| /* |
| * Copyright (C) 2012-2019 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 "CallLinkStatus.h" |
| |
| #include "BytecodeStructs.h" |
| #include "CallLinkInfo.h" |
| #include "CodeBlock.h" |
| #include "JSCInlines.h" |
| #include <wtf/CommaPrinter.h> |
| #include <wtf/ListDump.h> |
| |
| namespace JSC { |
| |
| namespace CallLinkStatusInternal { |
| static constexpr bool verbose = false; |
| } |
| |
| CallLinkStatus::CallLinkStatus(JSValue value) |
| : m_couldTakeSlowPath(false) |
| , m_isProved(false) |
| { |
| if (!value || !value.isCell()) { |
| m_couldTakeSlowPath = true; |
| return; |
| } |
| |
| m_variants.append(CallVariant(value.asCell())); |
| } |
| |
| CallLinkStatus CallLinkStatus::computeFor( |
| CodeBlock* profiledBlock, BytecodeIndex bytecodeIndex, const ICStatusMap& map, |
| ExitSiteData exitSiteData) |
| { |
| ConcurrentJSLocker locker(profiledBlock->m_lock); |
| |
| UNUSED_PARAM(profiledBlock); |
| UNUSED_PARAM(bytecodeIndex); |
| UNUSED_PARAM(map); |
| UNUSED_PARAM(exitSiteData); |
| #if ENABLE(DFG_JIT) |
| CallLinkInfo* callLinkInfo = map.get(CodeOrigin(bytecodeIndex)).callLinkInfo; |
| if (!callLinkInfo) |
| return CallLinkStatus(); |
| // doneLocation is nullptr when it is tied to LLInt (not Baseline). |
| if (!callLinkInfo->doneLocation()) { |
| if (exitSiteData.takesSlowPath) |
| return takesSlowPath(); |
| #if ENABLE(DFG_JIT) |
| if (profiledBlock->unlinkedCodeBlock()->hasExitSite(DFG::FrequentExitSite(bytecodeIndex, BadConstantValue))) { |
| // We could force this to be a closure call, but instead we'll just assume that it |
| // takes slow path. |
| return takesSlowPath(); |
| } |
| #endif |
| } |
| |
| return computeFor(locker, profiledBlock, *callLinkInfo, exitSiteData); |
| #else |
| return CallLinkStatus(); |
| #endif |
| } |
| |
| CallLinkStatus CallLinkStatus::computeFor( |
| CodeBlock* profiledBlock, BytecodeIndex bytecodeIndex, const ICStatusMap& map) |
| { |
| return computeFor(profiledBlock, bytecodeIndex, map, computeExitSiteData(profiledBlock, bytecodeIndex)); |
| } |
| |
| CallLinkStatus::ExitSiteData CallLinkStatus::computeExitSiteData(CodeBlock* profiledBlock, BytecodeIndex bytecodeIndex) |
| { |
| ExitSiteData exitSiteData; |
| #if ENABLE(DFG_JIT) |
| UnlinkedCodeBlock* codeBlock = profiledBlock->unlinkedCodeBlock(); |
| ConcurrentJSLocker locker(codeBlock->m_lock); |
| |
| auto takesSlowPath = [&] (ExitingInlineKind inlineKind) -> ExitFlag { |
| return ExitFlag( |
| codeBlock->hasExitSite(locker, DFG::FrequentExitSite(bytecodeIndex, BadType, ExitFromAnything, inlineKind)) |
| || codeBlock->hasExitSite(locker, DFG::FrequentExitSite(bytecodeIndex, BadExecutable, ExitFromAnything, inlineKind)), |
| inlineKind); |
| }; |
| |
| auto badFunction = [&] (ExitingInlineKind inlineKind) -> ExitFlag { |
| return ExitFlag(codeBlock->hasExitSite(locker, DFG::FrequentExitSite(bytecodeIndex, BadConstantValue, ExitFromAnything, inlineKind)), inlineKind); |
| }; |
| |
| exitSiteData.takesSlowPath |= takesSlowPath(ExitFromNotInlined); |
| exitSiteData.takesSlowPath |= takesSlowPath(ExitFromInlined); |
| exitSiteData.badFunction |= badFunction(ExitFromNotInlined); |
| exitSiteData.badFunction |= badFunction(ExitFromInlined); |
| #else |
| UNUSED_PARAM(profiledBlock); |
| UNUSED_PARAM(bytecodeIndex); |
| #endif |
| |
| return exitSiteData; |
| } |
| |
| #if ENABLE(JIT) |
| CallLinkStatus CallLinkStatus::computeFor( |
| const ConcurrentJSLocker& locker, CodeBlock* profiledBlock, CallLinkInfo& callLinkInfo) |
| { |
| // We don't really need this, but anytime we have to debug this code, it becomes indispensable. |
| UNUSED_PARAM(profiledBlock); |
| |
| CallLinkStatus result = computeFromCallLinkInfo(locker, callLinkInfo); |
| result.m_maxArgumentCountIncludingThis = callLinkInfo.maxArgumentCountIncludingThis(); |
| return result; |
| } |
| |
| CallLinkStatus CallLinkStatus::computeFromCallLinkInfo( |
| const ConcurrentJSLocker&, CallLinkInfo& callLinkInfo) |
| { |
| // We cannot tell you anything about direct calls. |
| if (callLinkInfo.isDirect()) |
| return CallLinkStatus(); |
| |
| if (callLinkInfo.clearedByGC() || callLinkInfo.clearedByVirtual()) |
| return takesSlowPath(); |
| |
| // Note that despite requiring that the locker is held, this code is racy with respect |
| // to the CallLinkInfo: it may get cleared while this code runs! This is because |
| // CallLinkInfo::unlink() may be called from a different CodeBlock than the one that owns |
| // the CallLinkInfo and currently we save space by not having CallLinkInfos know who owns |
| // them. So, there is no way for either the caller of CallLinkInfo::unlock() or unlock() |
| // itself to figure out which lock to lock. |
| // |
| // Fortunately, that doesn't matter. The only things we ask of CallLinkInfo - the slow |
| // path count, the stub, and the target - can all be asked racily. Stubs and targets can |
| // only be deleted at next GC, so if we load a non-null one, then it must contain data |
| // that is still marginally valid (i.e. the pointers ain't stale). This kind of raciness |
| // is probably OK for now. |
| |
| // PolymorphicCallStubRoutine is a GCAwareJITStubRoutine, so if non-null, it will stay alive |
| // until next GC even if the CallLinkInfo is concurrently cleared. Also, the variants list is |
| // never mutated after the PolymorphicCallStubRoutine is instantiated. We have some conservative |
| // fencing in place to make sure that we see the variants list after construction. |
| if (PolymorphicCallStubRoutine* stub = callLinkInfo.stub()) { |
| WTF::dependentLoadLoadFence(); |
| |
| if (!stub->hasEdges()) { |
| // This means we have an FTL profile, which has incomplete information. |
| // |
| // It's not clear if takesSlowPath() or CallLinkStatus() are appropriate here, but I |
| // think that takesSlowPath() is a narrow winner. |
| // |
| // Either way, this is telling us that the FTL had been led to believe that it's |
| // profitable not to inline anything. |
| return takesSlowPath(); |
| } |
| |
| CallEdgeList edges = stub->edges(); |
| |
| // Now that we've loaded the edges list, there are no further concurrency concerns. We will |
| // just manipulate and prune this list to our liking - mostly removing entries that are too |
| // infrequent and ensuring that it's sorted in descending order of frequency. |
| |
| RELEASE_ASSERT(edges.size()); |
| |
| std::sort( |
| edges.begin(), edges.end(), |
| [] (CallEdge a, CallEdge b) { |
| return a.count() > b.count(); |
| }); |
| RELEASE_ASSERT(edges.first().count() >= edges.last().count()); |
| |
| double totalCallsToKnown = 0; |
| double totalCallsToUnknown = callLinkInfo.slowPathCount(); |
| CallVariantList variants; |
| for (size_t i = 0; i < edges.size(); ++i) { |
| CallEdge edge = edges[i]; |
| // If the call is at the tail of the distribution, then we don't optimize it and we |
| // treat it as if it was a call to something unknown. We define the tail as being either |
| // a call that doesn't belong to the N most frequent callees (N = |
| // maxPolymorphicCallVariantsForInlining) or that has a total call count that is too |
| // small. |
| if (i >= Options::maxPolymorphicCallVariantsForInlining() |
| || edge.count() < Options::frequentCallThreshold()) |
| totalCallsToUnknown += edge.count(); |
| else { |
| totalCallsToKnown += edge.count(); |
| variants.append(edge.callee()); |
| } |
| } |
| |
| // Bail if we didn't find any calls that qualified. |
| RELEASE_ASSERT(!!totalCallsToKnown == !!variants.size()); |
| if (variants.isEmpty()) |
| return takesSlowPath(); |
| |
| // We require that the distribution of callees is skewed towards a handful of common ones. |
| if (totalCallsToKnown / totalCallsToUnknown < Options::minimumCallToKnownRate()) |
| return takesSlowPath(); |
| |
| RELEASE_ASSERT(totalCallsToKnown); |
| RELEASE_ASSERT(variants.size()); |
| |
| CallLinkStatus result; |
| result.m_variants = variants; |
| result.m_couldTakeSlowPath = !!totalCallsToUnknown; |
| result.m_isBasedOnStub = true; |
| return result; |
| } |
| |
| CallLinkStatus result; |
| |
| if (JSObject* target = callLinkInfo.lastSeenCallee()) { |
| CallVariant variant(target); |
| if (callLinkInfo.hasSeenClosure()) |
| variant = variant.despecifiedClosure(); |
| result.m_variants.append(variant); |
| } |
| |
| result.m_couldTakeSlowPath = !!callLinkInfo.slowPathCount(); |
| |
| return result; |
| } |
| |
| CallLinkStatus CallLinkStatus::computeFor( |
| const ConcurrentJSLocker& locker, CodeBlock* profiledBlock, CallLinkInfo& callLinkInfo, |
| ExitSiteData exitSiteData, ExitingInlineKind inlineKind) |
| { |
| CallLinkStatus result = computeFor(locker, profiledBlock, callLinkInfo); |
| result.accountForExits(exitSiteData, inlineKind); |
| return result; |
| } |
| |
| void CallLinkStatus::accountForExits(ExitSiteData exitSiteData, ExitingInlineKind inlineKind) |
| { |
| if (exitSiteData.badFunction.isSet(inlineKind)) { |
| if (isBasedOnStub()) { |
| // If we have a polymorphic stub, then having an exit site is not quite so useful. In |
| // most cases, the information in the stub has higher fidelity. |
| makeClosureCall(); |
| } else { |
| // We might not have a polymorphic stub for any number of reasons. When this happens, we |
| // are in less certain territory, so exit sites mean a lot. |
| m_couldTakeSlowPath = true; |
| } |
| } |
| |
| if (exitSiteData.takesSlowPath.isSet(inlineKind)) |
| m_couldTakeSlowPath = true; |
| } |
| |
| CallLinkStatus CallLinkStatus::computeFor( |
| CodeBlock* profiledBlock, CodeOrigin codeOrigin, |
| const ICStatusMap& baselineMap, const ICStatusContextStack& optimizedStack) |
| { |
| if (CallLinkStatusInternal::verbose) |
| dataLog("Figuring out call profiling for ", codeOrigin, "\n"); |
| ExitSiteData exitSiteData = computeExitSiteData(profiledBlock, codeOrigin.bytecodeIndex()); |
| if (CallLinkStatusInternal::verbose) { |
| dataLog("takesSlowPath = ", exitSiteData.takesSlowPath, "\n"); |
| dataLog("badFunction = ", exitSiteData.badFunction, "\n"); |
| } |
| |
| for (const ICStatusContext* context : optimizedStack) { |
| if (CallLinkStatusInternal::verbose) |
| dataLog("Examining status in ", pointerDump(context->optimizedCodeBlock), "\n"); |
| ICStatus status = context->get(codeOrigin); |
| |
| // If we have both a CallLinkStatus and a callLinkInfo for the same origin, then it means |
| // one of two things: |
| // |
| // 1) We initially thought that we'd be able to inline this call so we recorded a status |
| // but then we realized that it was pointless and gave up and emitted a normal call |
| // anyway. |
| // |
| // 2) We did a polymorphic call inline that had a slow path case. |
| // |
| // In the first case, it's essential that we use the callLinkInfo, since the status may |
| // be polymorphic but the link info benefits from polyvariant profiling. |
| // |
| // In the second case, it's essential that we use the status, since the callLinkInfo |
| // corresponds to the slow case. |
| // |
| // It would be annoying to distinguish those two cases. However, we know that: |
| // |
| // If the first case happens in the FTL, then it means that even with polyvariant |
| // profiling, we failed to do anything useful. That suggests that in the FTL, it's OK to |
| // prioritize the status. That status will again tell us to not do anything useful. |
| // |
| // The second case only happens in the FTL. |
| // |
| // Therefore, we prefer the status in the FTL and the info in the DFG. |
| // |
| // Luckily, this case doesn't matter for the other ICStatuses, since they never do the |
| // fast-path-slow-path control-flow-diamond style of IC inlining. It's either all fast |
| // path or it's a full IC. So, for them, if there is an IC status then it means case (1). |
| |
| bool checkStatusFirst = context->optimizedCodeBlock->jitType() == JITType::FTLJIT; |
| |
| auto bless = [&] (CallLinkStatus& result) { |
| if (!context->isInlined(codeOrigin)) |
| result.merge(computeFor(profiledBlock, codeOrigin.bytecodeIndex(), baselineMap, exitSiteData)); |
| }; |
| |
| auto checkInfo = [&] () -> CallLinkStatus { |
| if (!status.callLinkInfo) |
| return CallLinkStatus(); |
| |
| dataLogLnIf(CallLinkStatusInternal::verbose, "Have CallLinkInfo with CodeOrigin = ", codeOrigin, "\n"); |
| CallLinkStatus result; |
| { |
| ConcurrentJSLocker locker(context->optimizedCodeBlock->m_lock); |
| result = computeFor( |
| locker, context->optimizedCodeBlock, *status.callLinkInfo, exitSiteData, |
| context->inlineKind(codeOrigin)); |
| if (CallLinkStatusInternal::verbose) |
| dataLog("Got result: ", result, "\n"); |
| } |
| bless(result); |
| return result; |
| }; |
| |
| auto checkStatus = [&] () -> CallLinkStatus { |
| if (!status.callStatus) |
| return CallLinkStatus(); |
| CallLinkStatus result = *status.callStatus; |
| if (CallLinkStatusInternal::verbose) |
| dataLog("Have callStatus: ", result, "\n"); |
| result.accountForExits(exitSiteData, context->inlineKind(codeOrigin)); |
| bless(result); |
| return result; |
| }; |
| |
| if (checkStatusFirst) { |
| if (CallLinkStatus result = checkStatus()) |
| return result; |
| if (CallLinkStatus result = checkInfo()) |
| return result; |
| continue; |
| } |
| |
| if (CallLinkStatus result = checkInfo()) |
| return result; |
| if (CallLinkStatus result = checkStatus()) |
| return result; |
| } |
| |
| return computeFor(profiledBlock, codeOrigin.bytecodeIndex(), baselineMap, exitSiteData); |
| } |
| #endif |
| |
| void CallLinkStatus::setProvenConstantCallee(CallVariant variant) |
| { |
| m_variants = CallVariantList{ variant }; |
| m_couldTakeSlowPath = false; |
| m_isProved = true; |
| } |
| |
| bool CallLinkStatus::isClosureCall() const |
| { |
| for (unsigned i = m_variants.size(); i--;) { |
| if (m_variants[i].isClosureCall()) |
| return true; |
| } |
| return false; |
| } |
| |
| void CallLinkStatus::makeClosureCall() |
| { |
| m_variants = despecifiedVariantList(m_variants); |
| } |
| |
| bool CallLinkStatus::finalize(VM& vm) |
| { |
| for (CallVariant& variant : m_variants) { |
| if (!variant.finalize(vm)) |
| return false; |
| } |
| return true; |
| } |
| |
| void CallLinkStatus::merge(const CallLinkStatus& other) |
| { |
| m_couldTakeSlowPath |= other.m_couldTakeSlowPath; |
| |
| for (const CallVariant& otherVariant : other.m_variants) { |
| bool found = false; |
| for (CallVariant& thisVariant : m_variants) { |
| if (thisVariant.merge(otherVariant)) { |
| found = true; |
| break; |
| } |
| } |
| if (!found) |
| m_variants.append(otherVariant); |
| } |
| } |
| |
| void CallLinkStatus::filter(JSValue value) |
| { |
| m_variants.removeAllMatching( |
| [&] (CallVariant& variant) -> bool { |
| variant.filter(value); |
| return !variant; |
| }); |
| } |
| |
| void CallLinkStatus::dump(PrintStream& out) const |
| { |
| if (!isSet()) { |
| out.print("Not Set"); |
| return; |
| } |
| |
| CommaPrinter comma; |
| |
| if (m_isProved) |
| out.print(comma, "Statically Proved"); |
| |
| if (m_couldTakeSlowPath) |
| out.print(comma, "Could Take Slow Path"); |
| |
| if (m_isBasedOnStub) |
| out.print(comma, "Based On Stub"); |
| |
| if (!m_variants.isEmpty()) |
| out.print(comma, listDump(m_variants)); |
| |
| if (m_maxArgumentCountIncludingThis) |
| out.print(comma, "maxArgumentCountIncludingThis = ", m_maxArgumentCountIncludingThis); |
| } |
| |
| } // namespace JSC |
| |
