compiler/optimizing/sharpening.cc - platform/art - Git at Google

 /*
  * Copyright (C) 2015 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #include "sharpening.h"

 #include "base/casts.h"
 #include "base/enums.h"
 #include "class_linker.h"
 #include "code_generator.h"
 #include "driver/compiler_options.h"
 #include "driver/dex_compilation_unit.h"
 #include "utils/dex_cache_arrays_layout-inl.h"
 #include "driver/compiler_driver.h"
 #include "gc/heap.h"
 #include "gc/space/image_space.h"
 #include "handle_scope-inl.h"
 #include "mirror/dex_cache.h"
 #include "mirror/string.h"
 #include "nodes.h"
 #include "runtime.h"
 #include "scoped_thread_state_change-inl.h"

 namespace art {

 void HSharpening::Run() {
   // We don't care about the order of the blocks here.
   for (HBasicBlock* block : graph_->GetReversePostOrder()) {
     for (HInstructionIterator it(block->GetInstructions()); !it.Done(); it.Advance()) {
       HInstruction* instruction = it.Current();
       if (instruction->IsInvokeStaticOrDirect()) {
         ProcessInvokeStaticOrDirect(instruction->AsInvokeStaticOrDirect());
       } else if (instruction->IsLoadClass()) {
         ProcessLoadClass(instruction->AsLoadClass());
       } else if (instruction->IsLoadString()) {
         ProcessLoadString(instruction->AsLoadString());
       }
       // TODO: Move the sharpening of invoke-virtual/-interface/-super from HGraphBuilder
       //       here. Rewrite it to avoid the CompilerDriver's reliance on verifier data
       //       because we know the type better when inlining.
     }
   }
 }

 static bool IsInBootImage(ArtMethod* method) {
   const std::vector<gc::space::ImageSpace*>& image_spaces =
       Runtime::Current()->GetHeap()->GetBootImageSpaces();
   for (gc::space::ImageSpace* image_space : image_spaces) {
     const auto& method_section = image_space->GetImageHeader().GetMethodsSection();
     if (method_section.Contains(reinterpret_cast<uint8_t*>(method) - image_space->Begin())) {
       return true;
     }
   }
   return false;
 }

 static bool AOTCanEmbedMethod(ArtMethod* method, const CompilerOptions& options) {
   // Including patch information means the AOT code will be patched, which we don't
   // support in the compiler, and is anyways moving away b/33192586.
   return IsInBootImage(method) && !options.GetCompilePic() && !options.GetIncludePatchInformation();
 }

 void HSharpening::ProcessInvokeStaticOrDirect(HInvokeStaticOrDirect* invoke) {
   if (invoke->IsStringInit()) {
     // Not using the dex cache arrays. But we could still try to use a better dispatch...
     // TODO: Use direct_method and direct_code for the appropriate StringFactory method.
     return;
   }

   ArtMethod* callee = invoke->GetResolvedMethod();
   DCHECK(callee != nullptr);

   HInvokeStaticOrDirect::MethodLoadKind method_load_kind;
   HInvokeStaticOrDirect::CodePtrLocation code_ptr_location;
   uint64_t method_load_data = 0u;

   // Note: we never call an ArtMethod through a known code pointer, as
   // we do not want to keep on invoking it if it gets deoptimized. This
   // applies to both AOT and JIT.
   // This also avoids having to find out if the code pointer of an ArtMethod
   // is the resolution trampoline (for ensuring the class is initialized), or
   // the interpreter entrypoint. Such code pointers we do not want to call
   // directly.
   // Only in the case of a recursive call can we call directly, as we know the
   // class is initialized already or being initialized, and the call will not
   // be invoked once the method is deoptimized.

   if (callee == codegen_->GetGraph()->GetArtMethod()) {
     // Recursive call.
     method_load_kind = HInvokeStaticOrDirect::MethodLoadKind::kRecursive;
     code_ptr_location = HInvokeStaticOrDirect::CodePtrLocation::kCallSelf;
   } else if (Runtime::Current()->UseJitCompilation() ||
       AOTCanEmbedMethod(callee, codegen_->GetCompilerOptions())) {
     // JIT or on-device AOT compilation referencing a boot image method.
     // Use the method address directly.
     method_load_kind = HInvokeStaticOrDirect::MethodLoadKind::kDirectAddress;
     method_load_data = reinterpret_cast<uintptr_t>(callee);
     code_ptr_location = HInvokeStaticOrDirect::CodePtrLocation::kCallArtMethod;
   } else {
     // Use PC-relative access to the dex cache arrays.
     method_load_kind = HInvokeStaticOrDirect::MethodLoadKind::kDexCachePcRelative;
     DexCacheArraysLayout layout(GetInstructionSetPointerSize(codegen_->GetInstructionSet()),
                                 &graph_->GetDexFile());
     method_load_data = layout.MethodOffset(invoke->GetDexMethodIndex());
     code_ptr_location = HInvokeStaticOrDirect::CodePtrLocation::kCallArtMethod;
   }

   if (graph_->IsDebuggable()) {
     // For debuggable apps always use the code pointer from ArtMethod
     // so that we don't circumvent instrumentation stubs if installed.
     code_ptr_location = HInvokeStaticOrDirect::CodePtrLocation::kCallArtMethod;
   }

   HInvokeStaticOrDirect::DispatchInfo desired_dispatch_info = {
       method_load_kind, code_ptr_location, method_load_data
   };
   HInvokeStaticOrDirect::DispatchInfo dispatch_info =
       codegen_->GetSupportedInvokeStaticOrDirectDispatch(desired_dispatch_info, invoke);
   invoke->SetDispatchInfo(dispatch_info);
 }

 void HSharpening::ProcessLoadClass(HLoadClass* load_class) {
   ScopedObjectAccess soa(Thread::Current());
   StackHandleScope<1> hs(soa.Self());
   Runtime* runtime = Runtime::Current();
   ClassLinker* class_linker = runtime->GetClassLinker();
   const DexFile& dex_file = load_class->GetDexFile();
   dex::TypeIndex type_index = load_class->GetTypeIndex();
   Handle<mirror::DexCache> dex_cache = IsSameDexFile(dex_file, *compilation_unit_.GetDexFile())
       ? compilation_unit_.GetDexCache()
       : hs.NewHandle(class_linker->FindDexCache(soa.Self(), dex_file));
   mirror::Class* cls = dex_cache->GetResolvedType(type_index);
   SharpenClass(load_class, cls, handles_, codegen_, compiler_driver_);
 }

 void HSharpening::SharpenClass(HLoadClass* load_class,
                                mirror::Class* klass,
                                VariableSizedHandleScope* handles,
                                CodeGenerator* codegen,
                                CompilerDriver* compiler_driver) {
   ScopedAssertNoThreadSuspension sants("Sharpening class in compiler");
   DCHECK(load_class->GetLoadKind() == HLoadClass::LoadKind::kDexCacheViaMethod ||
          load_class->GetLoadKind() == HLoadClass::LoadKind::kReferrersClass)
       << load_class->GetLoadKind();
   DCHECK(!load_class->IsInDexCache()) << "HLoadClass should not be optimized before sharpening.";
   DCHECK(!load_class->IsInBootImage()) << "HLoadClass should not be optimized before sharpening.";

   const DexFile& dex_file = load_class->GetDexFile();
   dex::TypeIndex type_index = load_class->GetTypeIndex();

   bool is_in_dex_cache = false;
   bool is_in_boot_image = false;
   HLoadClass::LoadKind desired_load_kind = static_cast<HLoadClass::LoadKind>(-1);
   uint64_t address = 0u;  // Class or dex cache element address.
   Runtime* runtime = Runtime::Current();
   if (codegen->GetCompilerOptions().IsBootImage()) {
     // Compiling boot image. Check if the class is a boot image class.
     DCHECK(!runtime->UseJitCompilation());
     if (!compiler_driver->GetSupportBootImageFixup()) {
       // MIPS64 or compiler_driver_test. Do not sharpen.
       desired_load_kind = HLoadClass::LoadKind::kDexCacheViaMethod;
     } else if ((klass != nullptr) && compiler_driver->IsImageClass(
         dex_file.StringDataByIdx(dex_file.GetTypeId(type_index).descriptor_idx_))) {
       is_in_boot_image = true;
       is_in_dex_cache = true;
       desired_load_kind = codegen->GetCompilerOptions().GetCompilePic()
           ? HLoadClass::LoadKind::kBootImageLinkTimePcRelative
           : HLoadClass::LoadKind::kBootImageLinkTimeAddress;
     } else {
       // Not a boot image class. We must go through the dex cache.
       DCHECK(ContainsElement(compiler_driver->GetDexFilesForOatFile(), &dex_file));
       desired_load_kind = HLoadClass::LoadKind::kDexCachePcRelative;
     }
   } else {
     is_in_boot_image = (klass != nullptr) && runtime->GetHeap()->ObjectIsInBootImageSpace(klass);
     if (runtime->UseJitCompilation()) {
       // TODO: Make sure we don't set the "compile PIC" flag for JIT as that's bogus.
       // DCHECK(!codegen_->GetCompilerOptions().GetCompilePic());
       is_in_dex_cache = (klass != nullptr);
       if (is_in_boot_image) {
         // TODO: Use direct pointers for all non-moving spaces, not just boot image. Bug: 29530787
         desired_load_kind = HLoadClass::LoadKind::kBootImageAddress;
         address = reinterpret_cast64<uint64_t>(klass);
       } else if (is_in_dex_cache) {
         desired_load_kind = HLoadClass::LoadKind::kJitTableAddress;
         // We store in the address field the location of the stack reference maintained
         // by the handle. We do this now so that the code generation does not need to figure
         // out which class loader to use.
         address = reinterpret_cast<uint64_t>(handles->NewHandle(klass).GetReference());
       } else {
         // Class not loaded yet. This happens when the dex code requesting
         // this `HLoadClass` hasn't been executed in the interpreter.
         // Fallback to the dex cache.
         // TODO(ngeoffray): Generate HDeoptimize instead.
         desired_load_kind = HLoadClass::LoadKind::kDexCacheViaMethod;
       }
     } else if (is_in_boot_image && !codegen->GetCompilerOptions().GetCompilePic()) {
       // AOT app compilation. Check if the class is in the boot image.
       desired_load_kind = HLoadClass::LoadKind::kBootImageAddress;
       address = reinterpret_cast64<uint64_t>(klass);
     } else {
       // Not JIT and either the klass is not in boot image or we are compiling in PIC mode.
       // Use PC-relative load from the dex cache if the dex file belongs
       // to the oat file that we're currently compiling.
       desired_load_kind =
           ContainsElement(compiler_driver->GetDexFilesForOatFile(), &load_class->GetDexFile())
               ? HLoadClass::LoadKind::kDexCachePcRelative
               : HLoadClass::LoadKind::kDexCacheViaMethod;
     }
   }
   DCHECK_NE(desired_load_kind, static_cast<HLoadClass::LoadKind>(-1));

   if (is_in_boot_image) {
     load_class->MarkInBootImage();
   }

   if (load_class->NeedsAccessCheck()) {
     // We need to call the runtime anyway, so we simply get the class as that call's return value.
     return;
   }

   if (load_class->GetLoadKind() == HLoadClass::LoadKind::kReferrersClass) {
     // Loading from the ArtMethod* is the most efficient retrieval in code size.
     // TODO: This may not actually be true for all architectures and
     // locations of target classes. The additional register pressure
     // for using the ArtMethod* should be considered.
     return;
   }

   if (is_in_dex_cache) {
     load_class->MarkInDexCache();
   }

   HLoadClass::LoadKind load_kind = codegen->GetSupportedLoadClassKind(desired_load_kind);
   switch (load_kind) {
     case HLoadClass::LoadKind::kBootImageLinkTimeAddress:
     case HLoadClass::LoadKind::kBootImageLinkTimePcRelative:
     case HLoadClass::LoadKind::kDexCacheViaMethod:
       load_class->SetLoadKindWithTypeReference(load_kind, dex_file, type_index);
       break;
     case HLoadClass::LoadKind::kBootImageAddress:
     case HLoadClass::LoadKind::kJitTableAddress:
       DCHECK_NE(address, 0u);
       load_class->SetLoadKindWithAddress(load_kind, address);
       break;
     case HLoadClass::LoadKind::kDexCachePcRelative: {
       PointerSize pointer_size = InstructionSetPointerSize(codegen->GetInstructionSet());
       DexCacheArraysLayout layout(pointer_size, &dex_file);
       size_t element_index = layout.TypeOffset(type_index);
       load_class->SetLoadKindWithDexCacheReference(load_kind, dex_file, element_index);
       break;
     }
     default:
       LOG(FATAL) << "Unexpected load kind: " << load_kind;
       UNREACHABLE();
   }
 }

 void HSharpening::ProcessLoadString(HLoadString* load_string) {
   DCHECK_EQ(load_string->GetLoadKind(), HLoadString::LoadKind::kDexCacheViaMethod);

   const DexFile& dex_file = load_string->GetDexFile();
   dex::StringIndex string_index = load_string->GetStringIndex();

   HLoadString::LoadKind desired_load_kind = HLoadString::LoadKind::kDexCacheViaMethod;
   {
     Runtime* runtime = Runtime::Current();
     ClassLinker* class_linker = runtime->GetClassLinker();
     ScopedObjectAccess soa(Thread::Current());
     StackHandleScope<1> hs(soa.Self());
     Handle<mirror::DexCache> dex_cache = IsSameDexFile(dex_file, *compilation_unit_.GetDexFile())
         ? compilation_unit_.GetDexCache()
         : hs.NewHandle(class_linker->FindDexCache(soa.Self(), dex_file));
     mirror::String* string = nullptr;

     if (codegen_->GetCompilerOptions().IsBootImage()) {
       // Compiling boot image. Resolve the string and allocate it if needed, to ensure
       // the string will be added to the boot image.
       DCHECK(!runtime->UseJitCompilation());
       string = class_linker->ResolveString(dex_file, string_index, dex_cache);
       CHECK(string != nullptr);
       if (compiler_driver_->GetSupportBootImageFixup()) {
         DCHECK(ContainsElement(compiler_driver_->GetDexFilesForOatFile(), &dex_file));
         desired_load_kind = codegen_->GetCompilerOptions().GetCompilePic()
             ? HLoadString::LoadKind::kBootImageLinkTimePcRelative
             : HLoadString::LoadKind::kBootImageLinkTimeAddress;
       } else {
         // MIPS64 or compiler_driver_test. Do not sharpen.
         DCHECK_EQ(desired_load_kind, HLoadString::LoadKind::kDexCacheViaMethod);
       }
     } else if (runtime->UseJitCompilation()) {
       // TODO: Make sure we don't set the "compile PIC" flag for JIT as that's bogus.
       // DCHECK(!codegen_->GetCompilerOptions().GetCompilePic());
       string = class_linker->LookupString(dex_file, string_index, dex_cache);
       if (string != nullptr) {
         if (runtime->GetHeap()->ObjectIsInBootImageSpace(string)) {
           desired_load_kind = HLoadString::LoadKind::kBootImageAddress;
         } else {
           desired_load_kind = HLoadString::LoadKind::kJitTableAddress;
         }
       }
     } else {
       // AOT app compilation. Try to lookup the string without allocating if not found.
       string = class_linker->LookupString(dex_file, string_index, dex_cache);
       if (string != nullptr &&
           runtime->GetHeap()->ObjectIsInBootImageSpace(string) &&
           !codegen_->GetCompilerOptions().GetCompilePic()) {
         desired_load_kind = HLoadString::LoadKind::kBootImageAddress;
       } else {
         desired_load_kind = HLoadString::LoadKind::kBssEntry;
       }
     }
     if (string != nullptr) {
       load_string->SetString(handles_->NewHandle(string));
     }
   }

   HLoadString::LoadKind load_kind = codegen_->GetSupportedLoadStringKind(desired_load_kind);
   load_string->SetLoadKind(load_kind);
 }

 }  // namespace art
	/*
	* Copyright (C) 2015 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#include "sharpening.h"

	#include "base/casts.h"
	#include "base/enums.h"
	#include "class_linker.h"
	#include "code_generator.h"
	#include "driver/compiler_options.h"
	#include "driver/dex_compilation_unit.h"
	#include "utils/dex_cache_arrays_layout-inl.h"
	#include "driver/compiler_driver.h"
	#include "gc/heap.h"
	#include "gc/space/image_space.h"
	#include "handle_scope-inl.h"
	#include "mirror/dex_cache.h"
	#include "mirror/string.h"
	#include "nodes.h"
	#include "runtime.h"
	#include "scoped_thread_state_change-inl.h"

	namespace art {

	void HSharpening::Run() {
	// We don't care about the order of the blocks here.
	for (HBasicBlock* block : graph_->GetReversePostOrder()) {
	for (HInstructionIterator it(block->GetInstructions()); !it.Done(); it.Advance()) {
	HInstruction* instruction = it.Current();
	if (instruction->IsInvokeStaticOrDirect()) {
	ProcessInvokeStaticOrDirect(instruction->AsInvokeStaticOrDirect());
	} else if (instruction->IsLoadClass()) {
	ProcessLoadClass(instruction->AsLoadClass());
	} else if (instruction->IsLoadString()) {
	ProcessLoadString(instruction->AsLoadString());
	}
	// TODO: Move the sharpening of invoke-virtual/-interface/-super from HGraphBuilder
	// here. Rewrite it to avoid the CompilerDriver's reliance on verifier data
	// because we know the type better when inlining.
	}
	}
	}

	static bool IsInBootImage(ArtMethod* method) {
	const std::vector<gc::space::ImageSpace*>& image_spaces =
	Runtime::Current()->GetHeap()->GetBootImageSpaces();
	for (gc::space::ImageSpace* image_space : image_spaces) {
	const auto& method_section = image_space->GetImageHeader().GetMethodsSection();
	if (method_section.Contains(reinterpret_cast<uint8_t*>(method) - image_space->Begin())) {
	return true;
	}
	}
	return false;
	}

	static bool AOTCanEmbedMethod(ArtMethod* method, const CompilerOptions& options) {
	// Including patch information means the AOT code will be patched, which we don't
	// support in the compiler, and is anyways moving away b/33192586.
	return IsInBootImage(method) && !options.GetCompilePic() && !options.GetIncludePatchInformation();
	}

	void HSharpening::ProcessInvokeStaticOrDirect(HInvokeStaticOrDirect* invoke) {
	if (invoke->IsStringInit()) {
	// Not using the dex cache arrays. But we could still try to use a better dispatch...
	// TODO: Use direct_method and direct_code for the appropriate StringFactory method.
	return;
	}

	ArtMethod* callee = invoke->GetResolvedMethod();
	DCHECK(callee != nullptr);

	HInvokeStaticOrDirect::MethodLoadKind method_load_kind;
	HInvokeStaticOrDirect::CodePtrLocation code_ptr_location;
	uint64_t method_load_data = 0u;

	// Note: we never call an ArtMethod through a known code pointer, as
	// we do not want to keep on invoking it if it gets deoptimized. This
	// applies to both AOT and JIT.
	// This also avoids having to find out if the code pointer of an ArtMethod
	// is the resolution trampoline (for ensuring the class is initialized), or
	// the interpreter entrypoint. Such code pointers we do not want to call
	// directly.
	// Only in the case of a recursive call can we call directly, as we know the
	// class is initialized already or being initialized, and the call will not
	// be invoked once the method is deoptimized.

	if (callee == codegen_->GetGraph()->GetArtMethod()) {
	// Recursive call.
	method_load_kind = HInvokeStaticOrDirect::MethodLoadKind::kRecursive;
	code_ptr_location = HInvokeStaticOrDirect::CodePtrLocation::kCallSelf;
	} else if (Runtime::Current()->UseJitCompilation() \|\|
	AOTCanEmbedMethod(callee, codegen_->GetCompilerOptions())) {
	// JIT or on-device AOT compilation referencing a boot image method.
	// Use the method address directly.
	method_load_kind = HInvokeStaticOrDirect::MethodLoadKind::kDirectAddress;
	method_load_data = reinterpret_cast<uintptr_t>(callee);
	code_ptr_location = HInvokeStaticOrDirect::CodePtrLocation::kCallArtMethod;
	} else {
	// Use PC-relative access to the dex cache arrays.
	method_load_kind = HInvokeStaticOrDirect::MethodLoadKind::kDexCachePcRelative;
	DexCacheArraysLayout layout(GetInstructionSetPointerSize(codegen_->GetInstructionSet()),
	&graph_->GetDexFile());
	method_load_data = layout.MethodOffset(invoke->GetDexMethodIndex());
	code_ptr_location = HInvokeStaticOrDirect::CodePtrLocation::kCallArtMethod;
	}

	if (graph_->IsDebuggable()) {
	// For debuggable apps always use the code pointer from ArtMethod
	// so that we don't circumvent instrumentation stubs if installed.
	code_ptr_location = HInvokeStaticOrDirect::CodePtrLocation::kCallArtMethod;
	}

	HInvokeStaticOrDirect::DispatchInfo desired_dispatch_info = {
	method_load_kind, code_ptr_location, method_load_data
	};
	HInvokeStaticOrDirect::DispatchInfo dispatch_info =
	codegen_->GetSupportedInvokeStaticOrDirectDispatch(desired_dispatch_info, invoke);
	invoke->SetDispatchInfo(dispatch_info);
	}

	void HSharpening::ProcessLoadClass(HLoadClass* load_class) {
	ScopedObjectAccess soa(Thread::Current());
	StackHandleScope<1> hs(soa.Self());
	Runtime* runtime = Runtime::Current();
	ClassLinker* class_linker = runtime->GetClassLinker();
	const DexFile& dex_file = load_class->GetDexFile();
	dex::TypeIndex type_index = load_class->GetTypeIndex();
	Handle<mirror::DexCache> dex_cache = IsSameDexFile(dex_file, *compilation_unit_.GetDexFile())
	? compilation_unit_.GetDexCache()
	: hs.NewHandle(class_linker->FindDexCache(soa.Self(), dex_file));
	mirror::Class* cls = dex_cache->GetResolvedType(type_index);
	SharpenClass(load_class, cls, handles_, codegen_, compiler_driver_);
	}

	void HSharpening::SharpenClass(HLoadClass* load_class,
	mirror::Class* klass,
	VariableSizedHandleScope* handles,
	CodeGenerator* codegen,
	CompilerDriver* compiler_driver) {
	ScopedAssertNoThreadSuspension sants("Sharpening class in compiler");
	DCHECK(load_class->GetLoadKind() == HLoadClass::LoadKind::kDexCacheViaMethod \|\|
	load_class->GetLoadKind() == HLoadClass::LoadKind::kReferrersClass)
	<< load_class->GetLoadKind();
	DCHECK(!load_class->IsInDexCache()) << "HLoadClass should not be optimized before sharpening.";
	DCHECK(!load_class->IsInBootImage()) << "HLoadClass should not be optimized before sharpening.";

	const DexFile& dex_file = load_class->GetDexFile();
	dex::TypeIndex type_index = load_class->GetTypeIndex();

	bool is_in_dex_cache = false;
	bool is_in_boot_image = false;
	HLoadClass::LoadKind desired_load_kind = static_cast<HLoadClass::LoadKind>(-1);
	uint64_t address = 0u; // Class or dex cache element address.
	Runtime* runtime = Runtime::Current();
	if (codegen->GetCompilerOptions().IsBootImage()) {
	// Compiling boot image. Check if the class is a boot image class.
	DCHECK(!runtime->UseJitCompilation());
	if (!compiler_driver->GetSupportBootImageFixup()) {
	// MIPS64 or compiler_driver_test. Do not sharpen.
	desired_load_kind = HLoadClass::LoadKind::kDexCacheViaMethod;
	} else if ((klass != nullptr) && compiler_driver->IsImageClass(
	dex_file.StringDataByIdx(dex_file.GetTypeId(type_index).descriptor_idx_))) {
	is_in_boot_image = true;
	is_in_dex_cache = true;
	desired_load_kind = codegen->GetCompilerOptions().GetCompilePic()
	? HLoadClass::LoadKind::kBootImageLinkTimePcRelative
	: HLoadClass::LoadKind::kBootImageLinkTimeAddress;
	} else {
	// Not a boot image class. We must go through the dex cache.
	DCHECK(ContainsElement(compiler_driver->GetDexFilesForOatFile(), &dex_file));
	desired_load_kind = HLoadClass::LoadKind::kDexCachePcRelative;
	}
	} else {
	is_in_boot_image = (klass != nullptr) && runtime->GetHeap()->ObjectIsInBootImageSpace(klass);
	if (runtime->UseJitCompilation()) {
	// TODO: Make sure we don't set the "compile PIC" flag for JIT as that's bogus.
	// DCHECK(!codegen_->GetCompilerOptions().GetCompilePic());
	is_in_dex_cache = (klass != nullptr);
	if (is_in_boot_image) {
	// TODO: Use direct pointers for all non-moving spaces, not just boot image. Bug: 29530787
	desired_load_kind = HLoadClass::LoadKind::kBootImageAddress;
	address = reinterpret_cast64<uint64_t>(klass);
	} else if (is_in_dex_cache) {
	desired_load_kind = HLoadClass::LoadKind::kJitTableAddress;
	// We store in the address field the location of the stack reference maintained
	// by the handle. We do this now so that the code generation does not need to figure
	// out which class loader to use.
	address = reinterpret_cast<uint64_t>(handles->NewHandle(klass).GetReference());
	} else {
	// Class not loaded yet. This happens when the dex code requesting
	// this `HLoadClass` hasn't been executed in the interpreter.
	// Fallback to the dex cache.
	// TODO(ngeoffray): Generate HDeoptimize instead.
	desired_load_kind = HLoadClass::LoadKind::kDexCacheViaMethod;
	}
	} else if (is_in_boot_image && !codegen->GetCompilerOptions().GetCompilePic()) {
	// AOT app compilation. Check if the class is in the boot image.
	desired_load_kind = HLoadClass::LoadKind::kBootImageAddress;
	address = reinterpret_cast64<uint64_t>(klass);
	} else {
	// Not JIT and either the klass is not in boot image or we are compiling in PIC mode.
	// Use PC-relative load from the dex cache if the dex file belongs
	// to the oat file that we're currently compiling.
	desired_load_kind =
	ContainsElement(compiler_driver->GetDexFilesForOatFile(), &load_class->GetDexFile())
	? HLoadClass::LoadKind::kDexCachePcRelative
	: HLoadClass::LoadKind::kDexCacheViaMethod;
	}
	}
	DCHECK_NE(desired_load_kind, static_cast<HLoadClass::LoadKind>(-1));

	if (is_in_boot_image) {
	load_class->MarkInBootImage();
	}

	if (load_class->NeedsAccessCheck()) {
	// We need to call the runtime anyway, so we simply get the class as that call's return value.
	return;
	}

	if (load_class->GetLoadKind() == HLoadClass::LoadKind::kReferrersClass) {
	// Loading from the ArtMethod* is the most efficient retrieval in code size.
	// TODO: This may not actually be true for all architectures and
	// locations of target classes. The additional register pressure
	// for using the ArtMethod* should be considered.
	return;
	}

	if (is_in_dex_cache) {
	load_class->MarkInDexCache();
	}

	HLoadClass::LoadKind load_kind = codegen->GetSupportedLoadClassKind(desired_load_kind);
	switch (load_kind) {
	case HLoadClass::LoadKind::kBootImageLinkTimeAddress:
	case HLoadClass::LoadKind::kBootImageLinkTimePcRelative:
	case HLoadClass::LoadKind::kDexCacheViaMethod:
	load_class->SetLoadKindWithTypeReference(load_kind, dex_file, type_index);
	break;
	case HLoadClass::LoadKind::kBootImageAddress:
	case HLoadClass::LoadKind::kJitTableAddress:
	DCHECK_NE(address, 0u);
	load_class->SetLoadKindWithAddress(load_kind, address);
	break;
	case HLoadClass::LoadKind::kDexCachePcRelative: {
	PointerSize pointer_size = InstructionSetPointerSize(codegen->GetInstructionSet());
	DexCacheArraysLayout layout(pointer_size, &dex_file);
	size_t element_index = layout.TypeOffset(type_index);
	load_class->SetLoadKindWithDexCacheReference(load_kind, dex_file, element_index);
	break;
	}
	default:
	LOG(FATAL) << "Unexpected load kind: " << load_kind;
	UNREACHABLE();
	}
	}

	void HSharpening::ProcessLoadString(HLoadString* load_string) {
	DCHECK_EQ(load_string->GetLoadKind(), HLoadString::LoadKind::kDexCacheViaMethod);

	const DexFile& dex_file = load_string->GetDexFile();
	dex::StringIndex string_index = load_string->GetStringIndex();

	HLoadString::LoadKind desired_load_kind = HLoadString::LoadKind::kDexCacheViaMethod;
	{
	Runtime* runtime = Runtime::Current();
	ClassLinker* class_linker = runtime->GetClassLinker();
	ScopedObjectAccess soa(Thread::Current());
	StackHandleScope<1> hs(soa.Self());
	Handle<mirror::DexCache> dex_cache = IsSameDexFile(dex_file, *compilation_unit_.GetDexFile())
	? compilation_unit_.GetDexCache()
	: hs.NewHandle(class_linker->FindDexCache(soa.Self(), dex_file));
	mirror::String* string = nullptr;

	if (codegen_->GetCompilerOptions().IsBootImage()) {
	// Compiling boot image. Resolve the string and allocate it if needed, to ensure
	// the string will be added to the boot image.
	DCHECK(!runtime->UseJitCompilation());
	string = class_linker->ResolveString(dex_file, string_index, dex_cache);
	CHECK(string != nullptr);
	if (compiler_driver_->GetSupportBootImageFixup()) {
	DCHECK(ContainsElement(compiler_driver_->GetDexFilesForOatFile(), &dex_file));
	desired_load_kind = codegen_->GetCompilerOptions().GetCompilePic()
	? HLoadString::LoadKind::kBootImageLinkTimePcRelative
	: HLoadString::LoadKind::kBootImageLinkTimeAddress;
	} else {
	// MIPS64 or compiler_driver_test. Do not sharpen.
	DCHECK_EQ(desired_load_kind, HLoadString::LoadKind::kDexCacheViaMethod);
	}
	} else if (runtime->UseJitCompilation()) {
	// TODO: Make sure we don't set the "compile PIC" flag for JIT as that's bogus.
	// DCHECK(!codegen_->GetCompilerOptions().GetCompilePic());
	string = class_linker->LookupString(dex_file, string_index, dex_cache);
	if (string != nullptr) {
	if (runtime->GetHeap()->ObjectIsInBootImageSpace(string)) {
	desired_load_kind = HLoadString::LoadKind::kBootImageAddress;
	} else {
	desired_load_kind = HLoadString::LoadKind::kJitTableAddress;
	}
	}
	} else {
	// AOT app compilation. Try to lookup the string without allocating if not found.
	string = class_linker->LookupString(dex_file, string_index, dex_cache);
	if (string != nullptr &&
	runtime->GetHeap()->ObjectIsInBootImageSpace(string) &&
	!codegen_->GetCompilerOptions().GetCompilePic()) {
	desired_load_kind = HLoadString::LoadKind::kBootImageAddress;
	} else {
	desired_load_kind = HLoadString::LoadKind::kBssEntry;
	}
	}
	if (string != nullptr) {
	load_string->SetString(handles_->NewHandle(string));
	}
	}

	HLoadString::LoadKind load_kind = codegen_->GetSupportedLoadStringKind(desired_load_kind);
	load_string->SetLoadKind(load_kind);
	}

	} // namespace art