[Bug tree-optimization/118456] New: [15 Regression] wrong code due to ifcombine since r15-6773

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118456

            Bug ID: 118456
           Summary: [15 Regression] wrong code due to ifcombine since
                    r15-6773
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jakub at gcc dot gnu.org
  Target Milestone: ---

struct S { unsigned long long o; unsigned short a, b; } s;

__attribute__((noipa)) int
foo (void)
{
  return ((unsigned char) s.a) >> 3 == 17 && ((signed char) s.b) >> 2 == -27;
}

int
main ()
{
  s.a = 17 << 3;
  s.b = -27 << 2;
  if (foo () != 1)
    __builtin_abort ();
}

is miscompiled at -O2 starting with
r15-6773-gc96a6c2c264776d8138c6b303d005e74f047cfa0
r15-6865 doesn't fix that.