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9bcdbe205b
While symbolicating a crash dump for UserspaceEmulator I came across another data form we didn't support. ImplicitConst encodes a LEB128 value in the abbreviation record rather than - like all other values - in the .debug_info section.
97 lines
3.4 KiB
C++
97 lines
3.4 KiB
C++
/*
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* Copyright (c) 2020, Itamar S. <itamar8910@gmail.com>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include "DIE.h"
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#include "CompilationUnit.h"
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#include "DwarfInfo.h"
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#include <AK/ByteBuffer.h>
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#include <AK/MemoryStream.h>
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namespace Debug::Dwarf {
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DIE::DIE(const CompilationUnit& unit, u32 offset)
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: m_compilation_unit(unit)
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, m_offset(offset)
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{
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InputMemoryStream stream(m_compilation_unit.dwarf_info().debug_info_data());
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stream.discard_or_error(m_offset);
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stream.read_LEB128_unsigned(m_abbreviation_code);
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m_data_offset = stream.offset();
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if (m_abbreviation_code == 0) {
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// An abbreviation code of 0 ( = null DIE entry) means the end of a chain of siblings
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m_tag = EntryTag::None;
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} else {
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auto abbreviation_info = m_compilation_unit.abbreviations_map().get(m_abbreviation_code);
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VERIFY(abbreviation_info.has_value());
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m_tag = abbreviation_info.value().tag;
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m_has_children = abbreviation_info.value().has_children;
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// We iterate the attributes data only to calculate this DIE's size
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for (auto& attribute_spec : abbreviation_info.value().attribute_specifications) {
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m_compilation_unit.dwarf_info().get_attribute_value(attribute_spec.form, attribute_spec.value, stream, &m_compilation_unit);
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}
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}
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m_size = stream.offset() - m_offset;
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}
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Optional<AttributeValue> DIE::get_attribute(const Attribute& attribute) const
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{
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InputMemoryStream stream { m_compilation_unit.dwarf_info().debug_info_data() };
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stream.discard_or_error(m_data_offset);
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auto abbreviation_info = m_compilation_unit.abbreviations_map().get(m_abbreviation_code);
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VERIFY(abbreviation_info.has_value());
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for (const auto& attribute_spec : abbreviation_info.value().attribute_specifications) {
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auto value = m_compilation_unit.dwarf_info().get_attribute_value(attribute_spec.form, attribute_spec.value, stream, &m_compilation_unit);
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if (attribute_spec.attribute == attribute) {
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return value;
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}
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}
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return {};
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}
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void DIE::for_each_child(Function<void(const DIE& child)> callback) const
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{
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if (!m_has_children)
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return;
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NonnullOwnPtr<DIE> current_child = make<DIE>(m_compilation_unit, m_offset + m_size);
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while (true) {
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callback(*current_child);
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if (current_child->is_null())
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break;
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if (!current_child->has_children()) {
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current_child = make<DIE>(m_compilation_unit, current_child->offset() + current_child->size());
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continue;
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}
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auto sibling = current_child->get_attribute(Attribute::Sibling);
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u32 sibling_offset = 0;
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if (sibling.has_value()) {
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sibling_offset = sibling.value().data.as_u32;
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}
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if (!sibling.has_value()) {
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// NOTE: According to the spec, the compiler doesn't have to supply the sibling information.
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// When it doesn't, we have to recursively iterate the current child's children to find where they end
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current_child->for_each_child([&](const DIE& sub_child) {
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sibling_offset = sub_child.offset() + sub_child.size();
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});
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}
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current_child = make<DIE>(m_compilation_unit, sibling_offset);
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}
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}
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DIE DIE::get_die_at_offset(u32 offset) const
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{
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VERIFY(offset >= m_compilation_unit.offset() && offset < m_compilation_unit.offset() + m_compilation_unit.size());
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return DIE(m_compilation_unit, offset);
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}
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}
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