[Lldb-commits] [PATCH] D157609: [lldb] Search debug file paths when looking for split DWARF files

[Greg Clayton via Phabricator via lldb-commits]

clayborg added a comment.

Just one question if we should still try all of your new code if we have a full path to a DW_AT_comp_dir, but we don't find the .dwo file, should be allow your code to run and still try to just append the relative "dwo_name" (without comp dir) to each of the search paths?



================
Comment at: lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp:1755
+      dwo_file.AppendPathComponent(dwo_name);
+      found = FileSystem::Instance().Exists(dwo_file);
+    } else {
----------------
If "found == false" here, do we want to fall through to the "else" clause below? This would mean we have a full path to a DW_AT_comp_dir, but we didn't find the .dwo file and "dwo_name" is relative, so maybe we should try to use the relative "dwo_name" below without the comp dir if not found?


================
Comment at: lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp:1770-1771
+      // Or it's relative to one of the user specified debug directories.
+      const FileSpecList &debug_file_search_paths =
+          Target::GetDefaultDebugFileSearchPaths();
+      size_t num_directories = debug_file_search_paths.GetSize();
----------------
On major issue we have here is if someone creates a target first, then sets the debug file search paths, then this will always fail because Target::GetDefaultDebugFileSearchPaths() gets the global target settings. This is because before we have a target, if any target settings get set, they get set in this global target settings object. Then each time you create a target, it will get a copy of these global settings. So this would work:
```
(lldb) settings set target.debug-file-search-paths /my/objfiles
# Global target settings are set above
(lldb) target create a.out
(lldb) run
...
```

This wouldn't:
```
(lldb) target create a.out
(lldb) settings set target.debug-file-search-paths /my/objfiles
# Current target settings are set above, not the global settings
(lldb) run
...
```
Because the global settings have nothing for the "target.debug-file-search-paths", but the current lldb_private::Target that was created by "target create a.out" does have it set, but that isn't what we are getting here.

We don't have access to the current target anywhere in lldb_private::Module and its lldb_private::ObjectFile or lldb_private::SymbolFile because lldb_private::Module can be used in multiple targets, so the module doesn't know what target it is in. This isn't something that needs to be solved here, but we should understand the limitations.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D157609/new/

https://reviews.llvm.org/D157609