[Bug tree-optimization/127099] New: Wrong code with bitint and nested shifts

[ktkachov at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127099

            Bug ID: 127099
           Summary: Wrong code with bitint and nested shifts
           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 unsigned _BitInt(4) u4;

__attribute__ ((noipa))
unsigned int
f (unsigned int x)
{
  return (x << (u4) 15) << (u4) 15;
}

__attribute__ ((noipa))
unsigned int
reference (unsigned int x)
{
  return x << 30;
}

int
main (void)
{
  volatile unsigned int x = 1;
  if (f (x) != reference (x))
    __builtin_abort ();
  return 0;
}

aborts on aarch64 even at -O0, though passes with Clang