compiler/optimizing/stack_map_stream.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 "stack_map_stream.h"

 #include <memory>

 #include "art_method-inl.h"
 #include "base/stl_util.h"
 #include "dex/dex_file_types.h"
 #include "optimizing/optimizing_compiler.h"
 #include "runtime.h"
 #include "scoped_thread_state_change-inl.h"
 #include "stack_map.h"

 namespace art {

 constexpr static bool kVerifyStackMaps = kIsDebugBuild;

 uint32_t StackMapStream::GetStackMapNativePcOffset(size_t i) {
   return StackMap::UnpackNativePc(stack_maps_[i].packed_native_pc, instruction_set_);
 }

 void StackMapStream::SetStackMapNativePcOffset(size_t i, uint32_t native_pc_offset) {
   stack_maps_[i].packed_native_pc = StackMap::PackNativePc(native_pc_offset, instruction_set_);
 }

 void StackMapStream::BeginStackMapEntry(uint32_t dex_pc,
                                         uint32_t native_pc_offset,
                                         uint32_t register_mask,
                                         BitVector* stack_mask,
                                         uint32_t num_dex_registers,
                                         uint8_t inlining_depth) {
   DCHECK(!in_stack_map_) << "Mismatched Begin/End calls";
   in_stack_map_ = true;
   // num_dex_registers_ is the constant per-method number of registers.
   // However we initially don't know what the value is, so lazily initialize it.
   if (num_dex_registers_ == 0) {
     num_dex_registers_ = num_dex_registers;
   } else if (num_dex_registers > 0) {
     DCHECK_EQ(num_dex_registers_, num_dex_registers) << "Inconsistent register count";
   }

   current_stack_map_ = StackMapEntry {
     .packed_native_pc = StackMap::PackNativePc(native_pc_offset, instruction_set_),
     .dex_pc = dex_pc,
     .register_mask_index = kNoValue,
     .stack_mask_index = kNoValue,
     .inline_info_index = kNoValue,
     .dex_register_mask_index = kNoValue,
     .dex_register_map_index = kNoValue,
   };
   if (register_mask != 0) {
     uint32_t shift = LeastSignificantBit(register_mask);
     RegisterMaskEntry entry = { register_mask >> shift, shift };
     current_stack_map_.register_mask_index = register_masks_.Dedup(&entry);
   }
   // The compiler assumes the bit vector will be read during PrepareForFillIn(),
   // and it might modify the data before that. Therefore, just store the pointer.
   // See ClearSpillSlotsFromLoopPhisInStackMap in code_generator.h.
   lazy_stack_masks_.push_back(stack_mask);
   current_inline_infos_.clear();
   current_dex_registers_.clear();
   expected_num_dex_registers_ = num_dex_registers;

   if (kVerifyStackMaps) {
     size_t stack_map_index = stack_maps_.size();
     // Create lambda method, which will be executed at the very end to verify data.
     // Parameters and local variables will be captured(stored) by the lambda "[=]".
     dchecks_.emplace_back([=](const CodeInfo& code_info) {
       StackMap stack_map = code_info.GetStackMapAt(stack_map_index);
       CHECK_EQ(stack_map.GetNativePcOffset(instruction_set_), native_pc_offset);
       CHECK_EQ(stack_map.GetDexPc(), dex_pc);
       CHECK_EQ(code_info.GetRegisterMaskOf(stack_map), register_mask);
       BitMemoryRegion seen_stack_mask = code_info.GetStackMaskOf(stack_map);
       CHECK_GE(seen_stack_mask.size_in_bits(), stack_mask ? stack_mask->GetNumberOfBits() : 0);
       for (size_t b = 0; b < seen_stack_mask.size_in_bits(); b++) {
         CHECK_EQ(seen_stack_mask.LoadBit(b), stack_mask != nullptr && stack_mask->IsBitSet(b));
       }
       CHECK_EQ(stack_map.HasInlineInfo(), (inlining_depth != 0));
       CHECK_EQ(code_info.GetInlineDepthOf(stack_map), inlining_depth);
     });
   }
 }

 void StackMapStream::EndStackMapEntry() {
   DCHECK(in_stack_map_) << "Mismatched Begin/End calls";
   in_stack_map_ = false;
   DCHECK_EQ(expected_num_dex_registers_, current_dex_registers_.size());

   // Generate index into the InlineInfo table.
   if (!current_inline_infos_.empty()) {
     current_inline_infos_.back().is_last = InlineInfo::kLast;
     current_stack_map_.inline_info_index =
         inline_infos_.Dedup(current_inline_infos_.data(), current_inline_infos_.size());
   }

   // Generate delta-compressed dex register map.
   CreateDexRegisterMap();

   stack_maps_.Add(current_stack_map_);
 }

 void StackMapStream::AddDexRegisterEntry(DexRegisterLocation::Kind kind, int32_t value) {
   current_dex_registers_.push_back(DexRegisterLocation(kind, value));
 }

 void StackMapStream::AddInvoke(InvokeType invoke_type, uint32_t dex_method_index) {
   uint32_t packed_native_pc = current_stack_map_.packed_native_pc;
   size_t invoke_info_index = invoke_infos_.size();
   invoke_infos_.Add(InvokeInfoEntry {
     .packed_native_pc = packed_native_pc,
     .invoke_type = invoke_type,
     .method_info_index = method_infos_.Dedup(&dex_method_index),
   });

   if (kVerifyStackMaps) {
     dchecks_.emplace_back([=](const CodeInfo& code_info) {
       InvokeInfo invoke_info = code_info.GetInvokeInfo(invoke_info_index);
       CHECK_EQ(invoke_info.GetNativePcOffset(instruction_set_),
                StackMap::UnpackNativePc(packed_native_pc, instruction_set_));
       CHECK_EQ(invoke_info.GetInvokeType(), invoke_type);
       CHECK_EQ(method_infos_[invoke_info.GetMethodInfoIndex()], dex_method_index);
     });
   }
 }

 void StackMapStream::BeginInlineInfoEntry(ArtMethod* method,
                                           uint32_t dex_pc,
                                           uint32_t num_dex_registers,
                                           const DexFile* outer_dex_file) {
   DCHECK(!in_inline_info_) << "Mismatched Begin/End calls";
   in_inline_info_ = true;
   DCHECK_EQ(expected_num_dex_registers_, current_dex_registers_.size());

   expected_num_dex_registers_ += num_dex_registers;

   InlineInfoEntry entry = {
     .is_last = InlineInfo::kMore,
     .dex_pc = dex_pc,
     .method_info_index = kNoValue,
     .art_method_hi = kNoValue,
     .art_method_lo = kNoValue,
     .num_dex_registers = static_cast<uint32_t>(expected_num_dex_registers_),
   };
   if (EncodeArtMethodInInlineInfo(method)) {
     entry.art_method_hi = High32Bits(reinterpret_cast<uintptr_t>(method));
     entry.art_method_lo = Low32Bits(reinterpret_cast<uintptr_t>(method));
   } else {
     if (dex_pc != static_cast<uint32_t>(-1) && kIsDebugBuild) {
       ScopedObjectAccess soa(Thread::Current());
       DCHECK(IsSameDexFile(*outer_dex_file, *method->GetDexFile()));
     }
     uint32_t dex_method_index = method->GetDexMethodIndexUnchecked();
     entry.method_info_index = method_infos_.Dedup(&dex_method_index);
   }
   current_inline_infos_.push_back(entry);

   if (kVerifyStackMaps) {
     size_t stack_map_index = stack_maps_.size();
     size_t depth = current_inline_infos_.size() - 1;
     dchecks_.emplace_back([=](const CodeInfo& code_info) {
       StackMap stack_map = code_info.GetStackMapAt(stack_map_index);
       InlineInfo inline_info = code_info.GetInlineInfoAtDepth(stack_map, depth);
       CHECK_EQ(inline_info.GetDexPc(), dex_pc);
       bool encode_art_method = EncodeArtMethodInInlineInfo(method);
       CHECK_EQ(inline_info.EncodesArtMethod(), encode_art_method);
       if (encode_art_method) {
         CHECK_EQ(inline_info.GetArtMethod(), method);
       } else {
         CHECK_EQ(method_infos_[inline_info.GetMethodInfoIndex()],
                  method->GetDexMethodIndexUnchecked());
       }
     });
   }
 }

 void StackMapStream::EndInlineInfoEntry() {
   DCHECK(in_inline_info_) << "Mismatched Begin/End calls";
   in_inline_info_ = false;
   DCHECK_EQ(expected_num_dex_registers_, current_dex_registers_.size());
 }

 // Create delta-compressed dex register map based on the current list of DexRegisterLocations.
 // All dex registers for a stack map are concatenated - inlined registers are just appended.
 void StackMapStream::CreateDexRegisterMap() {
   // These are fields rather than local variables so that we can reuse the reserved memory.
   temp_dex_register_mask_.ClearAllBits();
   temp_dex_register_map_.clear();

   // Ensure that the arrays that hold previous state are big enough to be safely indexed below.
   if (previous_dex_registers_.size() < current_dex_registers_.size()) {
     previous_dex_registers_.resize(current_dex_registers_.size(), DexRegisterLocation::None());
     dex_register_timestamp_.resize(current_dex_registers_.size(), 0u);
   }

   // Set bit in the mask for each register that has been changed since the previous stack map.
   // Modified registers are stored in the catalogue and the catalogue index added to the list.
   for (size_t i = 0; i < current_dex_registers_.size(); i++) {
     DexRegisterLocation reg = current_dex_registers_[i];
     // Distance is difference between this index and the index of last modification.
     uint32_t distance = stack_maps_.size() - dex_register_timestamp_[i];
     if (previous_dex_registers_[i] != reg || distance > kMaxDexRegisterMapSearchDistance) {
       DexRegisterEntry entry = DexRegisterEntry{
         .kind = static_cast<uint32_t>(reg.GetKind()),
         .packed_value = DexRegisterInfo::PackValue(reg.GetKind(), reg.GetValue()),
       };
       uint32_t index = reg.IsLive() ? dex_register_catalog_.Dedup(&entry) : kNoValue;
       temp_dex_register_mask_.SetBit(i);
       temp_dex_register_map_.push_back(index);
       previous_dex_registers_[i] = reg;
       dex_register_timestamp_[i] = stack_maps_.size();
     }
   }

   // Set the mask and map for the current StackMap (which includes inlined registers).
   if (temp_dex_register_mask_.GetNumberOfBits() != 0) {
     current_stack_map_.dex_register_mask_index =
         dex_register_masks_.Dedup(temp_dex_register_mask_.GetRawStorage(),
                                   temp_dex_register_mask_.GetNumberOfBits());
   }
   if (!current_dex_registers_.empty()) {
     current_stack_map_.dex_register_map_index =
         dex_register_maps_.Dedup(temp_dex_register_map_.data(),
                                  temp_dex_register_map_.size());
   }

   if (kVerifyStackMaps) {
     size_t stack_map_index = stack_maps_.size();
     uint32_t depth = current_inline_infos_.size();
     // We need to make copy of the current registers for later (when the check is run).
     auto expected_dex_registers = std::make_shared<dchecked_vector<DexRegisterLocation>>(
         current_dex_registers_.begin(), current_dex_registers_.end());
     dchecks_.emplace_back([=](const CodeInfo& code_info) {
       StackMap stack_map = code_info.GetStackMapAt(stack_map_index);
       uint32_t expected_reg = 0;
       for (DexRegisterLocation reg : code_info.GetDexRegisterMapOf(stack_map)) {
         CHECK_EQ((*expected_dex_registers)[expected_reg++], reg);
       }
       for (uint32_t d = 0; d < depth; d++) {
         for (DexRegisterLocation reg : code_info.GetDexRegisterMapAtDepth(d, stack_map)) {
           CHECK_EQ((*expected_dex_registers)[expected_reg++], reg);
         }
       }
       CHECK_EQ(expected_reg, expected_dex_registers->size());
     });
   }
 }

 void StackMapStream::FillInMethodInfo(MemoryRegion region) {
   {
     MethodInfo info(region.begin(), method_infos_.size());
     for (size_t i = 0; i < method_infos_.size(); ++i) {
       info.SetMethodIndex(i, method_infos_[i]);
     }
   }
   if (kVerifyStackMaps) {
     // Check the data matches.
     MethodInfo info(region.begin());
     const size_t count = info.NumMethodIndices();
     DCHECK_EQ(count, method_infos_.size());
     for (size_t i = 0; i < count; ++i) {
       DCHECK_EQ(info.GetMethodIndex(i), method_infos_[i]);
     }
   }
 }

 size_t StackMapStream::PrepareForFillIn() {
   static_assert(sizeof(StackMapEntry) == StackMap::kCount * sizeof(uint32_t), "Layout");
   static_assert(sizeof(InvokeInfoEntry) == InvokeInfo::kCount * sizeof(uint32_t), "Layout");
   static_assert(sizeof(InlineInfoEntry) == InlineInfo::kCount * sizeof(uint32_t), "Layout");
   static_assert(sizeof(DexRegisterEntry) == DexRegisterInfo::kCount * sizeof(uint32_t), "Layout");
   DCHECK_EQ(out_.size(), 0u);

   // Read the stack masks now. The compiler might have updated them.
   for (size_t i = 0; i < lazy_stack_masks_.size(); i++) {
     BitVector* stack_mask = lazy_stack_masks_[i];
     if (stack_mask != nullptr && stack_mask->GetNumberOfBits() != 0) {
       stack_maps_[i].stack_mask_index =
         stack_masks_.Dedup(stack_mask->GetRawStorage(), stack_mask->GetNumberOfBits());
     }
   }

   size_t bit_offset = 0;
   stack_maps_.Encode(&out_, &bit_offset);
   register_masks_.Encode(&out_, &bit_offset);
   stack_masks_.Encode(&out_, &bit_offset);
   invoke_infos_.Encode(&out_, &bit_offset);
   inline_infos_.Encode(&out_, &bit_offset);
   dex_register_masks_.Encode(&out_, &bit_offset);
   dex_register_maps_.Encode(&out_, &bit_offset);
   dex_register_catalog_.Encode(&out_, &bit_offset);
   EncodeVarintBits(&out_, &bit_offset, num_dex_registers_);

   return UnsignedLeb128Size(out_.size()) +  out_.size();
 }

 void StackMapStream::FillInCodeInfo(MemoryRegion region) {
   DCHECK(in_stack_map_ == false) << "Mismatched Begin/End calls";
   DCHECK(in_inline_info_ == false) << "Mismatched Begin/End calls";
   DCHECK_NE(0u, out_.size()) << "PrepareForFillIn not called before FillIn";
   DCHECK_EQ(region.size(), UnsignedLeb128Size(out_.size()) +  out_.size());

   uint8_t* ptr = EncodeUnsignedLeb128(region.begin(), out_.size());
   region.CopyFromVector(ptr - region.begin(), out_);

   // Verify all written data (usually only in debug builds).
   if (kVerifyStackMaps) {
     CodeInfo code_info(region);
     CHECK_EQ(code_info.GetNumberOfStackMaps(), stack_maps_.size());
     for (const auto& dcheck : dchecks_) {
       dcheck(code_info);
     }
   }
 }

 size_t StackMapStream::ComputeMethodInfoSize() const {
   DCHECK_NE(0u, out_.size()) << "PrepareForFillIn not called before " << __FUNCTION__;
   return MethodInfo::ComputeSize(method_infos_.size());
 }

 }  // 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 "stack_map_stream.h"

	#include <memory>

	#include "art_method-inl.h"
	#include "base/stl_util.h"
	#include "dex/dex_file_types.h"
	#include "optimizing/optimizing_compiler.h"
	#include "runtime.h"
	#include "scoped_thread_state_change-inl.h"
	#include "stack_map.h"

	namespace art {

	constexpr static bool kVerifyStackMaps = kIsDebugBuild;

	uint32_t StackMapStream::GetStackMapNativePcOffset(size_t i) {
	return StackMap::UnpackNativePc(stack_maps_[i].packed_native_pc, instruction_set_);
	}

	void StackMapStream::SetStackMapNativePcOffset(size_t i, uint32_t native_pc_offset) {
	stack_maps_[i].packed_native_pc = StackMap::PackNativePc(native_pc_offset, instruction_set_);
	}

	void StackMapStream::BeginStackMapEntry(uint32_t dex_pc,
	uint32_t native_pc_offset,
	uint32_t register_mask,
	BitVector* stack_mask,
	uint32_t num_dex_registers,
	uint8_t inlining_depth) {
	DCHECK(!in_stack_map_) << "Mismatched Begin/End calls";
	in_stack_map_ = true;
	// num_dex_registers_ is the constant per-method number of registers.
	// However we initially don't know what the value is, so lazily initialize it.
	if (num_dex_registers_ == 0) {
	num_dex_registers_ = num_dex_registers;
	} else if (num_dex_registers > 0) {
	DCHECK_EQ(num_dex_registers_, num_dex_registers) << "Inconsistent register count";
	}

	current_stack_map_ = StackMapEntry {
	.packed_native_pc = StackMap::PackNativePc(native_pc_offset, instruction_set_),
	.dex_pc = dex_pc,
	.register_mask_index = kNoValue,
	.stack_mask_index = kNoValue,
	.inline_info_index = kNoValue,
	.dex_register_mask_index = kNoValue,
	.dex_register_map_index = kNoValue,
	};
	if (register_mask != 0) {
	uint32_t shift = LeastSignificantBit(register_mask);
	RegisterMaskEntry entry = { register_mask >> shift, shift };
	current_stack_map_.register_mask_index = register_masks_.Dedup(&entry);
	}
	// The compiler assumes the bit vector will be read during PrepareForFillIn(),
	// and it might modify the data before that. Therefore, just store the pointer.
	// See ClearSpillSlotsFromLoopPhisInStackMap in code_generator.h.
	lazy_stack_masks_.push_back(stack_mask);
	current_inline_infos_.clear();
	current_dex_registers_.clear();
	expected_num_dex_registers_ = num_dex_registers;

	if (kVerifyStackMaps) {
	size_t stack_map_index = stack_maps_.size();
	// Create lambda method, which will be executed at the very end to verify data.
	// Parameters and local variables will be captured(stored) by the lambda "[=]".
	dchecks_.emplace_back([=](const CodeInfo& code_info) {
	StackMap stack_map = code_info.GetStackMapAt(stack_map_index);
	CHECK_EQ(stack_map.GetNativePcOffset(instruction_set_), native_pc_offset);
	CHECK_EQ(stack_map.GetDexPc(), dex_pc);
	CHECK_EQ(code_info.GetRegisterMaskOf(stack_map), register_mask);
	BitMemoryRegion seen_stack_mask = code_info.GetStackMaskOf(stack_map);
	CHECK_GE(seen_stack_mask.size_in_bits(), stack_mask ? stack_mask->GetNumberOfBits() : 0);
	for (size_t b = 0; b < seen_stack_mask.size_in_bits(); b++) {
	CHECK_EQ(seen_stack_mask.LoadBit(b), stack_mask != nullptr && stack_mask->IsBitSet(b));
	}
	CHECK_EQ(stack_map.HasInlineInfo(), (inlining_depth != 0));
	CHECK_EQ(code_info.GetInlineDepthOf(stack_map), inlining_depth);
	});
	}
	}

	void StackMapStream::EndStackMapEntry() {
	DCHECK(in_stack_map_) << "Mismatched Begin/End calls";
	in_stack_map_ = false;
	DCHECK_EQ(expected_num_dex_registers_, current_dex_registers_.size());

	// Generate index into the InlineInfo table.
	if (!current_inline_infos_.empty()) {
	current_inline_infos_.back().is_last = InlineInfo::kLast;
	current_stack_map_.inline_info_index =
	inline_infos_.Dedup(current_inline_infos_.data(), current_inline_infos_.size());
	}

	// Generate delta-compressed dex register map.
	CreateDexRegisterMap();

	stack_maps_.Add(current_stack_map_);
	}

	void StackMapStream::AddDexRegisterEntry(DexRegisterLocation::Kind kind, int32_t value) {
	current_dex_registers_.push_back(DexRegisterLocation(kind, value));
	}

	void StackMapStream::AddInvoke(InvokeType invoke_type, uint32_t dex_method_index) {
	uint32_t packed_native_pc = current_stack_map_.packed_native_pc;
	size_t invoke_info_index = invoke_infos_.size();
	invoke_infos_.Add(InvokeInfoEntry {
	.packed_native_pc = packed_native_pc,
	.invoke_type = invoke_type,
	.method_info_index = method_infos_.Dedup(&dex_method_index),
	});

	if (kVerifyStackMaps) {
	dchecks_.emplace_back([=](const CodeInfo& code_info) {
	InvokeInfo invoke_info = code_info.GetInvokeInfo(invoke_info_index);
	CHECK_EQ(invoke_info.GetNativePcOffset(instruction_set_),
	StackMap::UnpackNativePc(packed_native_pc, instruction_set_));
	CHECK_EQ(invoke_info.GetInvokeType(), invoke_type);
	CHECK_EQ(method_infos_[invoke_info.GetMethodInfoIndex()], dex_method_index);
	});
	}
	}

	void StackMapStream::BeginInlineInfoEntry(ArtMethod* method,
	uint32_t dex_pc,
	uint32_t num_dex_registers,
	const DexFile* outer_dex_file) {
	DCHECK(!in_inline_info_) << "Mismatched Begin/End calls";
	in_inline_info_ = true;
	DCHECK_EQ(expected_num_dex_registers_, current_dex_registers_.size());

	expected_num_dex_registers_ += num_dex_registers;

	InlineInfoEntry entry = {
	.is_last = InlineInfo::kMore,
	.dex_pc = dex_pc,
	.method_info_index = kNoValue,
	.art_method_hi = kNoValue,
	.art_method_lo = kNoValue,
	.num_dex_registers = static_cast<uint32_t>(expected_num_dex_registers_),
	};
	if (EncodeArtMethodInInlineInfo(method)) {
	entry.art_method_hi = High32Bits(reinterpret_cast<uintptr_t>(method));
	entry.art_method_lo = Low32Bits(reinterpret_cast<uintptr_t>(method));
	} else {
	if (dex_pc != static_cast<uint32_t>(-1) && kIsDebugBuild) {
	ScopedObjectAccess soa(Thread::Current());
	DCHECK(IsSameDexFile(outer_dex_file, method->GetDexFile()));
	}
	uint32_t dex_method_index = method->GetDexMethodIndexUnchecked();
	entry.method_info_index = method_infos_.Dedup(&dex_method_index);
	}
	current_inline_infos_.push_back(entry);

	if (kVerifyStackMaps) {
	size_t stack_map_index = stack_maps_.size();
	size_t depth = current_inline_infos_.size() - 1;
	dchecks_.emplace_back([=](const CodeInfo& code_info) {
	StackMap stack_map = code_info.GetStackMapAt(stack_map_index);
	InlineInfo inline_info = code_info.GetInlineInfoAtDepth(stack_map, depth);
	CHECK_EQ(inline_info.GetDexPc(), dex_pc);
	bool encode_art_method = EncodeArtMethodInInlineInfo(method);
	CHECK_EQ(inline_info.EncodesArtMethod(), encode_art_method);
	if (encode_art_method) {
	CHECK_EQ(inline_info.GetArtMethod(), method);
	} else {
	CHECK_EQ(method_infos_[inline_info.GetMethodInfoIndex()],
	method->GetDexMethodIndexUnchecked());
	}
	});
	}
	}

	void StackMapStream::EndInlineInfoEntry() {
	DCHECK(in_inline_info_) << "Mismatched Begin/End calls";
	in_inline_info_ = false;
	DCHECK_EQ(expected_num_dex_registers_, current_dex_registers_.size());
	}

	// Create delta-compressed dex register map based on the current list of DexRegisterLocations.
	// All dex registers for a stack map are concatenated - inlined registers are just appended.
	void StackMapStream::CreateDexRegisterMap() {
	// These are fields rather than local variables so that we can reuse the reserved memory.
	temp_dex_register_mask_.ClearAllBits();
	temp_dex_register_map_.clear();

	// Ensure that the arrays that hold previous state are big enough to be safely indexed below.
	if (previous_dex_registers_.size() < current_dex_registers_.size()) {
	previous_dex_registers_.resize(current_dex_registers_.size(), DexRegisterLocation::None());
	dex_register_timestamp_.resize(current_dex_registers_.size(), 0u);
	}

	// Set bit in the mask for each register that has been changed since the previous stack map.
	// Modified registers are stored in the catalogue and the catalogue index added to the list.
	for (size_t i = 0; i < current_dex_registers_.size(); i++) {
	DexRegisterLocation reg = current_dex_registers_[i];
	// Distance is difference between this index and the index of last modification.
	uint32_t distance = stack_maps_.size() - dex_register_timestamp_[i];
	if (previous_dex_registers_[i] != reg \|\| distance > kMaxDexRegisterMapSearchDistance) {
	DexRegisterEntry entry = DexRegisterEntry{
	.kind = static_cast<uint32_t>(reg.GetKind()),
	.packed_value = DexRegisterInfo::PackValue(reg.GetKind(), reg.GetValue()),
	};
	uint32_t index = reg.IsLive() ? dex_register_catalog_.Dedup(&entry) : kNoValue;
	temp_dex_register_mask_.SetBit(i);
	temp_dex_register_map_.push_back(index);
	previous_dex_registers_[i] = reg;
	dex_register_timestamp_[i] = stack_maps_.size();
	}
	}

	// Set the mask and map for the current StackMap (which includes inlined registers).
	if (temp_dex_register_mask_.GetNumberOfBits() != 0) {
	current_stack_map_.dex_register_mask_index =
	dex_register_masks_.Dedup(temp_dex_register_mask_.GetRawStorage(),
	temp_dex_register_mask_.GetNumberOfBits());
	}
	if (!current_dex_registers_.empty()) {
	current_stack_map_.dex_register_map_index =
	dex_register_maps_.Dedup(temp_dex_register_map_.data(),
	temp_dex_register_map_.size());
	}

	if (kVerifyStackMaps) {
	size_t stack_map_index = stack_maps_.size();
	uint32_t depth = current_inline_infos_.size();
	// We need to make copy of the current registers for later (when the check is run).
	auto expected_dex_registers = std::make_shared<dchecked_vector<DexRegisterLocation>>(
	current_dex_registers_.begin(), current_dex_registers_.end());
	dchecks_.emplace_back([=](const CodeInfo& code_info) {
	StackMap stack_map = code_info.GetStackMapAt(stack_map_index);
	uint32_t expected_reg = 0;
	for (DexRegisterLocation reg : code_info.GetDexRegisterMapOf(stack_map)) {
	CHECK_EQ((*expected_dex_registers)[expected_reg++], reg);
	}
	for (uint32_t d = 0; d < depth; d++) {
	for (DexRegisterLocation reg : code_info.GetDexRegisterMapAtDepth(d, stack_map)) {
	CHECK_EQ((*expected_dex_registers)[expected_reg++], reg);
	}
	}
	CHECK_EQ(expected_reg, expected_dex_registers->size());
	});
	}
	}

	void StackMapStream::FillInMethodInfo(MemoryRegion region) {
	{
	MethodInfo info(region.begin(), method_infos_.size());
	for (size_t i = 0; i < method_infos_.size(); ++i) {
	info.SetMethodIndex(i, method_infos_[i]);
	}
	}
	if (kVerifyStackMaps) {
	// Check the data matches.
	MethodInfo info(region.begin());
	const size_t count = info.NumMethodIndices();
	DCHECK_EQ(count, method_infos_.size());
	for (size_t i = 0; i < count; ++i) {
	DCHECK_EQ(info.GetMethodIndex(i), method_infos_[i]);
	}
	}
	}

	size_t StackMapStream::PrepareForFillIn() {
	static_assert(sizeof(StackMapEntry) == StackMap::kCount * sizeof(uint32_t), "Layout");
	static_assert(sizeof(InvokeInfoEntry) == InvokeInfo::kCount * sizeof(uint32_t), "Layout");
	static_assert(sizeof(InlineInfoEntry) == InlineInfo::kCount * sizeof(uint32_t), "Layout");
	static_assert(sizeof(DexRegisterEntry) == DexRegisterInfo::kCount * sizeof(uint32_t), "Layout");
	DCHECK_EQ(out_.size(), 0u);

	// Read the stack masks now. The compiler might have updated them.
	for (size_t i = 0; i < lazy_stack_masks_.size(); i++) {
	BitVector* stack_mask = lazy_stack_masks_[i];
	if (stack_mask != nullptr && stack_mask->GetNumberOfBits() != 0) {
	stack_maps_[i].stack_mask_index =
	stack_masks_.Dedup(stack_mask->GetRawStorage(), stack_mask->GetNumberOfBits());
	}
	}

	size_t bit_offset = 0;
	stack_maps_.Encode(&out_, &bit_offset);
	register_masks_.Encode(&out_, &bit_offset);
	stack_masks_.Encode(&out_, &bit_offset);
	invoke_infos_.Encode(&out_, &bit_offset);
	inline_infos_.Encode(&out_, &bit_offset);
	dex_register_masks_.Encode(&out_, &bit_offset);
	dex_register_maps_.Encode(&out_, &bit_offset);
	dex_register_catalog_.Encode(&out_, &bit_offset);
	EncodeVarintBits(&out_, &bit_offset, num_dex_registers_);

	return UnsignedLeb128Size(out_.size()) + out_.size();
	}

	void StackMapStream::FillInCodeInfo(MemoryRegion region) {
	DCHECK(in_stack_map_ == false) << "Mismatched Begin/End calls";
	DCHECK(in_inline_info_ == false) << "Mismatched Begin/End calls";
	DCHECK_NE(0u, out_.size()) << "PrepareForFillIn not called before FillIn";
	DCHECK_EQ(region.size(), UnsignedLeb128Size(out_.size()) + out_.size());

	uint8_t* ptr = EncodeUnsignedLeb128(region.begin(), out_.size());
	region.CopyFromVector(ptr - region.begin(), out_);

	// Verify all written data (usually only in debug builds).
	if (kVerifyStackMaps) {
	CodeInfo code_info(region);
	CHECK_EQ(code_info.GetNumberOfStackMaps(), stack_maps_.size());
	for (const auto& dcheck : dchecks_) {
	dcheck(code_info);
	}
	}
	}

	size_t StackMapStream::ComputeMethodInfoSize() const {
	DCHECK_NE(0u, out_.size()) << "PrepareForFillIn not called before " << __FUNCTION__;
	return MethodInfo::ComputeSize(method_infos_.size());
	}

	} // namespace art