[fpc-devel] The "magic div" algorithm

[J. Gareth Moreton]

The problem is that Free Pascal automatically scales up inputs to the 
word size, usually 32-bits.  If you do a node dump of a division node, 
you'll see that the input will often have a typecast node cast upon it.  
It is possible to remove it, but it would have to be done at a different 
compiler stage.  I might see if it's possible to implement this at a 
later stage, since I've done just that for my latest merge request for 
"(x mod n) = 0".

Gareth aka. Kit

On 15/09/2021 18:36, Marģers . via fpc-devel wrote:
> Hi,
> Thank you for implementation.
>
> Is that true, that you can not detect word and byte size on division 
> by constant? Squeezing in 32 bit register it would make byte-code 
> shorter, not necessarily faster.
> ----- Reply to message -----
> *Subject: *Re: [fpc-devel] The "magic div" algorithm
> *From: * J. Gareth Moreton via fpc-devel 
> <fpc-devel at lists.freepascal.org> <mailto:fpc-devel at lists.freepascal.org>
> *To: * <fpc-devel at lists.freepascal.org> 
> <mailto:fpc-devel at lists.freepascal.org>
>
>     This one is for Marģers especially:
>
>     https://gitlab.com/freepascal.org/fpc/source/-/issues/39355
>     <https://gitlab.com/freepascal.org/fpc/source/-/issues/39355>
>
>     Gareth aka. Kit
>
>
>
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