1 files changed, 196 insertions, 250 deletions

diff --git a/Source/JavaScriptCore/bytecode/GetByIdStatus.cpp b/Source/JavaScriptCore/bytecode/GetByIdStatus.cpp
index 89e5035f3..fbb3da1a5 100644
--- a/Source/JavaScriptCore/bytecode/GetByIdStatus.cpp
+++ b/Source/JavaScriptCore/bytecode/GetByIdStatus.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2012-2015 Apple Inc. All rights reserved.
+ * Copyright (C) 2012, 2013 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -26,54 +26,23 @@
 #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>
+#include "Operations.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)
+GetByIdStatus GetByIdStatus::computeFromLLInt(CodeBlock* profiledBlock, unsigned bytecodeIndex, StringImpl* uid)
 {
     UNUSED_PARAM(profiledBlock);
     UNUSED_PARAM(bytecodeIndex);
     UNUSED_PARAM(uid);
+#if ENABLE(LLINT)
     Instruction* instruction = profiledBlock->instructions().begin() + bytecodeIndex;
     
-    if (instruction[0].u.opcode == LLInt::getOpcode(op_get_array_length))
+    if (instruction[0].u.opcode == LLInt::getOpcode(llint_op_get_array_length))
         return GetByIdStatus(NoInformation, false);
 
     Structure* structure = instruction[4].u.structure.get();
@@ -84,276 +53,253 @@ GetByIdStatus GetByIdStatus::computeFromLLInt(CodeBlock* profiledBlock, unsigned
         return GetByIdStatus(NoInformation, false);
 
     unsigned attributesIgnored;
-    PropertyOffset offset = structure->getConcurrently(uid, attributesIgnored);
+    JSCell* specificValue;
+    PropertyOffset offset = structure->getConcurrently(
+        *profiledBlock->vm(), uid, attributesIgnored, specificValue);
+    if (structure->isDictionary())
+        specificValue = 0;
     if (!isValidOffset(offset))
         return GetByIdStatus(NoInformation, false);
     
-    return GetByIdStatus(Simple, false, GetByIdVariant(StructureSet(structure), offset));
+    return GetByIdStatus(Simple, false, StructureSet(structure), offset, specificValue);
+#else
+    return GetByIdStatus(NoInformation, false);
+#endif
 }
 
-GetByIdStatus GetByIdStatus::computeFor(CodeBlock* profiledBlock, StubInfoMap& map, unsigned bytecodeIndex, UniquedStringImpl* uid)
+void GetByIdStatus::computeForChain(GetByIdStatus& result, CodeBlock* profiledBlock, StringImpl* uid)
 {
-    ConcurrentJITLocker locker(profiledBlock->m_lock);
+#if ENABLE(JIT)
+    // Validate the chain. If the chain is invalid, then currently the best thing
+    // we can do is to assume that TakesSlow is true. In the future, it might be
+    // worth exploring reifying the structure chain from the structure we've got
+    // instead of using the one from the cache, since that will do the right things
+    // if the structure chain has changed. But that may be harder, because we may
+    // then end up having a different type of access altogether. And it currently
+    // does not appear to be worth it to do so -- effectively, the heuristic we
+    // have now is that if the structure chain has changed between when it was
+    // cached on in the baseline JIT and when the DFG tried to inline the access,
+    // then we fall back on a polymorphic access.
+    if (!result.m_chain->isStillValid())
+        return;
 
-    GetByIdStatus result;
+    if (result.m_chain->head()->takesSlowPathInDFGForImpureProperty())
+        return;
+    size_t chainSize = result.m_chain->size();
+    for (size_t i = 0; i < chainSize; i++) {
+        if (result.m_chain->at(i)->takesSlowPathInDFGForImpureProperty())
+            return;
+    }
 
-#if ENABLE(DFG_JIT)
-    result = computeForStubInfoWithoutExitSiteFeedback(
-        locker, profiledBlock, map.get(CodeOrigin(bytecodeIndex)), uid,
-        CallLinkStatus::computeExitSiteData(locker, profiledBlock, bytecodeIndex));
+    JSObject* currentObject = result.m_chain->terminalPrototype();
+    Structure* currentStructure = result.m_chain->last();
     
-    if (!result.takesSlowPath()
-        && hasExitSite(locker, profiledBlock, bytecodeIndex))
-        return GetByIdStatus(result.makesCalls() ? MakesCalls : TakesSlowPath, true);
+    ASSERT_UNUSED(currentObject, currentObject);
+        
+    unsigned attributesIgnored;
+    JSCell* specificValue;
+        
+    result.m_offset = currentStructure->getConcurrently(
+        *profiledBlock->vm(), uid, attributesIgnored, specificValue);
+    if (currentStructure->isDictionary())
+        specificValue = 0;
+    if (!isValidOffset(result.m_offset))
+        return;
+        
+    result.m_structureSet.add(result.m_chain->head());
+    result.m_specificValue = JSValue(specificValue);
 #else
-    UNUSED_PARAM(map);
+    UNUSED_PARAM(result);
+    UNUSED_PARAM(profiledBlock);
+    UNUSED_PARAM(uid);
+    UNREACHABLE_FOR_PLATFORM();
 #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)
+GetByIdStatus GetByIdStatus::computeFor(CodeBlock* profiledBlock, StubInfoMap& map, unsigned bytecodeIndex, StringImpl* uid)
 {
-    if (!stubInfo)
-        return GetByIdStatus(NoInformation);
+    ConcurrentJITLocker locker(profiledBlock->m_lock);
     
-    if (!stubInfo->seen)
-        return GetByIdStatus(NoInformation);
+    UNUSED_PARAM(profiledBlock);
+    UNUSED_PARAM(bytecodeIndex);
+    UNUSED_PARAM(uid);
+#if ENABLE(JIT)
+    StructureStubInfo* stubInfo = map.get(CodeOrigin(bytecodeIndex));
+    if (!stubInfo || !stubInfo->seen)
+        return computeFromLLInt(profiledBlock, bytecodeIndex, uid);
     
-    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->resetByGC)
+        return GetByIdStatus(TakesSlowPath, true);
+
+    PolymorphicAccessStructureList* list;
+    int listSize;
+    switch (stubInfo->accessType) {
+    case access_get_by_id_self_list:
+        list = stubInfo->u.getByIdSelfList.structureList;
+        listSize = stubInfo->u.getByIdSelfList.listSize;
+        break;
+    case access_get_by_id_proto_list:
+        list = stubInfo->u.getByIdProtoList.structureList;
+        listSize = stubInfo->u.getByIdProtoList.listSize;
+        break;
+    default:
+        list = 0;
+        listSize = 0;
+        break;
+    }
+    for (int i = 0; i < listSize; ++i) {
+        if (!list->list[i].isDirect)
+            return GetByIdStatus(MakesCalls, true);
     }
     
-    if (stubInfo->tookSlowPath)
-        return GetByIdStatus(slowPathState);
+    // Next check if it takes slow case, in which case we want to be kind of careful.
+    if (profiledBlock->likelyToTakeSlowCase(bytecodeIndex))
+        return GetByIdStatus(TakesSlowPath, true);
     
     // 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);
+        return computeFromLLInt(profiledBlock, bytecodeIndex, uid);
         
     case access_get_by_id_self: {
         Structure* structure = stubInfo->u.getByIdSelf.baseObjectStructure.get();
         if (structure->takesSlowPathInDFGForImpureProperty())
-            return GetByIdStatus(slowPathState, true);
+            return GetByIdStatus(TakesSlowPath, true);
         unsigned attributesIgnored;
-        GetByIdVariant variant;
-        variant.m_offset = structure->getConcurrently(uid, attributesIgnored);
-        if (!isValidOffset(variant.m_offset))
-            return GetByIdStatus(slowPathState, true);
+        JSCell* specificValue;
+        result.m_offset = structure->getConcurrently(
+            *profiledBlock->vm(), uid, attributesIgnored, specificValue);
+        if (structure->isDictionary())
+            specificValue = 0;
         
-        variant.m_structureSet.add(structure);
-        bool didAppend = result.appendVariant(variant);
-        ASSERT_UNUSED(didAppend, didAppend);
-        return result;
+        if (isValidOffset(result.m_offset)) {
+            result.m_structureSet.add(structure);
+            result.m_specificValue = JSValue(specificValue);
+        }
+        
+        if (isValidOffset(result.m_offset))
+            ASSERT(result.m_structureSet.size());
+        break;
     }
         
-    case access_get_by_id_list: {
-        for (unsigned listIndex = 0; listIndex < list->size(); ++listIndex) {
-            Structure* structure = list->at(listIndex).structure();
+    case access_get_by_id_self_list: {
+        for (int i = 0; i < listSize; ++i) {
+            ASSERT(list->list[i].isDirect);
             
-            ComplexGetStatus complexGetStatus = ComplexGetStatus::computeFor(
-                structure, list->at(listIndex).conditionSet(), uid);
-             
-            switch (complexGetStatus.kind()) {
-            case ComplexGetStatus::ShouldSkip:
+            Structure* structure = list->list[i].base.get();
+            if (structure->takesSlowPathInDFGForImpureProperty())
+                return GetByIdStatus(TakesSlowPath, true);
+
+            if (result.m_structureSet.contains(structure))
                 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);
+            
+            unsigned attributesIgnored;
+            JSCell* specificValue;
+            PropertyOffset myOffset = structure->getConcurrently(
+                *profiledBlock->vm(), uid, attributesIgnored, specificValue);
+            if (structure->isDictionary())
+                specificValue = 0;
+            
+            if (!isValidOffset(myOffset)) {
+                result.m_offset = invalidOffset;
+                break;
+            }
+                    
+            if (!i) {
+                result.m_offset = myOffset;
+                result.m_specificValue = JSValue(specificValue);
+            } else if (result.m_offset != myOffset) {
+                result.m_offset = invalidOffset;
                 break;
-            } }
+            } else if (result.m_specificValue != JSValue(specificValue))
+                result.m_specificValue = JSValue();
+            
+            result.m_structureSet.add(structure);
         }
+                    
+        if (isValidOffset(result.m_offset))
+            ASSERT(result.m_structureSet.size());
+        break;
+    }
         
-        return result;
+    case access_get_by_id_proto: {
+        if (!stubInfo->u.getByIdProto.isDirect)
+            return GetByIdStatus(MakesCalls, true);
+        result.m_chain = adoptRef(new IntendedStructureChain(
+            profiledBlock,
+            stubInfo->u.getByIdProto.baseObjectStructure.get(),
+            stubInfo->u.getByIdProto.prototypeStructure.get()));
+        computeForChain(result, profiledBlock, uid);
+        break;
+    }
+        
+    case access_get_by_id_chain: {
+        if (!stubInfo->u.getByIdChain.isDirect)
+            return GetByIdStatus(MakesCalls, true);
+        result.m_chain = adoptRef(new IntendedStructureChain(
+            profiledBlock,
+            stubInfo->u.getByIdChain.baseObjectStructure.get(),
+            stubInfo->u.getByIdChain.chain.get(),
+            stubInfo->u.getByIdChain.count));
+        computeForChain(result, profiledBlock, uid);
+        break;
     }
         
     default:
-        return GetByIdStatus(slowPathState, true);
+        ASSERT(!isValidOffset(result.m_offset));
+        break;
     }
     
-    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;
+    if (!isValidOffset(result.m_offset)) {
+        result.m_state = TakesSlowPath;
+        result.m_structureSet.clear();
+        result.m_chain.clear();
+        result.m_specificValue = JSValue();
+    } else
+        result.m_state = Simple;
     
-        {
-            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);
+    return result;
+#else // ENABLE(JIT)
+    UNUSED_PARAM(map);
+    return GetByIdStatus(NoInformation, false);
+#endif // ENABLE(JIT)
 }
 
-GetByIdStatus GetByIdStatus::computeFor(const StructureSet& set, UniquedStringImpl* uid)
+GetByIdStatus GetByIdStatus::computeFor(VM& vm, Structure* structure, StringImpl* 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 (!structure)
+        return GetByIdStatus(TakesSlowPath);
 
-    if (parseIndex(*uid))
+    if (toUInt32FromStringImpl(uid) != PropertyName::NotAnIndex)
         return GetByIdStatus(TakesSlowPath);
     
+    if (structure->typeInfo().overridesGetOwnPropertySlot() && structure->typeInfo().type() != GlobalObjectType)
+        return GetByIdStatus(TakesSlowPath);
+    
+    if (!structure->propertyAccessesAreCacheable())
+        return GetByIdStatus(TakesSlowPath);
+
     GetByIdStatus result;
+    result.m_wasSeenInJIT = false; // To my knowledge nobody that uses computeFor(VM&, Structure*, StringImpl*) reads this field, but I might as well be honest: no, it wasn't seen in the JIT, since I computed it statically.
+    unsigned attributes;
+    JSCell* specificValue;
+    result.m_offset = structure->getConcurrently(vm, uid, attributes, specificValue);
+    if (!isValidOffset(result.m_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);
+    if (structure->isDictionary())
+        specificValue = 0;
+    result.m_structureSet.add(structure);
+    result.m_specificValue = JSValue(specificValue);
     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