This is the mail archive of the gcc-patches@gcc.gnu.org mailing list for the GCC project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: [PATCH i386 4/8] [AVX512] [1/n] Add substed patterns.


Hello Richard,
Thanks for remarks, they all seems reasonable.

One question

On 21 Oct 16:01, Richard Henderson wrote:
> > +(define_insn "avx512f_moves<mode>_mask"
> > +  [(set (match_operand:VF_128 0 "register_operand" "=v")
> > +	(vec_merge:VF_128
> > +	  (vec_merge:VF_128
> > +	    (match_operand:VF_128 2 "register_operand" "v")
> > +	    (match_operand:VF_128 3 "vector_move_operand" "0C")
> > +	    (match_operand:<avx512fmaskmode> 4 "register_operand" "k"))
> > +	  (match_operand:VF_128 1 "register_operand" "v")
> > +	  (const_int 1)))]
> > +  "TARGET_AVX512F"
> > +  "vmov<ssescalarmodesuffix>\t{%2, %1, %0%{%4%}%N3|%0%{%4%}%N3, %1, %2}"
> > +  [(set_attr "type" "ssemov")
> > +   (set_attr "prefix" "evex")
> > +   (set_attr "mode" "<sseinsnmode>")])
> 
> Nested vec_merge?  That seems... odd to say the least.
> How in the world does this get matched?

This is generic approach for all scalar `masked' instructions.

Reason is that we must save higher bits of vector (outer vec_merge)
and apply single-bit mask (inner vec_merge).


We may do it with unspecs though... But is it really better?

What do you think?

--
Thanks, K


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]