RE: [PATCH] target/ppc: Fix 64-bit decrementer

[Luis Fernando Fujita Pires]

> >      bool negative;
> >
> >      /* Truncate value to decr_width and sign extend for simplicity */
> > -    value &= ((1ULL << nr_bits) - 1);
> > +    value &= MAKE_64BIT_MASK(0, nr_bits);
> 
> What about:
> 
>        value = extract64(value, 0, nr_bits);
>        if (value != sextract64(value, 0, nr_bits)) { ...

Or:
    value = extract64(value, 0, nr_bits);
    value = ((target_long)value << (64 - nr_bits)) >> (64 - nr_bits);

Also avoiding the problem with an invalid 64-bit shift with:
> >          value |= (0xFFFFFFFFULL << nr_bits);

--
Luis Pires
Instituto de Pesquisas ELDORADO
Aviso Legal - Disclaimer <https://www.eldorado.org.br/disclaimer.html>