[llvm-debuginfo-analyzer][DOC] Convert 'README.txt' to markdown. (#86394)

CarlosAlbertoEnciso · web-flow · commit 9c0c98ed376f · 2024-03-27T05:27:44.000Z
As part of the WebAssembly support work #85566 The README.txt is a bit odd since it only lists issues and problems without talking about what works. It’s also hard to read on the GitHub web view. - Convert to Markdown and linking to the command docs https://llvm.org/docs/CommandGuide/llvm-debuginfo-analyzer - Rename some left 'elf reader' to 'DWARF reader'.
diff --git a/llvm/docs/CommandGuide/llvm-debuginfo-analyzer.rst b/llvm/docs/CommandGuide/llvm-debuginfo-analyzer.rst
@@ -2267,6 +2267,10 @@ EXIT STATUS
 :program:`llvm-debuginfo-analyzer` returns 0 if the input files were
 parsed and printed successfully. Otherwise, it returns 1.
 
+LIMITATIONS AND KNOWN ISSUES
+----------------------------
+See :download:`Limitations <../../tools/llvm-debuginfo-analyzer/README.md>`.
+
 SEE ALSO
 --------
 :manpage:`llvm-dwarfdump`
diff --git a/llvm/include/llvm/DebugInfo/LogicalView/Readers/LVCodeViewReader.h b/llvm/include/llvm/DebugInfo/LogicalView/Readers/LVCodeViewReader.h
@@ -58,7 +58,7 @@ class LVSymbolVisitorDelegate;
 
 using LVNames = SmallVector<StringRef, 16>;
 
-// The ELF reader uses the DWARF constants to create the logical elements.
+// The DWARF reader uses the DWARF constants to create the logical elements.
 // The DW_TAG_* and DW_AT_* are used to select the logical object and to
 // set specific attributes, such as name, type, etc.
 // As the CodeView constants are different to the DWARF constants, the
diff --git a/llvm/include/llvm/DebugInfo/LogicalView/Readers/LVDWARFReader.h b/llvm/include/llvm/DebugInfo/LogicalView/Readers/LVDWARFReader.h
@@ -49,7 +49,7 @@ class LVDWARFReader final : public LVBinaryReader {
 
   // In DWARF v4, the files are 1-indexed.
   // In DWARF v5, the files are 0-indexed.
-  // The ELF reader expects the indexes as 1-indexed.
+  // The DWARF reader expects the indexes as 1-indexed.
   bool IncrementFileIndex = false;
 
   // Address ranges collected for current DIE.
diff --git a/llvm/lib/DebugInfo/LogicalView/Readers/LVDWARFReader.cpp b/llvm/lib/DebugInfo/LogicalView/Readers/LVDWARFReader.cpp
@@ -878,7 +878,7 @@ Error LVDWARFReader::createScopes() {
     // Additional discussions here:
     // https://www.mail-archive.com/dwarf-discuss@lists.dwarfstd.org/msg00883.html
 
-    // The ELF Reader is expecting the files are 1-indexed, so using
+    // The DWARF reader is expecting the files are 1-indexed, so using
     // the .debug_line header information decide if the indexed require
     // an internal adjustment.
 
@@ -918,7 +918,7 @@ Error LVDWARFReader::createScopes() {
       // DWARF-5 -> Increment index.
       return true;
     };
-    // The ELF reader expects the indexes as 1-indexed.
+    // The DWARF reader expects the indexes as 1-indexed.
     IncrementFileIndex = DeduceIncrementFileIndex();
 
     DWARFDie UnitDie = CU->getUnitDIE();
diff --git a/llvm/tools/llvm-debuginfo-analyzer/README.md b/llvm/tools/llvm-debuginfo-analyzer/README.md
@@ -0,0 +1,170 @@
+# `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](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**.
+**[D125783](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/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](https://reviews.llvm.org/D125783#inline-1324359)**
+
+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](https://reviews.llvm.org/D137400) / [58758](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.
+**[D137933](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.
+**[D125777](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<ValueType>`` instead of ``null pointer``.
+**[D125783](https://reviews.llvm.org/D125783#inline-1294164)**
+
+The more idiomatic LLVM way to handle this would be to have ``find``
+return ``Optional<ValueType>``.
+
+### Pass references instead of pointers (**Comparison functions**).
+**[D125782](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.
+**[D125783](https://reviews.llvm.org/D125783#inline-1294211)**
+
+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](https://reviews.llvm.org/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](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.
+**[D125784](https://reviews.llvm.org/D125784#inline-1296195)**
+
+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](https://reviews.llvm.org/D125783#inline-1246155) /
+[D137156](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``.
+**[D125783](https://reviews.llvm.org/D125783#inline-1295012)**
+
+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](https://reviews.llvm.org/D125783#inline-1294142)**
+
+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.
diff --git a/llvm/tools/llvm-debuginfo-analyzer/README.txt b/llvm/tools/llvm-debuginfo-analyzer/README.txt
