[Bug tree-optimization/121347] New: wrong code at -O1 and above on x86_64-linux-gnu

[zhendong.su at inf dot ethz.ch via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121347

            Bug ID: 121347
           Summary: wrong code at -O1 and above on x86_64-linux-gnu
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zhendong.su at inf dot ethz.ch
  Target Milestone: ---

Compiler Explorer: https://godbolt.org/z/z7bxE57z5

Note:
- it is a regression from 7.* and affects 8.1 and later
- -fno-tree-slsr makes it disappear

[534] % gcctk -v
Using built-in specs.
COLLECT_GCC=gcctk
COLLECT_LTO_WRAPPER=/local/home/suz/software/local/gcc-trunk/bin/../libexec/gcc/x86_64-pc-linux-gnu/16.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-trunk/configure --disable-bootstrap
--enable-checking=yes --prefix=/local/suz-local/software/local/gcc-trunk
--enable-sanitizers --enable-languages=c,c++ --disable-werror --enable-multilib
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 16.0.0 20250801 (experimental) (GCC) 
[535] % 
[535] % gcctk -O3 small.c 
[536] % ./a.out
Aborted
[537] % 
[537] % cat small.c 
int a[] = {
  0,          4,          8,          4,          7,          1886057615,
  3915621685, 2657392035, 4,          2044508324, 0,          4,
  162941995,  1,          7,          2428444049, 498536548,  1789927666,
  4089016648, 4,          50548861,   1843258603, 107580753,  9,
  0,          2,          2,          6,          7,          1661365465,
  5,          7,          997073096,  6,          2,          2724688242,
  1006888145, 607687,     101629,     3,          901097722,  9000684,
  3686517206, 8065728,    853044451,  1,          705015759,  5,
  0,          6,          4,          104598,     565507253,  1,
  5,          3099436303, 4,          4,          30930,      70347812,
  7,          5,          5,          3060149565, 2,          31158534,
  2563907772, 4023717930, 907459465,  5,          3,          904427059,
  2013776290, 6,          2517215374, 0,          3,          141376813,
  9,          3865271297, 802195444,  6,          2238001368, 4066508878,
  70925,      453092731,  5,          4111451223, 706088902,  4,
  2344532202, 4240017532, 1658658271, 366619977,  2362670323, 224994405,
  303535960,  6,          7007092,    9037538,    70817,      1,
  3,          4079995,    6,          879679996,  909243462,  6,
  1141124467, 7,          1,          3708648649, 8,          6,
  3188396048, 4,          1466479909, 5,          10523913,   5,
  1591671054, 702138776,  0,          2,          504918807,  3,
  3082640443, 9,          4,          6,          62317068,   10842,
  5,          1,          70997,      3,          0,          2489596804,
  0,          2053790376, 5,          3,          3,          2097651377,
  4027552580, 2265490386, 503444072,  1762050814, 5,          5,
  5,          1852507879, 6,          2312317920, 6,          2,
  708143,     5,          3,          7,          604390888,  8,
  2,          340076626,  5,          2797360999, 1068828381, 9,
  0,          2936675148, 906185462,  1090812512, 3,          2825379669,
  829329135,  1181335161, 4,          60834842,   8085408,    6,
  3423369109, 8078467,    570562233,  1426400815, 3317316542, 608,
  4,          6,          1,          5,          3,          1,
  607071920,  0,          2,          40735498,   5,          1,
  3087877,    83908371,   2512341634, 803740692,  2075208622, 2,
  3,          90285,      2094854071, 1,          2029012,    4057260610,
  1759359992, 0,          1,          5,          1873836001, 7,
  2282248934, 200368,     1711684554, 6,          405801727,  5,
  1634467795, 1,          2685067896, 608007406,  1308918612, 956543938,
  2808555105, 3,          1,          1047427035, 8,          703836,
  1088359270, 936918000,  9,          3736837829, 202900863,  817233897,
  3183342108, 0,          2,          0,          207493,     3,
  1423857449, 1,          3009837614, 3294710456, 6,          711928724,
  3020668471, 5,          1510334235, 755167117};
int d, e, g;
int h(int i, char j) { return (i >> 8 & 16777215) ^ a[(i ^ j) & 255]; }
int fn2(int i, int j[]) {
  int k;
  unsigned b = 4294967295;
  for (int f = 0; f < i; ++f) {
    int c;
    k = b >> 8 ^ a[(b ^ j[f]) & 255];
    c = k;
    c = h(c, j[f] >> 8);
    c = h(c, j[f] >> 6);
    c = h(c, j[f] >> 24);
    b = c;
  }
  b = (b ^ 4294967295) % 2147483647;
  return b;
}
int r(int i, int j, int s, int t, int u, int v, int w) {
  int l;
  s = -v - s - 1;
  if (j) {
    j = -s - t - 1;
    goto n;
  }
  while (8 * j + 501 * v > 0) {
  n:
    v = -i - s - 1;
  }
  l = -i - t - 1;
  return fn2(8, (int[]){i, j, s, t, u, v, l, w});
}
static int y(int i, int j, int s, int t, int u) {
  int l;
  d = -999 - u;
  do {
    i = (r(-1, -1, -1, -1, -1, -1, -1) - 1946213370) * j +
      (r(1, 4, -2, 0, 1, 1, 1) - 1215528698) * i - 9;
    l = -99;
    if ((r(-1, -1, -1, -1, -1, -1, -1) - 1946213372) * j +
        (r(1, 3, -2, 0, -1, 0, -1) - 1683379045) * s)
      s = 83380045;
    j = -d;
  } while ((r(1, 4, -2, 0, 1, 1, 1) - 1215527698) * j +
           (r(-1, 1, -1, -1, -1, -1, -1) - 1946213370) * d +
           (r(1, 4, -2, 0, 1, 1, 1) - 1215527698) * s +
           (r(-1, 1, -1, -1, -1, -1, -1) - 1946213370) * u +
           (r(1, 1, 1, 1, 1, -1, 1) - 1946214370) > 0);
  return fn2(8, (int[]){i, j, 1, t, d, u, l, e});
}
int main() {
  if (y(-2147483, -2147483647, -1, 5, -2147483647) - 3 > 0)
    __builtin_abort();
  return 0;
}