[PATCH] Fold together repeated tests for divisibility by constants

[Richard Smith]

Ping.


On Wed, Aug 13, 2014 at 6:27 PM, Richard Smith <richard at metafoo.co.uk>
wrote:

> On Thu, Jul 31, 2014 at 4:58 PM, Joerg Sonnenberger <
> joerg at britannica.bec.de> wrote:
>
>> On Mon, Jul 21, 2014 at 06:55:05PM -0700, Richard Smith wrote:
>> > Index: include/llvm/ADT/APInt.h
>> > ===================================================================
>> > --- include/llvm/ADT/APInt.h  (revision 213404)
>> > +++ include/llvm/ADT/APInt.h  (working copy)
>> > @@ -1756,13 +1756,13 @@
>> >  /// \brief Returns the floor log base 2 of the specified APInt value.
>> >  inline unsigned logBase2(const APInt &APIVal) { return
>> APIVal.logBase2(); }
>> >
>> > -/// \brief Compute GCD of two APInt values.
>> > +/// \brief Compute GCD of two unsigned APInt values.
>> >  ///
>> >  /// This function returns the greatest common divisor of the two APInt
>> values
>> >  /// using Euclid's algorithm.
>> >  ///
>> >  /// \returns the greatest common divisor of Val1 and Val2
>> > -APInt GreatestCommonDivisor(const APInt &Val1, const APInt &Val2);
>> > +APInt GreatestCommonDivisor(APInt Val1, APInt Val2);
>>
>> Doesn't this create an unnecessary copy in many common cases?
>
>
> This is no worse than the previous algorithm, which began by making copies
> of both of its arguments, and is better in the case where the arguments are
> temporaries.
>
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