[Bug tree-optimization/94801] New: Failure to optimize narrowed __builtin_clz

[gabravier at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94801

            Bug ID: 94801
           Summary: Failure to optimize narrowed __builtin_clz
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gabravier at gmail dot com
  Target Milestone: ---

int f(int a)
{
    return __builtin_clz(a) >> 5;
}

Can be optimized to `return 0;`. This transformation is done by LLVM, but not
by GCC.

Comparison here : https://godbolt.org/z/jhqQ2u