1153 lines
36 KiB
C++
1153 lines
36 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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/*
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* JS Atomics pseudo-module.
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*
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* See "Spec: JavaScript Shared Memory, Atomics, and Locks" for the
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* full specification.
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*
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* In addition to what is specified there, we throw an Error object if
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* the futex API hooks have not been installed on the runtime.
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* Essentially that is an implementation error at a higher level.
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*
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*
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* Note on the current implementation of atomic operations.
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*
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* The Mozilla atomics are not sufficient to implement these APIs
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* because we need to support 8-bit, 16-bit, and 32-bit data: the
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* Mozilla atomics only support 32-bit data.
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*
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* At the moment we include mozilla/Atomics.h, which will define
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* MOZ_HAVE_CXX11_ATOMICS and include <atomic> if we have C++11
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* atomics.
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*
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* If MOZ_HAVE_CXX11_ATOMICS is set we'll use C++11 atomics.
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*
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* Otherwise, if the compiler has them we'll fall back on gcc/Clang
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* intrinsics.
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*
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* Otherwise, if we're on VC++2012, we'll use C++11 atomics even if
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* MOZ_HAVE_CXX11_ATOMICS is not defined. The compiler has the
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* atomics but they are disabled in Mozilla due to a performance bug.
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* That performance bug does not affect the Atomics code. See
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* mozilla/Atomics.h for further comments on that bug.
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*
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* Otherwise, if we're on VC++2010 or VC++2008, we'll emulate the
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* gcc/Clang intrinsics with simple code below using the VC++
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* intrinsics, like the VC++2012 solution this is a stopgap since
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* we're about to start using VC++2013 anyway.
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*
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* If none of those options are available then the build must disable
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* shared memory, or compilation will fail with a predictable error.
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*/
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#include "builtin/AtomicsObject.h"
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#include "mozilla/Atomics.h"
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#include "mozilla/FloatingPoint.h"
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#include "mozilla/Maybe.h"
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#include "mozilla/Unused.h"
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#include "jsapi.h"
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#include "jsfriendapi.h"
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#include "jsnum.h"
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#include "jit/AtomicOperations.h"
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#include "jit/InlinableNatives.h"
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#include "js/Class.h"
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#include "vm/GlobalObject.h"
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#include "vm/Time.h"
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#include "vm/TypedArrayObject.h"
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#include "wasm/WasmInstance.h"
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#include "jsobjinlines.h"
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using namespace js;
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const Class AtomicsObject::class_ = {
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"Atomics",
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JSCLASS_HAS_CACHED_PROTO(JSProto_Atomics)
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};
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static bool
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ReportBadArrayType(JSContext* cx)
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{
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JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_ATOMICS_BAD_ARRAY);
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return false;
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}
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static bool
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ReportOutOfRange(JSContext* cx)
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{
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// Use JSMSG_BAD_INDEX here even if it is generic, since that is
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// the message used by ToIntegerIndex for its initial range
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// checking.
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JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_BAD_INDEX);
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return false;
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}
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static bool
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ReportCannotWait(JSContext* cx)
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{
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JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_ATOMICS_WAIT_NOT_ALLOWED);
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return false;
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}
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static bool
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GetSharedTypedArray(JSContext* cx, HandleValue v,
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MutableHandle<TypedArrayObject*> viewp)
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{
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if (!v.isObject())
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return ReportBadArrayType(cx);
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if (!v.toObject().is<TypedArrayObject>())
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return ReportBadArrayType(cx);
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viewp.set(&v.toObject().as<TypedArrayObject>());
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if (!viewp->isSharedMemory())
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return ReportBadArrayType(cx);
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return true;
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}
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static bool
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GetTypedArrayIndex(JSContext* cx, HandleValue v, Handle<TypedArrayObject*> view, uint32_t* offset)
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{
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uint64_t index;
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if (!js::ToIntegerIndex(cx, v, &index))
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return false;
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if (index >= view->length())
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return ReportOutOfRange(cx);
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*offset = uint32_t(index);
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return true;
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}
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static int32_t
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CompareExchange(Scalar::Type viewType, int32_t oldCandidate, int32_t newCandidate,
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SharedMem<void*> viewData, uint32_t offset, bool* badArrayType = nullptr)
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{
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switch (viewType) {
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case Scalar::Int8: {
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int8_t oldval = (int8_t)oldCandidate;
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int8_t newval = (int8_t)newCandidate;
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oldval = jit::AtomicOperations::compareExchangeSeqCst(viewData.cast<int8_t*>() + offset,
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oldval, newval);
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return oldval;
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}
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case Scalar::Uint8: {
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uint8_t oldval = (uint8_t)oldCandidate;
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uint8_t newval = (uint8_t)newCandidate;
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oldval = jit::AtomicOperations::compareExchangeSeqCst(viewData.cast<uint8_t*>() + offset,
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oldval, newval);
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return oldval;
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}
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case Scalar::Int16: {
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int16_t oldval = (int16_t)oldCandidate;
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int16_t newval = (int16_t)newCandidate;
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oldval = jit::AtomicOperations::compareExchangeSeqCst(viewData.cast<int16_t*>() + offset,
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oldval, newval);
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return oldval;
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}
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case Scalar::Uint16: {
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uint16_t oldval = (uint16_t)oldCandidate;
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uint16_t newval = (uint16_t)newCandidate;
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oldval = jit::AtomicOperations::compareExchangeSeqCst(viewData.cast<uint16_t*>() + offset,
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oldval, newval);
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return oldval;
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}
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case Scalar::Int32: {
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int32_t oldval = oldCandidate;
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int32_t newval = newCandidate;
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oldval = jit::AtomicOperations::compareExchangeSeqCst(viewData.cast<int32_t*>() + offset,
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oldval, newval);
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return oldval;
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}
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case Scalar::Uint32: {
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uint32_t oldval = (uint32_t)oldCandidate;
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uint32_t newval = (uint32_t)newCandidate;
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oldval = jit::AtomicOperations::compareExchangeSeqCst(viewData.cast<uint32_t*>() + offset,
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oldval, newval);
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return (int32_t)oldval;
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}
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default:
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if (badArrayType)
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*badArrayType = true;
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return 0;
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}
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}
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bool
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js::atomics_compareExchange(JSContext* cx, unsigned argc, Value* vp)
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{
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CallArgs args = CallArgsFromVp(argc, vp);
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HandleValue objv = args.get(0);
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HandleValue idxv = args.get(1);
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HandleValue oldv = args.get(2);
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HandleValue newv = args.get(3);
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MutableHandleValue r = args.rval();
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Rooted<TypedArrayObject*> view(cx, nullptr);
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if (!GetSharedTypedArray(cx, objv, &view))
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return false;
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uint32_t offset;
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if (!GetTypedArrayIndex(cx, idxv, view, &offset))
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return false;
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int32_t oldCandidate;
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if (!ToInt32(cx, oldv, &oldCandidate))
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return false;
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int32_t newCandidate;
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if (!ToInt32(cx, newv, &newCandidate))
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return false;
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bool badType = false;
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int32_t result = CompareExchange(view->type(), oldCandidate, newCandidate,
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view->viewDataShared(), offset, &badType);
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if (badType)
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return ReportBadArrayType(cx);
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if (view->type() == Scalar::Uint32)
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r.setNumber((double)(uint32_t)result);
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else
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r.setInt32(result);
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return true;
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}
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bool
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js::atomics_load(JSContext* cx, unsigned argc, Value* vp)
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{
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CallArgs args = CallArgsFromVp(argc, vp);
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HandleValue objv = args.get(0);
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HandleValue idxv = args.get(1);
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MutableHandleValue r = args.rval();
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Rooted<TypedArrayObject*> view(cx, nullptr);
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if (!GetSharedTypedArray(cx, objv, &view))
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return false;
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uint32_t offset;
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if (!GetTypedArrayIndex(cx, idxv, view, &offset))
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return false;
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SharedMem<void*> viewData = view->viewDataShared();
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switch (view->type()) {
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case Scalar::Uint8: {
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uint8_t v = jit::AtomicOperations::loadSeqCst(viewData.cast<uint8_t*>() + offset);
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r.setInt32(v);
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return true;
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}
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case Scalar::Int8: {
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int8_t v = jit::AtomicOperations::loadSeqCst(viewData.cast<uint8_t*>() + offset);
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r.setInt32(v);
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return true;
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}
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case Scalar::Int16: {
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int16_t v = jit::AtomicOperations::loadSeqCst(viewData.cast<int16_t*>() + offset);
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r.setInt32(v);
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return true;
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}
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case Scalar::Uint16: {
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uint16_t v = jit::AtomicOperations::loadSeqCst(viewData.cast<uint16_t*>() + offset);
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r.setInt32(v);
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return true;
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}
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case Scalar::Int32: {
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int32_t v = jit::AtomicOperations::loadSeqCst(viewData.cast<int32_t*>() + offset);
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r.setInt32(v);
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return true;
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}
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case Scalar::Uint32: {
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uint32_t v = jit::AtomicOperations::loadSeqCst(viewData.cast<uint32_t*>() + offset);
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r.setNumber(v);
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return true;
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}
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default:
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return ReportBadArrayType(cx);
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}
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}
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enum XchgStoreOp {
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DoExchange,
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DoStore
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};
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template<XchgStoreOp op>
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static int32_t
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ExchangeOrStore(Scalar::Type viewType, int32_t numberValue, SharedMem<void*> viewData,
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uint32_t offset, bool* badArrayType = nullptr)
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{
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#define INT_OP(ptr, value) \
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JS_BEGIN_MACRO \
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if (op == DoStore) \
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jit::AtomicOperations::storeSeqCst(ptr, value); \
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else \
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value = jit::AtomicOperations::exchangeSeqCst(ptr, value); \
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JS_END_MACRO
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switch (viewType) {
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case Scalar::Int8: {
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int8_t value = (int8_t)numberValue;
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INT_OP(viewData.cast<int8_t*>() + offset, value);
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return value;
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}
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case Scalar::Uint8: {
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uint8_t value = (uint8_t)numberValue;
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INT_OP(viewData.cast<uint8_t*>() + offset, value);
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return value;
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}
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case Scalar::Int16: {
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int16_t value = (int16_t)numberValue;
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INT_OP(viewData.cast<int16_t*>() + offset, value);
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return value;
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}
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case Scalar::Uint16: {
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uint16_t value = (uint16_t)numberValue;
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INT_OP(viewData.cast<uint16_t*>() + offset, value);
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return value;
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}
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case Scalar::Int32: {
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int32_t value = numberValue;
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INT_OP(viewData.cast<int32_t*>() + offset, value);
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return value;
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}
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case Scalar::Uint32: {
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uint32_t value = (uint32_t)numberValue;
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INT_OP(viewData.cast<uint32_t*>() + offset, value);
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return (int32_t)value;
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}
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default:
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if (badArrayType)
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*badArrayType = true;
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return 0;
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}
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#undef INT_OP
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}
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template<XchgStoreOp op>
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static bool
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ExchangeOrStore(JSContext* cx, unsigned argc, Value* vp)
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{
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CallArgs args = CallArgsFromVp(argc, vp);
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HandleValue objv = args.get(0);
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HandleValue idxv = args.get(1);
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HandleValue valv = args.get(2);
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MutableHandleValue r = args.rval();
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Rooted<TypedArrayObject*> view(cx, nullptr);
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if (!GetSharedTypedArray(cx, objv, &view))
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return false;
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uint32_t offset;
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if (!GetTypedArrayIndex(cx, idxv, view, &offset))
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return false;
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double integerValue;
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if (!ToInteger(cx, valv, &integerValue))
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return false;
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bool badType = false;
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int32_t result = ExchangeOrStore<op>(view->type(), JS::ToInt32(integerValue),
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view->viewDataShared(), offset, &badType);
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if (badType)
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return ReportBadArrayType(cx);
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if (op == DoStore)
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r.setNumber(integerValue);
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else if (view->type() == Scalar::Uint32)
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r.setNumber((double)(uint32_t)result);
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else
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r.setInt32(result);
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return true;
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}
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bool
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js::atomics_store(JSContext* cx, unsigned argc, Value* vp)
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{
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return ExchangeOrStore<DoStore>(cx, argc, vp);
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}
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bool
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js::atomics_exchange(JSContext* cx, unsigned argc, Value* vp)
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{
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return ExchangeOrStore<DoExchange>(cx, argc, vp);
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}
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template<typename T>
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static bool
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AtomicsBinop(JSContext* cx, HandleValue objv, HandleValue idxv, HandleValue valv,
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MutableHandleValue r)
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{
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Rooted<TypedArrayObject*> view(cx, nullptr);
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if (!GetSharedTypedArray(cx, objv, &view))
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return false;
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uint32_t offset;
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if (!GetTypedArrayIndex(cx, idxv, view, &offset))
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return false;
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int32_t numberValue;
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if (!ToInt32(cx, valv, &numberValue))
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return false;
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SharedMem<void*> viewData = view->viewDataShared();
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switch (view->type()) {
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case Scalar::Int8: {
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int8_t v = (int8_t)numberValue;
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r.setInt32(T::operate(viewData.cast<int8_t*>() + offset, v));
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return true;
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}
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case Scalar::Uint8: {
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uint8_t v = (uint8_t)numberValue;
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r.setInt32(T::operate(viewData.cast<uint8_t*>() + offset, v));
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return true;
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}
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case Scalar::Int16: {
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int16_t v = (int16_t)numberValue;
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r.setInt32(T::operate(viewData.cast<int16_t*>() + offset, v));
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return true;
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}
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case Scalar::Uint16: {
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uint16_t v = (uint16_t)numberValue;
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r.setInt32(T::operate(viewData.cast<uint16_t*>() + offset, v));
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return true;
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}
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case Scalar::Int32: {
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int32_t v = numberValue;
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r.setInt32(T::operate(viewData.cast<int32_t*>() + offset, v));
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return true;
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}
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case Scalar::Uint32: {
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uint32_t v = (uint32_t)numberValue;
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r.setNumber((double)T::operate(viewData.cast<uint32_t*>() + offset, v));
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return true;
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}
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default:
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return ReportBadArrayType(cx);
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}
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}
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#define INTEGRAL_TYPES_FOR_EACH(NAME) \
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static int8_t operate(SharedMem<int8_t*> addr, int8_t v) { return NAME(addr, v); } \
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static uint8_t operate(SharedMem<uint8_t*> addr, uint8_t v) { return NAME(addr, v); } \
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static int16_t operate(SharedMem<int16_t*> addr, int16_t v) { return NAME(addr, v); } \
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static uint16_t operate(SharedMem<uint16_t*> addr, uint16_t v) { return NAME(addr, v); } \
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static int32_t operate(SharedMem<int32_t*> addr, int32_t v) { return NAME(addr, v); } \
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static uint32_t operate(SharedMem<uint32_t*> addr, uint32_t v) { return NAME(addr, v); }
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class PerformAdd
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{
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public:
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INTEGRAL_TYPES_FOR_EACH(jit::AtomicOperations::fetchAddSeqCst)
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static int32_t perform(int32_t x, int32_t y) { return x + y; }
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};
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bool
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js::atomics_add(JSContext* cx, unsigned argc, Value* vp)
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{
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CallArgs args = CallArgsFromVp(argc, vp);
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return AtomicsBinop<PerformAdd>(cx, args.get(0), args.get(1), args.get(2), args.rval());
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}
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class PerformSub
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{
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public:
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INTEGRAL_TYPES_FOR_EACH(jit::AtomicOperations::fetchSubSeqCst)
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static int32_t perform(int32_t x, int32_t y) { return x - y; }
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};
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bool
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js::atomics_sub(JSContext* cx, unsigned argc, Value* vp)
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{
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CallArgs args = CallArgsFromVp(argc, vp);
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return AtomicsBinop<PerformSub>(cx, args.get(0), args.get(1), args.get(2), args.rval());
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}
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class PerformAnd
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{
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public:
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INTEGRAL_TYPES_FOR_EACH(jit::AtomicOperations::fetchAndSeqCst)
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static int32_t perform(int32_t x, int32_t y) { return x & y; }
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};
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bool
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js::atomics_and(JSContext* cx, unsigned argc, Value* vp)
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{
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CallArgs args = CallArgsFromVp(argc, vp);
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return AtomicsBinop<PerformAnd>(cx, args.get(0), args.get(1), args.get(2), args.rval());
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}
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class PerformOr
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{
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public:
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INTEGRAL_TYPES_FOR_EACH(jit::AtomicOperations::fetchOrSeqCst)
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|
static int32_t perform(int32_t x, int32_t y) { return x | y; }
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};
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bool
|
|
js::atomics_or(JSContext* cx, unsigned argc, Value* vp)
|
|
{
|
|
CallArgs args = CallArgsFromVp(argc, vp);
|
|
return AtomicsBinop<PerformOr>(cx, args.get(0), args.get(1), args.get(2), args.rval());
|
|
}
|
|
|
|
class PerformXor
|
|
{
|
|
public:
|
|
INTEGRAL_TYPES_FOR_EACH(jit::AtomicOperations::fetchXorSeqCst)
|
|
static int32_t perform(int32_t x, int32_t y) { return x ^ y; }
|
|
};
|
|
|
|
bool
|
|
js::atomics_xor(JSContext* cx, unsigned argc, Value* vp)
|
|
{
|
|
CallArgs args = CallArgsFromVp(argc, vp);
|
|
return AtomicsBinop<PerformXor>(cx, args.get(0), args.get(1), args.get(2), args.rval());
|
|
}
|
|
|
|
bool
|
|
js::atomics_isLockFree(JSContext* cx, unsigned argc, Value* vp)
|
|
{
|
|
CallArgs args = CallArgsFromVp(argc, vp);
|
|
HandleValue v = args.get(0);
|
|
int32_t size;
|
|
if (v.isInt32()) {
|
|
size = v.toInt32();
|
|
} else {
|
|
double dsize;
|
|
if (!ToInteger(cx, v, &dsize))
|
|
return false;
|
|
if (!mozilla::NumberIsInt32(dsize, &size)) {
|
|
args.rval().setBoolean(false);
|
|
return true;
|
|
}
|
|
}
|
|
args.rval().setBoolean(jit::AtomicOperations::isLockfree(size));
|
|
return true;
|
|
}
|
|
|
|
// asm.js callouts for platforms that do not have non-word-sized
|
|
// atomics where we don't want to inline the logic for the atomics.
|
|
//
|
|
// Memory will always be shared since the callouts are only called from
|
|
// code that checks that the memory is shared.
|
|
//
|
|
// To test this, either run on eg Raspberry Pi Model 1, or invoke the ARM
|
|
// simulator build with ARMHWCAP=vfp set. Do not set any other flags; other
|
|
// vfp/neon flags force ARMv7 to be set.
|
|
|
|
int32_t
|
|
js::atomics_add_asm_callout(wasm::Instance* instance, int32_t vt, int32_t offset, int32_t value)
|
|
{
|
|
SharedMem<void*> heap = instance->memoryBase().cast<void*>();
|
|
size_t heapLength = instance->memoryLength();
|
|
|
|
if (size_t(offset) >= heapLength)
|
|
return 0;
|
|
|
|
switch (Scalar::Type(vt)) {
|
|
case Scalar::Int8:
|
|
return PerformAdd::operate(heap.cast<int8_t*>() + offset, value);
|
|
case Scalar::Uint8:
|
|
return PerformAdd::operate(heap.cast<uint8_t*>() + offset, value);
|
|
case Scalar::Int16:
|
|
return PerformAdd::operate(heap.cast<int16_t*>() + (offset >> 1), value);
|
|
case Scalar::Uint16:
|
|
return PerformAdd::operate(heap.cast<uint16_t*>() + (offset >> 1), value);
|
|
default:
|
|
MOZ_CRASH("Invalid size");
|
|
}
|
|
}
|
|
|
|
int32_t
|
|
js::atomics_sub_asm_callout(wasm::Instance* instance, int32_t vt, int32_t offset, int32_t value)
|
|
{
|
|
SharedMem<void*> heap = instance->memoryBase().cast<void*>();
|
|
size_t heapLength = instance->memoryLength();
|
|
|
|
if (size_t(offset) >= heapLength)
|
|
return 0;
|
|
|
|
switch (Scalar::Type(vt)) {
|
|
case Scalar::Int8:
|
|
return PerformSub::operate(heap.cast<int8_t*>() + offset, value);
|
|
case Scalar::Uint8:
|
|
return PerformSub::operate(heap.cast<uint8_t*>() + offset, value);
|
|
case Scalar::Int16:
|
|
return PerformSub::operate(heap.cast<int16_t*>() + (offset >> 1), value);
|
|
case Scalar::Uint16:
|
|
return PerformSub::operate(heap.cast<uint16_t*>() + (offset >> 1), value);
|
|
default:
|
|
MOZ_CRASH("Invalid size");
|
|
}
|
|
}
|
|
|
|
int32_t
|
|
js::atomics_and_asm_callout(wasm::Instance* instance, int32_t vt, int32_t offset, int32_t value)
|
|
{
|
|
SharedMem<void*> heap = instance->memoryBase().cast<void*>();
|
|
size_t heapLength = instance->memoryLength();
|
|
|
|
if (size_t(offset) >= heapLength)
|
|
return 0;
|
|
|
|
switch (Scalar::Type(vt)) {
|
|
case Scalar::Int8:
|
|
return PerformAnd::operate(heap.cast<int8_t*>() + offset, value);
|
|
case Scalar::Uint8:
|
|
return PerformAnd::operate(heap.cast<uint8_t*>() + offset, value);
|
|
case Scalar::Int16:
|
|
return PerformAnd::operate(heap.cast<int16_t*>() + (offset >> 1), value);
|
|
case Scalar::Uint16:
|
|
return PerformAnd::operate(heap.cast<uint16_t*>() + (offset >> 1), value);
|
|
default:
|
|
MOZ_CRASH("Invalid size");
|
|
}
|
|
}
|
|
|
|
int32_t
|
|
js::atomics_or_asm_callout(wasm::Instance* instance, int32_t vt, int32_t offset, int32_t value)
|
|
{
|
|
SharedMem<void*> heap = instance->memoryBase().cast<void*>();
|
|
size_t heapLength = instance->memoryLength();
|
|
|
|
if (size_t(offset) >= heapLength)
|
|
return 0;
|
|
|
|
switch (Scalar::Type(vt)) {
|
|
case Scalar::Int8:
|
|
return PerformOr::operate(heap.cast<int8_t*>() + offset, value);
|
|
case Scalar::Uint8:
|
|
return PerformOr::operate(heap.cast<uint8_t*>() + offset, value);
|
|
case Scalar::Int16:
|
|
return PerformOr::operate(heap.cast<int16_t*>() + (offset >> 1), value);
|
|
case Scalar::Uint16:
|
|
return PerformOr::operate(heap.cast<uint16_t*>() + (offset >> 1), value);
|
|
default:
|
|
MOZ_CRASH("Invalid size");
|
|
}
|
|
}
|
|
|
|
int32_t
|
|
js::atomics_xor_asm_callout(wasm::Instance* instance, int32_t vt, int32_t offset, int32_t value)
|
|
{
|
|
SharedMem<void*> heap = instance->memoryBase().cast<void*>();
|
|
size_t heapLength = instance->memoryLength();
|
|
|
|
if (size_t(offset) >= heapLength)
|
|
return 0;
|
|
|
|
switch (Scalar::Type(vt)) {
|
|
case Scalar::Int8:
|
|
return PerformXor::operate(heap.cast<int8_t*>() + offset, value);
|
|
case Scalar::Uint8:
|
|
return PerformXor::operate(heap.cast<uint8_t*>() + offset, value);
|
|
case Scalar::Int16:
|
|
return PerformXor::operate(heap.cast<int16_t*>() + (offset >> 1), value);
|
|
case Scalar::Uint16:
|
|
return PerformXor::operate(heap.cast<uint16_t*>() + (offset >> 1), value);
|
|
default:
|
|
MOZ_CRASH("Invalid size");
|
|
}
|
|
}
|
|
|
|
int32_t
|
|
js::atomics_xchg_asm_callout(wasm::Instance* instance, int32_t vt, int32_t offset, int32_t value)
|
|
{
|
|
SharedMem<void*> heap = instance->memoryBase().cast<void*>();
|
|
size_t heapLength = instance->memoryLength();
|
|
|
|
if (size_t(offset) >= heapLength)
|
|
return 0;
|
|
|
|
switch (Scalar::Type(vt)) {
|
|
case Scalar::Int8:
|
|
return ExchangeOrStore<DoExchange>(Scalar::Int8, value, heap, offset);
|
|
case Scalar::Uint8:
|
|
return ExchangeOrStore<DoExchange>(Scalar::Uint8, value, heap, offset);
|
|
case Scalar::Int16:
|
|
return ExchangeOrStore<DoExchange>(Scalar::Int16, value, heap, offset>>1);
|
|
case Scalar::Uint16:
|
|
return ExchangeOrStore<DoExchange>(Scalar::Uint16, value, heap, offset>>1);
|
|
default:
|
|
MOZ_CRASH("Invalid size");
|
|
}
|
|
}
|
|
|
|
int32_t
|
|
js::atomics_cmpxchg_asm_callout(wasm::Instance* instance, int32_t vt, int32_t offset, int32_t oldval, int32_t newval)
|
|
{
|
|
SharedMem<void*> heap = instance->memoryBase().cast<void*>();
|
|
size_t heapLength = instance->memoryLength();
|
|
|
|
if (size_t(offset) >= heapLength)
|
|
return 0;
|
|
|
|
switch (Scalar::Type(vt)) {
|
|
case Scalar::Int8:
|
|
return CompareExchange(Scalar::Int8, oldval, newval, heap, offset);
|
|
case Scalar::Uint8:
|
|
return CompareExchange(Scalar::Uint8, oldval, newval, heap, offset);
|
|
case Scalar::Int16:
|
|
return CompareExchange(Scalar::Int16, oldval, newval, heap, offset>>1);
|
|
case Scalar::Uint16:
|
|
return CompareExchange(Scalar::Uint16, oldval, newval, heap, offset>>1);
|
|
default:
|
|
MOZ_CRASH("Invalid size");
|
|
}
|
|
}
|
|
|
|
namespace js {
|
|
|
|
// Represents one waiting worker.
|
|
//
|
|
// The type is declared opaque in SharedArrayObject.h. Instances of
|
|
// js::FutexWaiter are stack-allocated and linked onto a list across a
|
|
// call to FutexRuntime::wait().
|
|
//
|
|
// The 'waiters' field of the SharedArrayRawBuffer points to the highest
|
|
// priority waiter in the list, and lower priority nodes are linked through
|
|
// the 'lower_pri' field. The 'back' field goes the other direction.
|
|
// The list is circular, so the 'lower_pri' field of the lowest priority
|
|
// node points to the first node in the list. The list has no dedicated
|
|
// header node.
|
|
|
|
class FutexWaiter
|
|
{
|
|
public:
|
|
FutexWaiter(uint32_t offset, JSRuntime* rt)
|
|
: offset(offset),
|
|
rt(rt),
|
|
lower_pri(nullptr),
|
|
back(nullptr)
|
|
{
|
|
}
|
|
|
|
uint32_t offset; // int32 element index within the SharedArrayBuffer
|
|
JSRuntime* rt; // The runtime of the waiter
|
|
FutexWaiter* lower_pri; // Lower priority nodes in circular doubly-linked list of waiters
|
|
FutexWaiter* back; // Other direction
|
|
};
|
|
|
|
class AutoLockFutexAPI
|
|
{
|
|
// We have to wrap this in a Maybe because of the way loading
|
|
// mozilla::Atomic pointers works.
|
|
mozilla::Maybe<js::UniqueLock<js::Mutex>> unique_;
|
|
|
|
public:
|
|
AutoLockFutexAPI() {
|
|
js::Mutex* lock = FutexRuntime::lock_;
|
|
unique_.emplace(*lock);
|
|
}
|
|
|
|
~AutoLockFutexAPI() {
|
|
unique_.reset();
|
|
}
|
|
|
|
js::UniqueLock<js::Mutex>& unique() { return *unique_; }
|
|
};
|
|
|
|
} // namespace js
|
|
|
|
bool
|
|
js::atomics_wait(JSContext* cx, unsigned argc, Value* vp)
|
|
{
|
|
CallArgs args = CallArgsFromVp(argc, vp);
|
|
HandleValue objv = args.get(0);
|
|
HandleValue idxv = args.get(1);
|
|
HandleValue valv = args.get(2);
|
|
HandleValue timeoutv = args.get(3);
|
|
MutableHandleValue r = args.rval();
|
|
|
|
JSRuntime* rt = cx->runtime();
|
|
|
|
Rooted<TypedArrayObject*> view(cx, nullptr);
|
|
if (!GetSharedTypedArray(cx, objv, &view))
|
|
return false;
|
|
if (view->type() != Scalar::Int32)
|
|
return ReportBadArrayType(cx);
|
|
uint32_t offset;
|
|
if (!GetTypedArrayIndex(cx, idxv, view, &offset))
|
|
return false;
|
|
int32_t value;
|
|
if (!ToInt32(cx, valv, &value))
|
|
return false;
|
|
mozilla::Maybe<mozilla::TimeDuration> timeout;
|
|
if (!timeoutv.isUndefined()) {
|
|
double timeout_ms;
|
|
if (!ToNumber(cx, timeoutv, &timeout_ms))
|
|
return false;
|
|
if (!mozilla::IsNaN(timeout_ms)) {
|
|
if (timeout_ms < 0)
|
|
timeout = mozilla::Some(mozilla::TimeDuration::FromSeconds(0.0));
|
|
else if (!mozilla::IsInfinite(timeout_ms))
|
|
timeout = mozilla::Some(mozilla::TimeDuration::FromMilliseconds(timeout_ms));
|
|
}
|
|
}
|
|
|
|
if (!rt->fx.canWait())
|
|
return ReportCannotWait(cx);
|
|
|
|
// This lock also protects the "waiters" field on SharedArrayRawBuffer,
|
|
// and it provides the necessary memory fence.
|
|
AutoLockFutexAPI lock;
|
|
|
|
SharedMem<int32_t*> addr = view->viewDataShared().cast<int32_t*>() + offset;
|
|
if (jit::AtomicOperations::loadSafeWhenRacy(addr) != value) {
|
|
r.setString(cx->names().futexNotEqual);
|
|
return true;
|
|
}
|
|
|
|
Rooted<SharedArrayBufferObject*> sab(cx, view->bufferShared());
|
|
SharedArrayRawBuffer* sarb = sab->rawBufferObject();
|
|
|
|
FutexWaiter w(offset, rt);
|
|
if (FutexWaiter* waiters = sarb->waiters()) {
|
|
w.lower_pri = waiters;
|
|
w.back = waiters->back;
|
|
waiters->back->lower_pri = &w;
|
|
waiters->back = &w;
|
|
} else {
|
|
w.lower_pri = w.back = &w;
|
|
sarb->setWaiters(&w);
|
|
}
|
|
|
|
FutexRuntime::WaitResult result = FutexRuntime::FutexOK;
|
|
bool retval = rt->fx.wait(cx, lock.unique(), timeout, &result);
|
|
if (retval) {
|
|
switch (result) {
|
|
case FutexRuntime::FutexOK:
|
|
r.setString(cx->names().futexOK);
|
|
break;
|
|
case FutexRuntime::FutexTimedOut:
|
|
r.setString(cx->names().futexTimedOut);
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (w.lower_pri == &w) {
|
|
sarb->setWaiters(nullptr);
|
|
} else {
|
|
w.lower_pri->back = w.back;
|
|
w.back->lower_pri = w.lower_pri;
|
|
if (sarb->waiters() == &w)
|
|
sarb->setWaiters(w.lower_pri);
|
|
}
|
|
return retval;
|
|
}
|
|
|
|
bool
|
|
js::atomics_notify(JSContext* cx, unsigned argc, Value* vp)
|
|
{
|
|
CallArgs args = CallArgsFromVp(argc, vp);
|
|
HandleValue objv = args.get(0);
|
|
HandleValue idxv = args.get(1);
|
|
HandleValue countv = args.get(2);
|
|
MutableHandleValue r = args.rval();
|
|
|
|
Rooted<TypedArrayObject*> view(cx, nullptr);
|
|
if (!GetSharedTypedArray(cx, objv, &view))
|
|
return false;
|
|
if (view->type() != Scalar::Int32)
|
|
return ReportBadArrayType(cx);
|
|
uint32_t offset;
|
|
if (!GetTypedArrayIndex(cx, idxv, view, &offset))
|
|
return false;
|
|
double count;
|
|
if (countv.isUndefined()) {
|
|
count = mozilla::PositiveInfinity<double>();
|
|
} else {
|
|
if (!ToInteger(cx, countv, &count))
|
|
return false;
|
|
if (count < 0.0)
|
|
count = 0.0;
|
|
}
|
|
|
|
AutoLockFutexAPI lock;
|
|
|
|
Rooted<SharedArrayBufferObject*> sab(cx, view->bufferShared());
|
|
SharedArrayRawBuffer* sarb = sab->rawBufferObject();
|
|
int32_t woken = 0;
|
|
|
|
FutexWaiter* waiters = sarb->waiters();
|
|
if (waiters && count > 0) {
|
|
FutexWaiter* iter = waiters;
|
|
do {
|
|
FutexWaiter* c = iter;
|
|
iter = iter->lower_pri;
|
|
if (c->offset != offset || !c->rt->fx.isWaiting())
|
|
continue;
|
|
c->rt->fx.notify(FutexRuntime::NotifyExplicit);
|
|
++woken;
|
|
--count;
|
|
} while (count > 0 && iter != waiters);
|
|
}
|
|
|
|
r.setInt32(woken);
|
|
return true;
|
|
}
|
|
|
|
/* static */ bool
|
|
js::FutexRuntime::initialize()
|
|
{
|
|
MOZ_ASSERT(!lock_);
|
|
lock_ = js_new<js::Mutex>(mutexid::FutexRuntime);
|
|
return lock_ != nullptr;
|
|
}
|
|
|
|
/* static */ void
|
|
js::FutexRuntime::destroy()
|
|
{
|
|
if (lock_) {
|
|
js::Mutex* lock = lock_;
|
|
js_delete(lock);
|
|
lock_ = nullptr;
|
|
}
|
|
}
|
|
|
|
/* static */ void
|
|
js::FutexRuntime::lock()
|
|
{
|
|
// Load the atomic pointer.
|
|
js::Mutex* lock = lock_;
|
|
|
|
lock->lock();
|
|
}
|
|
|
|
/* static */ mozilla::Atomic<js::Mutex*> FutexRuntime::lock_;
|
|
|
|
/* static */ void
|
|
js::FutexRuntime::unlock()
|
|
{
|
|
// Load the atomic pointer.
|
|
js::Mutex* lock = lock_;
|
|
|
|
lock->unlock();
|
|
}
|
|
|
|
js::FutexRuntime::FutexRuntime()
|
|
: cond_(nullptr),
|
|
state_(Idle),
|
|
canWait_(false)
|
|
{
|
|
}
|
|
|
|
bool
|
|
js::FutexRuntime::initInstance()
|
|
{
|
|
MOZ_ASSERT(lock_);
|
|
cond_ = js_new<js::ConditionVariable>();
|
|
return cond_ != nullptr;
|
|
}
|
|
|
|
void
|
|
js::FutexRuntime::destroyInstance()
|
|
{
|
|
if (cond_)
|
|
js_delete(cond_);
|
|
}
|
|
|
|
bool
|
|
js::FutexRuntime::isWaiting()
|
|
{
|
|
// When a worker is awoken for an interrupt it goes into state
|
|
// WaitingNotifiedForInterrupt for a short time before it actually
|
|
// wakes up and goes into WaitingInterrupted. In those states the
|
|
// worker is still waiting, and if an explicit notify arrives the
|
|
// worker transitions to Woken. See further comments in
|
|
// FutexRuntime::wait().
|
|
return state_ == Waiting || state_ == WaitingInterrupted || state_ == WaitingNotifiedForInterrupt;
|
|
}
|
|
|
|
bool
|
|
js::FutexRuntime::wait(JSContext* cx, js::UniqueLock<js::Mutex>& locked,
|
|
mozilla::Maybe<mozilla::TimeDuration>& timeout, WaitResult* result)
|
|
{
|
|
MOZ_ASSERT(&cx->runtime()->fx == this);
|
|
MOZ_ASSERT(cx->runtime()->fx.canWait());
|
|
MOZ_ASSERT(state_ == Idle || state_ == WaitingInterrupted);
|
|
|
|
// Disallow waiting when a runtime is processing an interrupt.
|
|
// See explanation below.
|
|
|
|
if (state_ == WaitingInterrupted) {
|
|
UnlockGuard<Mutex> unlock(locked);
|
|
JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_ATOMICS_WAIT_NOT_ALLOWED);
|
|
return false;
|
|
}
|
|
|
|
const bool isTimed = timeout.isSome();
|
|
|
|
auto finalEnd = timeout.map([](mozilla::TimeDuration& timeout) {
|
|
return mozilla::TimeStamp::Now() + timeout;
|
|
});
|
|
|
|
|
|
// 4000s is about the longest timeout slice that is guaranteed to
|
|
// work cross-platform.
|
|
auto maxSlice = mozilla::TimeDuration::FromSeconds(4000.0);
|
|
|
|
bool retval = true;
|
|
|
|
for (;;) {
|
|
// If we are doing a timed wait, calculate the end time for this wait
|
|
// slice.
|
|
auto sliceEnd = finalEnd.map([&](mozilla::TimeStamp& finalEnd) {
|
|
auto sliceEnd = mozilla::TimeStamp::Now() + maxSlice;
|
|
if (finalEnd < sliceEnd)
|
|
sliceEnd = finalEnd;
|
|
return sliceEnd;
|
|
});
|
|
|
|
state_ = Waiting;
|
|
|
|
if (isTimed) {
|
|
mozilla::Unused << cond_->wait_until(locked, *sliceEnd);
|
|
} else {
|
|
cond_->wait(locked);
|
|
}
|
|
|
|
switch (state_) {
|
|
case FutexRuntime::Waiting:
|
|
// Timeout or spurious wakeup.
|
|
if (isTimed) {
|
|
auto now = mozilla::TimeStamp::Now();
|
|
if (now >= *finalEnd) {
|
|
*result = FutexTimedOut;
|
|
goto finished;
|
|
}
|
|
}
|
|
break;
|
|
|
|
case FutexRuntime::Woken:
|
|
*result = FutexOK;
|
|
goto finished;
|
|
|
|
case FutexRuntime::WaitingNotifiedForInterrupt:
|
|
// The interrupt handler may reenter the engine. In that case
|
|
// there are two complications:
|
|
//
|
|
// - The waiting thread is not actually waiting on the
|
|
// condition variable so we have to record that it
|
|
// should be woken when the interrupt handler returns.
|
|
// To that end, we flag the thread as interrupted around
|
|
// the interrupt and check state_ when the interrupt
|
|
// handler returns. A notify() call that reaches the
|
|
// runtime during the interrupt sets state_ to Woken.
|
|
//
|
|
// - It is in principle possible for wait() to be
|
|
// reentered on the same thread/runtime and waiting on the
|
|
// same location and to yet again be interrupted and enter
|
|
// the interrupt handler. In this case, it is important
|
|
// that when another agent notifies waiters, all waiters using
|
|
// the same runtime on the same location are woken in LIFO
|
|
// order; FIFO may be the required order, but FIFO would
|
|
// fail to wake up the innermost call. Interrupts are
|
|
// outside any spec anyway. Also, several such suspended
|
|
// waiters may be woken at a time.
|
|
//
|
|
// For the time being we disallow waiting from within code
|
|
// that runs from within an interrupt handler; this may
|
|
// occasionally (very rarely) be surprising but is
|
|
// expedient. Other solutions exist, see bug #1131943. The
|
|
// code that performs the check is above, at the head of
|
|
// this function.
|
|
|
|
state_ = WaitingInterrupted;
|
|
{
|
|
UnlockGuard<Mutex> unlock(locked);
|
|
retval = cx->runtime()->handleInterrupt(cx);
|
|
}
|
|
if (!retval)
|
|
goto finished;
|
|
if (state_ == Woken) {
|
|
*result = FutexOK;
|
|
goto finished;
|
|
}
|
|
break;
|
|
|
|
default:
|
|
MOZ_CRASH("Bad FutexState in wait()");
|
|
}
|
|
}
|
|
finished:
|
|
state_ = Idle;
|
|
return retval;
|
|
}
|
|
|
|
void
|
|
js::FutexRuntime::notify(NotifyReason reason)
|
|
{
|
|
MOZ_ASSERT(isWaiting());
|
|
|
|
if ((state_ == WaitingInterrupted || state_ == WaitingNotifiedForInterrupt) && reason == NotifyExplicit) {
|
|
state_ = Woken;
|
|
return;
|
|
}
|
|
switch (reason) {
|
|
case NotifyExplicit:
|
|
state_ = Woken;
|
|
break;
|
|
case NotifyForJSInterrupt:
|
|
if (state_ == WaitingNotifiedForInterrupt)
|
|
return;
|
|
state_ = WaitingNotifiedForInterrupt;
|
|
break;
|
|
default:
|
|
MOZ_CRASH("bad NotifyReason in FutexRuntime::notify()");
|
|
}
|
|
cond_->notify_all();
|
|
}
|
|
|
|
const JSFunctionSpec AtomicsMethods[] = {
|
|
JS_INLINABLE_FN("compareExchange", atomics_compareExchange, 4,0, AtomicsCompareExchange),
|
|
JS_INLINABLE_FN("load", atomics_load, 2,0, AtomicsLoad),
|
|
JS_INLINABLE_FN("store", atomics_store, 3,0, AtomicsStore),
|
|
JS_INLINABLE_FN("exchange", atomics_exchange, 3,0, AtomicsExchange),
|
|
JS_INLINABLE_FN("add", atomics_add, 3,0, AtomicsAdd),
|
|
JS_INLINABLE_FN("sub", atomics_sub, 3,0, AtomicsSub),
|
|
JS_INLINABLE_FN("and", atomics_and, 3,0, AtomicsAnd),
|
|
JS_INLINABLE_FN("or", atomics_or, 3,0, AtomicsOr),
|
|
JS_INLINABLE_FN("xor", atomics_xor, 3,0, AtomicsXor),
|
|
JS_INLINABLE_FN("isLockFree", atomics_isLockFree, 1,0, AtomicsIsLockFree),
|
|
JS_FN("wait", atomics_wait, 4,0),
|
|
JS_FN("notify", atomics_notify, 3,0),
|
|
JS_FN("wake", atomics_notify, 3,0), //Legacy name
|
|
JS_FS_END
|
|
};
|
|
|
|
JSObject*
|
|
AtomicsObject::initClass(JSContext* cx, Handle<GlobalObject*> global)
|
|
{
|
|
// Create Atomics Object.
|
|
RootedObject objProto(cx, GlobalObject::getOrCreateObjectPrototype(cx, global));
|
|
if (!objProto)
|
|
return nullptr;
|
|
RootedObject Atomics(cx, NewObjectWithGivenProto(cx, &AtomicsObject::class_, objProto,
|
|
SingletonObject));
|
|
if (!Atomics)
|
|
return nullptr;
|
|
|
|
if (!JS_DefineFunctions(cx, Atomics, AtomicsMethods))
|
|
return nullptr;
|
|
|
|
RootedValue AtomicsValue(cx, ObjectValue(*Atomics));
|
|
|
|
// Everything is set up, install Atomics on the global object.
|
|
if (!DefineProperty(cx, global, cx->names().Atomics, AtomicsValue, nullptr, nullptr,
|
|
JSPROP_RESOLVING))
|
|
{
|
|
return nullptr;
|
|
}
|
|
|
|
global->setConstructor(JSProto_Atomics, AtomicsValue);
|
|
return Atomics;
|
|
}
|
|
|
|
JSObject*
|
|
js::InitAtomicsClass(JSContext* cx, HandleObject obj)
|
|
{
|
|
MOZ_ASSERT(obj->is<GlobalObject>());
|
|
Rooted<GlobalObject*> global(cx, &obj->as<GlobalObject>());
|
|
return AtomicsObject::initClass(cx, global);
|
|
}
|
|
|
|
#undef CXX11_ATOMICS
|
|
#undef GNU_ATOMICS
|