This pull request adds support for parsing the source language in both
DWARF and CodeView. Specifically,
- The `LVSourceLanguage` class is introduced to represent any supported
language by any of the debug info representations.
- Update `LVDWARFReader.cpp` and `LVCodeViewVisitor.cpp` to parse the
source language where it applies. Added a new `=Language` attribute;
`getAttributeLanguage()` is internally used to control whether this
information is being printed.
This PR was split from https://github.com/llvm/llvm-project/pull/137228
(which introduced support for `DW_TAG_module` and `DW_AT_byte_size`).
This PR improves `LVDWARFReader` by introducing handling of
`DW_AT_byte_size`. Most DWARF emitters include this attribute for types
to specify the size of an entity of the given type.
- Adds support for `DW_TAG_module` DIEs and recurse over their children.
Prior to this patch, entities hanging below `DW_TAG_module` were just
not visible. This DIE kind is commonly generated by Objective-C modules.
This patch will represent such entities, which will print as
```
[001] {CompileUnit} '/llvm/tools/clang/test/modules/<stdin>'
[002] {Producer} 'LLVM version 3.7.0'
{Directory} '/llvm/tools/clang/test/modules'
{File} '<stdin>'
[002] {Module} 'DebugModule'
```
The minimal test case included is just the result of
```
$ llc llvm/test/DebugInfo/X86/DIModule.ll
-accel-tables=Dwarf
-o llvm/unittests/DebugInfo/LogicalView/Inputs/test-dwarf-clang-module.o
-filetype=obj
```
For the given C++ code:
```
template <typename T> class Foo { T Member; };
template <template <typename T> class TemplateType>
class Bar {
TemplateType<int> Int;
};
template <template <template <typename> class> class TemplateTemplateType>
class Baz {
TemplateTemplateType<Foo> Foo;
};
typedef Baz<Bar> Example;
Example TT;
```
The '--attribute=encoded' option, will produce the logical view:
```
{Class} 'Foo<int>'
{Encoded} <int>
{Class} 'Bar<Foo>'
{Encoded} <> <-- Missing the template argument info (Foo)
{Class} 'Baz<Bar>'
{Encoded} <> <-- Missing the template argument info (Bar)
```
When the template argument is another template it is not included in the
{Encoded} field. The correct output should be:
```
{Class} 'Foo<int>'
{Encoded} <int>
{Class} 'Bar<Foo>'
{Encoded} <Foo>
{Class} 'Baz<Bar>'
{Encoded} <Bar>
```
- In the DWARF reader, for those attributes that can have an unsigned
value, allow for the following cases:
* Is an implicit constant
* Is an optional value
- The testing is done by creating a file with generated DWARF, using
`DwarfGenerator` (generate DWARF debug info for unit tests).
The code dealing with DW_AT_call_line/DW_AT_call_file is in the wrong
place. The correct functions were call, but with incorrect values:
DW_AT_call_line <-- Filename Index
DW_AT_call_file <-- Line number
The result of the function cannot be correctly interpreted without
knowing the precise form type (a type signature needs to be looked up
very differently from a supplementary debug info reference). The
function sort of worked because the two reference types (unit-relative
and section-relative) that can be handled uniformly are also the most
common types of references, but this setup made it easy to write code
which does not support other kinds of reference (and if one tried to
support them, the result didn't look pretty --
https://github.com/llvm/llvm-project/pull/97423/files#r1676217081).
The split is based on the reference type classification from DWARFv5
(Section 7.5.5 Classes and Forms), and it should enable uniform (if
slightly more verbose) hadling. Note that this only affects users which
want more control of how (or if) the references are resolved. Users
which just want to access the referenced DIE can use the higher level
API (DWARFDie::GetAttributeValueAsReferencedDie) which returns (or will
return after #97423 is merged) the correct die for all reference types
(except for supplementary references, which we don't support right now).
As part of the WebAssembly support work review
https://github.com/llvm/llvm-project/pull/82588
It was decided to rename:
Files: LVElfReader.cpp[h] -> LVDWARFReader.cpp[h]
ELFReaderTest.cpp -> DWARFReaderTest.cpp
Class: LVELFReader -> LVDWARFReader
The name LVDWARFReader would match the another reader LVCodeViewReader
as they will reflect the type of
debug information format that they are parsing.
