> I think your interpretation of "depends on" is reasonable, but it's not the
> way we've handled it for other extension dependencies. For the others we're
> treating "depends on" the way this code does, ie enabling the dependant
> extensions implicitly. IIRC that's how the RISC-V specs want it to be.
>
> That said, we do call it "implied" in the sources because that's really the
> right word for it. So we should probably add something to the docs that
> describes how/why things are this way, as I don't think it's the first time
> someone's been confused.
>
> Maybe just something like
>
> diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
> index 23d90db2925..429275d56df 100644
> --- a/gcc/doc/invoke.texi
> +++ b/gcc/doc/invoke.texi
> @@ -31037,6 +31037,10 @@ If both @option{-march} and @option{-mcpu=} are not
> specified, the default for
> this argument is system dependent, users who want a specific architecture
> extensions should specify one explicitly.
>
> +When the RISC-V specifications define an extension as depending on other
> +extensions, GCC will implicitly add the dependant extensions to the enabled
> +extension set if they weren't added explicitly.
> +
> @opindex mcpu
> @item -mcpu=@var{processor-string}
> Use architecture of and optimize the output for the given processor, specified
>
> would do it?
Makes sense to me. Thanks!
Andrea
