v8/include/cppgc/internal/write-barrier.h
Michael Lippautz 17ed49b560 heap, cppgc: Add write barrier for TracedReference
Adds publicly callable version of write barrier for TracedReferenceBase.

Bug: chromium:1056170
Change-Id: Ie45b4ebbe91d9f0e8f76b521dcbfd931232adcf6
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2565248
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#71524}
2020-12-01 12:15:01 +00:00

251 lines
8.9 KiB
C++

// Copyright 2020 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 INCLUDE_CPPGC_INTERNAL_WRITE_BARRIER_H_
#define INCLUDE_CPPGC_INTERNAL_WRITE_BARRIER_H_
#include "cppgc/internal/api-constants.h"
#include "cppgc/internal/process-heap.h"
#include "cppgc/trace-trait.h"
#include "v8config.h" // NOLINT(build/include_directory)
#if defined(CPPGC_CAGED_HEAP)
#include "cppgc/internal/caged-heap-local-data.h"
#endif
namespace cppgc {
class HeapHandle;
namespace internal {
class WriteBarrierTypeForCagedHeapPolicy;
class WriteBarrierTypeForNonCagedHeapPolicy;
class V8_EXPORT WriteBarrier final {
public:
enum class Type : uint8_t {
kNone,
kMarking,
kGenerational,
};
struct Params {
#if V8_ENABLE_CHECKS
Type type = Type::kNone;
#endif // !V8_ENABLE_CHECKS
#if defined(CPPGC_CAGED_HEAP)
uintptr_t start;
CagedHeapLocalData& caged_heap() const {
return *reinterpret_cast<CagedHeapLocalData*>(start);
}
uintptr_t slot_offset;
uintptr_t value_offset;
#endif // CPPGC_CAGED_HEAP
};
enum class ValueMode {
kValuePresent,
kNoValuePresent,
};
// Returns the required write barrier for a given `slot` and `value`.
static V8_INLINE Type GetWriteBarrierType(const void* slot, const void* value,
Params& params);
// Returns the required write barrier for a given `slot`.
static V8_INLINE Type GetWriteBarrierType(const void* slot, Params& params);
static V8_INLINE void DijkstraMarkingBarrier(const Params& params,
const void* object);
static V8_INLINE void DijkstraMarkingBarrierRange(
const Params& params, HeapHandle& heap, const void* first_element,
size_t element_size, size_t number_of_elements,
TraceCallback trace_callback);
static V8_INLINE void SteeleMarkingBarrier(const Params& params,
const void* object);
#if defined(CPPGC_YOUNG_GENERATION)
static V8_INLINE void GenerationalBarrier(const Params& params,
const void* slot);
#else // !CPPGC_YOUNG_GENERATION
static V8_INLINE void GenerationalBarrier(const Params& params,
const void* slot) {}
#endif // CPPGC_YOUNG_GENERATION
#if V8_ENABLE_CHECKS
static void CheckParams(Type expected_type, const Params& params);
#else // !V8_ENABLE_CHECKS
static void CheckParams(Type expected_type, const Params& params) {}
#endif // !V8_ENABLE_CHECKS
private:
WriteBarrier() = delete;
#if defined(CPPGC_CAGED_HEAP)
using WriteBarrierTypePolicy = WriteBarrierTypeForCagedHeapPolicy;
#else // !CPPGC_CAGED_HEAP
using WriteBarrierTypePolicy = WriteBarrierTypeForNonCagedHeapPolicy;
#endif // !CPPGC_CAGED_HEAP
static void DijkstraMarkingBarrierSlow(const void* value);
static void DijkstraMarkingBarrierSlowWithSentinelCheck(const void* value);
static void DijkstraMarkingBarrierRangeSlow(HeapHandle& heap_handle,
const void* first_element,
size_t element_size,
size_t number_of_elements,
TraceCallback trace_callback);
static void SteeleMarkingBarrierSlow(const void* value);
static void SteeleMarkingBarrierSlowWithSentinelCheck(const void* value);
#if defined(CPPGC_YOUNG_GENERATION)
static void GenerationalBarrierSlow(const CagedHeapLocalData& local_data,
const AgeTable& ageTable,
const void* slot, uintptr_t value_offset);
#endif // CPPGC_YOUNG_GENERATION
};
#if defined(CPPGC_CAGED_HEAP)
class WriteBarrierTypeForCagedHeapPolicy final {
public:
template <WriteBarrier::ValueMode value_mode>
static V8_INLINE WriteBarrier::Type Get(const void* slot, const void* value,
WriteBarrier::Params& params) {
const bool have_caged_heap =
value_mode == WriteBarrier::ValueMode::kValuePresent
? TryGetCagedHeap(slot, value, params)
: TryGetCagedHeap(slot, slot, params);
if (!have_caged_heap) {
return WriteBarrier::Type::kNone;
}
if (V8_UNLIKELY(params.caged_heap().is_marking_in_progress)) {
#if V8_ENABLE_CHECKS
params.type = WriteBarrier::Type::kMarking;
#endif // !V8_ENABLE_CHECKS
return WriteBarrier::Type::kMarking;
}
#if defined(CPPGC_YOUNG_GENERATION)
params.slot_offset = reinterpret_cast<uintptr_t>(slot) - params.start;
if (value_mode == WriteBarrier::ValueMode::kValuePresent) {
params.value_offset = reinterpret_cast<uintptr_t>(value) - params.start;
} else {
params.value_offset = 0;
}
#if V8_ENABLE_CHECKS
params.type = WriteBarrier::Type::kGenerational;
#endif // !V8_ENABLE_CHECKS
return WriteBarrier::Type::kGenerational;
#else // !CPPGC_YOUNG_GENERATION
return WriteBarrier::Type::kNone;
#endif // !CPPGC_YOUNG_GENERATION
}
private:
WriteBarrierTypeForCagedHeapPolicy() = delete;
static V8_INLINE bool TryGetCagedHeap(const void* slot, const void* value,
WriteBarrier::Params& params) {
params.start = reinterpret_cast<uintptr_t>(value) &
~(api_constants::kCagedHeapReservationAlignment - 1);
const uintptr_t slot_offset =
reinterpret_cast<uintptr_t>(slot) - params.start;
if (slot_offset > api_constants::kCagedHeapReservationSize) {
// Check if slot is on stack or value is sentinel or nullptr. This relies
// on the fact that kSentinelPointer is encoded as 0x1.
return false;
}
return true;
}
};
#endif // CPPGC_CAGED_HEAP
class WriteBarrierTypeForNonCagedHeapPolicy final {
public:
template <WriteBarrier::ValueMode value_mode>
static V8_INLINE WriteBarrier::Type Get(const void* slot, const void* value,
WriteBarrier::Params& params) {
WriteBarrier::Type type =
V8_LIKELY(!ProcessHeap::IsAnyIncrementalOrConcurrentMarking())
? WriteBarrier::Type::kNone
: WriteBarrier::Type::kMarking;
#if V8_ENABLE_CHECKS
params.type = type;
#endif // !V8_ENABLE_CHECKS
return type;
}
private:
WriteBarrierTypeForNonCagedHeapPolicy() = delete;
};
// static
WriteBarrier::Type WriteBarrier::GetWriteBarrierType(
const void* slot, const void* value, WriteBarrier::Params& params) {
return WriteBarrierTypePolicy::Get<ValueMode::kValuePresent>(slot, value,
params);
}
// static
WriteBarrier::Type WriteBarrier::GetWriteBarrierType(
const void* slot, WriteBarrier::Params& params) {
return WriteBarrierTypePolicy::Get<ValueMode::kNoValuePresent>(slot, nullptr,
params);
}
// static
void WriteBarrier::DijkstraMarkingBarrier(const Params& params,
const void* object) {
CheckParams(Type::kMarking, params);
#if defined(CPPGC_CAGED_HEAP)
// Caged heap already filters out sentinels.
DijkstraMarkingBarrierSlow(object);
#else // !CPPGC_CAGED_HEAP
DijkstraMarkingBarrierSlowWithSentinelCheck(object);
#endif // !CPPGC_CAGED_HEAP
}
// static
void WriteBarrier::DijkstraMarkingBarrierRange(const Params& params,
HeapHandle& heap,
const void* first_element,
size_t element_size,
size_t number_of_elements,
TraceCallback trace_callback) {
CheckParams(Type::kMarking, params);
DijkstraMarkingBarrierRangeSlow(heap, first_element, element_size,
number_of_elements, trace_callback);
}
// static
void WriteBarrier::SteeleMarkingBarrier(const Params& params,
const void* object) {
CheckParams(Type::kMarking, params);
#if defined(CPPGC_CAGED_HEAP)
// Caged heap already filters out sentinels.
SteeleMarkingBarrierSlow(object);
#else // !CPPGC_CAGED_HEAP
SteeleMarkingBarrierSlowWithSentinelCheck(object);
#endif // !CPPGC_CAGED_HEAP
}
#if defined(CPPGC_YOUNG_GENERATION)
// static
void WriteBarrier::GenerationalBarrier(const Params& params, const void* slot) {
CheckParams(Type::kGenerational, params);
const CagedHeapLocalData& local_data = params.caged_heap();
const AgeTable& age_table = local_data.age_table;
// Bail out if the slot is in young generation.
if (V8_LIKELY(age_table[params.slot_offset] == AgeTable::Age::kYoung)) return;
GenerationalBarrierSlow(local_data, age_table, slot, params.value_offset);
}
#endif // !CPPGC_YOUNG_GENERATION
} // namespace internal
} // namespace cppgc
#endif // INCLUDE_CPPGC_INTERNAL_WRITE_BARRIER_H_