Author: Tom Yang Date: 2025-10-31T15:08:39-07:00 New Revision: 74d4870aa503e90a614e4bc725d670abc5f90218
URL: https://github.com/llvm/llvm-project/commit/74d4870aa503e90a614e4bc725d670abc5f90218 DIFF: https://github.com/llvm/llvm-project/commit/74d4870aa503e90a614e4bc725d670abc5f90218.diff LOG: update ManualDWARFIndex::Index to use std::once (#165896) Small change to use (what I think is) a better practice -- we were using the `m_indexed` bool member to make sure we called `Index()` once, but we should just use `std::once`! This change shouldn't affect functionality. This change may also make concurrent access to `Index()` thread-safe, though the ManualDWARFIndex API isn't completely thread-safe due to `Decode()`. I'm not sure if ManualDWARFIndex was ever intended to be thread-safe. Test Plan: `ninja check-lldb` Tested basic debugging workflow of a couple of large projects I had built. Basically: ``` (lldb) target create <project> (lldb) b main (lldb) r (lldb) step ... ``` I A/B tested the performance of launching several modules with parallel module loading and didn't observe any performance regressions. --------- Co-authored-by: Tom Yang <[email protected]> Added: Modified: lldb/source/Plugins/SymbolFile/DWARF/ManualDWARFIndex.cpp lldb/source/Plugins/SymbolFile/DWARF/ManualDWARFIndex.h Removed: ################################################################################ diff --git a/lldb/source/Plugins/SymbolFile/DWARF/ManualDWARFIndex.cpp b/lldb/source/Plugins/SymbolFile/DWARF/ManualDWARFIndex.cpp index d90108f687f84..36dee1470e0a2 100644 --- a/lldb/source/Plugins/SymbolFile/DWARF/ManualDWARFIndex.cpp +++ b/lldb/source/Plugins/SymbolFile/DWARF/ManualDWARFIndex.cpp @@ -22,7 +22,6 @@ #include "lldb/Utility/Stream.h" #include "lldb/Utility/Timer.h" #include "lldb/lldb-private-enumerations.h" -#include "llvm/Support/FormatVariadic.h" #include "llvm/Support/ThreadPool.h" #include <atomic> #include <optional> @@ -33,10 +32,10 @@ using namespace lldb_private::plugin::dwarf; using namespace llvm::dwarf; void ManualDWARFIndex::Index() { - if (m_indexed) - return; - m_indexed = true; + std::call_once(m_indexed_flag, [this]() { IndexImpl(); }); +} +void ManualDWARFIndex::IndexImpl() { ElapsedTime elapsed(m_index_time); LLDB_SCOPED_TIMERF("%p", static_cast<void *>(m_dwarf)); if (LoadFromCache()) { diff --git a/lldb/source/Plugins/SymbolFile/DWARF/ManualDWARFIndex.h b/lldb/source/Plugins/SymbolFile/DWARF/ManualDWARFIndex.h index 0b5b2f3e84309..41e0e620a4896 100644 --- a/lldb/source/Plugins/SymbolFile/DWARF/ManualDWARFIndex.h +++ b/lldb/source/Plugins/SymbolFile/DWARF/ManualDWARFIndex.h @@ -66,8 +66,14 @@ class ManualDWARFIndex : public DWARFIndex { void Dump(Stream &s) override; private: + /// Reads the DWARF debug info to build the index once. + /// + /// Should be called before attempting to retrieve symbols. void Index(); + /// Call `ManualDWARFIndex::Index()` instead. + void IndexImpl(); + /// Decode a serialized version of this object from data. /// /// \param data @@ -170,7 +176,7 @@ class ManualDWARFIndex : public DWARFIndex { llvm::DenseSet<uint64_t> m_type_sigs_to_avoid; IndexSet<NameToDIE> m_set; - bool m_indexed = false; + std::once_flag m_indexed_flag; }; } // namespace dwarf } // namespace lldb_private::plugin _______________________________________________ lldb-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
