[Bug tree-optimization/66002] paq8p benchmark 50% slower than clang on sandybridge

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66002

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
high up in the profile are functions train() and dot_product(), also
ContextMap::mix1 and Mixer::p.  But

void train(short *t, short *w, int n, int err) {
  n=(n+7)&-8;
  for (int i=0; i<n; ++i) {
    int wt=w[i]+((t[i]*err*2>>16)+1>>1);
    if (wt<-32768) wt=-32768;
    if (wt>32767) wt=32767;
    w[i]=wt;
  }
}

seems to be the hottest function.

t.c:4:5: note: not vectorized: relevant stmt not supported: prephitmp_61 = _53
<= 65535 ? pretmp_60 : -32768;
t.c:4:5: note: bad operation or unsupported loop bound.
t.c:1:6: note: vectorized 0 loops in function.

  <bb 5>:
  # i_33 = PHI <0(4), i_28(7)>
  _9 = (long unsigned int) i_33;
  _10 = _9 * 2;
  _12 = w_11(D) + _10;
  _13 = *_12;
  _14 = (int) _13;
  _16 = t_15(D) + _10;
  _17 = *_16;
  _18 = (int) _17;
  _20 = _18 * err_19(D);
  _21 = _20 * 2;
  _22 = _21 >> 16;
  _23 = _22 + 1;
  _24 = _23 >> 1;
  wt_25 = _14 + _24;
  pretmp_60 = (short int) wt_25;
  _31 = (unsigned int) wt_25;
  _53 = _31 + 32768;
  prephitmp_61 = _53 <= 65535 ? pretmp_60 : -32768;
  _32 = _53 <= 65535;
  _52 = wt_25 < -32768;
  _51 = _32 | _52;
  prephitmp_59 = _51 ? prephitmp_61 : 32767;
  *_12 = prephitmp_59;
  i_28 = i_33 + 1;
  if (n_7 > i_28)
    goto <bb 7>;
  else
    goto <bb 6>;

  <bb 7>:
  goto <bb 5>;