runtime/stack.cc - platform/art - Git at Google

 /*
  * Copyright (C) 2011 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 "stack.h"

 #include "base/hex_dump.h"
 #include "mirror/art_method-inl.h"
 #include "mirror/class-inl.h"
 #include "mirror/object.h"
 #include "mirror/object-inl.h"
 #include "mirror/object_array-inl.h"
 #include "object_utils.h"
 #include "quick/quick_method_frame_info.h"
 #include "runtime.h"
 #include "thread.h"
 #include "thread_list.h"
 #include "throw_location.h"
 #include "verify_object-inl.h"
 #include "vmap_table.h"

 namespace art {

 mirror::Object* ShadowFrame::GetThisObject() const {
   mirror::ArtMethod* m = GetMethod();
   if (m->IsStatic()) {
     return NULL;
   } else if (m->IsNative()) {
     return GetVRegReference(0);
   } else {
     const DexFile::CodeItem* code_item = m->GetCodeItem();
     CHECK(code_item != NULL) << PrettyMethod(m);
     uint16_t reg = code_item->registers_size_ - code_item->ins_size_;
     return GetVRegReference(reg);
   }
 }

 mirror::Object* ShadowFrame::GetThisObject(uint16_t num_ins) const {
   mirror::ArtMethod* m = GetMethod();
   if (m->IsStatic()) {
     return NULL;
   } else {
     return GetVRegReference(NumberOfVRegs() - num_ins);
   }
 }

 ThrowLocation ShadowFrame::GetCurrentLocationForThrow() const {
   return ThrowLocation(GetThisObject(), GetMethod(), GetDexPC());
 }

 size_t ManagedStack::NumJniShadowFrameReferences() const {
   size_t count = 0;
   for (const ManagedStack* current_fragment = this; current_fragment != NULL;
        current_fragment = current_fragment->GetLink()) {
     for (ShadowFrame* current_frame = current_fragment->top_shadow_frame_; current_frame != NULL;
          current_frame = current_frame->GetLink()) {
       if (current_frame->GetMethod()->IsNative()) {
         // The JNI ShadowFrame only contains references. (For indirect reference.)
         count += current_frame->NumberOfVRegs();
       }
     }
   }
   return count;
 }

 bool ManagedStack::ShadowFramesContain(StackReference<mirror::Object>* shadow_frame_entry) const {
   for (const ManagedStack* current_fragment = this; current_fragment != NULL;
        current_fragment = current_fragment->GetLink()) {
     for (ShadowFrame* current_frame = current_fragment->top_shadow_frame_; current_frame != NULL;
          current_frame = current_frame->GetLink()) {
       if (current_frame->Contains(shadow_frame_entry)) {
         return true;
       }
     }
   }
   return false;
 }

 StackVisitor::StackVisitor(Thread* thread, Context* context)
     : thread_(thread), cur_shadow_frame_(NULL),
       cur_quick_frame_(NULL), cur_quick_frame_pc_(0), num_frames_(0), cur_depth_(0),
       context_(context) {
   DCHECK(thread == Thread::Current() || thread->IsSuspended()) << *thread;
 }

 StackVisitor::StackVisitor(Thread* thread, Context* context, size_t num_frames)
     : thread_(thread), cur_shadow_frame_(NULL),
       cur_quick_frame_(NULL), cur_quick_frame_pc_(0), num_frames_(num_frames), cur_depth_(0),
       context_(context) {
   DCHECK(thread == Thread::Current() || thread->IsSuspended()) << *thread;
 }

 uint32_t StackVisitor::GetDexPc(bool abort_on_failure) const {
   if (cur_shadow_frame_ != NULL) {
     return cur_shadow_frame_->GetDexPC();
   } else if (cur_quick_frame_ != NULL) {
     return GetMethod()->ToDexPc(cur_quick_frame_pc_, abort_on_failure);
   } else {
     return 0;
   }
 }

 mirror::Object* StackVisitor::GetThisObject() const {
   mirror::ArtMethod* m = GetMethod();
   if (m->IsStatic()) {
     return NULL;
   } else if (m->IsNative()) {
     if (cur_quick_frame_ != NULL) {
       HandleScope* hs = reinterpret_cast<HandleScope*>(
           reinterpret_cast<char*>(cur_quick_frame_) + m->GetHandleScopeOffsetInBytes());
       return hs->GetReference(0);
     } else {
       return cur_shadow_frame_->GetVRegReference(0);
     }
   } else {
     const DexFile::CodeItem* code_item = m->GetCodeItem();
     if (code_item == NULL) {
       UNIMPLEMENTED(ERROR) << "Failed to determine this object of abstract or proxy method: "
           << PrettyMethod(m);
       return nullptr;
     } else {
       uint16_t reg = code_item->registers_size_ - code_item->ins_size_;
       return reinterpret_cast<mirror::Object*>(GetVReg(m, reg, kReferenceVReg));
     }
   }
 }

 size_t StackVisitor::GetNativePcOffset() const {
   DCHECK(!IsShadowFrame());
   return GetMethod()->NativePcOffset(cur_quick_frame_pc_);
 }

 bool StackVisitor::GetVReg(mirror::ArtMethod* m, uint16_t vreg, VRegKind kind,
                            uint32_t* val) const {
   if (cur_quick_frame_ != NULL) {
     DCHECK(context_ != NULL);  // You can't reliably read registers without a context.
     DCHECK(m == GetMethod());
     const void* code_pointer = m->GetQuickOatCodePointer();
     DCHECK(code_pointer != nullptr);
     const VmapTable vmap_table(m->GetVmapTable(code_pointer));
     QuickMethodFrameInfo frame_info = m->GetQuickFrameInfo(code_pointer);
     uint32_t vmap_offset;
     // TODO: IsInContext stops before spotting floating point registers.
     if (vmap_table.IsInContext(vreg, kind, &vmap_offset)) {
       bool is_float = (kind == kFloatVReg) || (kind == kDoubleLoVReg) || (kind == kDoubleHiVReg);
       uint32_t spill_mask = is_float ? frame_info.FpSpillMask() : frame_info.CoreSpillMask();
       uint32_t reg = vmap_table.ComputeRegister(spill_mask, vmap_offset, kind);
       uintptr_t ptr_val;
       bool success = false;
       bool target64 = (kRuntimeISA == kArm64) || (kRuntimeISA == kX86_64);
       if (is_float) {
         success = GetFPR(reg, &ptr_val);
       } else {
         success = GetGPR(reg, &ptr_val);
       }
       if (success && target64) {
         bool wide_lo = (kind == kLongLoVReg) || (kind == kDoubleLoVReg);
         bool wide_hi = (kind == kLongHiVReg) || (kind == kDoubleHiVReg);
         int64_t value_long = static_cast<int64_t>(ptr_val);
         if (wide_lo) {
           ptr_val = static_cast<uintptr_t>(value_long & 0xFFFFFFFF);
         } else if (wide_hi) {
           ptr_val = static_cast<uintptr_t>(value_long >> 32);
         }
       }
       *val = ptr_val;
       return success;
     } else {
       const DexFile::CodeItem* code_item = m->GetCodeItem();
       DCHECK(code_item != NULL) << PrettyMethod(m);  // Can't be NULL or how would we compile its instructions?
       *val = *GetVRegAddr(cur_quick_frame_, code_item, frame_info.CoreSpillMask(),
                           frame_info.FpSpillMask(), frame_info.FrameSizeInBytes(), vreg);
       return true;
     }
   } else {
     *val = cur_shadow_frame_->GetVReg(vreg);
     return true;
   }
 }

 bool StackVisitor::SetVReg(mirror::ArtMethod* m, uint16_t vreg, uint32_t new_value,
                            VRegKind kind) {
   if (cur_quick_frame_ != NULL) {
     DCHECK(context_ != NULL);  // You can't reliably write registers without a context.
     DCHECK(m == GetMethod());
     const void* code_pointer = m->GetQuickOatCodePointer();
     DCHECK(code_pointer != nullptr);
     const VmapTable vmap_table(m->GetVmapTable(code_pointer));
     QuickMethodFrameInfo frame_info = m->GetQuickFrameInfo(code_pointer);
     uint32_t vmap_offset;
     // TODO: IsInContext stops before spotting floating point registers.
     if (vmap_table.IsInContext(vreg, kind, &vmap_offset)) {
       bool is_float = (kind == kFloatVReg) || (kind == kDoubleLoVReg) || (kind == kDoubleHiVReg);
       uint32_t spill_mask = is_float ? frame_info.FpSpillMask() : frame_info.CoreSpillMask();
       const uint32_t reg = vmap_table.ComputeRegister(spill_mask, vmap_offset, kind);
       bool target64 = (kRuntimeISA == kArm64) || (kRuntimeISA == kX86_64);
       // Deal with 32 or 64-bit wide registers in a way that builds on all targets.
       if (target64) {
         bool wide_lo = (kind == kLongLoVReg) || (kind == kDoubleLoVReg);
         bool wide_hi = (kind == kLongHiVReg) || (kind == kDoubleHiVReg);
         if (wide_lo || wide_hi) {
           uintptr_t old_reg_val;
           bool success = is_float ? GetFPR(reg, &old_reg_val) : GetGPR(reg, &old_reg_val);
           if (!success) {
             return false;
           }
           uint64_t new_vreg_portion = static_cast<uint64_t>(new_value);
           uint64_t old_reg_val_as_wide = static_cast<uint64_t>(old_reg_val);
           uint64_t mask = 0xffffffff;
           if (wide_lo) {
             mask = mask << 32;
           } else {
             new_vreg_portion = new_vreg_portion << 32;
           }
           new_value = static_cast<uintptr_t>((old_reg_val_as_wide & mask) | new_vreg_portion);
         }
       }
       if (is_float) {
         return SetFPR(reg, new_value);
       } else {
         return SetGPR(reg, new_value);
       }
     } else {
       const DexFile::CodeItem* code_item = m->GetCodeItem();
       DCHECK(code_item != NULL) << PrettyMethod(m);  // Can't be NULL or how would we compile its instructions?
       int offset = GetVRegOffset(code_item, frame_info.CoreSpillMask(), frame_info.FpSpillMask(),
                                  frame_info.FrameSizeInBytes(), vreg, kRuntimeISA);
       byte* vreg_addr = reinterpret_cast<byte*>(GetCurrentQuickFrame()) + offset;
       *reinterpret_cast<uint32_t*>(vreg_addr) = new_value;
       return true;
     }
   } else {
     cur_shadow_frame_->SetVReg(vreg, new_value);
     return true;
   }
 }

 uintptr_t* StackVisitor::GetGPRAddress(uint32_t reg) const {
   DCHECK(cur_quick_frame_ != NULL) << "This is a quick frame routine";
   return context_->GetGPRAddress(reg);
 }

 bool StackVisitor::GetGPR(uint32_t reg, uintptr_t* val) const {
   DCHECK(cur_quick_frame_ != NULL) << "This is a quick frame routine";
   return context_->GetGPR(reg, val);
 }

 bool StackVisitor::SetGPR(uint32_t reg, uintptr_t value) {
   DCHECK(cur_quick_frame_ != NULL) << "This is a quick frame routine";
   return context_->SetGPR(reg, value);
 }

 bool StackVisitor::GetFPR(uint32_t reg, uintptr_t* val) const {
   DCHECK(cur_quick_frame_ != NULL) << "This is a quick frame routine";
   return context_->GetFPR(reg, val);
 }

 bool StackVisitor::SetFPR(uint32_t reg, uintptr_t value) {
   DCHECK(cur_quick_frame_ != NULL) << "This is a quick frame routine";
   return context_->SetFPR(reg, value);
 }

 uintptr_t StackVisitor::GetReturnPc() const {
   byte* sp = reinterpret_cast<byte*>(GetCurrentQuickFrame());
   DCHECK(sp != NULL);
   byte* pc_addr = sp + GetMethod()->GetReturnPcOffsetInBytes();
   return *reinterpret_cast<uintptr_t*>(pc_addr);
 }

 void StackVisitor::SetReturnPc(uintptr_t new_ret_pc) {
   byte* sp = reinterpret_cast<byte*>(GetCurrentQuickFrame());
   CHECK(sp != NULL);
   byte* pc_addr = sp + GetMethod()->GetReturnPcOffsetInBytes();
   *reinterpret_cast<uintptr_t*>(pc_addr) = new_ret_pc;
 }

 size_t StackVisitor::ComputeNumFrames(Thread* thread) {
   struct NumFramesVisitor : public StackVisitor {
     explicit NumFramesVisitor(Thread* thread)
         : StackVisitor(thread, NULL), frames(0) {}

     bool VisitFrame() OVERRIDE {
       frames++;
       return true;
     }

     size_t frames;
   };
   NumFramesVisitor visitor(thread);
   visitor.WalkStack(true);
   return visitor.frames;
 }

 bool StackVisitor::GetNextMethodAndDexPc(mirror::ArtMethod** next_method, uint32_t* next_dex_pc) {
   struct HasMoreFramesVisitor : public StackVisitor {
     explicit HasMoreFramesVisitor(Thread* thread, size_t num_frames, size_t frame_height)
         : StackVisitor(thread, nullptr, num_frames), frame_height_(frame_height),
           found_frame_(false), has_more_frames_(false), next_method_(nullptr), next_dex_pc_(0) {
     }

     bool VisitFrame() OVERRIDE SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
       if (found_frame_) {
         mirror::ArtMethod* method = GetMethod();
         if (method != nullptr && !method->IsRuntimeMethod()) {
           has_more_frames_ = true;
           next_method_ = method;
           next_dex_pc_ = GetDexPc();
           return false;  // End stack walk once next method is found.
         }
       } else if (GetFrameHeight() == frame_height_) {
         found_frame_ = true;
       }
       return true;
     }

     size_t frame_height_;
     bool found_frame_;
     bool has_more_frames_;
     mirror::ArtMethod* next_method_;
     uint32_t next_dex_pc_;
   };
   HasMoreFramesVisitor visitor(thread_, GetNumFrames(), GetFrameHeight());
   visitor.WalkStack(true);
   *next_method = visitor.next_method_;
   *next_dex_pc = visitor.next_dex_pc_;
   return visitor.has_more_frames_;
 }

 void StackVisitor::DescribeStack(Thread* thread) {
   struct DescribeStackVisitor : public StackVisitor {
     explicit DescribeStackVisitor(Thread* thread)
         : StackVisitor(thread, NULL) {}

     bool VisitFrame() OVERRIDE SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
       LOG(INFO) << "Frame Id=" << GetFrameId() << " " << DescribeLocation();
       return true;
     }
   };
   DescribeStackVisitor visitor(thread);
   visitor.WalkStack(true);
 }

 std::string StackVisitor::DescribeLocation() const {
   std::string result("Visiting method '");
   mirror::ArtMethod* m = GetMethod();
   if (m == NULL) {
     return "upcall";
   }
   result += PrettyMethod(m);
   result += StringPrintf("' at dex PC 0x%04x", GetDexPc());
   if (!IsShadowFrame()) {
     result += StringPrintf(" (native PC %p)", reinterpret_cast<void*>(GetCurrentQuickFramePc()));
   }
   return result;
 }

 instrumentation::InstrumentationStackFrame& StackVisitor::GetInstrumentationStackFrame(uint32_t depth) const {
   CHECK_LT(depth, thread_->GetInstrumentationStack()->size());
   return thread_->GetInstrumentationStack()->at(depth);
 }

 void StackVisitor::SanityCheckFrame() const {
   if (kIsDebugBuild) {
     mirror::ArtMethod* method = GetMethod();
     CHECK_EQ(method->GetClass(), mirror::ArtMethod::GetJavaLangReflectArtMethod());
     if (cur_quick_frame_ != nullptr) {
       method->AssertPcIsWithinQuickCode(cur_quick_frame_pc_);
       // Frame sanity.
       size_t frame_size = method->GetFrameSizeInBytes();
       CHECK_NE(frame_size, 0u);
       // A rough guess at an upper size we expect to see for a frame.
       // 256 registers
       // 2 words HandleScope overhead
       // 3+3 register spills
       // TODO: this seems architecture specific for the case of JNI frames.
       // TODO: 083-compiler-regressions ManyFloatArgs shows this estimate is wrong.
       // const size_t kMaxExpectedFrameSize = (256 + 2 + 3 + 3) * sizeof(word);
       const size_t kMaxExpectedFrameSize = 2 * KB;
       CHECK_LE(frame_size, kMaxExpectedFrameSize);
       size_t return_pc_offset = method->GetReturnPcOffsetInBytes();
       CHECK_LT(return_pc_offset, frame_size);
     }
   }
 }

 void StackVisitor::WalkStack(bool include_transitions) {
   DCHECK(thread_ == Thread::Current() || thread_->IsSuspended());
   CHECK_EQ(cur_depth_, 0U);
   bool exit_stubs_installed = Runtime::Current()->GetInstrumentation()->AreExitStubsInstalled();
   uint32_t instrumentation_stack_depth = 0;

   for (const ManagedStack* current_fragment = thread_->GetManagedStack(); current_fragment != NULL;
        current_fragment = current_fragment->GetLink()) {
     cur_shadow_frame_ = current_fragment->GetTopShadowFrame();
     cur_quick_frame_ = current_fragment->GetTopQuickFrame();
     cur_quick_frame_pc_ = current_fragment->GetTopQuickFramePc();

     if (cur_quick_frame_ != NULL) {  // Handle quick stack frames.
       // Can't be both a shadow and a quick fragment.
       DCHECK(current_fragment->GetTopShadowFrame() == NULL);
       mirror::ArtMethod* method = cur_quick_frame_->AsMirrorPtr();
       while (method != NULL) {
         SanityCheckFrame();
         bool should_continue = VisitFrame();
         if (UNLIKELY(!should_continue)) {
           return;
         }

         if (context_ != NULL) {
           context_->FillCalleeSaves(*this);
         }
         size_t frame_size = method->GetFrameSizeInBytes();
         // Compute PC for next stack frame from return PC.
         size_t return_pc_offset = method->GetReturnPcOffsetInBytes(frame_size);
         byte* return_pc_addr = reinterpret_cast<byte*>(cur_quick_frame_) + return_pc_offset;
         uintptr_t return_pc = *reinterpret_cast<uintptr_t*>(return_pc_addr);
         if (UNLIKELY(exit_stubs_installed)) {
           // While profiling, the return pc is restored from the side stack, except when walking
           // the stack for an exception where the side stack will be unwound in VisitFrame.
           if (GetQuickInstrumentationExitPc() == return_pc) {
             const instrumentation::InstrumentationStackFrame& instrumentation_frame =
                 GetInstrumentationStackFrame(instrumentation_stack_depth);
             instrumentation_stack_depth++;
             if (GetMethod() == Runtime::Current()->GetCalleeSaveMethod(Runtime::kSaveAll)) {
               // Skip runtime save all callee frames which are used to deliver exceptions.
             } else if (instrumentation_frame.interpreter_entry_) {
               mirror::ArtMethod* callee = Runtime::Current()->GetCalleeSaveMethod(Runtime::kRefsAndArgs);
               CHECK_EQ(GetMethod(), callee) << "Expected: " << PrettyMethod(callee) << " Found: "
                                             << PrettyMethod(GetMethod());
             } else if (instrumentation_frame.method_ != GetMethod()) {
               LOG(FATAL)  << "Expected: " << PrettyMethod(instrumentation_frame.method_)
                           << " Found: " << PrettyMethod(GetMethod());
             }
             if (num_frames_ != 0) {
               // Check agreement of frame Ids only if num_frames_ is computed to avoid infinite
               // recursion.
               CHECK(instrumentation_frame.frame_id_ == GetFrameId())
                     << "Expected: " << instrumentation_frame.frame_id_
                     << " Found: " << GetFrameId();
             }
             return_pc = instrumentation_frame.return_pc_;
           }
         }
         cur_quick_frame_pc_ = return_pc;
         byte* next_frame = reinterpret_cast<byte*>(cur_quick_frame_) + frame_size;
         cur_quick_frame_ = reinterpret_cast<StackReference<mirror::ArtMethod>*>(next_frame);
         cur_depth_++;
         method = cur_quick_frame_->AsMirrorPtr();
       }
     } else if (cur_shadow_frame_ != NULL) {
       do {
         SanityCheckFrame();
         bool should_continue = VisitFrame();
         if (UNLIKELY(!should_continue)) {
           return;
         }
         cur_depth_++;
         cur_shadow_frame_ = cur_shadow_frame_->GetLink();
       } while (cur_shadow_frame_ != NULL);
     }
     if (include_transitions) {
       bool should_continue = VisitFrame();
       if (!should_continue) {
         return;
       }
     }
     cur_depth_++;
   }
   if (num_frames_ != 0) {
     CHECK_EQ(cur_depth_, num_frames_);
   }
 }

 }  // namespace art
	/*
	* Copyright (C) 2011 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 "stack.h"

	#include "base/hex_dump.h"
	#include "mirror/art_method-inl.h"
	#include "mirror/class-inl.h"
	#include "mirror/object.h"
	#include "mirror/object-inl.h"
	#include "mirror/object_array-inl.h"
	#include "object_utils.h"
	#include "quick/quick_method_frame_info.h"
	#include "runtime.h"
	#include "thread.h"
	#include "thread_list.h"
	#include "throw_location.h"
	#include "verify_object-inl.h"
	#include "vmap_table.h"

	namespace art {

	mirror::Object* ShadowFrame::GetThisObject() const {
	mirror::ArtMethod* m = GetMethod();
	if (m->IsStatic()) {
	return NULL;
	} else if (m->IsNative()) {
	return GetVRegReference(0);
	} else {
	const DexFile::CodeItem* code_item = m->GetCodeItem();
	CHECK(code_item != NULL) << PrettyMethod(m);
	uint16_t reg = code_item->registers_size_ - code_item->ins_size_;
	return GetVRegReference(reg);
	}
	}

	mirror::Object* ShadowFrame::GetThisObject(uint16_t num_ins) const {
	mirror::ArtMethod* m = GetMethod();
	if (m->IsStatic()) {
	return NULL;
	} else {
	return GetVRegReference(NumberOfVRegs() - num_ins);
	}
	}

	ThrowLocation ShadowFrame::GetCurrentLocationForThrow() const {
	return ThrowLocation(GetThisObject(), GetMethod(), GetDexPC());
	}

	size_t ManagedStack::NumJniShadowFrameReferences() const {
	size_t count = 0;
	for (const ManagedStack* current_fragment = this; current_fragment != NULL;
	current_fragment = current_fragment->GetLink()) {
	for (ShadowFrame* current_frame = current_fragment->top_shadow_frame_; current_frame != NULL;
	current_frame = current_frame->GetLink()) {
	if (current_frame->GetMethod()->IsNative()) {
	// The JNI ShadowFrame only contains references. (For indirect reference.)
	count += current_frame->NumberOfVRegs();
	}
	}
	}
	return count;
	}

	bool ManagedStack::ShadowFramesContain(StackReference<mirror::Object>* shadow_frame_entry) const {
	for (const ManagedStack* current_fragment = this; current_fragment != NULL;
	current_fragment = current_fragment->GetLink()) {
	for (ShadowFrame* current_frame = current_fragment->top_shadow_frame_; current_frame != NULL;
	current_frame = current_frame->GetLink()) {
	if (current_frame->Contains(shadow_frame_entry)) {
	return true;
	}
	}
	}
	return false;
	}

	StackVisitor::StackVisitor(Thread* thread, Context* context)
	: thread_(thread), cur_shadow_frame_(NULL),
	cur_quick_frame_(NULL), cur_quick_frame_pc_(0), num_frames_(0), cur_depth_(0),
	context_(context) {
	DCHECK(thread == Thread::Current() \|\| thread->IsSuspended()) << *thread;
	}

	StackVisitor::StackVisitor(Thread* thread, Context* context, size_t num_frames)
	: thread_(thread), cur_shadow_frame_(NULL),
	cur_quick_frame_(NULL), cur_quick_frame_pc_(0), num_frames_(num_frames), cur_depth_(0),
	context_(context) {
	DCHECK(thread == Thread::Current() \|\| thread->IsSuspended()) << *thread;
	}

	uint32_t StackVisitor::GetDexPc(bool abort_on_failure) const {
	if (cur_shadow_frame_ != NULL) {
	return cur_shadow_frame_->GetDexPC();
	} else if (cur_quick_frame_ != NULL) {
	return GetMethod()->ToDexPc(cur_quick_frame_pc_, abort_on_failure);
	} else {
	return 0;
	}
	}

	mirror::Object* StackVisitor::GetThisObject() const {
	mirror::ArtMethod* m = GetMethod();
	if (m->IsStatic()) {
	return NULL;
	} else if (m->IsNative()) {
	if (cur_quick_frame_ != NULL) {
	HandleScope* hs = reinterpret_cast<HandleScope*>(
	reinterpret_cast<char*>(cur_quick_frame_) + m->GetHandleScopeOffsetInBytes());
	return hs->GetReference(0);
	} else {
	return cur_shadow_frame_->GetVRegReference(0);
	}
	} else {
	const DexFile::CodeItem* code_item = m->GetCodeItem();
	if (code_item == NULL) {
	UNIMPLEMENTED(ERROR) << "Failed to determine this object of abstract or proxy method: "
	<< PrettyMethod(m);
	return nullptr;
	} else {
	uint16_t reg = code_item->registers_size_ - code_item->ins_size_;
	return reinterpret_cast<mirror::Object*>(GetVReg(m, reg, kReferenceVReg));
	}
	}
	}

	size_t StackVisitor::GetNativePcOffset() const {
	DCHECK(!IsShadowFrame());
	return GetMethod()->NativePcOffset(cur_quick_frame_pc_);
	}

	bool StackVisitor::GetVReg(mirror::ArtMethod* m, uint16_t vreg, VRegKind kind,
	uint32_t* val) const {
	if (cur_quick_frame_ != NULL) {
	DCHECK(context_ != NULL); // You can't reliably read registers without a context.
	DCHECK(m == GetMethod());
	const void* code_pointer = m->GetQuickOatCodePointer();
	DCHECK(code_pointer != nullptr);
	const VmapTable vmap_table(m->GetVmapTable(code_pointer));
	QuickMethodFrameInfo frame_info = m->GetQuickFrameInfo(code_pointer);
	uint32_t vmap_offset;
	// TODO: IsInContext stops before spotting floating point registers.
	if (vmap_table.IsInContext(vreg, kind, &vmap_offset)) {
	bool is_float = (kind == kFloatVReg) \|\| (kind == kDoubleLoVReg) \|\| (kind == kDoubleHiVReg);
	uint32_t spill_mask = is_float ? frame_info.FpSpillMask() : frame_info.CoreSpillMask();
	uint32_t reg = vmap_table.ComputeRegister(spill_mask, vmap_offset, kind);
	uintptr_t ptr_val;
	bool success = false;
	bool target64 = (kRuntimeISA == kArm64) \|\| (kRuntimeISA == kX86_64);
	if (is_float) {
	success = GetFPR(reg, &ptr_val);
	} else {
	success = GetGPR(reg, &ptr_val);
	}
	if (success && target64) {
	bool wide_lo = (kind == kLongLoVReg) \|\| (kind == kDoubleLoVReg);
	bool wide_hi = (kind == kLongHiVReg) \|\| (kind == kDoubleHiVReg);
	int64_t value_long = static_cast<int64_t>(ptr_val);
	if (wide_lo) {
	ptr_val = static_cast<uintptr_t>(value_long & 0xFFFFFFFF);
	} else if (wide_hi) {
	ptr_val = static_cast<uintptr_t>(value_long >> 32);
	}
	}
	*val = ptr_val;
	return success;
	} else {
	const DexFile::CodeItem* code_item = m->GetCodeItem();
	DCHECK(code_item != NULL) << PrettyMethod(m); // Can't be NULL or how would we compile its instructions?
	val = GetVRegAddr(cur_quick_frame_, code_item, frame_info.CoreSpillMask(),
	frame_info.FpSpillMask(), frame_info.FrameSizeInBytes(), vreg);
	return true;
	}
	} else {
	*val = cur_shadow_frame_->GetVReg(vreg);
	return true;
	}
	}

	bool StackVisitor::SetVReg(mirror::ArtMethod* m, uint16_t vreg, uint32_t new_value,
	VRegKind kind) {
	if (cur_quick_frame_ != NULL) {
	DCHECK(context_ != NULL); // You can't reliably write registers without a context.
	DCHECK(m == GetMethod());
	const void* code_pointer = m->GetQuickOatCodePointer();
	DCHECK(code_pointer != nullptr);
	const VmapTable vmap_table(m->GetVmapTable(code_pointer));
	QuickMethodFrameInfo frame_info = m->GetQuickFrameInfo(code_pointer);
	uint32_t vmap_offset;
	// TODO: IsInContext stops before spotting floating point registers.
	if (vmap_table.IsInContext(vreg, kind, &vmap_offset)) {
	bool is_float = (kind == kFloatVReg) \|\| (kind == kDoubleLoVReg) \|\| (kind == kDoubleHiVReg);
	uint32_t spill_mask = is_float ? frame_info.FpSpillMask() : frame_info.CoreSpillMask();
	const uint32_t reg = vmap_table.ComputeRegister(spill_mask, vmap_offset, kind);
	bool target64 = (kRuntimeISA == kArm64) \|\| (kRuntimeISA == kX86_64);
	// Deal with 32 or 64-bit wide registers in a way that builds on all targets.
	if (target64) {
	bool wide_lo = (kind == kLongLoVReg) \|\| (kind == kDoubleLoVReg);
	bool wide_hi = (kind == kLongHiVReg) \|\| (kind == kDoubleHiVReg);
	if (wide_lo \|\| wide_hi) {
	uintptr_t old_reg_val;
	bool success = is_float ? GetFPR(reg, &old_reg_val) : GetGPR(reg, &old_reg_val);
	if (!success) {
	return false;
	}
	uint64_t new_vreg_portion = static_cast<uint64_t>(new_value);
	uint64_t old_reg_val_as_wide = static_cast<uint64_t>(old_reg_val);
	uint64_t mask = 0xffffffff;
	if (wide_lo) {
	mask = mask << 32;
	} else {
	new_vreg_portion = new_vreg_portion << 32;
	}
	new_value = static_cast<uintptr_t>((old_reg_val_as_wide & mask) \| new_vreg_portion);
	}
	}
	if (is_float) {
	return SetFPR(reg, new_value);
	} else {
	return SetGPR(reg, new_value);
	}
	} else {
	const DexFile::CodeItem* code_item = m->GetCodeItem();
	DCHECK(code_item != NULL) << PrettyMethod(m); // Can't be NULL or how would we compile its instructions?
	int offset = GetVRegOffset(code_item, frame_info.CoreSpillMask(), frame_info.FpSpillMask(),
	frame_info.FrameSizeInBytes(), vreg, kRuntimeISA);
	byte* vreg_addr = reinterpret_cast<byte*>(GetCurrentQuickFrame()) + offset;
	reinterpret_cast<uint32_t>(vreg_addr) = new_value;
	return true;
	}
	} else {
	cur_shadow_frame_->SetVReg(vreg, new_value);
	return true;
	}
	}

	uintptr_t* StackVisitor::GetGPRAddress(uint32_t reg) const {
	DCHECK(cur_quick_frame_ != NULL) << "This is a quick frame routine";
	return context_->GetGPRAddress(reg);
	}

	bool StackVisitor::GetGPR(uint32_t reg, uintptr_t* val) const {
	DCHECK(cur_quick_frame_ != NULL) << "This is a quick frame routine";
	return context_->GetGPR(reg, val);
	}

	bool StackVisitor::SetGPR(uint32_t reg, uintptr_t value) {
	DCHECK(cur_quick_frame_ != NULL) << "This is a quick frame routine";
	return context_->SetGPR(reg, value);
	}

	bool StackVisitor::GetFPR(uint32_t reg, uintptr_t* val) const {
	DCHECK(cur_quick_frame_ != NULL) << "This is a quick frame routine";
	return context_->GetFPR(reg, val);
	}

	bool StackVisitor::SetFPR(uint32_t reg, uintptr_t value) {
	DCHECK(cur_quick_frame_ != NULL) << "This is a quick frame routine";
	return context_->SetFPR(reg, value);
	}

	uintptr_t StackVisitor::GetReturnPc() const {
	byte* sp = reinterpret_cast<byte*>(GetCurrentQuickFrame());
	DCHECK(sp != NULL);
	byte* pc_addr = sp + GetMethod()->GetReturnPcOffsetInBytes();
	return reinterpret_cast<uintptr_t>(pc_addr);
	}

	void StackVisitor::SetReturnPc(uintptr_t new_ret_pc) {
	byte* sp = reinterpret_cast<byte*>(GetCurrentQuickFrame());
	CHECK(sp != NULL);
	byte* pc_addr = sp + GetMethod()->GetReturnPcOffsetInBytes();
	reinterpret_cast<uintptr_t>(pc_addr) = new_ret_pc;
	}

	size_t StackVisitor::ComputeNumFrames(Thread* thread) {
	struct NumFramesVisitor : public StackVisitor {
	explicit NumFramesVisitor(Thread* thread)
	: StackVisitor(thread, NULL), frames(0) {}

	bool VisitFrame() OVERRIDE {
	frames++;
	return true;
	}

	size_t frames;
	};
	NumFramesVisitor visitor(thread);
	visitor.WalkStack(true);
	return visitor.frames;
	}

	bool StackVisitor::GetNextMethodAndDexPc(mirror::ArtMethod** next_method, uint32_t* next_dex_pc) {
	struct HasMoreFramesVisitor : public StackVisitor {
	explicit HasMoreFramesVisitor(Thread* thread, size_t num_frames, size_t frame_height)
	: StackVisitor(thread, nullptr, num_frames), frame_height_(frame_height),
	found_frame_(false), has_more_frames_(false), next_method_(nullptr), next_dex_pc_(0) {
	}

	bool VisitFrame() OVERRIDE SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
	if (found_frame_) {
	mirror::ArtMethod* method = GetMethod();
	if (method != nullptr && !method->IsRuntimeMethod()) {
	has_more_frames_ = true;
	next_method_ = method;
	next_dex_pc_ = GetDexPc();
	return false; // End stack walk once next method is found.
	}
	} else if (GetFrameHeight() == frame_height_) {
	found_frame_ = true;
	}
	return true;
	}

	size_t frame_height_;
	bool found_frame_;
	bool has_more_frames_;
	mirror::ArtMethod* next_method_;
	uint32_t next_dex_pc_;
	};
	HasMoreFramesVisitor visitor(thread_, GetNumFrames(), GetFrameHeight());
	visitor.WalkStack(true);
	*next_method = visitor.next_method_;
	*next_dex_pc = visitor.next_dex_pc_;
	return visitor.has_more_frames_;
	}

	void StackVisitor::DescribeStack(Thread* thread) {
	struct DescribeStackVisitor : public StackVisitor {
	explicit DescribeStackVisitor(Thread* thread)
	: StackVisitor(thread, NULL) {}

	bool VisitFrame() OVERRIDE SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
	LOG(INFO) << "Frame Id=" << GetFrameId() << " " << DescribeLocation();
	return true;
	}
	};
	DescribeStackVisitor visitor(thread);
	visitor.WalkStack(true);
	}

	std::string StackVisitor::DescribeLocation() const {
	std::string result("Visiting method '");
	mirror::ArtMethod* m = GetMethod();
	if (m == NULL) {
	return "upcall";
	}
	result += PrettyMethod(m);
	result += StringPrintf("' at dex PC 0x%04x", GetDexPc());
	if (!IsShadowFrame()) {
	result += StringPrintf(" (native PC %p)", reinterpret_cast<void*>(GetCurrentQuickFramePc()));
	}
	return result;
	}

	instrumentation::InstrumentationStackFrame& StackVisitor::GetInstrumentationStackFrame(uint32_t depth) const {
	CHECK_LT(depth, thread_->GetInstrumentationStack()->size());
	return thread_->GetInstrumentationStack()->at(depth);
	}

	void StackVisitor::SanityCheckFrame() const {
	if (kIsDebugBuild) {
	mirror::ArtMethod* method = GetMethod();
	CHECK_EQ(method->GetClass(), mirror::ArtMethod::GetJavaLangReflectArtMethod());
	if (cur_quick_frame_ != nullptr) {
	method->AssertPcIsWithinQuickCode(cur_quick_frame_pc_);
	// Frame sanity.
	size_t frame_size = method->GetFrameSizeInBytes();
	CHECK_NE(frame_size, 0u);
	// A rough guess at an upper size we expect to see for a frame.
	// 256 registers
	// 2 words HandleScope overhead
	// 3+3 register spills
	// TODO: this seems architecture specific for the case of JNI frames.
	// TODO: 083-compiler-regressions ManyFloatArgs shows this estimate is wrong.
	// const size_t kMaxExpectedFrameSize = (256 + 2 + 3 + 3) * sizeof(word);
	const size_t kMaxExpectedFrameSize = 2 * KB;
	CHECK_LE(frame_size, kMaxExpectedFrameSize);
	size_t return_pc_offset = method->GetReturnPcOffsetInBytes();
	CHECK_LT(return_pc_offset, frame_size);
	}
	}
	}

	void StackVisitor::WalkStack(bool include_transitions) {
	DCHECK(thread_ == Thread::Current() \|\| thread_->IsSuspended());
	CHECK_EQ(cur_depth_, 0U);
	bool exit_stubs_installed = Runtime::Current()->GetInstrumentation()->AreExitStubsInstalled();
	uint32_t instrumentation_stack_depth = 0;

	for (const ManagedStack* current_fragment = thread_->GetManagedStack(); current_fragment != NULL;
	current_fragment = current_fragment->GetLink()) {
	cur_shadow_frame_ = current_fragment->GetTopShadowFrame();
	cur_quick_frame_ = current_fragment->GetTopQuickFrame();
	cur_quick_frame_pc_ = current_fragment->GetTopQuickFramePc();

	if (cur_quick_frame_ != NULL) { // Handle quick stack frames.
	// Can't be both a shadow and a quick fragment.
	DCHECK(current_fragment->GetTopShadowFrame() == NULL);
	mirror::ArtMethod* method = cur_quick_frame_->AsMirrorPtr();
	while (method != NULL) {
	SanityCheckFrame();
	bool should_continue = VisitFrame();
	if (UNLIKELY(!should_continue)) {
	return;
	}

	if (context_ != NULL) {
	context_->FillCalleeSaves(*this);
	}
	size_t frame_size = method->GetFrameSizeInBytes();
	// Compute PC for next stack frame from return PC.
	size_t return_pc_offset = method->GetReturnPcOffsetInBytes(frame_size);
	byte* return_pc_addr = reinterpret_cast<byte*>(cur_quick_frame_) + return_pc_offset;
	uintptr_t return_pc = reinterpret_cast<uintptr_t>(return_pc_addr);
	if (UNLIKELY(exit_stubs_installed)) {
	// While profiling, the return pc is restored from the side stack, except when walking
	// the stack for an exception where the side stack will be unwound in VisitFrame.
	if (GetQuickInstrumentationExitPc() == return_pc) {
	const instrumentation::InstrumentationStackFrame& instrumentation_frame =
	GetInstrumentationStackFrame(instrumentation_stack_depth);
	instrumentation_stack_depth++;
	if (GetMethod() == Runtime::Current()->GetCalleeSaveMethod(Runtime::kSaveAll)) {
	// Skip runtime save all callee frames which are used to deliver exceptions.
	} else if (instrumentation_frame.interpreter_entry_) {
	mirror::ArtMethod* callee = Runtime::Current()->GetCalleeSaveMethod(Runtime::kRefsAndArgs);
	CHECK_EQ(GetMethod(), callee) << "Expected: " << PrettyMethod(callee) << " Found: "
	<< PrettyMethod(GetMethod());
	} else if (instrumentation_frame.method_ != GetMethod()) {
	LOG(FATAL) << "Expected: " << PrettyMethod(instrumentation_frame.method_)
	<< " Found: " << PrettyMethod(GetMethod());
	}
	if (num_frames_ != 0) {
	// Check agreement of frame Ids only if num_frames_ is computed to avoid infinite
	// recursion.
	CHECK(instrumentation_frame.frame_id_ == GetFrameId())
	<< "Expected: " << instrumentation_frame.frame_id_
	<< " Found: " << GetFrameId();
	}
	return_pc = instrumentation_frame.return_pc_;
	}
	}
	cur_quick_frame_pc_ = return_pc;
	byte* next_frame = reinterpret_cast<byte*>(cur_quick_frame_) + frame_size;
	cur_quick_frame_ = reinterpret_cast<StackReference<mirror::ArtMethod>*>(next_frame);
	cur_depth_++;
	method = cur_quick_frame_->AsMirrorPtr();
	}
	} else if (cur_shadow_frame_ != NULL) {
	do {
	SanityCheckFrame();
	bool should_continue = VisitFrame();
	if (UNLIKELY(!should_continue)) {
	return;
	}
	cur_depth_++;
	cur_shadow_frame_ = cur_shadow_frame_->GetLink();
	} while (cur_shadow_frame_ != NULL);
	}
	if (include_transitions) {
	bool should_continue = VisitFrame();
	if (!should_continue) {
	return;
	}
	}
	cur_depth_++;
	}
	if (num_frames_ != 0) {
	CHECK_EQ(cur_depth_, num_frames_);
	}
	}

	} // namespace art