Re: [PATCH 1/2] Introduce prefetch-minimum stride option

[Luis Machado <luis.machado@linaro.org>]

Hi,

On 05/15/2018 06:37 AM, Kyrill Tkachov wrote:
> Hi Luis,
> 
> On 14/05/18 22:18, Luis Machado wrote:
>> Hi,
>>
>> Here's an updated version of the patch (now reverted) that addresses 
>> the previous bootstrap problem (signedness and long long/int conversion).
>>
>> I've checked that it bootstraps properly on both aarch64-linux and 
>> x86_64-linux and that tests look sane.
>>
>> James, would you please give this one a try to see if you can still 
>> reproduce PR85682? I couldn't reproduce it in multiple attempts.
>>
> 
> The patch doesn't hit the regressions in PR85682 from what I can see.
> I have a comment on the patch below.
> 

Great. Thanks for checking Kyrill.

> --- a/gcc/tree-ssa-loop-prefetch.c
> +++ b/gcc/tree-ssa-loop-prefetch.c
> @@ -992,6 +992,23 @@ prune_by_reuse (struct mem_ref_group *groups)
>   static bool
>   should_issue_prefetch_p (struct mem_ref *ref)
>   {
> +  /* Some processors may have a hardware prefetcher that may conflict with
> +     prefetch hints for a range of strides.  Make sure we don't issue
> +     prefetches for such cases if the stride is within this particular
> +     range.  */
> +  if (cst_and_fits_in_hwi (ref->group->step)
> +      && abs_hwi (int_cst_value (ref->group->step)) <
> +      (HOST_WIDE_INT) PREFETCH_MINIMUM_STRIDE)
> +    {
> 
> The '<' should go on the line below together with PREFETCH_MINIMUM_STRIDE.

I've fixed this locally now.