https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81904
--- Comment #4 from Hongtao.liu <crazylht at gmail dot com> ---
(In reply to Richard Biener from comment #2)
> __m128d h(__m128d x, __m128d y, __m128d z){
> __m128d tem = _mm_mul_pd (x,y);
> __m128d tem2 = tem + z;
> __m128d tem3 = tem - z;
> return __builtin_shuffle (tem2, tem3, (__m128i) {0, 3});
> }
>
> doesn't quite work (the combiner pattern for fmaddsub is missing). Tried
> {0, 2} as well.
>
> :
> .LFB5021:
> .cfi_startproc
> vmovapd %xmm0, %xmm3
> vfmsub132pd %xmm1, %xmm2, %xmm0
> vfmadd132pd %xmm1, %xmm2, %xmm3
> vshufpd $2, %xmm0, %xmm3, %xmm0
tem2_6 = .FMA (x_2(D), y_3(D), z_5(D));
# DEBUG tem2 => tem2_6
# DEBUG BEGIN_STMT
tem3_7 = .FMS (x_2(D), y_3(D), z_5(D));
# DEBUG tem3 => NULL
# DEBUG BEGIN_STMT
_8 = VEC_PERM_EXPR <tem2_6, tem3_7, { 0, 3 }>;
Can it be handled in match.pd? rewrite fmaddsub pattern into vec_merge fma fms
<addsub_cst> looks too complex.
Similar for VEC_ADDSUB + MUL -> VEC_FMADDSUB.
