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Title: bpo-47009: Let PRECALL_NO_KW_LIST_APPEND do its own POP_TOP by sweeneyde · Pull Request #32239 · python/cpython · GitHub

Open Graph Title: bpo-47009: Let PRECALL_NO_KW_LIST_APPEND do its own POP_TOP by sweeneyde · Pull Request #32239 · python/cpython

X Title: bpo-47009: Let PRECALL_NO_KW_LIST_APPEND do its own POP_TOP by sweeneyde · Pull Request #32239 · python/cpython

Description: Most code won't do y = L.append(x) or whatnot, so PRECALL_NO_KW_LIST_APPEND is almost always followed by POP_TOP. We can verify at specialization time. This saves a Py_INCREF(Py_None), a SET_TOP(Py_None), and POP_TOP's Py_DECREF(POP()); DISPATCH();. Some microbenchmarks: from pyperf import Runner, perf_counter def bench_append(loops, length): src = list(map(float, range(length))) arr = [] t0 = perf_counter() for i in range(loops): arr.clear() for x in src: arr.append(x) return perf_counter() - t0 def bench_append_less_gc(loops, length): src = list(map(float, range(length))) out = [None] * loops t0 = perf_counter() for i in range(loops): arr = [] for x in src: arr.append(x) out[i] = arr return perf_counter() - t0 runner = Runner() for n in [100, 1_000, 10_000, 100_000]: runner.bench_time_func(f"append {n}", bench_append, n, inner_loops=n) runner.bench_time_func(f"append-less-gc {n}", bench_append_less_gc, n, inner_loops=n) From GCC, --enable-optimizations, --with-lto: - append 100000: 14.9 ns +- 0.3 ns -> 13.3 ns +- 0.4 ns: 1.12x faster - append 10000: 15.1 ns +- 0.3 ns -> 13.6 ns +- 0.5 ns: 1.11x faster - append-less-gc 100000: 16.4 ns +- 0.5 ns -> 14.9 ns +- 0.4 ns: 1.10x faster - append 1000: 15.6 ns +- 0.3 ns -> 14.2 ns +- 0.3 ns: 1.09x faster - append 100: 18.9 ns +- 0.6 ns -> 17.3 ns +- 0.6 ns: 1.09x faster - append-less-gc 100: 27.4 ns +- 1.1 ns -> 25.2 ns +- 1.2 ns: 1.09x faster - append-less-gc 10000: 19.2 ns +- 0.3 ns -> 17.8 ns +- 0.2 ns: 1.08x faster - append-less-gc 1000: 22.0 ns +- 0.6 ns -> 20.8 ns +- 0.3 ns: 1.06x faster Geometric mean: 1.09x faster https://bugs.python.org/issue47009

Open Graph Description: Most code won't do y = L.append(x) or whatnot, so PRECALL_NO_KW_LIST_APPEND is almost always followed by POP_TOP. We can verify at specialization time. This saves a Py_INCREF(Py_None), a SET_TO...

X Description: Most code won't do y = L.append(x) or whatnot, so PRECALL_NO_KW_LIST_APPEND is almost always followed by POP_TOP. We can verify at specialization time. This saves a Py_INCREF(Py_None), a SE...

Opengraph URL: https://github.com/python/cpython/pull/32239

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