Pytorch backend: analysis

[DonAurelio]

Fixed

• Fixed entry/exit duration corruption on nested/reentrant ATen ops.
• Fixed the tracer failing to load in CI (undefined symbol: at::addGlobalCallback) on --as-needed toolchains, via -Wl,--no-as-needed,-ltorch_cpu,--as-needed.
• Added overload_name to the tracepoints so overloaded ops stay distinct (e.g. aten::empty.memory_format no longer collapses to aten::empty).
• Renamed the tracepoint provider pytorch.tp → pytorch_tracepoints.h.
• Changed torch-library discovery to warn instead of aborting when import torch fails.
• Added a tested-version check (1.11.0–2.14.0) that warns on untested PyTorch releases.
• Added LTTNG_UST_PYTORCH_LIBRARY_PATH.

Added (analysis)

• Added the interval filter (btx_pytorchinterval_callbacks.cpp) that merges op entry/exit events into completed duration intervals.
• Registered the pytorch backend (id 10, level 6) with the tally and default --backends lists so iprof produces the aggregated op table and timeline.
• Added the btx_pytorch_model.yaml.

Added (CI)

• Added a bats integration test that traces torch.empty(3) and asserts aten::empty.memory_format appears in the tally.
• Added a CPU-only torch==2.14.0 install step to the presubmit workflow so the integration test runs on every PR.

[TApplencourt]

Also I think pytorch may work on the github-CI machine? So we can add a integration tests if you don't mind. :)

[TApplencourt]

If you can do one more commit to fix clang-format and rubucopt, and then we merge. : )

1 file inspected, no offenses detected
Inspecting 1 file
C

Offenses:

xprof/xprof.rb.in:156:15: C: [Correctable] Style/TrailingUnderscoreVariable: Do not use trailing _s in parallel assignment. Prefer stdout_str, = exec("#{whichlib64_bin} #{binary} #{libs.join(' ')}",
                    opts: { 'LD_LIBRARY_PATH' => ld_path },
                    ignore_exit_codes: [1, 2]).
  stdout_str, _, _ = exec("#{whichlib64_bin} #{binary} #{libs.join(' ')}",
              ^^^^^
xprof/xprof.rb.in:157:21: C: [Correctable] Layout/ArgumentAlignment: Align the arguments of a method call if they span more than one line.
                    opts: { 'LD_LIBRARY_PATH' => ld_path }, ...
                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
xprof/xprof.rb.in:895:26: C: [Correctable] Layout/ExtraSpacing: Unnecessary spacing detected.
    stdout_str, _, status  = exec(torch_probe, ignore_exit_codes: [1, 127])
                         ^

1 file inspected, 3 offenses detected, 3 offenses autocorrectable

Thanks a lot!

[nscottnichols]

LGTM!