Index: llvm/tools/llvm-debuginfo-analyzer/README.txt =================================================================== --- /dev/null +++ llvm/tools/llvm-debuginfo-analyzer/README.txt @@ -0,0 +1,218 @@ +//===- llvm/tools/llvm-debuginfo-analyzer/README.txt ----------------------===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// +// +// This file contains notes collected during the development, review and test. +// It describes limitations, know issues and future work. +// +//===----------------------------------------------------------------------===// + +//===----------------------------------------------------------------------===// +// Remove the use of macros in 'LVReader.h' that describe the bumpallocators. +//===----------------------------------------------------------------------===// +https://reviews.llvm.org/D137933#inline-1389904 + +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. +//===----------------------------------------------------------------------===// +https://reviews.llvm.org/D125783#inline-1324376 + +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/ELFReaderTest.cpp + +into LIT tests: + llvm-project/llvm/test/DebugInfo/LogicalView/CodeViewReader.test + llvm-project/llvm/test/DebugInfo/LogicalView/ELFReader.test + +//===----------------------------------------------------------------------===// +// Eliminate calls to 'getInputFileDirectory()' in the unit tests. +//===----------------------------------------------------------------------===// +https://reviews.llvm.org/D125783#inline-1324359 + +Rewrite the unittests 'LFReaderTest' and 'CodeViewReaderTest'to eliminate +the call: + + getInputFileDirectory() + +as use of that call is discouraged. + +See: Use a lit test instead of a unit test for the logical readers. + +//===----------------------------------------------------------------------===// +// Fix mismatch between %d/%x format strings and uint64_t type. +//===----------------------------------------------------------------------===// +https://reviews.llvm.org/D137400 +https://github.com/llvm/llvm-project/issues/58758 + +Incorrect printing of uint64_t on 32-bit platforms. +Add the PRIx64 specifier to the printing code (format()). + +//===----------------------------------------------------------------------===// +// Remove 'LVScope::Children' container. +//===----------------------------------------------------------------------===// +https://reviews.llvm.org/D137933#inline-1373902 + +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. +//===----------------------------------------------------------------------===// +https://reviews.llvm.org/D125777#inline-1291801 + +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 instead of null pointer. +//===----------------------------------------------------------------------===// +https://reviews.llvm.org/D125783#inline-1294164 + +The more idiomatic LLVM way to handle this would be to have 'find ' +return Optional. + +//===----------------------------------------------------------------------===// +// Pass references instead of pointers (Comparison functions). +//===----------------------------------------------------------------------===// +https://reviews.llvm.org/D125782#inline-1293920 + +In the comparison functions, pass references instead of pointers (when +pointers cannot be null). + +//===----------------------------------------------------------------------===// +// Use StringMap where possible. +//===----------------------------------------------------------------------===// +https://reviews.llvm.org/D125783#inline-1294211 + +LLVM has a StringMap class that is advertised as more efficient than +std::map. Mainly it does fewer allocations +because the key is not a std::string. + +Replace the use of std::map with String Map. +One specific case is the LVSymbolNames definitions. + +//===----------------------------------------------------------------------===// +// Calculate unique offset for CodeView elements. +//===----------------------------------------------------------------------===// +In order to have the same logical functionality as the ELF 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 COFF 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 COFF +library. + +We had a similar case with code shared with llvm-pdbutil that was moved +to the PDB library: https://reviews.llvm.org/D122226 + +//===----------------------------------------------------------------------===// +// Move 'getSymbolKindName'/'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. +//===----------------------------------------------------------------------===// +https://reviews.llvm.org/D125784#inline-1221421 + +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. +//===----------------------------------------------------------------------===// +https://reviews.llvm.org/D125784#inline-1296195 + +Optimize the 'findd' 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'. +//===----------------------------------------------------------------------===// +https://reviews.llvm.org/D125783#inline-1246155 +https://reviews.llvm.org/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'. +//===----------------------------------------------------------------------===// +https://reviews.llvm.org/D125783#inline-1295012 + +The tool can handle only linked executables. It does not support +relocatable files compiled with -ffunction-sections. + +//===----------------------------------------------------------------------===// +// Add support for DWARF v5 .debug_names section. +// Add support for CodeView public symbols stream. +//===----------------------------------------------------------------------===// +https://reviews.llvm.org/D125783#inline-1294142 + +The ELF 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 collects 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. +//===----------------------------------------------------------------------===// +- WebAssembly (Wasm). + https://github.com/llvm/llvm-project/issues/57040#issuecomment-1211336680 + +- Extended COFF (XCOFF) + +//===----------------------------------------------------------------------===//