bytecode/PutByIdStatus.cpp

   1 /*
   2  * Copyright (C) 2012, 2013, 2014 Apple Inc. All rights reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  *
  13  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
  14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
  17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  24  */
  25
  26 #include "config.h"
  27 #include "PutByIdStatus.h"
  28
  29 #include "CodeBlock.h"
  30 #include "LLIntData.h"
  31 #include "LowLevelInterpreter.h"
  32 #include "JSCInlines.h"
  33 #include "PolymorphicPutByIdList.h"
  34 #include "Structure.h"
  35 #include "StructureChain.h"
  36 #include <wtf/ListDump.h>
  37
  38 namespace JSC {
  39
  40 bool PutByIdStatus::appendVariant(const PutByIdVariant& variant)
  41 {
  42     for (unsigned i = 0; i < m_variants.size(); ++i) {
  43         if (m_variants[i].oldStructure() == variant.oldStructure())
  44             return false;
  45     }
  46     m_variants.append(variant);
  47     return true;
  48 }
  49
  50 #if ENABLE(DFG_JIT)
  51 bool PutByIdStatus::hasExitSite(const ConcurrentJITLocker& locker, CodeBlock* profiledBlock, unsigned bytecodeIndex, ExitingJITType exitType)
  52 {
  53     return profiledBlock->hasExitSite(locker, DFG::FrequentExitSite(bytecodeIndex, BadCache, exitType))
  54         || profiledBlock->hasExitSite(locker, DFG::FrequentExitSite(bytecodeIndex, BadCacheWatchpoint, exitType))
  55         || profiledBlock->hasExitSite(locker, DFG::FrequentExitSite(bytecodeIndex, BadWeakConstantCache, exitType))
  56         || profiledBlock->hasExitSite(locker, DFG::FrequentExitSite(bytecodeIndex, BadWeakConstantCacheWatchpoint, exitType));
  57
  58 }
  59 #endif
  60
  61 PutByIdStatus PutByIdStatus::computeFromLLInt(CodeBlock* profiledBlock, unsigned bytecodeIndex, StringImpl* uid)
  62 {
  63     UNUSED_PARAM(profiledBlock);
  64     UNUSED_PARAM(bytecodeIndex);
  65     UNUSED_PARAM(uid);
  66     Instruction* instruction = profiledBlock->instructions().begin() + bytecodeIndex;
  67
  68     Structure* structure = instruction[4].u.structure.get();
  69     if (!structure)
  70         return PutByIdStatus(NoInformation);
  71
  72     if (instruction[0].u.opcode == LLInt::getOpcode(op_put_by_id)
  73         || instruction[0].u.opcode == LLInt::getOpcode(op_put_by_id_out_of_line)) {
  74         PropertyOffset offset = structure->getConcurrently(*profiledBlock->vm(), uid);
  75         if (!isValidOffset(offset))
  76             return PutByIdStatus(NoInformation);
  77
  78         return PutByIdVariant::replace(structure, offset);
  79     }
  80
  81     ASSERT(structure->transitionWatchpointSetHasBeenInvalidated());
  82
  83     ASSERT(instruction[0].u.opcode == LLInt::getOpcode(op_put_by_id_transition_direct)
  84         || instruction[0].u.opcode == LLInt::getOpcode(op_put_by_id_transition_normal)
  85         || instruction[0].u.opcode == LLInt::getOpcode(op_put_by_id_transition_direct_out_of_line)
  86         || instruction[0].u.opcode == LLInt::getOpcode(op_put_by_id_transition_normal_out_of_line));
  87
  88     Structure* newStructure = instruction[6].u.structure.get();
  89     StructureChain* chain = instruction[7].u.structureChain.get();
  90     ASSERT(newStructure);
  91     ASSERT(chain);
  92
  93     PropertyOffset offset = newStructure->getConcurrently(*profiledBlock->vm(), uid);
  94     if (!isValidOffset(offset))
  95         return PutByIdStatus(NoInformation);
  96
  97     return PutByIdVariant::transition(
  98         structure, newStructure,
  99         chain ? adoptRef(new IntendedStructureChain(profiledBlock, structure, chain)) : 0,
 100         offset);
 101 }
 102
 103 PutByIdStatus PutByIdStatus::computeFor(CodeBlock* profiledBlock, StubInfoMap& map, unsigned bytecodeIndex, StringImpl* uid)
 104 {
 105     ConcurrentJITLocker locker(profiledBlock->m_lock);
 106
 107     UNUSED_PARAM(profiledBlock);
 108     UNUSED_PARAM(bytecodeIndex);
 109     UNUSED_PARAM(uid);
 110 #if ENABLE(DFG_JIT)
 111     if (profiledBlock->likelyToTakeSlowCase(bytecodeIndex)
 112         || hasExitSite(locker, profiledBlock, bytecodeIndex))
 113         return PutByIdStatus(TakesSlowPath);
 114
 115     StructureStubInfo* stubInfo = map.get(CodeOrigin(bytecodeIndex));
 116     PutByIdStatus result = computeForStubInfo(locker, profiledBlock, stubInfo, uid);
 117     if (!result)
 118         return computeFromLLInt(profiledBlock, bytecodeIndex, uid);
 119
 120     return result;
 121 #else // ENABLE(JIT)
 122     UNUSED_PARAM(map);
 123     return PutByIdStatus(NoInformation);
 124 #endif // ENABLE(JIT)
 125 }
 126
 127 #if ENABLE(JIT)
 128 PutByIdStatus PutByIdStatus::computeForStubInfo(const ConcurrentJITLocker&, CodeBlock* profiledBlock, StructureStubInfo* stubInfo, StringImpl* uid)
 129 {
 130     if (!stubInfo || !stubInfo->seen)
 131         return PutByIdStatus();
 132
 133     if (stubInfo->resetByGC)
 134         return PutByIdStatus(TakesSlowPath);
 135
 136     switch (stubInfo->accessType) {
 137     case access_unset:
 138         // If the JIT saw it but didn't optimize it, then assume that this takes slow path.
 139         return PutByIdStatus(TakesSlowPath);
 140
 141     case access_put_by_id_replace: {
 142         PropertyOffset offset =
 143             stubInfo->u.putByIdReplace.baseObjectStructure->getConcurrently(
 144                 *profiledBlock->vm(), uid);
 145         if (isValidOffset(offset)) {
 146             return PutByIdVariant::replace(
 147                 stubInfo->u.putByIdReplace.baseObjectStructure.get(), offset);
 148         }
 149         return PutByIdStatus(TakesSlowPath);
 150     }
 151
 152     case access_put_by_id_transition_normal:
 153     case access_put_by_id_transition_direct: {
 154         ASSERT(stubInfo->u.putByIdTransition.previousStructure->transitionWatchpointSetHasBeenInvalidated());
 155         PropertyOffset offset =
 156             stubInfo->u.putByIdTransition.structure->getConcurrently(
 157                 *profiledBlock->vm(), uid);
 158         if (isValidOffset(offset)) {
 159             return PutByIdVariant::transition(
 160                 stubInfo->u.putByIdTransition.previousStructure.get(),
 161                 stubInfo->u.putByIdTransition.structure.get(),
 162                 stubInfo->u.putByIdTransition.chain ? adoptRef(new IntendedStructureChain(
 163                     profiledBlock, stubInfo->u.putByIdTransition.previousStructure.get(),
 164                     stubInfo->u.putByIdTransition.chain.get())) : 0,
 165                 offset);
 166         }
 167         return PutByIdStatus(TakesSlowPath);
 168     }
 169
 170     case access_put_by_id_list: {
 171         PolymorphicPutByIdList* list = stubInfo->u.putByIdList.list;
 172
 173         PutByIdStatus result;
 174         result.m_state = Simple;
 175
 176         for (unsigned i = 0; i < list->size(); ++i) {
 177             const PutByIdAccess& access = list->at(i);
 178
 179             switch (access.type()) {
 180             case PutByIdAccess::Replace: {
 181                 Structure* structure = access.structure();
 182                 PropertyOffset offset = structure->getConcurrently(*profiledBlock->vm(), uid);
 183                 if (!isValidOffset(offset))
 184                     return PutByIdStatus(TakesSlowPath);
 185                 if (!result.appendVariant(PutByIdVariant::replace(structure, offset)))
 186                     return PutByIdStatus(TakesSlowPath);
 187                 break;
 188             }
 189
 190             case PutByIdAccess::Transition: {
 191                 PropertyOffset offset =
 192                     access.newStructure()->getConcurrently(*profiledBlock->vm(), uid);
 193                 if (!isValidOffset(offset))
 194                     return PutByIdStatus(TakesSlowPath);
 195                 bool ok = result.appendVariant(PutByIdVariant::transition(
 196                     access.oldStructure(), access.newStructure(),
 197                     access.chain() ? adoptRef(new IntendedStructureChain(
 198                         profiledBlock, access.oldStructure(), access.chain())) : 0,
 199                     offset));
 200                 if (!ok)
 201                     return PutByIdStatus(TakesSlowPath);
 202                 break;
 203             }
 204             case PutByIdAccess::Setter:
 205             case PutByIdAccess::CustomSetter:
 206                 return PutByIdStatus(MakesCalls);
 207
 208             default:
 209                 return PutByIdStatus(TakesSlowPath);
 210             }
 211         }
 212
 213         return result;
 214     }
 215
 216     default:
 217         return PutByIdStatus(TakesSlowPath);
 218     }
 219 }
 220 #endif
 221
 222 PutByIdStatus PutByIdStatus::computeFor(CodeBlock* baselineBlock, CodeBlock* dfgBlock, StubInfoMap& baselineMap, StubInfoMap& dfgMap, CodeOrigin codeOrigin, StringImpl* uid)
 223 {
 224 #if ENABLE(DFG_JIT)
 225     if (dfgBlock) {
 226         {
 227             ConcurrentJITLocker locker(baselineBlock->m_lock);
 228             if (hasExitSite(locker, baselineBlock, codeOrigin.bytecodeIndex, ExitFromFTL))
 229                 return PutByIdStatus(TakesSlowPath);
 230         }
 231
 232         PutByIdStatus result;
 233         {
 234             ConcurrentJITLocker locker(dfgBlock->m_lock);
 235             result = computeForStubInfo(locker, dfgBlock, dfgMap.get(codeOrigin), uid);
 236         }
 237
 238         // We use TakesSlowPath in some cases where the stub was unset. That's weird and
 239         // it would be better not to do that. But it means that we have to defend
 240         // ourselves here.
 241         if (result.isSimple())
 242             return result;
 243     }
 244 #else
 245     UNUSED_PARAM(dfgBlock);
 246     UNUSED_PARAM(dfgMap);
 247 #endif
 248
 249     return computeFor(baselineBlock, baselineMap, codeOrigin.bytecodeIndex, uid);
 250 }
 251
 252 PutByIdStatus PutByIdStatus::computeFor(VM& vm, JSGlobalObject* globalObject, Structure* structure, StringImpl* uid, bool isDirect)
 253 {
 254     if (toUInt32FromStringImpl(uid) != PropertyName::NotAnIndex)
 255         return PutByIdStatus(TakesSlowPath);
 256
 257     if (!structure)
 258         return PutByIdStatus(TakesSlowPath);
 259
 260     if (structure->typeInfo().overridesGetOwnPropertySlot() && structure->typeInfo().type() != GlobalObjectType)
 261         return PutByIdStatus(TakesSlowPath);
 262
 263     if (!structure->propertyAccessesAreCacheable())
 264         return PutByIdStatus(TakesSlowPath);
 265
 266     unsigned attributes;
 267     JSCell* specificValue;
 268     PropertyOffset offset = structure->getConcurrently(vm, uid, attributes, specificValue);
 269     if (isValidOffset(offset)) {
 270         if (attributes & CustomAccessor)
 271             return PutByIdStatus(MakesCalls);
 272
 273         if (attributes & (Accessor | ReadOnly))
 274             return PutByIdStatus(TakesSlowPath);
 275         if (specificValue) {
 276             // We need the PutById slow path to verify that we're storing the right value into
 277             // the specialized slot.
 278             return PutByIdStatus(TakesSlowPath);
 279         }
 280         return PutByIdVariant::replace(structure, offset);
 281     }
 282
 283     // Our hypothesis is that we're doing a transition. Before we prove that this is really
 284     // true, we want to do some sanity checks.
 285
 286     // Don't cache put transitions on dictionaries.
 287     if (structure->isDictionary())
 288         return PutByIdStatus(TakesSlowPath);
 289
 290     // If the structure corresponds to something that isn't an object, then give up, since
 291     // we don't want to be adding properties to strings.
 292     if (structure->typeInfo().type() == StringType)
 293         return PutByIdStatus(TakesSlowPath);
 294
 295     RefPtr<IntendedStructureChain> chain;
 296     if (!isDirect) {
 297         chain = adoptRef(new IntendedStructureChain(globalObject, structure));
 298
 299         // If the prototype chain has setters or read-only properties, then give up.
 300         if (chain->mayInterceptStoreTo(vm, uid))
 301             return PutByIdStatus(TakesSlowPath);
 302
 303         // If the prototype chain hasn't been normalized (i.e. there are proxies or dictionaries)
 304         // then give up. The dictionary case would only happen if this structure has not been
 305         // used in an optimized put_by_id transition. And really the only reason why we would
 306         // bail here is that I don't really feel like having the optimizing JIT go and flatten
 307         // dictionaries if we have evidence to suggest that those objects were never used as
 308         // prototypes in a cacheable prototype access - i.e. there's a good chance that some of
 309         // the other checks below will fail.
 310         if (!chain->isNormalized())
 311             return PutByIdStatus(TakesSlowPath);
 312     }
 313
 314     // We only optimize if there is already a structure that the transition is cached to.
 315     // Among other things, this allows us to guard against a transition with a specific
 316     // value.
 317     //
 318     // - If we're storing a value that could be specific: this would only be a problem if
 319     //   the existing transition did have a specific value already, since if it didn't,
 320     //   then we would behave "as if" we were not storing a specific value. If it did
 321     //   have a specific value, then we'll know - the fact that we pass 0 for
 322     //   specificValue will tell us.
 323     //
 324     // - If we're not storing a value that could be specific: again, this would only be a
 325     //   problem if the existing transition did have a specific value, which we check for
 326     //   by passing 0 for the specificValue.
 327     Structure* transition = Structure::addPropertyTransitionToExistingStructureConcurrently(structure, uid, 0, 0, offset);
 328     if (!transition)
 329         return PutByIdStatus(TakesSlowPath); // This occurs in bizarre cases only. See above.
 330     ASSERT(!transition->transitionDidInvolveSpecificValue());
 331     ASSERT(isValidOffset(offset));
 332
 333     return PutByIdVariant::transition(structure, transition, chain.release(), offset);
 334 }
 335
 336 void PutByIdStatus::dump(PrintStream& out) const
 337 {
 338     switch (m_state) {
 339     case NoInformation:
 340         out.print("(NoInformation)");
 341         return;
 342
 343     case Simple:
 344         out.print("(", listDump(m_variants), ")");
 345         return;
 346
 347     case TakesSlowPath:
 348         out.print("(TakesSlowPath)");
 349         return;
 350     case MakesCalls:
 351         out.print("(MakesCalls)");
 352         return;
 353     }
 354
 355     RELEASE_ASSERT_NOT_REACHED();
 356 }
 357
 358 } // namespace JSC
 359