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[LLDB][NativePDB] Improve ParseDeclsForContext time.
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1. When we evaluating an expression multiple times and the searching scope is translation unit, ParseDeclsForContext iterates the type info and symbol info multiple times, though only the debug info is parsed once. Using llvm::call_once to make it only iterating and parsing once.

2. When evaluating an expression with identifier whose parent scope is a namespace, ParseDeclsForContext needs to search the entire type info to complete those records whose name is prefixed with the namespace's name and the entire symbol info to to parse functions and non-local variables. Caching parsed namespaces to avoid unnecessary searching.

Reviewed By: labath

Differential Revision: https://reviews.llvm.org/D136006
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@ZequanWu
ZequanWu committed Oct 21, 2022
1 parent 3073074 commit 9b809cc
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Showing 2 changed files with 71 additions and 44 deletions.
106 changes: 64 additions & 42 deletions lldb/source/Plugins/SymbolFile/NativePDB/PdbAstBuilder.cpp
View file
Expand Up @@ -21,7 +21,6 @@
#include "lldb/Core/Module.h"
#include "lldb/Symbol/ObjectFile.h"
#include "lldb/Utility/LLDBAssert.h"

#include "PdbUtil.h"
#include "UdtRecordCompleter.h"
#include "SymbolFileNativePDB.h"
Expand Down Expand Up @@ -1232,8 +1231,11 @@ static bool isBlockDecl(clang::DeclContext &context) {
return llvm::isa<clang::BlockDecl>(&context);
}

void PdbAstBuilder::ParseAllNamespacesPlusChildrenOf(
llvm::Optional<llvm::StringRef> parent) {
void PdbAstBuilder::ParseNamespace(clang::DeclContext &context) {
clang::NamespaceDecl *ns = llvm::dyn_cast<clang::NamespaceDecl>(&context);
if (m_parsed_namespaces.contains(ns))
return;
std::string qname = ns->getQualifiedNameAsString();
SymbolFileNativePDB *pdb = static_cast<SymbolFileNativePDB *>(
m_clang.GetSymbolFile()->GetBackingSymbolFile());
PdbIndex &index = pdb->GetIndex();
Expand All @@ -1247,12 +1249,6 @@ void PdbAstBuilder::ParseAllNamespacesPlusChildrenOf(

CVTagRecord tag = CVTagRecord::create(cvt);

if (!parent) {
clang::QualType qt = GetOrCreateType(tid);
CompleteType(qt);
continue;
}

// Call CreateDeclInfoForType unconditionally so that the namespace info
// gets created. But only call CreateRecordType if the namespace name
// matches.
Expand All @@ -1263,41 +1259,68 @@ void PdbAstBuilder::ParseAllNamespacesPlusChildrenOf(
continue;

clang::NamespaceDecl *ns = llvm::cast<clang::NamespaceDecl>(context);
std::string actual_ns = ns->getQualifiedNameAsString();
if (llvm::StringRef(actual_ns).startswith(*parent)) {
clang::QualType qt = GetOrCreateType(tid);
CompleteType(qt);
continue;
llvm::StringRef ns_name = ns->getName();
if (ns_name.startswith(qname)) {
ns_name = ns_name.drop_front(qname.size());
if (ns_name.startswith("::"))
GetOrCreateType(tid);
}
}
ParseAllFunctionsAndNonLocalVars();
m_parsed_namespaces.insert(ns);
}

uint32_t module_count = index.dbi().modules().getModuleCount();
for (uint16_t modi = 0; modi < module_count; ++modi) {
CompilandIndexItem &cii = index.compilands().GetOrCreateCompiland(modi);
const CVSymbolArray &symbols = cii.m_debug_stream.getSymbolArray();
auto iter = symbols.begin();
while (iter != symbols.end()) {
PdbCompilandSymId sym_id{modi, iter.offset()};

switch (iter->kind()) {
case S_GPROC32:
case S_LPROC32:
GetOrCreateFunctionDecl(sym_id);
iter = symbols.at(getScopeEndOffset(*iter));
break;
case S_GDATA32:
case S_GTHREAD32:
case S_LDATA32:
case S_LTHREAD32:
GetOrCreateVariableDecl(PdbCompilandSymId(modi, 0), sym_id);
++iter;
break;
default:
++iter;
void PdbAstBuilder::ParseAllTypes() {
llvm::call_once(m_parse_all_types, [this]() {
SymbolFileNativePDB *pdb = static_cast<SymbolFileNativePDB *>(
m_clang.GetSymbolFile()->GetBackingSymbolFile());
PdbIndex &index = pdb->GetIndex();
TypeIndex ti{index.tpi().TypeIndexBegin()};
for (const CVType &cvt : index.tpi().typeArray()) {
PdbTypeSymId tid{ti};
++ti;

if (!IsTagRecord(cvt))
continue;

GetOrCreateType(tid);
}
});
}

void PdbAstBuilder::ParseAllFunctionsAndNonLocalVars() {
llvm::call_once(m_parse_functions_and_non_local_vars, [this]() {
SymbolFileNativePDB *pdb = static_cast<SymbolFileNativePDB *>(
m_clang.GetSymbolFile()->GetBackingSymbolFile());
PdbIndex &index = pdb->GetIndex();
uint32_t module_count = index.dbi().modules().getModuleCount();
for (uint16_t modi = 0; modi < module_count; ++modi) {
CompilandIndexItem &cii = index.compilands().GetOrCreateCompiland(modi);
const CVSymbolArray &symbols = cii.m_debug_stream.getSymbolArray();
auto iter = symbols.begin();
while (iter != symbols.end()) {
PdbCompilandSymId sym_id{modi, iter.offset()};

switch (iter->kind()) {
case S_GPROC32:
case S_LPROC32:
GetOrCreateFunctionDecl(sym_id);
iter = symbols.at(getScopeEndOffset(*iter));
break;
case S_GDATA32:
case S_GTHREAD32:
case S_LDATA32:
case S_LTHREAD32:
GetOrCreateVariableDecl(PdbCompilandSymId(modi, 0), sym_id);
++iter;
break;
default:
++iter;
continue;
}
}
}
}
});
}

static CVSymbolArray skipFunctionParameters(clang::Decl &decl,
Expand Down Expand Up @@ -1384,14 +1407,13 @@ void PdbAstBuilder::ParseDeclsForContext(clang::DeclContext &context) {
// work (such as parsing the items that appear within the namespaces) at the
// same time.
if (context.isTranslationUnit()) {
ParseAllNamespacesPlusChildrenOf(llvm::None);
ParseAllTypes();
ParseAllFunctionsAndNonLocalVars();
return;
}

if (context.isNamespace()) {
clang::NamespaceDecl &ns = *llvm::dyn_cast<clang::NamespaceDecl>(&context);
std::string qname = ns.getQualifiedNameAsString();
ParseAllNamespacesPlusChildrenOf(llvm::StringRef{qname});
ParseNamespace(context);
return;
}

Expand Down
9 changes: 7 additions & 2 deletions lldb/source/Plugins/SymbolFile/NativePDB/PdbAstBuilder.h
View file
Expand Up @@ -11,6 +11,7 @@

#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/Threading.h"

#include "Plugins/ExpressionParser/Clang/ClangASTImporter.h"

Expand Down Expand Up @@ -122,7 +123,9 @@ class PdbAstBuilder {
TypeIndex func_ti, CompilerType func_ct,
uint32_t param_count, clang::StorageClass func_storage,
bool is_inline, clang::DeclContext *parent);
void ParseAllNamespacesPlusChildrenOf(llvm::Optional<llvm::StringRef> parent);
void ParseNamespace(clang::DeclContext &parent);
void ParseAllTypes();
void ParseAllFunctionsAndNonLocalVars();
void ParseDeclsForSimpleContext(clang::DeclContext &context);
void ParseBlockChildren(PdbCompilandSymId block_id);

Expand All @@ -135,7 +138,8 @@ class PdbAstBuilder {
TypeSystemClang &m_clang;

ClangASTImporter m_importer;

llvm::once_flag m_parse_functions_and_non_local_vars;
llvm::once_flag m_parse_all_types;
llvm::DenseMap<clang::Decl *, DeclStatus> m_decl_to_status;
llvm::DenseMap<lldb::user_id_t, clang::Decl *> m_uid_to_decl;
llvm::DenseMap<lldb::user_id_t, clang::QualType> m_uid_to_type;
Expand All @@ -145,6 +149,7 @@ class PdbAstBuilder {
llvm::DenseMap<lldb::opaque_compiler_type_t,
llvm::SmallSet<std::pair<llvm::StringRef, CompilerType>, 8>>
m_cxx_record_map;
llvm::DenseSet<clang::NamespaceDecl *> m_parsed_namespaces;
};

} // namespace npdb
Expand Down

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