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LibDebug: Add caches of DIE objects to DwarfInfo

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There is one cache that indexes DIE objects by the start address of
their range, and another cache that indexes by their offset in the
debug_info section.

Both caches are implemented with RedBlackTree, and are optional - they
will only be populated if 'build_cached_dies' is invoked.
This commit is contained in:
Itamar 2021-06-19 11:50:24 +03:00 • committed by Andreas Kling
parent a5f69efa5c
commit 92d4962d04
2 changed files with 74 additions and 2 deletions
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57
Userland/Libraries/LibDebug/Dwarf/DwarfInfo.cpp
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@ -1,13 +1,15 @@
/*
* Copyright (c) 2020, Itamar S. <itamar8910@gmail.com>
* Copyright (c) 2020-2021, Itamar S. <itamar8910@gmail.com>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include "DwarfInfo.h"
#include "AttributeValue.h"
#include "CompilationUnit.h"
#include <AK/MemoryStream.h>
#include <LibDebug/DebugInfo.h>
namespace Debug::Dwarf {
@ -233,4 +235,57 @@ AttributeValue DwarfInfo::get_attribute_value(AttributeDataForm form, ssize_t im
return value;
}
void DwarfInfo::build_cached_dies() const
{
auto insert_to_cache = [this](const DIE& die, DIERange& range) {
m_cached_dies_by_range.insert(range.start_address, DIEAndRange { die, range });
m_cached_dies_by_offset.insert(die.offset(), die);
};
auto get_ranges_of_die = [this](const DIE& die) -> Vector<DIERange> {
// TODO support DW_AT_ranges (appears when range is non-contiguous)
auto start = die.get_attribute(Attribute::LowPc);
auto end = die.get_attribute(Attribute::HighPc);
if (!start.has_value() || !end.has_value())
return {};
VERIFY(sizeof(FlatPtr) == sizeof(u32));
VERIFY(start->type == Dwarf::AttributeValue::Type::UnsignedNumber);
// DW_AT_high_pc attribute can have different meanings depending on the attribute form.
// (Dwarf version 5, section 2.17.2).
uint32_t range_end = 0;
if (end->form == Dwarf::AttributeDataForm::Addr)
range_end = end->data.as_u32;
else
range_end = start->data.as_u32 + end->data.as_u32;
return { DIERange { start.value().data.as_u32, range_end } };
};
// If we simply use a lambda, type deduction fails because it's used recursively.
Function<void(const DIE& die)> insert_to_cache_recursively;
insert_to_cache_recursively = [&](const DIE& die) {
if (die.offset() == 0 || die.parent_offset().has_value()) {
auto ranges = get_ranges_of_die(die);
for (auto& range : ranges) {
insert_to_cache(die, range);
}
}
die.for_each_child([&](const DIE& child) {
if (!child.is_null()) {
insert_to_cache_recursively(child);
}
});
};
for_each_compilation_unit([&](const CompilationUnit& compilation_unit) {
insert_to_cache_recursively(compilation_unit.root_die());
});
m_built_cached_dies = true;
}
}