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/*
* Copyright (C) 2016 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.
*/
#ifndef ART_LIBELFFILE_DWARF_DEBUG_ABBREV_WRITER_H_
#define ART_LIBELFFILE_DWARF_DEBUG_ABBREV_WRITER_H_
#include <cstdint>
#include <type_traits>
#include <unordered_map>
#include "base/casts.h"
#include "base/leb128.h"
#include "base/stl_util.h"
#include "dwarf/dwarf_constants.h"
#include "dwarf/writer.h"
namespace art {
namespace dwarf {
// Writer for the .debug_abbrev.
//
// Abbreviations specify the format of entries in .debug_info.
// Each entry specifies abbreviation code, which in turns
// determines all the attributes and their format.
// It is possible to think of them as type definitions.
template <typename Vector = std::vector<uint8_t>>
class DebugAbbrevWriter final : private Writer<Vector> {
static_assert(std::is_same<typename Vector::value_type, uint8_t>::value, "Invalid value type");
public:
explicit DebugAbbrevWriter(Vector* buffer)
: Writer<Vector>(buffer),
current_abbrev_(buffer->get_allocator()) {
this->PushUint8(0); // Add abbrev table terminator.
}
// Start abbreviation declaration.
void StartAbbrev(Tag tag) {
DCHECK(current_abbrev_.empty());
EncodeUnsignedLeb128(&current_abbrev_, tag);
has_children_offset_ = current_abbrev_.size();
current_abbrev_.push_back(0); // Place-holder for DW_CHILDREN.
}
// Add attribute specification.
void AddAbbrevAttribute(Attribute name, Form type) {
EncodeUnsignedLeb128(&current_abbrev_, name);
EncodeUnsignedLeb128(&current_abbrev_, type);
}
// End abbreviation declaration and return its code.
// This will deduplicate abbreviations.
uint32_t EndAbbrev(Children has_children) {
DCHECK(!current_abbrev_.empty());
current_abbrev_[has_children_offset_] = has_children;
auto it = abbrev_codes_.insert(std::make_pair(std::move(current_abbrev_), NextAbbrevCode()));
uint32_t abbrev_code = it.first->second;
if (UNLIKELY(it.second)) { // Inserted new entry.
const Vector& abbrev = it.first->first;
this->Pop(); // Remove abbrev table terminator.
this->PushUleb128(abbrev_code);
this->PushData(abbrev.data(), abbrev.size());
this->PushUint8(0); // Attribute list end.
this->PushUint8(0); // Attribute list end.
this->PushUint8(0); // Add abbrev table terminator.
}
current_abbrev_.clear();
return abbrev_code;
}
// Get the next free abbrev code.
uint32_t NextAbbrevCode() {
return dchecked_integral_cast<uint32_t>(1 + abbrev_codes_.size());
}
private:
Vector current_abbrev_;
size_t has_children_offset_ = 0;
std::unordered_map<Vector, uint32_t, FNVHash<Vector> > abbrev_codes_;
};
} // namespace dwarf
} // namespace art
#endif // ART_LIBELFFILE_DWARF_DEBUG_ABBREV_WRITER_H_