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      1 /*
      2  * Copyright (C) 2012 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #include "reg_type_cache-inl.h"
     18 
     19 #include "base/casts.h"
     20 #include "class_linker-inl.h"
     21 #include "dex_file-inl.h"
     22 #include "mirror/class-inl.h"
     23 #include "mirror/object-inl.h"
     24 #include "reg_type-inl.h"
     25 
     26 namespace art {
     27 namespace verifier {
     28 
     29 bool RegTypeCache::primitive_initialized_ = false;
     30 uint16_t RegTypeCache::primitive_count_ = 0;
     31 const PreciseConstType* RegTypeCache::small_precise_constants_[kMaxSmallConstant - kMinSmallConstant + 1];
     32 
     33 static bool MatchingPrecisionForClass(const RegType* entry, bool precise)
     34     SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
     35   if (entry->IsPreciseReference() == precise) {
     36     // We were or weren't looking for a precise reference and we found what we need.
     37     return true;
     38   } else {
     39     if (!precise && entry->GetClass()->CannotBeAssignedFromOtherTypes()) {
     40       // We weren't looking for a precise reference, as we're looking up based on a descriptor, but
     41       // we found a matching entry based on the descriptor. Return the precise entry in that case.
     42       return true;
     43     }
     44     return false;
     45   }
     46 }
     47 
     48 void RegTypeCache::FillPrimitiveAndSmallConstantTypes() {
     49   entries_.push_back(UndefinedType::GetInstance());
     50   entries_.push_back(ConflictType::GetInstance());
     51   entries_.push_back(BooleanType::GetInstance());
     52   entries_.push_back(ByteType::GetInstance());
     53   entries_.push_back(ShortType::GetInstance());
     54   entries_.push_back(CharType::GetInstance());
     55   entries_.push_back(IntegerType::GetInstance());
     56   entries_.push_back(LongLoType::GetInstance());
     57   entries_.push_back(LongHiType::GetInstance());
     58   entries_.push_back(FloatType::GetInstance());
     59   entries_.push_back(DoubleLoType::GetInstance());
     60   entries_.push_back(DoubleHiType::GetInstance());
     61   for (int32_t value = kMinSmallConstant; value <= kMaxSmallConstant; ++value) {
     62     int32_t i = value - kMinSmallConstant;
     63     DCHECK_EQ(entries_.size(), small_precise_constants_[i]->GetId());
     64     entries_.push_back(small_precise_constants_[i]);
     65   }
     66   DCHECK_EQ(entries_.size(), primitive_count_);
     67 }
     68 
     69 const RegType& RegTypeCache::FromDescriptor(mirror::ClassLoader* loader, const char* descriptor,
     70                                             bool precise) {
     71   DCHECK(RegTypeCache::primitive_initialized_);
     72   if (descriptor[1] == '\0') {
     73     switch (descriptor[0]) {
     74       case 'Z':
     75         return Boolean();
     76       case 'B':
     77         return Byte();
     78       case 'S':
     79         return Short();
     80       case 'C':
     81         return Char();
     82       case 'I':
     83         return Integer();
     84       case 'J':
     85         return LongLo();
     86       case 'F':
     87         return Float();
     88       case 'D':
     89         return DoubleLo();
     90       case 'V':  // For void types, conflict types.
     91       default:
     92         return Conflict();
     93     }
     94   } else if (descriptor[0] == 'L' || descriptor[0] == '[') {
     95     return From(loader, descriptor, precise);
     96   } else {
     97     return Conflict();
     98   }
     99 }
    100 
    101 const RegType& RegTypeCache::RegTypeFromPrimitiveType(Primitive::Type prim_type) const {
    102   DCHECK(RegTypeCache::primitive_initialized_);
    103   switch (prim_type) {
    104     case Primitive::kPrimBoolean:
    105       return *BooleanType::GetInstance();
    106     case Primitive::kPrimByte:
    107       return *ByteType::GetInstance();
    108     case Primitive::kPrimShort:
    109       return *ShortType::GetInstance();
    110     case Primitive::kPrimChar:
    111       return *CharType::GetInstance();
    112     case Primitive::kPrimInt:
    113       return *IntegerType::GetInstance();
    114     case Primitive::kPrimLong:
    115       return *LongLoType::GetInstance();
    116     case Primitive::kPrimFloat:
    117       return *FloatType::GetInstance();
    118     case Primitive::kPrimDouble:
    119       return *DoubleLoType::GetInstance();
    120     case Primitive::kPrimVoid:
    121     default:
    122       return *ConflictType::GetInstance();
    123   }
    124 }
    125 
    126 bool RegTypeCache::MatchDescriptor(size_t idx, const StringPiece& descriptor, bool precise) {
    127   const RegType* entry = entries_[idx];
    128   if (descriptor != entry->descriptor_) {
    129     return false;
    130   }
    131   if (entry->HasClass()) {
    132     return MatchingPrecisionForClass(entry, precise);
    133   }
    134   // There is no notion of precise unresolved references, the precise information is just dropped
    135   // on the floor.
    136   DCHECK(entry->IsUnresolvedReference());
    137   return true;
    138 }
    139 
    140 mirror::Class* RegTypeCache::ResolveClass(const char* descriptor, mirror::ClassLoader* loader) {
    141   // Class was not found, must create new type.
    142   // Try resolving class
    143   ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
    144   Thread* self = Thread::Current();
    145   StackHandleScope<1> hs(self);
    146   Handle<mirror::ClassLoader> class_loader(hs.NewHandle(loader));
    147   mirror::Class* klass = nullptr;
    148   if (can_load_classes_) {
    149     klass = class_linker->FindClass(self, descriptor, class_loader);
    150   } else {
    151     klass = class_linker->LookupClass(self, descriptor, ComputeModifiedUtf8Hash(descriptor),
    152                                       loader);
    153     if (klass != nullptr && !klass->IsLoaded()) {
    154       // We found the class but without it being loaded its not safe for use.
    155       klass = nullptr;
    156     }
    157   }
    158   return klass;
    159 }
    160 
    161 const RegType& RegTypeCache::From(mirror::ClassLoader* loader, const char* descriptor,
    162                                   bool precise) {
    163   // Try looking up the class in the cache first. We use a StringPiece to avoid continual strlen
    164   // operations on the descriptor.
    165   StringPiece descriptor_sp(descriptor);
    166   for (size_t i = primitive_count_; i < entries_.size(); i++) {
    167     if (MatchDescriptor(i, descriptor_sp, precise)) {
    168       return *(entries_[i]);
    169     }
    170   }
    171   // Class not found in the cache, will create a new type for that.
    172   // Try resolving class.
    173   mirror::Class* klass = ResolveClass(descriptor, loader);
    174   if (klass != nullptr) {
    175     // Class resolved, first look for the class in the list of entries
    176     // Class was not found, must create new type.
    177     // To pass the verification, the type should be imprecise,
    178     // instantiable or an interface with the precise type set to false.
    179     DCHECK(!precise || klass->IsInstantiable());
    180     // Create a precise type if:
    181     // 1- Class is final and NOT an interface. a precise interface is meaningless !!
    182     // 2- Precise Flag passed as true.
    183     RegType* entry;
    184     // Create an imprecise type if we can't tell for a fact that it is precise.
    185     if (klass->CannotBeAssignedFromOtherTypes() || precise) {
    186       DCHECK(!(klass->IsAbstract()) || klass->IsArrayClass());
    187       DCHECK(!klass->IsInterface());
    188       entry = new PreciseReferenceType(klass, descriptor_sp.as_string(), entries_.size());
    189     } else {
    190       entry = new ReferenceType(klass, descriptor_sp.as_string(), entries_.size());
    191     }
    192     AddEntry(entry);
    193     return *entry;
    194   } else {  // Class not resolved.
    195     // We tried loading the class and failed, this might get an exception raised
    196     // so we want to clear it before we go on.
    197     if (can_load_classes_) {
    198       DCHECK(Thread::Current()->IsExceptionPending());
    199       Thread::Current()->ClearException();
    200     } else {
    201       DCHECK(!Thread::Current()->IsExceptionPending());
    202     }
    203     if (IsValidDescriptor(descriptor)) {
    204       RegType* entry = new UnresolvedReferenceType(descriptor_sp.as_string(), entries_.size());
    205       AddEntry(entry);
    206       return *entry;
    207     } else {
    208       // The descriptor is broken return the unknown type as there's nothing sensible that
    209       // could be done at runtime
    210       return Conflict();
    211     }
    212   }
    213 }
    214 
    215 const RegType& RegTypeCache::FromClass(const char* descriptor, mirror::Class* klass, bool precise) {
    216   DCHECK(klass != nullptr);
    217   if (klass->IsPrimitive()) {
    218     // Note: precise isn't used for primitive classes. A char is assignable to an int. All
    219     // primitive classes are final.
    220     return RegTypeFromPrimitiveType(klass->GetPrimitiveType());
    221   } else {
    222     // Look for the reference in the list of entries to have.
    223     for (size_t i = primitive_count_; i < entries_.size(); i++) {
    224       const RegType* cur_entry = entries_[i];
    225       if (cur_entry->klass_.Read() == klass && MatchingPrecisionForClass(cur_entry, precise)) {
    226         return *cur_entry;
    227       }
    228     }
    229     // No reference to the class was found, create new reference.
    230     RegType* entry;
    231     if (precise) {
    232       entry = new PreciseReferenceType(klass, descriptor, entries_.size());
    233     } else {
    234       entry = new ReferenceType(klass, descriptor, entries_.size());
    235     }
    236     AddEntry(entry);
    237     return *entry;
    238   }
    239 }
    240 
    241 RegTypeCache::RegTypeCache(bool can_load_classes) : can_load_classes_(can_load_classes) {
    242   if (kIsDebugBuild) {
    243     Thread::Current()->AssertThreadSuspensionIsAllowable(gAborting == 0);
    244   }
    245   entries_.reserve(64);
    246   FillPrimitiveAndSmallConstantTypes();
    247 }
    248 
    249 RegTypeCache::~RegTypeCache() {
    250   CHECK_LE(primitive_count_, entries_.size());
    251   // Delete only the non primitive types.
    252   if (entries_.size() == kNumPrimitivesAndSmallConstants) {
    253     // All entries are from the global pool, nothing to delete.
    254     return;
    255   }
    256   std::vector<const RegType*>::iterator non_primitive_begin = entries_.begin();
    257   std::advance(non_primitive_begin, kNumPrimitivesAndSmallConstants);
    258   STLDeleteContainerPointers(non_primitive_begin, entries_.end());
    259 }
    260 
    261 void RegTypeCache::ShutDown() {
    262   if (RegTypeCache::primitive_initialized_) {
    263     UndefinedType::Destroy();
    264     ConflictType::Destroy();
    265     BooleanType::Destroy();
    266     ByteType::Destroy();
    267     ShortType::Destroy();
    268     CharType::Destroy();
    269     IntegerType::Destroy();
    270     LongLoType::Destroy();
    271     LongHiType::Destroy();
    272     FloatType::Destroy();
    273     DoubleLoType::Destroy();
    274     DoubleHiType::Destroy();
    275     for (int32_t value = kMinSmallConstant; value <= kMaxSmallConstant; ++value) {
    276       const PreciseConstType* type = small_precise_constants_[value - kMinSmallConstant];
    277       delete type;
    278       small_precise_constants_[value - kMinSmallConstant] = nullptr;
    279     }
    280     RegTypeCache::primitive_initialized_ = false;
    281     RegTypeCache::primitive_count_ = 0;
    282   }
    283 }
    284 
    285 template <class Type>
    286 const Type* RegTypeCache::CreatePrimitiveTypeInstance(const std::string& descriptor) {
    287   mirror::Class* klass = nullptr;
    288   // Try loading the class from linker.
    289   if (!descriptor.empty()) {
    290     klass = art::Runtime::Current()->GetClassLinker()->FindSystemClass(Thread::Current(),
    291                                                                        descriptor.c_str());
    292     DCHECK(klass != nullptr);
    293   }
    294   const Type* entry = Type::CreateInstance(klass, descriptor, RegTypeCache::primitive_count_);
    295   RegTypeCache::primitive_count_++;
    296   return entry;
    297 }
    298 
    299 void RegTypeCache::CreatePrimitiveAndSmallConstantTypes() {
    300   CreatePrimitiveTypeInstance<UndefinedType>("");
    301   CreatePrimitiveTypeInstance<ConflictType>("");
    302   CreatePrimitiveTypeInstance<BooleanType>("Z");
    303   CreatePrimitiveTypeInstance<ByteType>("B");
    304   CreatePrimitiveTypeInstance<ShortType>("S");
    305   CreatePrimitiveTypeInstance<CharType>("C");
    306   CreatePrimitiveTypeInstance<IntegerType>("I");
    307   CreatePrimitiveTypeInstance<LongLoType>("J");
    308   CreatePrimitiveTypeInstance<LongHiType>("J");
    309   CreatePrimitiveTypeInstance<FloatType>("F");
    310   CreatePrimitiveTypeInstance<DoubleLoType>("D");
    311   CreatePrimitiveTypeInstance<DoubleHiType>("D");
    312   for (int32_t value = kMinSmallConstant; value <= kMaxSmallConstant; ++value) {
    313     PreciseConstType* type = new PreciseConstType(value, primitive_count_);
    314     small_precise_constants_[value - kMinSmallConstant] = type;
    315     primitive_count_++;
    316   }
    317 }
    318 
    319 const RegType& RegTypeCache::FromUnresolvedMerge(const RegType& left, const RegType& right) {
    320   BitVector types(1,                                    // Allocate at least a word.
    321                   true,                                 // Is expandable.
    322                   Allocator::GetMallocAllocator());     // TODO: Arenas in the verifier.
    323   const RegType* left_resolved;
    324   if (left.IsUnresolvedMergedReference()) {
    325     const UnresolvedMergedType* left_merge = down_cast<const UnresolvedMergedType*>(&left);
    326     types.Copy(&left_merge->GetUnresolvedTypes());
    327     left_resolved = &left_merge->GetResolvedPart();
    328   } else if (left.IsUnresolvedTypes()) {
    329     types.SetBit(left.GetId());
    330     left_resolved = &Zero();
    331   } else {
    332     left_resolved = &left;
    333   }
    334 
    335   const RegType* right_resolved;
    336   if (right.IsUnresolvedMergedReference()) {
    337     const UnresolvedMergedType* right_merge = down_cast<const UnresolvedMergedType*>(&right);
    338     types.Union(&right_merge->GetUnresolvedTypes());
    339     right_resolved = &right_merge->GetResolvedPart();
    340   } else if (right.IsUnresolvedTypes()) {
    341     types.SetBit(right.GetId());
    342     right_resolved = &Zero();
    343   } else {
    344     right_resolved = &right;
    345   }
    346 
    347   // Merge the resolved parts. Left and right might be equal, so use SafeMerge.
    348   const RegType& resolved_parts_merged = left_resolved->SafeMerge(*right_resolved, this);
    349   // If we get a conflict here, the merge result is a conflict, not an unresolved merge type.
    350   if (resolved_parts_merged.IsConflict()) {
    351     return Conflict();
    352   }
    353 
    354   // Check if entry already exists.
    355   for (size_t i = primitive_count_; i < entries_.size(); i++) {
    356     const RegType* cur_entry = entries_[i];
    357     if (cur_entry->IsUnresolvedMergedReference()) {
    358       const UnresolvedMergedType* cmp_type = down_cast<const UnresolvedMergedType*>(cur_entry);
    359       const RegType& resolved_part = cmp_type->GetResolvedPart();
    360       const BitVector& unresolved_part = cmp_type->GetUnresolvedTypes();
    361       // Use SameBitsSet. "types" is expandable to allow merging in the components, but the
    362       // BitVector in the final RegType will be made non-expandable.
    363       if (&resolved_part == &resolved_parts_merged &&
    364               types.SameBitsSet(&unresolved_part)) {
    365         return *cur_entry;
    366       }
    367     }
    368   }
    369 
    370   // Create entry.
    371   RegType* entry = new UnresolvedMergedType(resolved_parts_merged,
    372                                             types,
    373                                             this,
    374                                             entries_.size());
    375   AddEntry(entry);
    376   return *entry;
    377 }
    378 
    379 const RegType& RegTypeCache::FromUnresolvedSuperClass(const RegType& child) {
    380   // Check if entry already exists.
    381   for (size_t i = primitive_count_; i < entries_.size(); i++) {
    382     const RegType* cur_entry = entries_[i];
    383     if (cur_entry->IsUnresolvedSuperClass()) {
    384       const UnresolvedSuperClass* tmp_entry =
    385           down_cast<const UnresolvedSuperClass*>(cur_entry);
    386       uint16_t unresolved_super_child_id =
    387           tmp_entry->GetUnresolvedSuperClassChildId();
    388       if (unresolved_super_child_id == child.GetId()) {
    389         return *cur_entry;
    390       }
    391     }
    392   }
    393   RegType* entry = new UnresolvedSuperClass(child.GetId(), this, entries_.size());
    394   AddEntry(entry);
    395   return *entry;
    396 }
    397 
    398 const UninitializedType& RegTypeCache::Uninitialized(const RegType& type, uint32_t allocation_pc) {
    399   UninitializedType* entry = nullptr;
    400   const std::string& descriptor(type.GetDescriptor());
    401   if (type.IsUnresolvedTypes()) {
    402     for (size_t i = primitive_count_; i < entries_.size(); i++) {
    403       const RegType* cur_entry = entries_[i];
    404       if (cur_entry->IsUnresolvedAndUninitializedReference() &&
    405           down_cast<const UnresolvedUninitializedRefType*>(cur_entry)->GetAllocationPc()
    406               == allocation_pc &&
    407           (cur_entry->GetDescriptor() == descriptor)) {
    408         return *down_cast<const UnresolvedUninitializedRefType*>(cur_entry);
    409       }
    410     }
    411     entry = new UnresolvedUninitializedRefType(descriptor, allocation_pc, entries_.size());
    412   } else {
    413     mirror::Class* klass = type.GetClass();
    414     for (size_t i = primitive_count_; i < entries_.size(); i++) {
    415       const RegType* cur_entry = entries_[i];
    416       if (cur_entry->IsUninitializedReference() &&
    417           down_cast<const UninitializedReferenceType*>(cur_entry)
    418               ->GetAllocationPc() == allocation_pc &&
    419           cur_entry->GetClass() == klass) {
    420         return *down_cast<const UninitializedReferenceType*>(cur_entry);
    421       }
    422     }
    423     entry = new UninitializedReferenceType(klass, descriptor, allocation_pc, entries_.size());
    424   }
    425   AddEntry(entry);
    426   return *entry;
    427 }
    428 
    429 const RegType& RegTypeCache::FromUninitialized(const RegType& uninit_type) {
    430   RegType* entry;
    431 
    432   if (uninit_type.IsUnresolvedTypes()) {
    433     const std::string& descriptor(uninit_type.GetDescriptor());
    434     for (size_t i = primitive_count_; i < entries_.size(); i++) {
    435       const RegType* cur_entry = entries_[i];
    436       if (cur_entry->IsUnresolvedReference() &&
    437           cur_entry->GetDescriptor() == descriptor) {
    438         return *cur_entry;
    439       }
    440     }
    441     entry = new UnresolvedReferenceType(descriptor, entries_.size());
    442   } else {
    443     mirror::Class* klass = uninit_type.GetClass();
    444     if (uninit_type.IsUninitializedThisReference() && !klass->IsFinal()) {
    445       // For uninitialized "this reference" look for reference types that are not precise.
    446       for (size_t i = primitive_count_; i < entries_.size(); i++) {
    447         const RegType* cur_entry = entries_[i];
    448         if (cur_entry->IsReference() && cur_entry->GetClass() == klass) {
    449           return *cur_entry;
    450         }
    451       }
    452       entry = new ReferenceType(klass, "", entries_.size());
    453     } else if (klass->IsInstantiable()) {
    454       // We're uninitialized because of allocation, look or create a precise type as allocations
    455       // may only create objects of that type.
    456       for (size_t i = primitive_count_; i < entries_.size(); i++) {
    457         const RegType* cur_entry = entries_[i];
    458         if (cur_entry->IsPreciseReference() && cur_entry->GetClass() == klass) {
    459           return *cur_entry;
    460         }
    461       }
    462       entry = new PreciseReferenceType(klass, uninit_type.GetDescriptor(), entries_.size());
    463     } else {
    464       return Conflict();
    465     }
    466   }
    467   AddEntry(entry);
    468   return *entry;
    469 }
    470 
    471 const UninitializedType& RegTypeCache::UninitializedThisArgument(const RegType& type) {
    472   UninitializedType* entry;
    473   const std::string& descriptor(type.GetDescriptor());
    474   if (type.IsUnresolvedTypes()) {
    475     for (size_t i = primitive_count_; i < entries_.size(); i++) {
    476       const RegType* cur_entry = entries_[i];
    477       if (cur_entry->IsUnresolvedAndUninitializedThisReference() &&
    478           cur_entry->GetDescriptor() == descriptor) {
    479         return *down_cast<const UninitializedType*>(cur_entry);
    480       }
    481     }
    482     entry = new UnresolvedUninitializedThisRefType(descriptor, entries_.size());
    483   } else {
    484     mirror::Class* klass = type.GetClass();
    485     for (size_t i = primitive_count_; i < entries_.size(); i++) {
    486       const RegType* cur_entry = entries_[i];
    487       if (cur_entry->IsUninitializedThisReference() && cur_entry->GetClass() == klass) {
    488         return *down_cast<const UninitializedType*>(cur_entry);
    489       }
    490     }
    491     entry = new UninitializedThisReferenceType(klass, descriptor, entries_.size());
    492   }
    493   AddEntry(entry);
    494   return *entry;
    495 }
    496 
    497 const ConstantType& RegTypeCache::FromCat1NonSmallConstant(int32_t value, bool precise) {
    498   for (size_t i = primitive_count_; i < entries_.size(); i++) {
    499     const RegType* cur_entry = entries_[i];
    500     if (cur_entry->klass_.IsNull() && cur_entry->IsConstant() &&
    501         cur_entry->IsPreciseConstant() == precise &&
    502         (down_cast<const ConstantType*>(cur_entry))->ConstantValue() == value) {
    503       return *down_cast<const ConstantType*>(cur_entry);
    504     }
    505   }
    506   ConstantType* entry;
    507   if (precise) {
    508     entry = new PreciseConstType(value, entries_.size());
    509   } else {
    510     entry = new ImpreciseConstType(value, entries_.size());
    511   }
    512   AddEntry(entry);
    513   return *entry;
    514 }
    515 
    516 const ConstantType& RegTypeCache::FromCat2ConstLo(int32_t value, bool precise) {
    517   for (size_t i = primitive_count_; i < entries_.size(); i++) {
    518     const RegType* cur_entry = entries_[i];
    519     if (cur_entry->IsConstantLo() && (cur_entry->IsPrecise() == precise) &&
    520         (down_cast<const ConstantType*>(cur_entry))->ConstantValueLo() == value) {
    521       return *down_cast<const ConstantType*>(cur_entry);
    522     }
    523   }
    524   ConstantType* entry;
    525   if (precise) {
    526     entry = new PreciseConstLoType(value, entries_.size());
    527   } else {
    528     entry = new ImpreciseConstLoType(value, entries_.size());
    529   }
    530   AddEntry(entry);
    531   return *entry;
    532 }
    533 
    534 const ConstantType& RegTypeCache::FromCat2ConstHi(int32_t value, bool precise) {
    535   for (size_t i = primitive_count_; i < entries_.size(); i++) {
    536     const RegType* cur_entry = entries_[i];
    537     if (cur_entry->IsConstantHi() && (cur_entry->IsPrecise() == precise) &&
    538         (down_cast<const ConstantType*>(cur_entry))->ConstantValueHi() == value) {
    539       return *down_cast<const ConstantType*>(cur_entry);
    540     }
    541   }
    542   ConstantType* entry;
    543   if (precise) {
    544     entry = new PreciseConstHiType(value, entries_.size());
    545   } else {
    546     entry = new ImpreciseConstHiType(value, entries_.size());
    547   }
    548   AddEntry(entry);
    549   return *entry;
    550 }
    551 
    552 const RegType& RegTypeCache::GetComponentType(const RegType& array, mirror::ClassLoader* loader) {
    553   if (!array.IsArrayTypes()) {
    554     return Conflict();
    555   } else if (array.IsUnresolvedTypes()) {
    556     const std::string& descriptor(array.GetDescriptor());
    557     const std::string component(descriptor.substr(1, descriptor.size() - 1));
    558     return FromDescriptor(loader, component.c_str(), false);
    559   } else {
    560     mirror::Class* klass = array.GetClass()->GetComponentType();
    561     std::string temp;
    562     if (klass->IsErroneous()) {
    563       // Arrays may have erroneous component types, use unresolved in that case.
    564       // We assume that the primitive classes are not erroneous, so we know it is a
    565       // reference type.
    566       return FromDescriptor(loader, klass->GetDescriptor(&temp), false);
    567     } else {
    568       return FromClass(klass->GetDescriptor(&temp), klass,
    569                        klass->CannotBeAssignedFromOtherTypes());
    570     }
    571   }
    572 }
    573 
    574 void RegTypeCache::Dump(std::ostream& os) {
    575   for (size_t i = 0; i < entries_.size(); i++) {
    576     const RegType* cur_entry = entries_[i];
    577     if (cur_entry != nullptr) {
    578       os << i << ": " << cur_entry->Dump() << "\n";
    579     }
    580   }
    581 }
    582 
    583 void RegTypeCache::VisitStaticRoots(RootVisitor* visitor) {
    584   // Visit the primitive types, this is required since if there are no active verifiers they wont
    585   // be in the entries array, and therefore not visited as roots.
    586   if (primitive_initialized_) {
    587     RootInfo ri(kRootUnknown);
    588     UndefinedType::GetInstance()->VisitRoots(visitor, ri);
    589     ConflictType::GetInstance()->VisitRoots(visitor, ri);
    590     BooleanType::GetInstance()->VisitRoots(visitor, ri);
    591     ByteType::GetInstance()->VisitRoots(visitor, ri);
    592     ShortType::GetInstance()->VisitRoots(visitor, ri);
    593     CharType::GetInstance()->VisitRoots(visitor, ri);
    594     IntegerType::GetInstance()->VisitRoots(visitor, ri);
    595     LongLoType::GetInstance()->VisitRoots(visitor, ri);
    596     LongHiType::GetInstance()->VisitRoots(visitor, ri);
    597     FloatType::GetInstance()->VisitRoots(visitor, ri);
    598     DoubleLoType::GetInstance()->VisitRoots(visitor, ri);
    599     DoubleHiType::GetInstance()->VisitRoots(visitor, ri);
    600     for (int32_t value = kMinSmallConstant; value <= kMaxSmallConstant; ++value) {
    601       small_precise_constants_[value - kMinSmallConstant]->VisitRoots(visitor, ri);
    602     }
    603   }
    604 }
    605 
    606 void RegTypeCache::VisitRoots(RootVisitor* visitor, const RootInfo& root_info) {
    607   // Exclude the static roots that are visited by VisitStaticRoots().
    608   for (size_t i = primitive_count_; i < entries_.size(); ++i) {
    609     entries_[i]->VisitRoots(visitor, root_info);
    610   }
    611 }
    612 
    613 void RegTypeCache::AddEntry(RegType* new_entry) {
    614   entries_.push_back(new_entry);
    615 }
    616 
    617 }  // namespace verifier
    618 }  // namespace art
    619