Enable the tail call interpreter on 3.14+ clang builds

[zanieb]

No description provided.

[charliermarsh]

Coool

[Fidget-Spinner]

For the time being, you also need to check that the current toolchain is clang-19 or higher and the arch is aarch64/x86_64. GCC doesn't support this.

Btw, not sure why Aarch64-linux-gnu is failing. It's using gcc but I was under the impression that had clang support. That's a separate thing altogether though.

[zanieb]

I think we use gcc when we cross-compile — #484 tracks switching to native runners so we can use clang and PGO.

[zanieb]

(there was some confusion about this in #484 (comment) so we'll see..)

[Fidget-Spinner]

LGTM, to my untrained eye at least.

[Fidget-Spinner]

If you want a quick and dirty test that it's doing something for performance. Try running alpha4 vs alpha5 on this short pystones benchmark script. I got a 25% speedup or so on my computer https://gist.github.com/Fidget-Spinner/e7bf204bf605680b0fc1540fe3777acf

[zanieb]

CI passed on 1f3cccd — rebasing onto main

[zanieb]

A quick bench of 2to3 on a not so quiet machine

a4.json
=======

Performance version: 1.11.0
Report on macOS-14.7.2-arm64-arm-64bit-Mach-O
Number of logical CPUs: 16
Start date: 2025-02-12 08:20:38.410341
End date: 2025-02-12 08:20:52.793913

a5.json
=======

Performance version: 1.11.0
Report on macOS-14.7.2-arm64-arm-64bit-Mach-O
Number of logical CPUs: 16
Start date: 2025-02-12 08:19:19.514312
End date: 2025-02-12 08:19:32.304519

### 2to3 ###
Mean +- std dev: 138 ms +- 5 ms -> 119 ms +- 2 ms: 1.15x faster
Significant (t=27.00)

And the pystones bench

❯ hyperfine "$(uv python find 3.14.0a4) ./pystones.py" "./python/install/bin/python ./pystones.py"
Benchmark 1: /Users/zb/.local/share/uv/python/cpython-3.14.0a4-macos-aarch64-none/bin/python3.14 ./pystones.py
  Time (mean ± σ):      73.0 ms ±   0.9 ms    [User: 69.9 ms, System: 2.4 ms]
  Range (min … max):    71.1 ms …  75.6 ms    40 runs
 
Benchmark 2: ./python/install/bin/python ./pystones.py
  Time (mean ± σ):      56.8 ms ±   1.0 ms    [User: 53.6 ms, System: 2.5 ms]
  Range (min … max):    55.5 ms …  60.8 ms    50 runs
 
Summary
  ./python/install/bin/python ./pystones.py ran
    1.28 ± 0.03 times faster than /Users/zb/.local/share/uv/python/cpython-3.14.0a4-macos-aarch64-none/bin/python3.14 ./pystones.py