gh-100239: specialize bytes binary operations

[Wulian233]

The following was generated by Codex:

• bytes[3]: 20,000,000 iterations
• 7 repeats
• PYTHON_UOPS_OPTIMIZE=0
• compared normal specialization vs PYTHON_SPECIALIZATION_OFF=1

Results:

Benchmark	Specialized median	Unspecialized median	Speedup
bytes[3]	0.513025s	0.701673s	~26.9% faster

Details

import statistics
import time

N = 20_000_000
REPEAT = 7


def bench_bytes_index():
    b = b"foobar"
    x = 0
    for _ in range(N):
        x = b[3]
    return x


# Warm up for specialization.
for _ in range(5):
    bench_bytes_index()

samples = []
for _ in range(REPEAT):
    t0 = time.perf_counter()
    result = bench_bytes_index()
    samples.append(time.perf_counter() - t0)

print("result", result)
print("samples", " ".join(f"{s:.6f}" for s in samples))
print("median", f"{statistics.median(samples):.6f}")

• Issue: Specialize long tail of binary operations using a table. #100239

[eendebakpt]

The implementation here is seems copied from bytes_subscript (in byteobject.c) and still has a large overlap. Can you refactor the bytes_subscript into multiple methods so that the method here only becomes a very thin wrapper?

[corona10]

I am not sure we actually need this specialization. Is there any metrics that that this operation is executed frequently in performance benchmark.
We can add tons of specialization it we want, but IIUC, we just pick few of them.

[eendebakpt]

I am not sure we actually need this specialization. Is there any metrics that that this operation is executed frequently in performance benchmark. We can add tons of specialization it we want, but IIUC, we just pick few of them.

I agree we should limit the number of specializations. The bytes indexing seems worthwhile atm, the bytes slicing not so much.

Another option: reconsider an extension mechanism. It was implemented once and reverted (because of a python release date and some technical worries): #133395. If we can get similar performance improvements with the extension mechanism, when we can leave which ops to specialize to the user and outside cpython.

[read-the-docs-community]

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