Re: [PATCH] tree-optimization/113552 - fix num_call accounting in simd clone vectorization

[Jakub Jelinek <jakub@redhat.com>]

On Tue, Jan 23, 2024 at 12:56:52PM +0100, Richard Biener wrote:
> The following avoids using exact_log2 on the number of SIMD clone calls
> to be emitted when vectorizing calls since that can easily be not
> a power of two in which case it will return -1.  For different simd
> clones the number of calls will differ by a multiply with a power of two
> only so using floor_log2 is good enough here.
> 
> Bootstrap and regtest running on x86_64-unknown-linux-gnu.
> 
> 	PR tree-optimization/113552
> 	* tree-vect-stmts.cc (vectorizable_simd_clone_call): Use
> 	floor_log2 instead of exact_log2 on the number of calls.

Is there any target which supports non-power-of-two simdlen?
If not, perhaps we should add !pow2p_hwi (num_calls) to the continue;
condition a few lines earlier?

> diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc
> index 09749ae3817..1dbe1115da4 100644
> --- a/gcc/tree-vect-stmts.cc
> +++ b/gcc/tree-vect-stmts.cc
> @@ -4071,7 +4071,7 @@ vectorizable_simd_clone_call (vec_info *vinfo, stmt_vec_info stmt_info,
>  	    || (nargs != simd_nargs))
>  	  continue;
>  	if (num_calls != 1)
> -	  this_badness += exact_log2 (num_calls) * 4096;
> +	  this_badness += floor_log2 (num_calls) * 4096;
>  	if (n->simdclone->inbranch)
>  	  this_badness += 8192;
>  	int target_badness = targetm.simd_clone.usable (n);
> -- 
> 2.35.3

	Jakub