[Bug tree-optimization/96930] New: Failure to optimize out 64-bit arithmetic when it can't happen with division transformed into right shift

[gabravier at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96930

            Bug ID: 96930
           Summary: Failure to optimize out 64-bit arithmetic when it
                    can't happen with division transformed into right
                    shift
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gabravier at gmail dot com
  Target Milestone: ---

unsigned f(unsigned a, unsigned b)
{
    return a / (unsigned long long)(1U << b);
}

This can be optimized to `return a >> b;`. This transformation is done by LLVM,
but not by GCC.