[Bug tree-optimization/126475] New: [13/14/15/16/17 Regression] x * { 0.0f, 1.0f, ... } must not become x & mask when NaNs/Infs are honoured

"ktkachov at gcc dot gnu.org via Gcc-bugs" <[email protected]>
Newsgroups gmane.comp.gcc.bugs
Message-ID <[email protected]/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126475

            Bug ID: 126475
           Summary: [13/14/15/16/17 Regression] x * { 0.0f, 1.0f, ... }
                    must not become x & mask when NaNs/Infs are honoured
           Product: gcc
           Version: 17.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ktkachov at gcc dot gnu.org
  Target Milestone: ---

typedef float v4sf __attribute__((vector_size (16)));

__attribute__((noipa))
static v4sf f (v4sf x)
{
  return x * (v4sf) { 0.0f, 1.0f, 0.0f, 1.0f };
}

__attribute__((noipa))
static v4sf mk (float a, float b, float c, float d)
{
  v4sf r = { a, b, c, d };
  return r;
}

int main (void)
{
  v4sf x = mk (__builtin_inff (), 1.0f, __builtin_nanf (""), 3.0f);
  v4sf r = f (x);

  __builtin_printf ("r = %f %f %f %f\n", (double) r[0], (double) r[1],
                    (double) r[2], (double) r[3]);
  __builtin_printf ("isnan(r[0]) = %d  isnan(r[2]) = %d\n",
                    __builtin_isnan (r[0]), __builtin_isnan (r[2]));

  if (r[1] != 1.0f || r[3] != 3.0f)
    __builtin_abort ();
  /* +Inf * 0.0f and NaN * 0.0f are both NaN in IEEE-754.  */
  if (!__builtin_isnan (r[0]) || !__builtin_isnan (r[2]))
    __builtin_abort ();
  return 0;
}

aborts at -O2 -fno-signed-zeros on aarch64. GCC 8 seems to work fine, so
marking as regression.
lmpx.com only provides a reader for public news (NNTP) servers. It is not affiliated with the servers or forums shown here and is not responsible for the content of articles, which is written by their respective authors.