/*
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* Copyright (C) 2012 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "art_method-inl.h"
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#include "base/callee_save_type.h"
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#include "callee_save_frame.h"
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#include "class_linker-inl.h"
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#include "class_table-inl.h"
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#include "dex/dex_file-inl.h"
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#include "dex/dex_file_types.h"
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#include "entrypoints/entrypoint_utils-inl.h"
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#include "gc/heap.h"
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#include "mirror/class-inl.h"
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#include "mirror/class_loader.h"
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#include "mirror/object-inl.h"
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#include "mirror/object_array-inl.h"
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#include "oat_file.h"
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#include "runtime.h"
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namespace art {
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static void StoreObjectInBss(ArtMethod* outer_method,
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const OatFile* oat_file,
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size_t bss_offset,
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ObjPtr<mirror::Object> object) REQUIRES_SHARED(Locks::mutator_lock_) {
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// Used for storing Class or String in .bss GC roots.
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static_assert(sizeof(GcRoot<mirror::Class>) == sizeof(GcRoot<mirror::Object>), "Size check.");
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static_assert(sizeof(GcRoot<mirror::String>) == sizeof(GcRoot<mirror::Object>), "Size check.");
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DCHECK_NE(bss_offset, IndexBssMappingLookup::npos);
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DCHECK_ALIGNED(bss_offset, sizeof(GcRoot<mirror::Object>));
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if (UNLIKELY(!oat_file->IsExecutable())) {
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// There are situations where we execute bytecode tied to an oat file opened
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// as non-executable (i.e. the AOT-compiled code cannot be executed) and we
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// can JIT that bytecode and get here without the .bss being mmapped.
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return;
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}
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GcRoot<mirror::Object>* slot = reinterpret_cast<GcRoot<mirror::Object>*>(
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const_cast<uint8_t*>(oat_file->BssBegin() + bss_offset));
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DCHECK_GE(slot, oat_file->GetBssGcRoots().data());
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DCHECK_LT(slot, oat_file->GetBssGcRoots().data() + oat_file->GetBssGcRoots().size());
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if (slot->IsNull()) {
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// This may race with another thread trying to store the very same value but that's OK.
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*slot = GcRoot<mirror::Object>(object);
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// We need a write barrier for the class loader that holds the GC roots in the .bss.
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ObjPtr<mirror::ClassLoader> class_loader = outer_method->GetClassLoader();
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Runtime* runtime = Runtime::Current();
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if (kIsDebugBuild) {
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ClassTable* class_table = runtime->GetClassLinker()->ClassTableForClassLoader(class_loader);
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CHECK(class_table != nullptr && !class_table->InsertOatFile(oat_file))
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<< "Oat file with .bss GC roots was not registered in class table: "
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<< oat_file->GetLocation();
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}
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if (class_loader != nullptr) {
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WriteBarrier::ForEveryFieldWrite(class_loader);
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} else {
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runtime->GetClassLinker()->WriteBarrierForBootOatFileBssRoots(oat_file);
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}
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} else {
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// Each slot serves to store exactly one Class or String.
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DCHECK_EQ(object, slot->Read());
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}
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}
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static inline void StoreTypeInBss(ArtMethod* outer_method,
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dex::TypeIndex type_idx,
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ObjPtr<mirror::Class> resolved_type)
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REQUIRES_SHARED(Locks::mutator_lock_) {
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const DexFile* dex_file = outer_method->GetDexFile();
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DCHECK(dex_file != nullptr);
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const OatDexFile* oat_dex_file = dex_file->GetOatDexFile();
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if (oat_dex_file != nullptr) {
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size_t bss_offset = IndexBssMappingLookup::GetBssOffset(oat_dex_file->GetTypeBssMapping(),
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type_idx.index_,
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dex_file->NumTypeIds(),
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sizeof(GcRoot<mirror::Class>));
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if (bss_offset != IndexBssMappingLookup::npos) {
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StoreObjectInBss(outer_method, oat_dex_file->GetOatFile(), bss_offset, resolved_type);
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}
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}
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}
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static inline void StoreStringInBss(ArtMethod* outer_method,
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dex::StringIndex string_idx,
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ObjPtr<mirror::String> resolved_string)
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REQUIRES_SHARED(Locks::mutator_lock_) {
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const DexFile* dex_file = outer_method->GetDexFile();
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DCHECK(dex_file != nullptr);
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const OatDexFile* oat_dex_file = dex_file->GetOatDexFile();
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if (oat_dex_file != nullptr) {
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size_t bss_offset = IndexBssMappingLookup::GetBssOffset(oat_dex_file->GetStringBssMapping(),
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string_idx.index_,
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dex_file->NumStringIds(),
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sizeof(GcRoot<mirror::Class>));
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if (bss_offset != IndexBssMappingLookup::npos) {
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StoreObjectInBss(outer_method, oat_dex_file->GetOatFile(), bss_offset, resolved_string);
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}
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}
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}
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static ALWAYS_INLINE bool CanReferenceBss(ArtMethod* outer_method, ArtMethod* caller)
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REQUIRES_SHARED(Locks::mutator_lock_) {
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// .bss references are used only for AOT-compiled code and only when the instruction
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// originates from the outer method's dex file and the type or string index is tied to
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// that dex file. As we do not want to check if the call is coming from AOT-compiled
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// code (that could be expensive), simply check if the caller has the same dex file.
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//
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// If we've accepted running AOT-compiled code despite the runtime class loader
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// resolving the caller to a different dex file, this check shall prevent us from
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// filling the .bss slot and we shall keep going through the slow path. This is slow
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// but correct; we do not really care that much about performance in this odd case.
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//
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// JIT can inline throwing instructions across dex files and this check prevents
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// looking up the index in the wrong dex file in that case. If the caller and outer
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// method have the same dex file, we may or may not find a .bss slot to update;
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// if we do, this can still benefit AOT-compiled code executed later.
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return outer_method->GetDexFile() == caller->GetDexFile();
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}
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extern "C" mirror::Class* artInitializeStaticStorageFromCode(mirror::Class* klass, Thread* self)
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REQUIRES_SHARED(Locks::mutator_lock_) {
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// Called to ensure static storage base is initialized for direct static field reads and writes.
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// A class may be accessing another class' fields when it doesn't have access, as access has been
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// given by inheritance.
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ScopedQuickEntrypointChecks sqec(self);
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DCHECK(klass != nullptr);
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ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
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StackHandleScope<1> hs(self);
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Handle<mirror::Class> h_klass = hs.NewHandle(klass);
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bool success = class_linker->EnsureInitialized(
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self, h_klass, /* can_init_fields= */ true, /* can_init_parents= */ true);
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if (UNLIKELY(!success)) {
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return nullptr;
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}
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return h_klass.Get();
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}
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extern "C" mirror::Class* artResolveTypeFromCode(uint32_t type_idx, Thread* self)
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REQUIRES_SHARED(Locks::mutator_lock_) {
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// Called when the .bss slot was empty or for main-path runtime call.
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ScopedQuickEntrypointChecks sqec(self);
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auto caller_and_outer = GetCalleeSaveMethodCallerAndOuterMethod(
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self, CalleeSaveType::kSaveEverythingForClinit);
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ArtMethod* caller = caller_and_outer.caller;
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ObjPtr<mirror::Class> result = ResolveVerifyAndClinit(dex::TypeIndex(type_idx),
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caller,
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self,
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/* can_run_clinit= */ false,
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/* verify_access= */ false);
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if (LIKELY(result != nullptr) && CanReferenceBss(caller_and_outer.outer_method, caller)) {
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StoreTypeInBss(caller_and_outer.outer_method, dex::TypeIndex(type_idx), result);
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}
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return result.Ptr();
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}
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extern "C" mirror::Class* artResolveTypeAndVerifyAccessFromCode(uint32_t type_idx, Thread* self)
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REQUIRES_SHARED(Locks::mutator_lock_) {
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// Called when caller isn't guaranteed to have access to a type.
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ScopedQuickEntrypointChecks sqec(self);
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auto caller_and_outer = GetCalleeSaveMethodCallerAndOuterMethod(self,
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CalleeSaveType::kSaveEverything);
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ArtMethod* caller = caller_and_outer.caller;
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ObjPtr<mirror::Class> result = ResolveVerifyAndClinit(dex::TypeIndex(type_idx),
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caller,
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self,
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/* can_run_clinit= */ false,
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/* verify_access= */ true);
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// Do not StoreTypeInBss(); access check entrypoint is never used together with .bss.
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return result.Ptr();
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}
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extern "C" mirror::MethodHandle* artResolveMethodHandleFromCode(uint32_t method_handle_idx,
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Thread* self)
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REQUIRES_SHARED(Locks::mutator_lock_) {
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ScopedQuickEntrypointChecks sqec(self);
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auto caller_and_outer =
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GetCalleeSaveMethodCallerAndOuterMethod(self, CalleeSaveType::kSaveEverything);
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ArtMethod* caller = caller_and_outer.caller;
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ObjPtr<mirror::MethodHandle> result = ResolveMethodHandleFromCode(caller, method_handle_idx);
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return result.Ptr();
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}
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extern "C" mirror::MethodType* artResolveMethodTypeFromCode(uint32_t proto_idx, Thread* self)
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REQUIRES_SHARED(Locks::mutator_lock_) {
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ScopedQuickEntrypointChecks sqec(self);
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auto caller_and_outer = GetCalleeSaveMethodCallerAndOuterMethod(self,
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CalleeSaveType::kSaveEverything);
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ArtMethod* caller = caller_and_outer.caller;
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ObjPtr<mirror::MethodType> result = ResolveMethodTypeFromCode(caller, dex::ProtoIndex(proto_idx));
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return result.Ptr();
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}
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extern "C" mirror::String* artResolveStringFromCode(int32_t string_idx, Thread* self)
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REQUIRES_SHARED(Locks::mutator_lock_) {
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ScopedQuickEntrypointChecks sqec(self);
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auto caller_and_outer = GetCalleeSaveMethodCallerAndOuterMethod(self,
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CalleeSaveType::kSaveEverything);
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ArtMethod* caller = caller_and_outer.caller;
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ObjPtr<mirror::String> result =
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Runtime::Current()->GetClassLinker()->ResolveString(dex::StringIndex(string_idx), caller);
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if (LIKELY(result != nullptr) && CanReferenceBss(caller_and_outer.outer_method, caller)) {
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StoreStringInBss(caller_and_outer.outer_method, dex::StringIndex(string_idx), result);
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}
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return result.Ptr();
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}
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} // namespace art
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