* block, LInstruction* ins);
void allocateForInstruction(LInstruction* ins);
void allocateForDefinition(LInstruction* ins, LDefinition* def);
LAllocation* stackLocation(uint32_t vreg);
RegisterIndex registerIndex(AnyRegister reg);
AnyRegister ensureHasRegister(LInstruction* ins, uint32_t vreg);
RegisterIndex allocateRegister(LInstruction* ins, uint32_t vreg);
void syncRegister(LInstruction* ins, RegisterIndex index);
void evictRegister(LInstruction* ins, RegisterIndex index);
void evictAliasedRegister(LInstruction* ins, RegisterIndex index);
void loadRegister(LInstruction* ins, uint32_t vreg, RegisterIndex index, LDefinition::Type type);
RegisterIndex findExistingRegister(uint32_t vreg);
bool allocationRequiresRegister(const LAllocation* alloc, AnyRegister reg);
bool registerIsReserved(LInstruction* ins, AnyRegister reg);
};
} // namespace jit
} // namespace js
#endif /* jit_StupidAllocator_h */
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