[Bug target/110625] [AArch64] Vect: SLP fails to vectorize a loop as the reduction_latency calculated by new costs is too large

["tnfchris at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110625

--- Comment #18 from Tamar Christina <tnfchris at gcc dot gnu.org> ---
Hi, here's the reduced case:

----
> cat analyse.i

double x264_weights_analyse___trans_tmp_1;
float x264_weights_analyse_ref_mean;
x264_weights_analyse() {
  x264_weights_analyse___trans_tmp_1 = floor(x264_weights_analyse_ref_mean);
}

----
> cat pixel.i

unsigned x264_pixel_satd_8x4___trans_tmp_1;
x264_pixel_satd_8x4_sum;
x264_pixel_satd_8x4() {
  for (int i; i; i++) {
    x264_pixel_satd_8x4___trans_tmp_1 = i;
    x264_pixel_satd_8x4_sum += x264_pixel_satd_8x4___trans_tmp_1;
  }
  return (unsigned)x264_pixel_satd_8x4_sum >> 1;
}

---

reproduce with:

gcc -c -o pixel.o pixel.i -mcpu=neoverse-v1 -flto=auto -Ofast -w
gcc -c -o analyse.o analyse.i -mcpu=neoverse-v1 -flto=auto -Ofast -w
gcc -flto=auto -Ofast pixel.o analyse.o -lm -o x264_r -r -w