// Copyright 2015 the V8 project authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef V8_INTERPRETER_BYTECODE_REGISTER_ALLOCATOR_H_
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#define V8_INTERPRETER_BYTECODE_REGISTER_ALLOCATOR_H_
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#include "src/interpreter/bytecode-register.h"
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#include "src/interpreter/bytecodes.h"
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#include "src/zone/zone-containers.h"
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namespace v8 {
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namespace internal {
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namespace interpreter {
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// A class that allows the allocation of contiguous temporary registers.
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class BytecodeRegisterAllocator final {
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public:
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// Enables observation of register allocation and free events.
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class Observer {
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public:
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virtual ~Observer() {}
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virtual void RegisterAllocateEvent(Register reg) = 0;
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virtual void RegisterListAllocateEvent(RegisterList reg_list) = 0;
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virtual void RegisterListFreeEvent(RegisterList reg_list) = 0;
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};
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explicit BytecodeRegisterAllocator(int start_index)
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: next_register_index_(start_index),
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max_register_count_(start_index),
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observer_(nullptr) {}
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~BytecodeRegisterAllocator() {}
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// Returns a new register.
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Register NewRegister() {
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Register reg(next_register_index_++);
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max_register_count_ = std::max(next_register_index_, max_register_count_);
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if (observer_) {
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observer_->RegisterAllocateEvent(reg);
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}
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return reg;
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}
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// Returns a consecutive list of |count| new registers.
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RegisterList NewRegisterList(int count) {
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RegisterList reg_list(next_register_index_, count);
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next_register_index_ += count;
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max_register_count_ = std::max(next_register_index_, max_register_count_);
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if (observer_) {
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observer_->RegisterListAllocateEvent(reg_list);
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}
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return reg_list;
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}
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// Returns a growable register list.
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RegisterList NewGrowableRegisterList() {
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RegisterList reg_list(next_register_index_, 0);
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return reg_list;
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}
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// Appends a new register to |reg_list| increasing it's count by one and
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// returning the register added.
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//
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// Note: no other new registers must be currently allocated since the register
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// list was originally allocated.
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Register GrowRegisterList(RegisterList* reg_list) {
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Register reg(NewRegister());
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reg_list->IncrementRegisterCount();
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// If the following CHECK fails then a register was allocated (and not
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// freed) between the creation of the RegisterList and this call to add a
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// Register.
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CHECK_EQ(reg.index(), reg_list->last_register().index());
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return reg;
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}
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// Release all registers above |register_index|.
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void ReleaseRegisters(int register_index) {
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int count = next_register_index_ - register_index;
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next_register_index_ = register_index;
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if (observer_) {
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observer_->RegisterListFreeEvent(RegisterList(register_index, count));
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}
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}
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// Returns true if the register |reg| is a live register.
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bool RegisterIsLive(Register reg) const {
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return reg.index() < next_register_index_;
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}
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// Returns a register list for all currently live registers.
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RegisterList AllLiveRegisters() const {
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return RegisterList(0, next_register_index());
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}
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void set_observer(Observer* observer) { observer_ = observer; }
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int next_register_index() const { return next_register_index_; }
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int maximum_register_count() const { return max_register_count_; }
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private:
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int next_register_index_;
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int max_register_count_;
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Observer* observer_;
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DISALLOW_COPY_AND_ASSIGN(BytecodeRegisterAllocator);
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};
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} // namespace interpreter
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} // namespace internal
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} // namespace v8
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#endif // V8_INTERPRETER_BYTECODE_REGISTER_ALLOCATOR_H_
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