Aldy Hernandez <[EMAIL PROTECTED]> writes:
> I've been converting the ppc options to use the .opt machinery, and
> am confused as to how to approach subtargets.
>
> What's the deal with these?
>
> I need options only for certain subtargets. For example, aix.h has
> some options that should not be available by other targets.
>
> I don't see anything relevant in options.texi, and I don't see any
> converted backend that has this problem.
>
> Should we just include the options for all subtargets, or should we
> add generic functionality (I volunteer if so).
Sorry for the slow answer. I see Zack has already replied, and I guess
you've long figured this out, but just for the record:
The idea is that you only put the options that apply to all targets
in MACHINE.opt. If a subtarget has extra options, they should go
in their own .opt file and config.gcc should add those files to
$extra_options.
As for where this documented: well, it's actually in the "Anatomy of
a Target Back End" section (sourcebuild.texi):
A back end for a target architecture in GCC has the following parts:
[...]
@item
An optional @[EMAIL PROTECTED] file in the @[EMAIL PROTECTED]
directory, containing a list of target-specific options. You can also
add other option files using the @code{extra_options} variable in
@file{config.gcc}. @xref{Options}.
...but as so often with gcc documentation, you can probably only find
it if you already know what it says.
Richard
