SLP Vectorizer Options trigger Assertion in cost computation on `s390x`

[dominik-steenken]

While running experiments with csmith, i ran into the following example (already reduced with cvise):

static int c[][10];
short d;
long *e;
long f;
int g, k;
char h, i;
static int j[3];
void l();
static int *m() {
  short *n = &d;
  d = 0;
  for (; d <= 2;)
    if (*n)
      ;
    else
      return j;
  return &g;
}
void p() { l(); }
void l() {
  int *q;
  h = 0;
  for (; h <= 6; h++) {
    int **r = &q;
    *e = 4073709551615;
    *r = m();
    k = 0;
    for (; k <= 6; k++) {
      i = 2;
      for (; i <= 6; i++)
        **r |= c[k][h] ^= f;
    }
  }
}

When compiling this with the options

  -O3 \
  -S \
  -w \
  -c \
  -o a.out \
  --target=s390x-ibm-linux \
  -march=z13 \
  -mllvm -slp-max-reg-size=256 \
  -mllvm -slp-vectorize-hor-store \
  -mllvm -slp-vectorize-non-power-of-2 \
  -mllvm -enable-tbaa=false \

The assertion (Idx + EltsPerVector) <= BaseVF && "SK_ExtractSubvector index out of range" fails in llvm::slpvectorizer::BoUpSLP::ShuffleCostEstimator::computeExtractCost. This does not seem to be an issue on X86.

repro.tar.gz