Offline symbol resolving improvements (parallel image resolving, new fast libdw based resolving backend)

[tiago-rodrigues]

• Add parallel implementation of offline symbol resolving (process images in parallel, use '-m' to specify the level of parallelism, -1 [default] is max core count)
• Add a couple of more offline symbol resolving backend implementations for linux (use '-n' to choose the backend to use):
  • a libdw based backend that is ~100x faster than addr2line and LGPL licensed (requires libdw package to be installed and LIBDW_OFFLINE_SYMBOL_RESOLUTION_SUPPORT to be enabled)
  • a libacktrace based backend (using the libbacktrace version that exists in the tracy codebase). This backend is not fully functional as it need to load the .so into memory to resolve the symbols which is not always possible (enable with LIBBACKTRACE_OFFLINE_SYMBOL_RESOLUTION_SUPPORT)
• Add option to exclude certain images from being resolved (specified via -x)

[tiago-rodrigues]

@Lectem : this is the PR I was mentioning here: #1024 (comment)

@wolfpld : what would be the right way to add the dependency to "libdw"? As it's significantly faster than addr2line, I would like to make it the default offline resolver in the update util.
Would the the only way be to use CPM and clone and build elfutils/the libdw part of it at least?

I left the backtrace implementation for reference as @Lectem mentioned he wanted to attempt implementing it, I however never succeeded in getting it to work for all .so's maybe there is a way. Still I think libdw is the best option at the cost of this extra dependency.

[Lectem]

Interesting, so from what I saw, we could use the offline_callbacks to check that the build-id is correct ? One of the main issues I'd like to fix is the that we might not be using the correct debug information. (Both when using update or with the server once we finish working on #1009 ).
On Windows this can be done by providing the PDB GUID, and on linux using the build-id.

If we do integrate libDw and that it supports build-id checks and we can do file lookup with debuginfod, then there'd be less/little need for modifying libbacktrace. (Except that libbacktrace supports more formats, could be used on platforms other than Linux, and doesn't require installing a package).

[wolfpld]

If we do integrate libDw and that it supports build-id checks and we can do file lookup with debuginfod, then there'd be less/little need for modifying libbacktrace. (Except that libbacktrace supports more formats, could be used on platforms other than Linux, and doesn't require installing a package).

There are changes in Tracy libbacktrace that are required for inline functions to be properly reported.

[tiago-rodrigues]

I've made the new back-ends optional so it passes on CI and still allows users to enable them if they want. Although I would like the libdw backend to the the default, unfortunately I don't see how I would do that with CPM and pulling and building elfutils to do this.