Author: Armin Rigo <[email protected]>
Branch: py3.5
Changeset: r94819:06970e67d972
Date: 2018-07-06 19:26 +0200
http://bitbucket.org/pypy/pypy/changeset/06970e67d972/
Log: Cache the pow() result for small values up to 1000. This is enough
to recover the original pypy2 speed on #2854.
diff --git a/lib-python/3/fractions.py b/lib-python/3/fractions.py
--- a/lib-python/3/fractions.py
+++ b/lib-python/3/fractions.py
@@ -566,7 +566,7 @@
else:
return Fraction(round(self / shift) * shift)
- def __hash__(self):
+ def __hash__(self, CACHE=[-1] * 1001):
"""hash(self)"""
# XXX since this method is expensive, consider caching the result
@@ -580,12 +580,23 @@
# dinv is the inverse of self._denominator modulo the prime
# _PyHASH_MODULUS, or 0 if self._denominator is divisible by
# _PyHASH_MODULUS.
- dinv = pow(self._denominator, _PyHASH_MODULUS - 2, _PyHASH_MODULUS)
+
+ # PyPy3: added caching of pow() results for denominators up to 1000
+ denom = self._denominator
+ assert denom >= 0
+ if denom < len(CACHE):
+ dinv = CACHE[denom]
+ if dinv == -1:
+ dinv = pow(denom, _PyHASH_MODULUS - 2, _PyHASH_MODULUS)
+ CACHE[denom] = dinv
+ else:
+ dinv = pow(denom, _PyHASH_MODULUS - 2, _PyHASH_MODULUS)
+
if not dinv:
hash_ = _PyHASH_INF
else:
hash_ = abs(self._numerator) * dinv % _PyHASH_MODULUS
- result = hash_ if self >= 0 else -hash_
+ result = hash_ if self._numerator >= 0 else -hash_
return -2 if result == -1 else result
def __eq__(a, b):
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