Martin Sebor <mse...@gmail.com> writes:
> Richard,
>
> If you agree, I'd like to update the conversion section of
> the poly_int manual to make the conversion to make it clearer
> that the to_constant() function can be used even with class
> types like offset_int besides scalars.
>
> Also, when testing this I also tried converting poly64_int
> into wide_int but that doesn't work. Is there a way to do
> that?
Not in one go, because you have to specify the intended precision
of the wide_int when constructing it from something like HOST_WIDE_INT.
(That's deliberate.)
>
> Thanks
> Martin
>
> gcc/ChangeLog:
>
> * doc/poly-int.texi (is_constant): Expand.
>
> Index: gcc/doc/poly-int.texi
> ===================================================================
> --- gcc/doc/poly-int.texi (revision 258004)
> +++ gcc/doc/poly-int.texi (working copy)
> @@ -836,9 +836,24 @@ Return true if @code{poly_int} @var{value} is a co
>
> @item @var{value}.is_constant (&@var{c1})
> Return true if @code{poly_int} @var{value} is a compile-time constant,
> -storing it in @var{c1} if so. @var{c1} must be able to hold all
> -constant values of @var{value} without loss of precision.
> +storing it in @var{c1} if so. @var{c1} may be a scalar or a wide int
> +class type capable of holding all constant values of @var{value} without
Not sure about "a scalar or a wide int", since that implies that wide ints
aren't scalar. Even more pedantic, sorry, but c1 is an object rather than
a type.
At a higher level, I'm a bit nervous about singling this out as a special
case, since all the poly_int stuff allows HOST_WIDE_INT, offset_int and
wide_int to be combined in the (hopefully) natural way. E.g. you can
add offset_ints to poly_int64s, assign HOST_WIDE_INTs to poly_offset_ints,
and so on.
But if we do keep it like this, how about:
@var{c1} must be some form of integer object that can hold all constant
values of @var{value} without loss of precision; it can be either a normal
C++ integer or a wide-int class like @code{offset_int}.
?
> +loss of precision. The following example illustrates using the function
> +to convert a @code{poly64_int} to @code{HOST_WIDE_INT} and to
> +@code{offset_int}.
> +@smallexample
> +void f (poly64_int pi)
poly_int64
> +@{
> + HOST_WIDE_INT hwi;
> + if (pi.is_constant (&hwi))
> + ; // Use hwi...
> + offset_int off;
> + if (pi.is_constant (&off))
> + ; // Use off...
> +@}
> +@end smallexample
>
> +
> @item @var{value}.to_constant ()
> Assert that @var{value} is a compile-time constant and return its value.
> When using this function, please add a comment explaining why the
No need for the extra blank line.
Thanks,
Richard
