llvm-debuginfo-analyzer

These are the notes collected during the development, review and test. They describe limitations, known issues and future work.

Remove the use of macros in LVReader.h that describe the bumpallocators.

D137933

Use a standard (or LLVM) map with typeinfo (would need a specialization to expose equality and hasher) for the allocators and the creation functions could be a function template.

Use a lit test instead of a unit test for the logical readers.

D125783

As the DebugInfoLogicalView library is sufficiently exposed via the llvm-debuginfo-analyzer tool, follow the LLVM general approach and use lit tests to validate the logical readers.

Convert the unitests:

llvm-project/llvm/unittests/DebugInfo/LogicalView/CodeViewReaderTest.cpp
llvm-project/llvm/unittests/DebugInfo/LogicalView/DWARFReaderTest.cpp

into lit tests:

llvm-project/llvm/test/DebugInfo/LogicalView/CodeViewReader.test
llvm-project/llvm/test/DebugInfo/LogicalView/DWARFReader.test

Eliminate calls to getInputFileDirectory() in the unittests.

D125783

Rewrite the unittests ReaderTest and CodeViewReaderTest to eliminate the call:

  getInputFileDirectory()

as use of that call is discouraged.

Fix mismatch between %d/%x format strings and uint64_t type.

D137400 / 58758

Incorrect printing of uint64_t on 32-bit platforms. Add the PRIx64 specifier to the printing code (format()).

Remove LVScope::Children container.

D137933

Use a chaining iterator over the other containers rather than keep a separate container Children that mirrors their contents.

Use TableGen for command line options.

D125777

The current trend is to use TableGen for command-line options in tools. Change command line options to use tablegen as many other LLVM tools.

LVDoubleMap to return optional<ValueType> instead of null pointer.

D125783

The more idiomatic LLVM way to handle this would be to have find return Optional<ValueType>.

Pass references instead of pointers (Comparison functions).

D125782

In the comparison functions, pass references instead of pointers (when pointers cannot be null).

Use StringMap where possible.

D125783

LLVM has a StringMap class that is advertised as more efficient than std::map<std::string, ValueType>. Mainly it does fewer allocations because the key is not a std::string.

Replace the use of std::map<std::string, ValueType> with StringMap. One specific case is the LVSymbolNames definitions.

Calculate unique offset for CodeView elements.

In order to have the same logical functionality as the DWARF reader, such as:

• find scopes contribution to debug info
• sort by its physical location

The logical elements must have an unique offset (similar like the DWARF DIE offset).

Move initializeFileAndStringTables to the CodeView Library.

There is some code in the CodeView reader that was extracted/adapted from tools/llvm-readobj/COFFDumper.cpp that can be moved to the CodeView library.

We had a similar case with code shared with llvm-pdbutil that was moved to the PDB library: D122226

Move getSymbolKindName and formatRegisterId to the CodeView Library.

There is some code in the CodeView reader that was extracted/adapted from lib/DebugInfo/CodeView/SymbolDumper.cpp that can be used.

Use of std::unordered_set instead of std::set.

D125784

Replace the std::set usage for DeducedScopes, UnresolvedScopes and IdentifiedNamespaces with std::unordered_set and get the benefit of the O(1) while inserting/searching, as the order is not important.

Optimize LVNamespaceDeduction::find funtion.

D125784

Optimize the find method to use the proposed code:

  LVStringRefs::iterator Iter = std::find_if(Components.begin(), Components.end(),
    [](StringRef Name) {
        return IdentifiedNamespaces.find(Name) == IdentifiedNamespaces.end();
    });
  LVStringRefs::size_type FirstNonNamespace = std::distance(Components.begin(), Iter);

Move all the printing support to a common module.

Factor out printing functionality from the logical elements into a common module.

Refactor LVBinaryReader::processLines.

D125783 / D137156

During the traversal of the debug information sections, we created the logical lines representing the disassembled instructions from the text section and the logical lines representing the line records from the debug line section. Using the ranges associated with the logical scopes, we will allocate those logical lines to their logical scopes.

Consider the case when any of those lines become orphans, causing incorrect scope parent for disassembly or line records.

Add support for -ffunction-sections.

D125783

Only linked executables are handled. It does not support relocatable files compiled with -ffunction-sections.

Add support for DWARF v5 .debug_names section / CodeView public symbols stream.

D125783

The DWARF and CodeView readers use the public names information to create the instructions (LVLineAssembler). Instead of relying on DWARF section names (.debug_pubnames, .debug_names) and CodeView public symbol stream (S_PUB32), the readers should collect the needed information while processing the debug information.

If the object file supports the above section names and stream, use them to create the public names.

Add support for some extra DWARF locations.

The following DWARF debug location operands are not supported:

• DW_OP_const_type
• DW_OP_entry_value
• DW_OP_implicit_value

Add support for additional binary formats.

• Extended COFF (XCOFF)

Add support for JSON or YAML

The logical view uses its own and non-standard free form text when displaying information on logical elements.