runtime/quick_exception_handler.cc - platform/art - Gitiles

 /*
  * Copyright (C) 2014 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 "quick_exception_handler.h"

 #include "arch/context.h"
 #include "dex_instruction.h"
 #include "entrypoints/entrypoint_utils.h"
 #include "handle_scope-inl.h"
 #include "mirror/art_method-inl.h"
 #include "mirror/class-inl.h"
 #include "mirror/class_loader.h"
 #include "mirror/throwable.h"
 #include "verifier/method_verifier.h"

 namespace art {

 static constexpr bool kDebugExceptionDelivery = false;
 static constexpr size_t kInvalidFrameId = 0xffffffff;

 QuickExceptionHandler::QuickExceptionHandler(Thread* self, bool is_deoptimization)
   : self_(self), context_(self->GetLongJumpContext()), is_deoptimization_(is_deoptimization),
     method_tracing_active_(is_deoptimization ||
                            Runtime::Current()->GetInstrumentation()->AreExitStubsInstalled()),
     handler_quick_frame_(nullptr), handler_quick_frame_pc_(0), handler_method_(nullptr),
     handler_dex_pc_(0), clear_exception_(false), handler_frame_id_(kInvalidFrameId) {
 }

 // Finds catch handler or prepares for deoptimization.
 class CatchBlockStackVisitor FINAL : public StackVisitor {
  public:
   CatchBlockStackVisitor(Thread* self, Context* context, Handle<mirror::Throwable>* exception,
                          QuickExceptionHandler* exception_handler)
       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_)
       : StackVisitor(self, context), self_(self), exception_(exception),
         exception_handler_(exception_handler) {
   }

   bool VisitFrame() OVERRIDE SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
     mirror::ArtMethod* method = GetMethod();
     exception_handler_->SetHandlerFrameId(GetFrameId());
     if (method == nullptr) {
       // This is the upcall, we remember the frame and last pc so that we may long jump to them.
       exception_handler_->SetHandlerQuickFramePc(GetCurrentQuickFramePc());
       exception_handler_->SetHandlerQuickFrame(GetCurrentQuickFrame());
       uint32_t next_dex_pc;
       mirror::ArtMethod* next_art_method;
       bool has_next = GetNextMethodAndDexPc(&next_art_method, &next_dex_pc);
       // Report the method that did the down call as the handler.
       exception_handler_->SetHandlerDexPc(next_dex_pc);
       exception_handler_->SetHandlerMethod(next_art_method);
       if (!has_next) {
         // No next method? Check exception handler is set up for the unhandled exception handler
         // case.
         DCHECK_EQ(0U, exception_handler_->GetHandlerDexPc());
         DCHECK(nullptr == exception_handler_->GetHandlerMethod());
       }
       return false;  // End stack walk.
     }
     if (method->IsRuntimeMethod()) {
       // Ignore callee save method.
       DCHECK(method->IsCalleeSaveMethod());
       return true;
     }
     StackHandleScope<1> hs(self_);
     return HandleTryItems(hs.NewHandle(method));
   }

  private:
   bool HandleTryItems(Handle<mirror::ArtMethod> method)
       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
     uint32_t dex_pc = DexFile::kDexNoIndex;
     if (!method->IsNative()) {
       dex_pc = GetDexPc();
     }
     if (dex_pc != DexFile::kDexNoIndex) {
       bool clear_exception = false;
       StackHandleScope<1> hs(Thread::Current());
       Handle<mirror::Class> to_find(hs.NewHandle((*exception_)->GetClass()));
       uint32_t found_dex_pc = mirror::ArtMethod::FindCatchBlock(method, to_find, dex_pc,
                                                                 &clear_exception);
       exception_handler_->SetClearException(clear_exception);
       if (found_dex_pc != DexFile::kDexNoIndex) {
         exception_handler_->SetHandlerMethod(method.Get());
         exception_handler_->SetHandlerDexPc(found_dex_pc);
         exception_handler_->SetHandlerQuickFramePc(method->ToNativePc(found_dex_pc));
         exception_handler_->SetHandlerQuickFrame(GetCurrentQuickFrame());
         return false;  // End stack walk.
       }
     }
     return true;  // Continue stack walk.
   }

   Thread* const self_;
   // The exception we're looking for the catch block of.
   Handle<mirror::Throwable>* exception_;
   // The quick exception handler we're visiting for.
   QuickExceptionHandler* const exception_handler_;

   DISALLOW_COPY_AND_ASSIGN(CatchBlockStackVisitor);
 };

 void QuickExceptionHandler::FindCatch(const ThrowLocation& throw_location,
                                       mirror::Throwable* exception,
                                       bool is_exception_reported) {
   DCHECK(!is_deoptimization_);
   if (kDebugExceptionDelivery) {
     mirror::String* msg = exception->GetDetailMessage();
     std::string str_msg(msg != nullptr ? msg->ToModifiedUtf8() : "");
     self_->DumpStack(LOG(INFO) << "Delivering exception: " << PrettyTypeOf(exception)
                      << ": " << str_msg << "\n");
   }
   StackHandleScope<1> hs(self_);
   Handle<mirror::Throwable> exception_ref(hs.NewHandle(exception));

   // Walk the stack to find catch handler or prepare for deoptimization.
   CatchBlockStackVisitor visitor(self_, context_, &exception_ref, this);
   visitor.WalkStack(true);

   if (kDebugExceptionDelivery) {
     if (handler_quick_frame_->AsMirrorPtr() == nullptr) {
       LOG(INFO) << "Handler is upcall";
     }
     if (handler_method_ != nullptr) {
       const DexFile& dex_file = *handler_method_->GetDeclaringClass()->GetDexCache()->GetDexFile();
       int line_number = dex_file.GetLineNumFromPC(handler_method_, handler_dex_pc_);
       LOG(INFO) << "Handler: " << PrettyMethod(handler_method_) << " (line: " << line_number << ")";
     }
   }
   if (clear_exception_) {
     // Exception was cleared as part of delivery.
     DCHECK(!self_->IsExceptionPending());
   } else {
     // Put exception back in root set with clear throw location.
     self_->SetException(ThrowLocation(), exception_ref.Get());
     self_->SetExceptionReportedToInstrumentation(is_exception_reported);
   }
   // The debugger may suspend this thread and walk its stack. Let's do this before popping
   // instrumentation frames.
   if (!is_exception_reported) {
     instrumentation::Instrumentation* instrumentation = Runtime::Current()->GetInstrumentation();
     instrumentation->ExceptionCaughtEvent(self_, throw_location, handler_method_, handler_dex_pc_,
                                           exception_ref.Get());
       // We're not catching this exception but let's remind we already reported the exception above
       // to avoid reporting it twice.
       self_->SetExceptionReportedToInstrumentation(true);
   }
   bool caught_exception = (handler_method_ != nullptr && handler_dex_pc_ != DexFile::kDexNoIndex);
   if (caught_exception) {
     // We're catching this exception so we finish reporting it. We do it here to avoid doing it
     // in the compiled code.
     self_->SetExceptionReportedToInstrumentation(false);
   }
 }

 // Prepares deoptimization.
 class DeoptimizeStackVisitor FINAL : public StackVisitor {
  public:
   DeoptimizeStackVisitor(Thread* self, Context* context, QuickExceptionHandler* exception_handler)
       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_)
       : StackVisitor(self, context), self_(self), exception_handler_(exception_handler),
         prev_shadow_frame_(nullptr) {
     CHECK(!self_->HasDeoptimizationShadowFrame());
   }

   bool VisitFrame() OVERRIDE SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
     exception_handler_->SetHandlerFrameId(GetFrameId());
     mirror::ArtMethod* method = GetMethod();
     if (method == nullptr) {
       // This is the upcall, we remember the frame and last pc so that we may long jump to them.
       exception_handler_->SetHandlerQuickFramePc(GetCurrentQuickFramePc());
       exception_handler_->SetHandlerQuickFrame(GetCurrentQuickFrame());
       return false;  // End stack walk.
     } else if (method->IsRuntimeMethod()) {
       // Ignore callee save method.
       DCHECK(method->IsCalleeSaveMethod());
       return true;
     } else {
       return HandleDeoptimization(method);
     }
   }

  private:
   static VRegKind GetVRegKind(uint16_t reg, const std::vector<int32_t>& kinds) {
     return static_cast<VRegKind>(kinds.at(reg * 2));
   }

   bool HandleDeoptimization(mirror::ArtMethod* m) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
     const DexFile::CodeItem* code_item = m->GetCodeItem();
     CHECK(code_item != nullptr);
     uint16_t num_regs = code_item->registers_size_;
     uint32_t dex_pc = GetDexPc();
     const Instruction* inst = Instruction::At(code_item->insns_ + dex_pc);
     uint32_t new_dex_pc = dex_pc + inst->SizeInCodeUnits();
     ShadowFrame* new_frame = ShadowFrame::Create(num_regs, nullptr, m, new_dex_pc);
     StackHandleScope<2> hs(self_);
     mirror::Class* declaring_class = m->GetDeclaringClass();
     Handle<mirror::DexCache> h_dex_cache(hs.NewHandle(declaring_class->GetDexCache()));
     Handle<mirror::ClassLoader> h_class_loader(hs.NewHandle(declaring_class->GetClassLoader()));
     verifier::MethodVerifier verifier(h_dex_cache->GetDexFile(), &h_dex_cache, &h_class_loader,
                                       &m->GetClassDef(), code_item, m->GetDexMethodIndex(), m,
                                       m->GetAccessFlags(), false, true, true);
     verifier.Verify();
     const std::vector<int32_t> kinds(verifier.DescribeVRegs(dex_pc));
     for (uint16_t reg = 0; reg < num_regs; ++reg) {
       VRegKind kind = GetVRegKind(reg, kinds);
       switch (kind) {
         case kUndefined:
           new_frame->SetVReg(reg, 0xEBADDE09);
           break;
         case kConstant:
           new_frame->SetVReg(reg, kinds.at((reg * 2) + 1));
           break;
         case kReferenceVReg:
           new_frame->SetVRegReference(reg,
                                       reinterpret_cast<mirror::Object*>(GetVReg(m, reg, kind)));
           break;
         case kLongLoVReg:
           if (GetVRegKind(reg + 1, kinds), kLongHiVReg) {
             // Treat it as a "long" register pair.
             new_frame->SetVRegLong(reg, GetVRegPair(m, reg, kLongLoVReg, kLongHiVReg));
           } else {
             new_frame->SetVReg(reg, GetVReg(m, reg, kind));
           }
           break;
         case kLongHiVReg:
           if (GetVRegKind(reg - 1, kinds), kLongLoVReg) {
             // Nothing to do: we treated it as a "long" register pair.
           } else {
             new_frame->SetVReg(reg, GetVReg(m, reg, kind));
           }
           break;
         case kDoubleLoVReg:
           if (GetVRegKind(reg + 1, kinds), kDoubleHiVReg) {
             // Treat it as a "double" register pair.
             new_frame->SetVRegLong(reg, GetVRegPair(m, reg, kDoubleLoVReg, kDoubleHiVReg));
           } else {
             new_frame->SetVReg(reg, GetVReg(m, reg, kind));
           }
           break;
         case kDoubleHiVReg:
           if (GetVRegKind(reg - 1, kinds), kDoubleLoVReg) {
             // Nothing to do: we treated it as a "double" register pair.
           } else {
             new_frame->SetVReg(reg, GetVReg(m, reg, kind));
           }
           break;
         default:
           new_frame->SetVReg(reg, GetVReg(m, reg, kind));
           break;
       }
     }
     if (prev_shadow_frame_ != nullptr) {
       prev_shadow_frame_->SetLink(new_frame);
     } else {
       self_->SetDeoptimizationShadowFrame(new_frame);
     }
     prev_shadow_frame_ = new_frame;
     return true;
   }

   Thread* const self_;
   QuickExceptionHandler* const exception_handler_;
   ShadowFrame* prev_shadow_frame_;

   DISALLOW_COPY_AND_ASSIGN(DeoptimizeStackVisitor);
 };

 void QuickExceptionHandler::DeoptimizeStack() {
   DCHECK(is_deoptimization_);
   if (kDebugExceptionDelivery) {
     self_->DumpStack(LOG(INFO) << "Deoptimizing: ");
   }

   DeoptimizeStackVisitor visitor(self_, context_, this);
   visitor.WalkStack(true);

   // Restore deoptimization exception
   self_->SetException(ThrowLocation(), Thread::GetDeoptimizationException());
 }

 // Unwinds all instrumentation stack frame prior to catch handler or upcall.
 class InstrumentationStackVisitor : public StackVisitor {
  public:
   InstrumentationStackVisitor(Thread* self, bool is_deoptimization, size_t frame_id)
       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_)
       : StackVisitor(self, nullptr),
         self_(self), frame_id_(frame_id),
         instrumentation_frames_to_pop_(0) {
     CHECK_NE(frame_id_, kInvalidFrameId);
   }

   bool VisitFrame() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
     size_t current_frame_id = GetFrameId();
     if (current_frame_id > frame_id_) {
       CHECK(GetMethod() != nullptr);
       if (UNLIKELY(GetQuickInstrumentationExitPc() == GetReturnPc())) {
         ++instrumentation_frames_to_pop_;
       }
       return true;
     } else {
       // We reached the frame of the catch handler or the upcall.
       return false;
     }
   }

   size_t GetInstrumentationFramesToPop() const {
     return instrumentation_frames_to_pop_;
   }

  private:
   Thread* const self_;
   const size_t frame_id_;
   size_t instrumentation_frames_to_pop_;

   DISALLOW_COPY_AND_ASSIGN(InstrumentationStackVisitor);
 };

 void QuickExceptionHandler::UpdateInstrumentationStack() {
   if (method_tracing_active_) {
     InstrumentationStackVisitor visitor(self_, is_deoptimization_, handler_frame_id_);
     visitor.WalkStack(true);

     size_t instrumentation_frames_to_pop = visitor.GetInstrumentationFramesToPop();
     instrumentation::Instrumentation* instrumentation = Runtime::Current()->GetInstrumentation();
     for (size_t i = 0; i < instrumentation_frames_to_pop; ++i) {
       instrumentation->PopMethodForUnwind(self_, is_deoptimization_);
     }
   }
 }

 void QuickExceptionHandler::DoLongJump() {
   // Place context back on thread so it will be available when we continue.
   self_->ReleaseLongJumpContext(context_);
   context_->SetSP(reinterpret_cast<uintptr_t>(handler_quick_frame_));
   CHECK_NE(handler_quick_frame_pc_, 0u);
   context_->SetPC(handler_quick_frame_pc_);
   context_->SmashCallerSaves();
   context_->DoLongJump();
 }

 }  // namespace art
	/*
	* Copyright (C) 2014 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 "quick_exception_handler.h"

	#include "arch/context.h"
	#include "dex_instruction.h"
	#include "entrypoints/entrypoint_utils.h"
	#include "handle_scope-inl.h"
	#include "mirror/art_method-inl.h"
	#include "mirror/class-inl.h"
	#include "mirror/class_loader.h"
	#include "mirror/throwable.h"
	#include "verifier/method_verifier.h"

	namespace art {

	static constexpr bool kDebugExceptionDelivery = false;
	static constexpr size_t kInvalidFrameId = 0xffffffff;

	QuickExceptionHandler::QuickExceptionHandler(Thread* self, bool is_deoptimization)
	: self_(self), context_(self->GetLongJumpContext()), is_deoptimization_(is_deoptimization),
	method_tracing_active_(is_deoptimization \|\|
	Runtime::Current()->GetInstrumentation()->AreExitStubsInstalled()),
	handler_quick_frame_(nullptr), handler_quick_frame_pc_(0), handler_method_(nullptr),
	handler_dex_pc_(0), clear_exception_(false), handler_frame_id_(kInvalidFrameId) {
	}

	// Finds catch handler or prepares for deoptimization.
	class CatchBlockStackVisitor FINAL : public StackVisitor {
	public:
	CatchBlockStackVisitor(Thread* self, Context* context, Handle<mirror::Throwable>* exception,
	QuickExceptionHandler* exception_handler)
	SHARED_LOCKS_REQUIRED(Locks::mutator_lock_)
	: StackVisitor(self, context), self_(self), exception_(exception),
	exception_handler_(exception_handler) {
	}

	bool VisitFrame() OVERRIDE SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
	mirror::ArtMethod* method = GetMethod();
	exception_handler_->SetHandlerFrameId(GetFrameId());
	if (method == nullptr) {
	// This is the upcall, we remember the frame and last pc so that we may long jump to them.
	exception_handler_->SetHandlerQuickFramePc(GetCurrentQuickFramePc());
	exception_handler_->SetHandlerQuickFrame(GetCurrentQuickFrame());
	uint32_t next_dex_pc;
	mirror::ArtMethod* next_art_method;
	bool has_next = GetNextMethodAndDexPc(&next_art_method, &next_dex_pc);
	// Report the method that did the down call as the handler.
	exception_handler_->SetHandlerDexPc(next_dex_pc);
	exception_handler_->SetHandlerMethod(next_art_method);
	if (!has_next) {
	// No next method? Check exception handler is set up for the unhandled exception handler
	// case.
	DCHECK_EQ(0U, exception_handler_->GetHandlerDexPc());
	DCHECK(nullptr == exception_handler_->GetHandlerMethod());
	}
	return false; // End stack walk.
	}
	if (method->IsRuntimeMethod()) {
	// Ignore callee save method.
	DCHECK(method->IsCalleeSaveMethod());
	return true;
	}
	StackHandleScope<1> hs(self_);
	return HandleTryItems(hs.NewHandle(method));
	}

	private:
	bool HandleTryItems(Handle<mirror::ArtMethod> method)
	SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
	uint32_t dex_pc = DexFile::kDexNoIndex;
	if (!method->IsNative()) {
	dex_pc = GetDexPc();
	}
	if (dex_pc != DexFile::kDexNoIndex) {
	bool clear_exception = false;
	StackHandleScope<1> hs(Thread::Current());
	Handle<mirror::Class> to_find(hs.NewHandle((*exception_)->GetClass()));
	uint32_t found_dex_pc = mirror::ArtMethod::FindCatchBlock(method, to_find, dex_pc,
	&clear_exception);
	exception_handler_->SetClearException(clear_exception);
	if (found_dex_pc != DexFile::kDexNoIndex) {
	exception_handler_->SetHandlerMethod(method.Get());
	exception_handler_->SetHandlerDexPc(found_dex_pc);
	exception_handler_->SetHandlerQuickFramePc(method->ToNativePc(found_dex_pc));
	exception_handler_->SetHandlerQuickFrame(GetCurrentQuickFrame());
	return false; // End stack walk.
	}
	}
	return true; // Continue stack walk.
	}

	Thread* const self_;
	// The exception we're looking for the catch block of.
	Handle<mirror::Throwable>* exception_;
	// The quick exception handler we're visiting for.
	QuickExceptionHandler* const exception_handler_;

	DISALLOW_COPY_AND_ASSIGN(CatchBlockStackVisitor);
	};

	void QuickExceptionHandler::FindCatch(const ThrowLocation& throw_location,
	mirror::Throwable* exception,
	bool is_exception_reported) {
	DCHECK(!is_deoptimization_);
	if (kDebugExceptionDelivery) {
	mirror::String* msg = exception->GetDetailMessage();
	std::string str_msg(msg != nullptr ? msg->ToModifiedUtf8() : "");
	self_->DumpStack(LOG(INFO) << "Delivering exception: " << PrettyTypeOf(exception)
	<< ": " << str_msg << "\n");
	}
	StackHandleScope<1> hs(self_);
	Handle<mirror::Throwable> exception_ref(hs.NewHandle(exception));

	// Walk the stack to find catch handler or prepare for deoptimization.
	CatchBlockStackVisitor visitor(self_, context_, &exception_ref, this);
	visitor.WalkStack(true);

	if (kDebugExceptionDelivery) {
	if (handler_quick_frame_->AsMirrorPtr() == nullptr) {
	LOG(INFO) << "Handler is upcall";
	}
	if (handler_method_ != nullptr) {
	const DexFile& dex_file = *handler_method_->GetDeclaringClass()->GetDexCache()->GetDexFile();
	int line_number = dex_file.GetLineNumFromPC(handler_method_, handler_dex_pc_);
	LOG(INFO) << "Handler: " << PrettyMethod(handler_method_) << " (line: " << line_number << ")";
	}
	}
	if (clear_exception_) {
	// Exception was cleared as part of delivery.
	DCHECK(!self_->IsExceptionPending());
	} else {
	// Put exception back in root set with clear throw location.
	self_->SetException(ThrowLocation(), exception_ref.Get());
	self_->SetExceptionReportedToInstrumentation(is_exception_reported);
	}
	// The debugger may suspend this thread and walk its stack. Let's do this before popping
	// instrumentation frames.
	if (!is_exception_reported) {
	instrumentation::Instrumentation* instrumentation = Runtime::Current()->GetInstrumentation();
	instrumentation->ExceptionCaughtEvent(self_, throw_location, handler_method_, handler_dex_pc_,
	exception_ref.Get());
	// We're not catching this exception but let's remind we already reported the exception above
	// to avoid reporting it twice.
	self_->SetExceptionReportedToInstrumentation(true);
	}
	bool caught_exception = (handler_method_ != nullptr && handler_dex_pc_ != DexFile::kDexNoIndex);
	if (caught_exception) {
	// We're catching this exception so we finish reporting it. We do it here to avoid doing it
	// in the compiled code.
	self_->SetExceptionReportedToInstrumentation(false);
	}
	}

	// Prepares deoptimization.
	class DeoptimizeStackVisitor FINAL : public StackVisitor {
	public:
	DeoptimizeStackVisitor(Thread* self, Context* context, QuickExceptionHandler* exception_handler)
	SHARED_LOCKS_REQUIRED(Locks::mutator_lock_)
	: StackVisitor(self, context), self_(self), exception_handler_(exception_handler),
	prev_shadow_frame_(nullptr) {
	CHECK(!self_->HasDeoptimizationShadowFrame());
	}

	bool VisitFrame() OVERRIDE SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
	exception_handler_->SetHandlerFrameId(GetFrameId());
	mirror::ArtMethod* method = GetMethod();
	if (method == nullptr) {
	// This is the upcall, we remember the frame and last pc so that we may long jump to them.
	exception_handler_->SetHandlerQuickFramePc(GetCurrentQuickFramePc());
	exception_handler_->SetHandlerQuickFrame(GetCurrentQuickFrame());
	return false; // End stack walk.
	} else if (method->IsRuntimeMethod()) {
	// Ignore callee save method.
	DCHECK(method->IsCalleeSaveMethod());
	return true;
	} else {
	return HandleDeoptimization(method);
	}
	}

	private:
	static VRegKind GetVRegKind(uint16_t reg, const std::vector<int32_t>& kinds) {
	return static_cast<VRegKind>(kinds.at(reg * 2));
	}

	bool HandleDeoptimization(mirror::ArtMethod* m) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
	const DexFile::CodeItem* code_item = m->GetCodeItem();
	CHECK(code_item != nullptr);
	uint16_t num_regs = code_item->registers_size_;
	uint32_t dex_pc = GetDexPc();
	const Instruction* inst = Instruction::At(code_item->insns_ + dex_pc);
	uint32_t new_dex_pc = dex_pc + inst->SizeInCodeUnits();
	ShadowFrame* new_frame = ShadowFrame::Create(num_regs, nullptr, m, new_dex_pc);
	StackHandleScope<2> hs(self_);
	mirror::Class* declaring_class = m->GetDeclaringClass();
	Handle<mirror::DexCache> h_dex_cache(hs.NewHandle(declaring_class->GetDexCache()));
	Handle<mirror::ClassLoader> h_class_loader(hs.NewHandle(declaring_class->GetClassLoader()));
	verifier::MethodVerifier verifier(h_dex_cache->GetDexFile(), &h_dex_cache, &h_class_loader,
	&m->GetClassDef(), code_item, m->GetDexMethodIndex(), m,
	m->GetAccessFlags(), false, true, true);
	verifier.Verify();
	const std::vector<int32_t> kinds(verifier.DescribeVRegs(dex_pc));
	for (uint16_t reg = 0; reg < num_regs; ++reg) {
	VRegKind kind = GetVRegKind(reg, kinds);
	switch (kind) {
	case kUndefined:
	new_frame->SetVReg(reg, 0xEBADDE09);
	break;
	case kConstant:
	new_frame->SetVReg(reg, kinds.at((reg * 2) + 1));
	break;
	case kReferenceVReg:
	new_frame->SetVRegReference(reg,
	reinterpret_cast<mirror::Object*>(GetVReg(m, reg, kind)));
	break;
	case kLongLoVReg:
	if (GetVRegKind(reg + 1, kinds), kLongHiVReg) {
	// Treat it as a "long" register pair.
	new_frame->SetVRegLong(reg, GetVRegPair(m, reg, kLongLoVReg, kLongHiVReg));
	} else {
	new_frame->SetVReg(reg, GetVReg(m, reg, kind));
	}
	break;
	case kLongHiVReg:
	if (GetVRegKind(reg - 1, kinds), kLongLoVReg) {
	// Nothing to do: we treated it as a "long" register pair.
	} else {
	new_frame->SetVReg(reg, GetVReg(m, reg, kind));
	}
	break;
	case kDoubleLoVReg:
	if (GetVRegKind(reg + 1, kinds), kDoubleHiVReg) {
	// Treat it as a "double" register pair.
	new_frame->SetVRegLong(reg, GetVRegPair(m, reg, kDoubleLoVReg, kDoubleHiVReg));
	} else {
	new_frame->SetVReg(reg, GetVReg(m, reg, kind));
	}
	break;
	case kDoubleHiVReg:
	if (GetVRegKind(reg - 1, kinds), kDoubleLoVReg) {
	// Nothing to do: we treated it as a "double" register pair.
	} else {
	new_frame->SetVReg(reg, GetVReg(m, reg, kind));
	}
	break;
	default:
	new_frame->SetVReg(reg, GetVReg(m, reg, kind));
	break;
	}
	}
	if (prev_shadow_frame_ != nullptr) {
	prev_shadow_frame_->SetLink(new_frame);
	} else {
	self_->SetDeoptimizationShadowFrame(new_frame);
	}
	prev_shadow_frame_ = new_frame;
	return true;
	}

	Thread* const self_;
	QuickExceptionHandler* const exception_handler_;
	ShadowFrame* prev_shadow_frame_;

	DISALLOW_COPY_AND_ASSIGN(DeoptimizeStackVisitor);
	};

	void QuickExceptionHandler::DeoptimizeStack() {
	DCHECK(is_deoptimization_);
	if (kDebugExceptionDelivery) {
	self_->DumpStack(LOG(INFO) << "Deoptimizing: ");
	}

	DeoptimizeStackVisitor visitor(self_, context_, this);
	visitor.WalkStack(true);

	// Restore deoptimization exception
	self_->SetException(ThrowLocation(), Thread::GetDeoptimizationException());
	}

	// Unwinds all instrumentation stack frame prior to catch handler or upcall.
	class InstrumentationStackVisitor : public StackVisitor {
	public:
	InstrumentationStackVisitor(Thread* self, bool is_deoptimization, size_t frame_id)
	SHARED_LOCKS_REQUIRED(Locks::mutator_lock_)
	: StackVisitor(self, nullptr),
	self_(self), frame_id_(frame_id),
	instrumentation_frames_to_pop_(0) {
	CHECK_NE(frame_id_, kInvalidFrameId);
	}

	bool VisitFrame() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
	size_t current_frame_id = GetFrameId();
	if (current_frame_id > frame_id_) {
	CHECK(GetMethod() != nullptr);
	if (UNLIKELY(GetQuickInstrumentationExitPc() == GetReturnPc())) {
	++instrumentation_frames_to_pop_;
	}
	return true;
	} else {
	// We reached the frame of the catch handler or the upcall.
	return false;
	}
	}

	size_t GetInstrumentationFramesToPop() const {
	return instrumentation_frames_to_pop_;
	}

	private:
	Thread* const self_;
	const size_t frame_id_;
	size_t instrumentation_frames_to_pop_;

	DISALLOW_COPY_AND_ASSIGN(InstrumentationStackVisitor);
	};

	void QuickExceptionHandler::UpdateInstrumentationStack() {
	if (method_tracing_active_) {
	InstrumentationStackVisitor visitor(self_, is_deoptimization_, handler_frame_id_);
	visitor.WalkStack(true);

	size_t instrumentation_frames_to_pop = visitor.GetInstrumentationFramesToPop();
	instrumentation::Instrumentation* instrumentation = Runtime::Current()->GetInstrumentation();
	for (size_t i = 0; i < instrumentation_frames_to_pop; ++i) {
	instrumentation->PopMethodForUnwind(self_, is_deoptimization_);
	}
	}
	}

	void QuickExceptionHandler::DoLongJump() {
	// Place context back on thread so it will be available when we continue.
	self_->ReleaseLongJumpContext(context_);
	context_->SetSP(reinterpret_cast<uintptr_t>(handler_quick_frame_));
	CHECK_NE(handler_quick_frame_pc_, 0u);
	context_->SetPC(handler_quick_frame_pc_);
	context_->SmashCallerSaves();
	context_->DoLongJump();
	}

	} // namespace art