1 files changed, 359 insertions, 0 deletions
diff --git a/Source/JavaScriptCore/bytecode/GetByIdStatus.cpp b/Source/JavaScriptCore/bytecode/GetByIdStatus.cpp
new file mode 100644
index 000000000..89e5035f3
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+++ b/Source/JavaScriptCore/bytecode/GetByIdStatus.cpp
@@ -0,0 +1,359 @@
+/*
+ * Copyright (C) 2012-2015 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 "GetByIdStatus.h"
+
+#include "AccessorCallJITStubRoutine.h"
+#include "CodeBlock.h"
+#include "ComplexGetStatus.h"
+#include "JSCInlines.h"
+#include "JSScope.h"
+#include "LLIntData.h"
+#include "LowLevelInterpreter.h"
+#include "PolymorphicGetByIdList.h"
+#include <wtf/ListDump.h>
+
+namespace JSC {
+
+bool GetByIdStatus::appendVariant(const GetByIdVariant& variant)
+{
+    // Attempt to merge this variant with an already existing variant.
+    for (unsigned i = 0; i < m_variants.size(); ++i) {
+        if (m_variants[i].attemptToMerge(variant))
+            return true;
+    }
+    
+    // Make sure there is no overlap. We should have pruned out opportunities for
+    // overlap but it's possible that an inline cache got into a weird state. We are
+    // defensive and bail if we detect crazy.
+    for (unsigned i = 0; i < m_variants.size(); ++i) {
+        if (m_variants[i].structureSet().overlaps(variant.structureSet()))
+            return false;
+    }
+    
+    m_variants.append(variant);
+    return true;
+}
+
+#if ENABLE(DFG_JIT)
+bool GetByIdStatus::hasExitSite(const ConcurrentJITLocker& locker, CodeBlock* profiledBlock, unsigned bytecodeIndex)
+{
+    return profiledBlock->hasExitSite(locker, DFG::FrequentExitSite(bytecodeIndex, BadCache))
+        || profiledBlock->hasExitSite(locker, DFG::FrequentExitSite(bytecodeIndex, BadConstantCache));
+}
+#endif
+
+GetByIdStatus GetByIdStatus::computeFromLLInt(CodeBlock* profiledBlock, unsigned bytecodeIndex, UniquedStringImpl* uid)
+{
+    UNUSED_PARAM(profiledBlock);
+    UNUSED_PARAM(bytecodeIndex);
+    UNUSED_PARAM(uid);
+    Instruction* instruction = profiledBlock->instructions().begin() + bytecodeIndex;
+    
+    if (instruction[0].u.opcode == LLInt::getOpcode(op_get_array_length))
+        return GetByIdStatus(NoInformation, false);
+
+    Structure* structure = instruction[4].u.structure.get();
+    if (!structure)
+        return GetByIdStatus(NoInformation, false);
+
+    if (structure->takesSlowPathInDFGForImpureProperty())
+        return GetByIdStatus(NoInformation, false);
+
+    unsigned attributesIgnored;
+    PropertyOffset offset = structure->getConcurrently(uid, attributesIgnored);
+    if (!isValidOffset(offset))
+        return GetByIdStatus(NoInformation, false);
+    
+    return GetByIdStatus(Simple, false, GetByIdVariant(StructureSet(structure), offset));
+}
+
+GetByIdStatus GetByIdStatus::computeFor(CodeBlock* profiledBlock, StubInfoMap& map, unsigned bytecodeIndex, UniquedStringImpl* uid)
+{
+    ConcurrentJITLocker locker(profiledBlock->m_lock);
+
+    GetByIdStatus result;
+
+#if ENABLE(DFG_JIT)
+    result = computeForStubInfoWithoutExitSiteFeedback(
+        locker, profiledBlock, map.get(CodeOrigin(bytecodeIndex)), uid,
+        CallLinkStatus::computeExitSiteData(locker, profiledBlock, bytecodeIndex));
+    
+    if (!result.takesSlowPath()
+        && hasExitSite(locker, profiledBlock, bytecodeIndex))
+        return GetByIdStatus(result.makesCalls() ? MakesCalls : TakesSlowPath, true);
+#else
+    UNUSED_PARAM(map);
+#endif
+
+    if (!result)
+        return computeFromLLInt(profiledBlock, bytecodeIndex, uid);
+    
+    return result;
+}
+
+#if ENABLE(JIT)
+GetByIdStatus GetByIdStatus::computeForStubInfo(const ConcurrentJITLocker& locker, CodeBlock* profiledBlock, StructureStubInfo* stubInfo, CodeOrigin codeOrigin, UniquedStringImpl* uid)
+{
+    GetByIdStatus result = GetByIdStatus::computeForStubInfoWithoutExitSiteFeedback(
+        locker, profiledBlock, stubInfo, uid,
+        CallLinkStatus::computeExitSiteData(locker, profiledBlock, codeOrigin.bytecodeIndex));
+
+    if (!result.takesSlowPath() && GetByIdStatus::hasExitSite(locker, profiledBlock, codeOrigin.bytecodeIndex))
+        return GetByIdStatus(result.makesCalls() ? GetByIdStatus::MakesCalls : GetByIdStatus::TakesSlowPath, true);
+    return result;
+}
+#endif // ENABLE(JIT)
+
+#if ENABLE(JIT)
+GetByIdStatus GetByIdStatus::computeForStubInfoWithoutExitSiteFeedback(
+    const ConcurrentJITLocker& locker, CodeBlock* profiledBlock, StructureStubInfo* stubInfo, UniquedStringImpl* uid,
+    CallLinkStatus::ExitSiteData callExitSiteData)
+{
+    if (!stubInfo)
+        return GetByIdStatus(NoInformation);
+    
+    if (!stubInfo->seen)
+        return GetByIdStatus(NoInformation);
+    
+    PolymorphicGetByIdList* list = 0;
+    State slowPathState = TakesSlowPath;
+    if (stubInfo->accessType == access_get_by_id_list) {
+        list = stubInfo->u.getByIdList.list;
+        for (unsigned i = 0; i < list->size(); ++i) {
+            const GetByIdAccess& access = list->at(i);
+            if (access.doesCalls())
+                slowPathState = MakesCalls;
+        }
+    }
+    
+    if (stubInfo->tookSlowPath)
+        return GetByIdStatus(slowPathState);
+    
+    // Finally figure out if we can derive an access strategy.
+    GetByIdStatus result;
+    result.m_state = Simple;
+    result.m_wasSeenInJIT = true; // This is interesting for bytecode dumping only.
+    switch (stubInfo->accessType) {
+    case access_unset:
+        return GetByIdStatus(NoInformation);
+        
+    case access_get_by_id_self: {
+        Structure* structure = stubInfo->u.getByIdSelf.baseObjectStructure.get();
+        if (structure->takesSlowPathInDFGForImpureProperty())
+            return GetByIdStatus(slowPathState, true);
+        unsigned attributesIgnored;
+        GetByIdVariant variant;
+        variant.m_offset = structure->getConcurrently(uid, attributesIgnored);
+        if (!isValidOffset(variant.m_offset))
+            return GetByIdStatus(slowPathState, true);
+        
+        variant.m_structureSet.add(structure);
+        bool didAppend = result.appendVariant(variant);
+        ASSERT_UNUSED(didAppend, didAppend);
+        return result;
+    }
+        
+    case access_get_by_id_list: {
+        for (unsigned listIndex = 0; listIndex < list->size(); ++listIndex) {
+            Structure* structure = list->at(listIndex).structure();
+            
+            ComplexGetStatus complexGetStatus = ComplexGetStatus::computeFor(
+                structure, list->at(listIndex).conditionSet(), uid);
+             
+            switch (complexGetStatus.kind()) {
+            case ComplexGetStatus::ShouldSkip:
+                continue;
+                 
+            case ComplexGetStatus::TakesSlowPath:
+                return GetByIdStatus(slowPathState, true);
+                 
+            case ComplexGetStatus::Inlineable: {
+                std::unique_ptr<CallLinkStatus> callLinkStatus;
+                switch (list->at(listIndex).type()) {
+                case GetByIdAccess::SimpleInline:
+                case GetByIdAccess::SimpleStub: {
+                    break;
+                }
+                case GetByIdAccess::Getter: {
+                    AccessorCallJITStubRoutine* stub = static_cast<AccessorCallJITStubRoutine*>(
+                        list->at(listIndex).stubRoutine());
+                    callLinkStatus = std::make_unique<CallLinkStatus>(
+                        CallLinkStatus::computeFor(
+                            locker, profiledBlock, *stub->m_callLinkInfo, callExitSiteData));
+                    break;
+                }
+                case GetByIdAccess::SimpleMiss:
+                case GetByIdAccess::CustomGetter:
+                case GetByIdAccess::WatchedStub:{
+                    // FIXME: It would be totally sweet to support this at some point in the future.
+                    // https://bugs.webkit.org/show_bug.cgi?id=133052
+                    return GetByIdStatus(slowPathState, true);
+                }
+                default:
+                    RELEASE_ASSERT_NOT_REACHED();
+                }
+                 
+                GetByIdVariant variant(
+                    StructureSet(structure), complexGetStatus.offset(),
+                    complexGetStatus.conditionSet(), WTF::move(callLinkStatus));
+                 
+                if (!result.appendVariant(variant))
+                    return GetByIdStatus(slowPathState, true);
+                break;
+            } }
+        }
+        
+        return result;
+    }
+        
+    default:
+        return GetByIdStatus(slowPathState, true);
+    }
+    
+    RELEASE_ASSERT_NOT_REACHED();
+    return GetByIdStatus();
+}
+#endif // ENABLE(JIT)
+
+GetByIdStatus GetByIdStatus::computeFor(
+    CodeBlock* profiledBlock, CodeBlock* dfgBlock, StubInfoMap& baselineMap,
+    StubInfoMap& dfgMap, CodeOrigin codeOrigin, UniquedStringImpl* uid)
+{
+#if ENABLE(DFG_JIT)
+    if (dfgBlock) {
+        CallLinkStatus::ExitSiteData exitSiteData;
+        {
+            ConcurrentJITLocker locker(profiledBlock->m_lock);
+            exitSiteData = CallLinkStatus::computeExitSiteData(
+                locker, profiledBlock, codeOrigin.bytecodeIndex);
+        }
+        
+        GetByIdStatus result;
+        {
+            ConcurrentJITLocker locker(dfgBlock->m_lock);
+            result = computeForStubInfoWithoutExitSiteFeedback(
+                locker, dfgBlock, dfgMap.get(codeOrigin), uid, exitSiteData);
+        }
+        
+        if (result.takesSlowPath())
+            return result;
+    
+        {
+            ConcurrentJITLocker locker(profiledBlock->m_lock);
+            if (hasExitSite(locker, profiledBlock, codeOrigin.bytecodeIndex))
+                return GetByIdStatus(TakesSlowPath, true);
+        }
+        
+        if (result.isSet())
+            return result;
+    }
+#else
+    UNUSED_PARAM(dfgBlock);
+    UNUSED_PARAM(dfgMap);
+#endif
+
+    return computeFor(profiledBlock, baselineMap, codeOrigin.bytecodeIndex, uid);
+}
+
+GetByIdStatus GetByIdStatus::computeFor(const StructureSet& set, UniquedStringImpl* uid)
+{
+    // For now we only handle the super simple self access case. We could handle the
+    // prototype case in the future.
+    
+    if (set.isEmpty())
+        return GetByIdStatus();
+
+    if (parseIndex(*uid))
+        return GetByIdStatus(TakesSlowPath);
+    
+    GetByIdStatus result;
+    result.m_state = Simple;
+    result.m_wasSeenInJIT = false;
+    for (unsigned i = 0; i < set.size(); ++i) {
+        Structure* structure = set[i];
+        if (structure->typeInfo().overridesGetOwnPropertySlot() && structure->typeInfo().type() != GlobalObjectType)
+            return GetByIdStatus(TakesSlowPath);
+        
+        if (!structure->propertyAccessesAreCacheable())
+            return GetByIdStatus(TakesSlowPath);
+        
+        unsigned attributes;
+        PropertyOffset offset = structure->getConcurrently(uid, attributes);
+        if (!isValidOffset(offset))
+            return GetByIdStatus(TakesSlowPath); // It's probably a prototype lookup. Give up on life for now, even though we could totally be way smarter about it.
+        if (attributes & Accessor)
+            return GetByIdStatus(MakesCalls); // We could be smarter here, like strenght-reducing this to a Call.
+        
+        if (!result.appendVariant(GetByIdVariant(structure, offset)))
+            return GetByIdStatus(TakesSlowPath);
+    }
+    
+    return result;
+}
+
+bool GetByIdStatus::makesCalls() const
+{
+    switch (m_state) {
+    case NoInformation:
+    case TakesSlowPath:
+        return false;
+    case Simple:
+        for (unsigned i = m_variants.size(); i--;) {
+            if (m_variants[i].callLinkStatus())
+                return true;
+        }
+        return false;
+    case MakesCalls:
+        return true;
+    }
+    RELEASE_ASSERT_NOT_REACHED();
+
+    return false;
+}
+
+void GetByIdStatus::dump(PrintStream& out) const
+{
+    out.print("(");
+    switch (m_state) {
+    case NoInformation:
+        out.print("NoInformation");
+        break;
+    case Simple:
+        out.print("Simple");
+        break;
+    case TakesSlowPath:
+        out.print("TakesSlowPath");
+        break;
+    case MakesCalls:
+        out.print("MakesCalls");
+        break;
+    }
+    out.print(", ", listDump(m_variants), ", seenInJIT = ", m_wasSeenInJIT, ")");
+}
+
+} // namespace JSC
+