## Summary This PR improves `SymbolFileDWARF::FindTypes()` by utilizing the newly added parent chain `DW_IDX_parent` in `.debug_names`. The proposal was originally discussed in [this RFC](https://discourse.llvm.org/t/rfc-improve-dwarf-5-debug-names-type-lookup-parsing-speed/74151). ## Implementation To leverage the parent chain for `SymbolFileDWARF::FindTypes()`, this PR adds a new API: `GetTypesWithQuery` in `DWARFIndex` base class. The API performs the same function as `GetTypes` with additional filtering using `TypeQuery`. Since this only introduces filtering, the callback mechanisms at all call sites remain unchanged. A default implementation is given in `DWARFIndex` class which parses debug info and performs the matching. In the `DebugNameDWARFIndex` override, the parent_contexts in the `TypeQuery` is cross checked with parent chain in `.debug_names` for for much faster filtering before fallback to base implementation for final filtering. Unlike the `GetFullyQualifiedType` API, which fully consumes the `DW_IDX_parent` parent chain for exact matching, these new APIs perform partial subset matching for type/namespace queries. This is necessary to support queries involving anonymous or inline namespaces. For instance, a user might request `NS1::NS2::NS3::Foo`, while the index table's parent chain might contain `NS1::inline_NS2::NS3::Foo`, which would fail exact matching. ## Performance Results In one of our internal target using `.debug_names` + split dwarf. Expanding a "this" pointer in locals view in VSCode: 94s => 48s. (Not sure why I got 94s this time instead of 70s last week). --------- Co-authored-by: jeffreytan81 <jeffreytan@fb.com>
154 lines
5.5 KiB
C++
154 lines
5.5 KiB
C++
//===-- DWARFIndex.cpp ----------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "Plugins/SymbolFile/DWARF/DWARFIndex.h"
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#include "DWARFDebugInfoEntry.h"
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#include "DWARFDeclContext.h"
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#include "Plugins/Language/ObjC/ObjCLanguage.h"
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#include "Plugins/SymbolFile/DWARF/DWARFDIE.h"
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#include "Plugins/SymbolFile/DWARF/SymbolFileDWARF.h"
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#include "lldb/Core/Mangled.h"
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#include "lldb/Core/Module.h"
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#include "lldb/Target/Language.h"
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using namespace lldb_private;
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using namespace lldb;
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using namespace lldb_private::plugin::dwarf;
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DWARFIndex::~DWARFIndex() = default;
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bool DWARFIndex::ProcessFunctionDIE(
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const Module::LookupInfo &lookup_info, DWARFDIE die,
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const CompilerDeclContext &parent_decl_ctx,
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llvm::function_ref<bool(DWARFDIE die)> callback) {
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llvm::StringRef name = lookup_info.GetLookupName().GetStringRef();
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FunctionNameType name_type_mask = lookup_info.GetNameTypeMask();
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if (!(name_type_mask & eFunctionNameTypeFull)) {
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ConstString name_to_match_against;
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if (const char *mangled_die_name = die.GetMangledName()) {
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name_to_match_against = ConstString(mangled_die_name);
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} else {
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SymbolFileDWARF *symbols = die.GetDWARF();
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if (ConstString demangled_die_name =
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symbols->ConstructFunctionDemangledName(die))
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name_to_match_against = demangled_die_name;
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}
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if (!lookup_info.NameMatchesLookupInfo(name_to_match_against,
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lookup_info.GetLanguageType()))
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return true;
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}
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// Exit early if we're searching exclusively for methods or selectors and
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// we have a context specified (no methods in namespaces).
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uint32_t looking_for_nonmethods =
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name_type_mask & ~(eFunctionNameTypeMethod | eFunctionNameTypeSelector);
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if (!looking_for_nonmethods && parent_decl_ctx.IsValid())
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return true;
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// Otherwise, we need to also check that the context matches. If it does not
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// match, we do nothing.
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if (!SymbolFileDWARF::DIEInDeclContext(parent_decl_ctx, die))
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return true;
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// In case of a full match, we just insert everything we find.
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if (name_type_mask & eFunctionNameTypeFull && die.GetMangledName() == name)
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return callback(die);
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// If looking for ObjC selectors, we need to also check if the name is a
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// possible selector.
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if (name_type_mask & eFunctionNameTypeSelector &&
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ObjCLanguage::IsPossibleObjCMethodName(die.GetName()))
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return callback(die);
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bool looking_for_methods = name_type_mask & lldb::eFunctionNameTypeMethod;
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bool looking_for_functions = name_type_mask & lldb::eFunctionNameTypeBase;
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if (looking_for_methods || looking_for_functions) {
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// If we're looking for either methods or functions, we definitely want this
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// die. Otherwise, only keep it if the die type matches what we are
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// searching for.
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if ((looking_for_methods && looking_for_functions) ||
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looking_for_methods == die.IsMethod())
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return callback(die);
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}
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return true;
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}
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DWARFIndex::DIERefCallbackImpl::DIERefCallbackImpl(
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const DWARFIndex &index, llvm::function_ref<bool(DWARFDIE die)> callback,
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llvm::StringRef name)
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: m_index(index),
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m_dwarf(*llvm::cast<SymbolFileDWARF>(
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index.m_module.GetSymbolFile()->GetBackingSymbolFile())),
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m_callback(callback), m_name(name) {}
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bool DWARFIndex::DIERefCallbackImpl::operator()(DIERef ref) const {
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if (DWARFDIE die = m_dwarf.GetDIE(ref))
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return m_callback(die);
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m_index.ReportInvalidDIERef(ref, m_name);
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return true;
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}
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bool DWARFIndex::DIERefCallbackImpl::operator()(
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const llvm::AppleAcceleratorTable::Entry &entry) const {
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return this->operator()(DIERef(std::nullopt, DIERef::Section::DebugInfo,
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*entry.getDIESectionOffset()));
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}
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void DWARFIndex::ReportInvalidDIERef(DIERef ref, llvm::StringRef name) const {
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m_module.ReportErrorIfModifyDetected(
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"the DWARF debug information has been modified (accelerator table had "
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"bad die {0:x16} for '{1}')\n",
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ref.die_offset(), name.str().c_str());
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}
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void DWARFIndex::GetFullyQualifiedType(
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const DWARFDeclContext &context,
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llvm::function_ref<bool(DWARFDIE die)> callback) {
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GetTypes(context, [&](DWARFDIE die) {
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return GetFullyQualifiedTypeImpl(context, die, callback);
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});
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}
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bool DWARFIndex::GetFullyQualifiedTypeImpl(
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const DWARFDeclContext &context, DWARFDIE die,
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llvm::function_ref<bool(DWARFDIE die)> callback) {
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DWARFDeclContext dwarf_decl_ctx = die.GetDWARFDeclContext();
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if (dwarf_decl_ctx == context)
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return callback(die);
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return true;
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}
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void DWARFIndex::GetTypesWithQuery(
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TypeQuery &query, llvm::function_ref<bool(DWARFDIE die)> callback) {
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GetTypes(query.GetTypeBasename(), [&](DWARFDIE die) {
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return ProcessTypeDIEMatchQuery(query, die, callback);
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});
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}
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bool DWARFIndex::ProcessTypeDIEMatchQuery(
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TypeQuery &query, DWARFDIE die,
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llvm::function_ref<bool(DWARFDIE die)> callback) {
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// Nothing to match from query
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if (query.GetContextRef().size() <= 1)
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return callback(die);
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std::vector<lldb_private::CompilerContext> die_context;
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if (query.GetModuleSearch())
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die_context = die.GetDeclContext();
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else
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die_context = die.GetTypeLookupContext();
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if (!query.ContextMatches(die_context))
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return true;
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return callback(die);
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}
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