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| author | Xinhang Xu <xuxinhang4567@126.com> | 2021-12-27 18:36:55 (GMT) |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2021-12-27 18:36:55 (GMT) |
| commit | 3581c7abbe15bad6ae08fc38887e5948f8f39e08 (patch) | |
| tree | 09951be8f8b78d6c22f66e3b1bab2d50bb2f9bbd /Objects/longobject.c | |
| parent | 360fedc2d2ce6ccb0dab554ef45fe83f7aea1862 (diff) | |
| download | cpython-3581c7abbe15bad6ae08fc38887e5948f8f39e08.zip cpython-3581c7abbe15bad6ae08fc38887e5948f8f39e08.tar.gz cpython-3581c7abbe15bad6ae08fc38887e5948f8f39e08.tar.bz2 | |
bpo-46055: Speed up binary shifting operators (GH-30044)
Co-authored-by: Mark Dickinson <dickinsm@gmail.com>
Diffstat (limited to 'Objects/longobject.c')
| -rw-r--r-- | Objects/longobject.c | 17 |
1 files changed, 16 insertions, 1 deletions
diff --git a/Objects/longobject.c b/Objects/longobject.c index ddb3def..09ae945 100644 --- a/Objects/longobject.c +++ b/Objects/longobject.c @@ -4493,6 +4493,15 @@ long_rshift1(PyLongObject *a, Py_ssize_t wordshift, digit remshift) Py_ssize_t newsize, hishift, i, j; twodigits accum; + if (IS_MEDIUM_VALUE(a)) { + stwodigits m, x; + digit shift; + m = medium_value(a); + shift = wordshift == 0 ? remshift : PyLong_SHIFT; + x = m < 0 ? ~(~m >> shift) : m >> shift; + return _PyLong_FromSTwoDigits(x); + } + if (Py_SIZE(a) < 0) { /* Right shifting negative numbers is harder */ PyLongObject *a1, *a2; @@ -4566,11 +4575,17 @@ _PyLong_Rshift(PyObject *a, size_t shiftby) static PyObject * long_lshift1(PyLongObject *a, Py_ssize_t wordshift, digit remshift) { - /* This version due to Tim Peters */ PyLongObject *z = NULL; Py_ssize_t oldsize, newsize, i, j; twodigits accum; + if (wordshift == 0 && IS_MEDIUM_VALUE(a)) { + stwodigits m = medium_value(a); + // bypass undefined shift operator behavior + stwodigits x = m < 0 ? -(-m << remshift) : m << remshift; + return _PyLong_FromSTwoDigits(x); + } + oldsize = Py_ABS(Py_SIZE(a)); newsize = oldsize + wordshift; if (remshift) |