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Refactor cu_cache to use die_cache abstraction and reduce cu die cloning

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This commit is contained in:
Jeremy Rifkin 2025-02-17 21:13:08 -06:00
parent 83527947a2
commit a4faef7f1e
No known key found for this signature in database
GPG Key ID: 19AA8270105E8EB4
1 changed files with 37 additions and 29 deletions
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66
src/symbols/dwarf/dwarf_resolver.cpp
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@ -101,7 +101,16 @@ namespace libdwarf {
std::size_t ranges_count() const {
return range_entries.size();
}
optional<const die_object&> lookup(Dwarf_Addr pc) const {
struct die_and_data {
const die_object& die;
const T& data;
};
using lookup_result = typename std::conditional<
std::is_same<T, monostate>::value,
const die_object&,
die_and_data
>::type;
optional<lookup_result> lookup(Dwarf_Addr pc) const {
auto vec_it = first_less_than_or_equal(
range_entries.begin(),
range_entries.end(),
@ -113,7 +122,11 @@ namespace libdwarf {
if(vec_it == range_entries.end()) {
return nullopt;
}
return dies.at(vec_it->die.die_index);
if constexpr(std::is_same<T, monostate>::value) {
return dies.at(vec_it->die.die_index);
} else {
return die_and_data{dies.at(vec_it->die.die_index), vec_it->data};
}
}
};
@ -180,7 +193,8 @@ namespace libdwarf {
// Map from CU -> Sorted subprograms vector
std::unordered_map<Dwarf_Off, die_cache<monostate>> subprograms_cache;
// Vector of ranges and their corresponding CU offsets
std::vector<cu_entry> cu_cache;
// data stored for each cache entry is a Dwarf_Half dwversion
die_cache<Dwarf_Half> cu_cache;
bool generated_cu_cache = false;
// Map from CU -> {srcfiles, count}
std::unordered_map<Dwarf_Off, srcfiles> srcfiles_cache;
@ -365,23 +379,25 @@ namespace libdwarf {
// TODO: Also assuming same dwversion
const auto& skeleton_cu = skeleton.unwrap().cu_die;
auto ranges_vec = skeleton_cu.get_rangelist_entries(skeleton_cu, dwversion);
for(auto range : ranges_vec) {
// TODO: Reduce cloning here
cu_cache.push_back({ cu_die.clone(), dwversion, range.first, range.second });
if(!ranges_vec.empty()) {
auto cu_die_handle = cu_cache.add_die(cu_die.clone());
for(auto range : ranges_vec) {
cu_cache.insert(cu_die_handle, range.first, range.second, dwversion);
}
}
return false;
} else {
auto ranges_vec = cu_die.get_rangelist_entries(cu_die, dwversion);
for(auto range : ranges_vec) {
// TODO: Reduce cloning here
cu_cache.push_back({ cu_die.clone(), dwversion, range.first, range.second });
if(!ranges_vec.empty()) {
auto cu_die_handle = cu_cache.add_die(cu_die.clone());
for(auto range : ranges_vec) {
cu_cache.insert(cu_die_handle, range.first, range.second, dwversion);
}
}
return true;
}
});
std::sort(cu_cache.begin(), cu_cache.end(), [] (const cu_entry& a, const cu_entry& b) {
return a.low < b.low;
});
cu_cache.finalize();
generated_cu_cache = true;
}
}
@ -969,17 +985,13 @@ namespace libdwarf {
} else {
lazy_generate_cu_cache();
// look up the cu
auto vec_it = first_less_than_or_equal(
cu_cache.begin(),
cu_cache.end(),
pc,
[] (Dwarf_Addr pc, const cu_entry& entry) {
return pc < entry.low;
}
);
// TODO: Vec-it is already range-based, this range check is redundant
// If the vector has been empty this can happen
if(vec_it != cu_cache.end()) {
auto res = cu_cache.lookup(pc);
// res can be nullopt if the cu_cache vector is empty
// It can also happen for something like _start, where there is a cached CU for the object but
// _start is outside of the CU's PC range
if(res) {
const auto& die = res.unwrap().die;
const auto dwversion = res.unwrap().data;
// TODO: Cache the range list?
// NOTE: If we have a corresponding skeleton, we assume we have one CU matching the skeleton CU
if(
@ -990,14 +1002,10 @@ namespace libdwarf {
skeleton.unwrap().dwversion,
pc
)
) || vec_it->die.pc_in_die(vec_it->die, vec_it->dwversion, pc)
) || die.pc_in_die(die, dwversion, pc)
) {
return cu_info{maybe_owned_die_object::ref(vec_it->die), vec_it->dwversion};
return cu_info{maybe_owned_die_object::ref(die), dwversion};
}
} else {
// I've had this happen for _start, where there is a cached CU for the object but _start is outside
// of the CU's PC range
// ASSERT(cu_cache.size() == 0, "Vec should be empty?");
}
return nullopt;
}