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/*
* Copyright (C) 2016-2019 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "JITWorklist.h"
#if ENABLE(JIT)
#include "JIT.h"
#include "JSCInlines.h"
#include "VMInlines.h"
namespace JSC {
class JITWorklist::Plan : public ThreadSafeRefCounted<JITWorklist::Plan> {
public:
Plan(CodeBlock* codeBlock, unsigned loopOSREntryBytecodeOffset)
: m_codeBlock(codeBlock)
, m_jit(codeBlock->vm(), codeBlock, loopOSREntryBytecodeOffset)
{
m_jit.doMainThreadPreparationBeforeCompile();
}
void compileInThread()
{
m_jit.compileWithoutLinking(JITCompilationCanFail);
LockHolder locker(m_lock);
m_isFinishedCompiling = true;
}
void finalize()
{
CompilationResult result = m_jit.link();
switch (result) {
case CompilationFailed:
CODEBLOCK_LOG_EVENT(m_codeBlock, "delayJITCompile", ("compilation failed"));
if (Options::verboseOSR())
dataLogF(" JIT compilation failed.\n");
m_codeBlock->dontJITAnytimeSoon();
m_codeBlock->m_didFailJITCompilation = true;
return;
case CompilationSuccessful:
if (Options::verboseOSR())
dataLogF(" JIT compilation successful.\n");
m_codeBlock->ownerExecutable()->installCode(m_codeBlock);
m_codeBlock->jitSoon();
return;
default:
RELEASE_ASSERT_NOT_REACHED();
return;
}
}
CodeBlock* codeBlock() { return m_codeBlock; }
VM& vm() { return m_codeBlock->vm(); }
bool isFinishedCompiling()
{
LockHolder locker(m_lock);
return m_isFinishedCompiling;
}
static void compileNow(CodeBlock* codeBlock, unsigned loopOSREntryBytecodeOffset)
{
Plan plan(codeBlock, loopOSREntryBytecodeOffset);
plan.compileInThread();
plan.finalize();
}
private:
CodeBlock* m_codeBlock;
JIT m_jit;
Lock m_lock;
bool m_isFinishedCompiling { false };
};
class JITWorklist::Thread : public AutomaticThread {
public:
Thread(const AbstractLocker& locker, JITWorklist& worklist)
: AutomaticThread(locker, worklist.m_lock, worklist.m_condition.copyRef())
, m_worklist(worklist)
{
m_worklist.m_numAvailableThreads++;
}
const char* name() const override
{
#if OS(LINUX)
return "JITWorker";
#else
return "JIT Worklist Helper Thread";
#endif
}
protected:
PollResult poll(const AbstractLocker&) override
{
RELEASE_ASSERT(m_worklist.m_numAvailableThreads);
if (m_worklist.m_queue.isEmpty())
return PollResult::Wait;
m_myPlans = WTFMove(m_worklist.m_queue);
m_worklist.m_numAvailableThreads--;
return PollResult::Work;
}
WorkResult work() override
{
RELEASE_ASSERT(!m_myPlans.isEmpty());
for (RefPtr<Plan>& plan : m_myPlans) {
plan->compileInThread();
plan = nullptr;
// Make sure that the main thread realizes that we just compiled something. Notifying
// a condition is basically free if nobody is waiting.
LockHolder locker(*m_worklist.m_lock);
m_worklist.m_condition->notifyAll(locker);
}
m_myPlans.clear();
LockHolder locker(*m_worklist.m_lock);
m_worklist.m_numAvailableThreads++;
return WorkResult::Continue;
}
private:
JITWorklist& m_worklist;
Plans m_myPlans;
};
JITWorklist::JITWorklist()
: m_lock(Box<Lock>::create())
, m_condition(AutomaticThreadCondition::create())
{
LockHolder locker(*m_lock);
m_thread = new Thread(locker, *this);
}
JITWorklist::~JITWorklist()
{
UNREACHABLE_FOR_PLATFORM();
}
bool JITWorklist::completeAllForVM(VM& vm)
{
bool result = false;
DeferGC deferGC(vm.heap);
for (;;) {
Vector<RefPtr<Plan>, 32> myPlans;
{
LockHolder locker(*m_lock);
for (;;) {
bool didFindUnfinishedPlan = false;
m_plans.removeAllMatching(
[&] (RefPtr<Plan>& plan) {
if (&plan->vm() != &vm)
return false;
if (!plan->isFinishedCompiling()) {
didFindUnfinishedPlan = true;
return false;
}
myPlans.append(WTFMove(plan));
return true;
});
// If we found plans then we should finalize them now.
if (!myPlans.isEmpty())
break;
// If we don't find plans, then we're either done or we need to wait, depending on
// whether we found some unfinished plans.
if (!didFindUnfinishedPlan)
return result;
m_condition->wait(*m_lock);
}
}
RELEASE_ASSERT(!myPlans.isEmpty());
result = true;
finalizePlans(myPlans);
}
}
void JITWorklist::poll(VM& vm)
{
DeferGC deferGC(vm.heap);
Plans myPlans;
{
LockHolder locker(*m_lock);
m_plans.removeAllMatching(
[&] (RefPtr<Plan>& plan) {
if (&plan->vm() != &vm)
return false;
if (!plan->isFinishedCompiling())
return false;
myPlans.append(WTFMove(plan));
return true;
});
}
finalizePlans(myPlans);
}
void JITWorklist::compileLater(CodeBlock* codeBlock, unsigned loopOSREntryBytecodeOffset)
{
DeferGC deferGC(codeBlock->vm().heap);
RELEASE_ASSERT(codeBlock->jitType() == JITType::InterpreterThunk);
if (codeBlock->m_didFailJITCompilation) {
codeBlock->dontJITAnytimeSoon();
return;
}
if (!Options::useConcurrentJIT()) {
Plan::compileNow(codeBlock, loopOSREntryBytecodeOffset);
return;
}
codeBlock->jitSoon();
{
LockHolder locker(*m_lock);
if (m_planned.contains(codeBlock))
return;
if (m_numAvailableThreads) {
m_planned.add(codeBlock);
RefPtr<Plan> plan = adoptRef(new Plan(codeBlock, loopOSREntryBytecodeOffset));
m_plans.append(plan);
m_queue.append(plan);
m_condition->notifyAll(locker);
return;
}
}
// Compiling on the main thread if the helper thread isn't available is a defense against this
// pathology:
//
// 1) Do something that is allowed to take a while, like load a giant piece of initialization
// code. This plans the compile of the init code, but doesn't finish it. It will take a
// while.
//
// 2) Do something that is supposed to be quick. Now all baseline compiles, and so all DFG and
// FTL compiles, of everything is blocked on the long-running baseline compile of that
// initialization code.
//
// The single-threaded concurrent JIT has this tendency to convoy everything while at the same
// time postponing when it happens, which means that the convoy delays are less predictable.
// This works around the issue. If the concurrent JIT thread is convoyed, we revert to main
// thread compiles. This is probably not as good as if we had multiple JIT threads. Maybe we
// can do that someday.
Plan::compileNow(codeBlock, loopOSREntryBytecodeOffset);
}
void JITWorklist::compileNow(CodeBlock* codeBlock, unsigned loopOSREntryBytecodeOffset)
{
VM& vm = codeBlock->vm();
DeferGC deferGC(vm.heap);
if (codeBlock->jitType() != JITType::InterpreterThunk)
return;
bool isPlanned;
{
LockHolder locker(*m_lock);
isPlanned = m_planned.contains(codeBlock);
}
if (isPlanned) {
RELEASE_ASSERT(Options::useConcurrentJIT());
// This is expensive, but probably good enough.
completeAllForVM(vm);
}
// Now it might be compiled!
if (codeBlock->jitType() != JITType::InterpreterThunk)
return;
// We do this in case we had previously attempted, and then failed, to compile with the
// baseline JIT.
codeBlock->resetJITData();
// OK, just compile it.
JIT::compile(vm, codeBlock, JITCompilationMustSucceed, loopOSREntryBytecodeOffset);
codeBlock->ownerExecutable()->installCode(codeBlock);
}
void JITWorklist::finalizePlans(Plans& myPlans)
{
for (RefPtr<Plan>& plan : myPlans) {
plan->finalize();
LockHolder locker(*m_lock);
m_planned.remove(plan->codeBlock());
}
}
static JITWorklist* theGlobalJITWorklist { nullptr };
JITWorklist* JITWorklist::existingGlobalWorklistOrNull()
{
return theGlobalJITWorklist;
}
JITWorklist& JITWorklist::ensureGlobalWorklist()
{
static std::once_flag once;
std::call_once(
once,
[] {
auto* worklist = new JITWorklist();
WTF::storeStoreFence();
theGlobalJITWorklist = worklist;
});
return *theGlobalJITWorklist;
}
} // namespace JSC
#endif // ENABLE(JIT)