[Bug rtl-optimization/124020] Improve bitmanip recognition for riscv

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124020

--- Comment #3 from Jeffrey A. Law <law at gcc dot gnu.org> ---
Another example from 500.perlbench:

void set_opset_bits(char *bitmap, int cond, int bit)
{
        if (cond)
            *bitmap |= 1 << bit;
        *bitmap &= ~(1 << bit);
}