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Re: generic retuning part 1 - x86-tune-costs update
On November 30, 2017 7:14:12 PM GMT+01:00, Jan Hubicka <hubicka@ucw.cz> wrote:
>>
>> I have benchmarked this quite thoroughly while switching the defaults
>for Core
>> and Zen. Disabling alignment is pretty much consistent for
>specfp/int for
>> 2000,2006 and 2017 (last is Zen only) and quite consistent one. I
>will analyze
>> fma3d. It did not show with the alignment change alone, so it may be
>related
>> to other costs or just bad luck.
>
>I have opened https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83232 for
>that.
>The problem is that SLP gives up vectorization when it sees vectorized
>used
>in the same basic block. Preivously there was alignment prologue while
>now
>we fully unroll the loop. Missed SLP introduce memory mismatch stall.
>
>I am bit lost on why SLP gives up though.
I will have a look - it shouldn't give up so easily. Maybe it's a costing issue.
Richard.
>Honza