[Bug tree-optimization/96226] New: Failure to optimize shift+not to rotate

[gabravier at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96226

            Bug ID: 96226
           Summary: Failure to optimize shift+not to rotate
           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: ---

int32_t f(int32_t x)
{
    return ~(1 << (x & 0x1F));
}

This can be transformed to doing a rotate of -2 and x. This transformation is
done by LLVM, but not by GCC.

PS: GCC seems capable of doing this optimization, but only if `x & 0x1F` is
replaced with `x`, which either means that GCC is underoptimizing this or that
LLVM is somehow wrong.