[Bug tree-optimization/57567] New: Missed optimsation : compare + or

[john@bass-software.com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57567

            Bug ID: 57567
           Summary: Missed optimsation : compare + or
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: john@bass-software.com

Using 4.9.0 20130608 (experimental) [trunk revision 199851], target
arm-unknown-eabi.

The following case produces suboptimal code:

unsigned
test (unsigned t)
{
  if (t != (unsigned)-1)
    t |= 3;
  return t;
}

Result:

    cmn    r0, #1
    orrne    r0, r0, #3

A simple:

    orr    r0, r0, #3

would be enough.