Author: Uri Blass
Date: 11:40:22 12/17/03
Go up one level in this thread
On December 17, 2003 at 14:25:02, Anthony Cozzie wrote:
>On December 17, 2003 at 14:22:22, Uri Blass wrote:
>
>>I find that a lot of functions in Craftyget as a parameter TREE* RESTRICT
>>
>>What is the meaning of the RESTRICT word?
>>
>>I looked for that word in Crafty and except cases when Crafty get that parameter
>>in functions
>>I could only find in chess.h the following lines that I also do not understand.
>>
>>#if defined (_MSC_VER) && (_MSC_VER >= 1300) && (!defined(_M_IX86) || (_MSC_VER
>>>= 1400))
>># define RESTRICT __restrict
>>#else
>># define RESTRICT
>>#endif
>>
>>
>>Uri
>
>restrict means an unaliased pointer. e.g.
>
>void vectoradd(double *a, double *b, double *c, int len)
>{
> for(int i = 0; i < len; i++)
> c[i] = b[i] + a[i];
>}
>
>the compiler doesn't know that a != b != c unless you use __restrict or specify
>it as a command line option.
>
>anthony
what is exactly the advantage of using Restrict?
Does it cause Crafty to be slightly faster or does it prevent errors of
overwriting(in your example changing a[i] when you change c[i] because the
compiler may believe that a=c inspite of the fact that you used different
varaibles)?
I see that crafty use a lot of pointers without restrict(for example
HashProbe is using int * beta and int * threat)
Why does it use Restrict only for the big struct of TREE.
Uri
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