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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.
#include "src/base/macros.h"
#include "src/base/platform/mutex.h"
#include "src/base/platform/time.h"
#include "src/builtins/builtins-utils-inl.h"
#include "src/builtins/builtins.h"
#include "src/codegen/code-factory.h"
#include "src/common/globals.h"
#include "src/execution/futex-emulation.h"
#include "src/heap/factory.h"
#include "src/logging/counters.h"
#include "src/numbers/conversions-inl.h"
#include "src/objects/js-array-buffer-inl.h"
#include "src/objects/objects-inl.h"
namespace v8 {
namespace internal {
// See builtins-arraybuffer.cc for implementations of
// SharedArrayBuffer.prototye.byteLength and SharedArrayBuffer.prototype.slice
// #sec-atomics.islockfree
inline bool AtomicIsLockFree(double size) {
// According to the standard, 1, 2, and 4 byte atomics are supposed to be
// 'lock free' on every platform. But what exactly does 'lock free' mean?
// For example, on x64 V8 uses a lock prefix to implement the semantics of
// many atomic operations. Is that considered a lock? Probably not.
//
// On the other hand, V8 emits a few instructions for some arm atomics which
// do appear to be a low level form of a spin lock. With an abundance of
// caution, we only claim to have 'true lock free' support for 8 byte sizes
// on x64 platforms. If people care about this function returning true, then
// we need to clarify exactly what 'lock free' means at the standard level.
bool is_lock_free = size == 1 || size == 2 || size == 4;
#if V8_TARGET_ARCH_x64
is_lock_free |= size == 8;
#endif
return is_lock_free;
}
// ES #sec-atomics.islockfree
BUILTIN(AtomicsIsLockFree) {
HandleScope scope(isolate);
Handle<Object> size = args.atOrUndefined(isolate, 1);
ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, size,
Object::ToNumber(isolate, size));
return *isolate->factory()->ToBoolean(AtomicIsLockFree(size->Number()));
}
// ES #sec-validatesharedintegertypedarray
V8_WARN_UNUSED_RESULT MaybeHandle<JSTypedArray> ValidateSharedIntegerTypedArray(
Isolate* isolate, Handle<Object> object,
bool only_int32_and_big_int64 = false) {
if (object->IsJSTypedArray()) {
Handle<JSTypedArray> typed_array = Handle<JSTypedArray>::cast(object);
if (typed_array->GetBuffer()->is_shared()) {
if (only_int32_and_big_int64) {
if (typed_array->type() == kExternalInt32Array ||
typed_array->type() == kExternalBigInt64Array) {
return typed_array;
}
} else {
if (typed_array->type() != kExternalFloat32Array &&
typed_array->type() != kExternalFloat64Array &&
typed_array->type() != kExternalUint8ClampedArray)
return typed_array;
}
}
}
THROW_NEW_ERROR(
isolate,
NewTypeError(only_int32_and_big_int64
? MessageTemplate::kNotInt32OrBigInt64SharedTypedArray
: MessageTemplate::kNotIntegerSharedTypedArray,
object),
JSTypedArray);
}
// ES #sec-validateatomicaccess
// ValidateAtomicAccess( typedArray, requestIndex )
V8_WARN_UNUSED_RESULT Maybe<size_t> ValidateAtomicAccess(
Isolate* isolate, Handle<JSTypedArray> typed_array,
Handle<Object> request_index) {
Handle<Object> access_index_obj;
ASSIGN_RETURN_ON_EXCEPTION_VALUE(
isolate, access_index_obj,
Object::ToIndex(isolate, request_index,
MessageTemplate::kInvalidAtomicAccessIndex),
Nothing<size_t>());
size_t access_index;
if (!TryNumberToSize(*access_index_obj, &access_index) ||
typed_array->WasDetached() || access_index >= typed_array->length()) {
isolate->Throw(*isolate->factory()->NewRangeError(
MessageTemplate::kInvalidAtomicAccessIndex));
return Nothing<size_t>();
}
return Just<size_t>(access_index);
}
namespace {
inline size_t GetAddress64(size_t index, size_t byte_offset) {
return (index << 3) + byte_offset;
}
inline size_t GetAddress32(size_t index, size_t byte_offset) {
return (index << 2) + byte_offset;
}
MaybeHandle<Object> AtomicsWake(Isolate* isolate, Handle<Object> array,
Handle<Object> index, Handle<Object> count) {
Handle<JSTypedArray> sta;
ASSIGN_RETURN_ON_EXCEPTION(
isolate, sta, ValidateSharedIntegerTypedArray(isolate, array, true),
Object);
Maybe<size_t> maybe_index = ValidateAtomicAccess(isolate, sta, index);
MAYBE_RETURN_NULL(maybe_index);
size_t i = maybe_index.FromJust();
uint32_t c;
if (count->IsUndefined(isolate)) {
c = kMaxUInt32;
} else {
ASSIGN_RETURN_ON_EXCEPTION(isolate, count,
Object::ToInteger(isolate, count), Object);
double count_double = count->Number();
if (count_double < 0)
count_double = 0;
else if (count_double > kMaxUInt32)
count_double = kMaxUInt32;
c = static_cast<uint32_t>(count_double);
}
Handle<JSArrayBuffer> array_buffer = sta->GetBuffer();
if (sta->type() == kExternalBigInt64Array) {
return Handle<Object>(
FutexEmulation::Wake(array_buffer, GetAddress64(i, sta->byte_offset()),
c),
isolate);
} else {
DCHECK(sta->type() == kExternalInt32Array);
return Handle<Object>(
FutexEmulation::Wake(array_buffer, GetAddress32(i, sta->byte_offset()),
c),
isolate);
}
}
} // namespace
// ES #sec-atomics.wake
// Atomics.wake( typedArray, index, count )
BUILTIN(AtomicsWake) {
HandleScope scope(isolate);
Handle<Object> array = args.atOrUndefined(isolate, 1);
Handle<Object> index = args.atOrUndefined(isolate, 2);
Handle<Object> count = args.atOrUndefined(isolate, 3);
isolate->CountUsage(v8::Isolate::UseCounterFeature::kAtomicsWake);
RETURN_RESULT_OR_FAILURE(isolate, AtomicsWake(isolate, array, index, count));
}
// ES #sec-atomics.notify
// Atomics.notify( typedArray, index, count )
BUILTIN(AtomicsNotify) {
HandleScope scope(isolate);
Handle<Object> array = args.atOrUndefined(isolate, 1);
Handle<Object> index = args.atOrUndefined(isolate, 2);
Handle<Object> count = args.atOrUndefined(isolate, 3);
isolate->CountUsage(v8::Isolate::UseCounterFeature::kAtomicsNotify);
RETURN_RESULT_OR_FAILURE(isolate, AtomicsWake(isolate, array, index, count));
}
// ES #sec-atomics.wait
// Atomics.wait( typedArray, index, value, timeout )
BUILTIN(AtomicsWait) {
HandleScope scope(isolate);
Handle<Object> array = args.atOrUndefined(isolate, 1);
Handle<Object> index = args.atOrUndefined(isolate, 2);
Handle<Object> value = args.atOrUndefined(isolate, 3);
Handle<Object> timeout = args.atOrUndefined(isolate, 4);
Handle<JSTypedArray> sta;
ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
isolate, sta, ValidateSharedIntegerTypedArray(isolate, array, true));
Maybe<size_t> maybe_index = ValidateAtomicAccess(isolate, sta, index);
if (maybe_index.IsNothing()) return ReadOnlyRoots(isolate).exception();
size_t i = maybe_index.FromJust();
// According to the spec, we have to check value's type before
// looking at the timeout.
if (sta->type() == kExternalBigInt64Array) {
ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, value,
BigInt::FromObject(isolate, value));
} else {
DCHECK(sta->type() == kExternalInt32Array);
ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, value,
Object::ToInt32(isolate, value));
}
double timeout_number;
if (timeout->IsUndefined(isolate)) {
timeout_number = ReadOnlyRoots(isolate).infinity_value().Number();
} else {
ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, timeout,
Object::ToNumber(isolate, timeout));
timeout_number = timeout->Number();
if (std::isnan(timeout_number))
timeout_number = ReadOnlyRoots(isolate).infinity_value().Number();
else if (timeout_number < 0)
timeout_number = 0;
}
if (!isolate->allow_atomics_wait()) {
THROW_NEW_ERROR_RETURN_FAILURE(
isolate, NewTypeError(MessageTemplate::kAtomicsWaitNotAllowed));
}
Handle<JSArrayBuffer> array_buffer = sta->GetBuffer();
if (sta->type() == kExternalBigInt64Array) {
return FutexEmulation::WaitJs64(
isolate, array_buffer, GetAddress64(i, sta->byte_offset()),
Handle<BigInt>::cast(value)->AsInt64(), timeout_number);
} else {
DCHECK(sta->type() == kExternalInt32Array);
return FutexEmulation::WaitJs32(isolate, array_buffer,
GetAddress32(i, sta->byte_offset()),
NumberToInt32(*value), timeout_number);
}
}
} // namespace internal
} // namespace v8
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