fma speedup by avoiding to create a Context. Thanks Mark Dickinson.
diff --git a/Lib/decimal.py b/Lib/decimal.py
index 0ce9a34..ee65b12 100644
--- a/Lib/decimal.py
+++ b/Lib/decimal.py
@@ -1636,24 +1636,39 @@
"""
other = _convert_other(other, raiseit=True)
+
+ # compute product; raise InvalidOperation if either operand is
+ # a signaling NaN or if the product is zero times infinity.
+ if self._is_special or other._is_special:
+ if context is None:
+ context = getcontext()
+ if self._exp == 'N':
+ return context._raise_error(InvalidOperation, 'sNaN',
+ 1, self)
+ if other._exp == 'N':
+ return context._raise_error(InvalidOperation, 'sNaN',
+ 1, other)
+ if self._exp == 'n':
+ product = self
+ elif other._exp == 'n':
+ product = other
+ elif self._exp == 'F':
+ if not other:
+ return context._raise_error(InvalidOperation,
+ 'INF * 0 in fma')
+ product = Infsign[self._sign ^ other._sign]
+ elif other._exp == 'F':
+ if not self:
+ return context._raise_error(InvalidOperation,
+ '0 * INF in fma')
+ product = Infsign[self._sign ^ other._sign]
+ else:
+ product = _dec_from_triple(self._sign ^ other._sign,
+ str(int(self._int) * int(other._int)),
+ self._exp + other._exp)
+
third = _convert_other(third, raiseit=True)
-
- if context is None:
- context = getcontext()
-
- # do self*other in fresh context with no traps and no rounding
- mul_context = Context(traps=[], flags=[],
- _rounding_decision=NEVER_ROUND)
- product = self.__mul__(other, mul_context)
-
- if mul_context.flags[InvalidOperation]:
- # reraise in current context
- return context._raise_error(InvalidOperation,
- 'invalid multiplication in fma',
- 1, product)
-
- ans = product.__add__(third, context)
- return ans
+ return product.__add__(third, context)
def _power_modulo(self, other, modulo, context=None):
"""Three argument version of __pow__"""