Re: Using .opt files for target options

[Zack Weinberg <zack at codesourcery dot com>]

Richard Sandiford <rsandifo@redhat.com> writes:

> The aim of this patch is to extend the front- and middle-end
> options-handling machinery so that it can be used for target
> options as well.  In other words, it lets you specify target
> options using target-specific .opt files.

I'm very glad to see this happen.  Your code generally looks sound,
and Neil has already approved it, but there's a detail I'd like to
bring up.  You've currently got a special case in the flag_var logic
to handle target_flags_explicit.  That's fine as far as it goes, but
it doesn't help with anything that's currently being done with
TARGET_OPTIONS, nor with things that are moved out of target_flags
after conversion to an .opt file.  Also, it still requires special
handling in OVERRIDE_OPTIONS.

What target_flags_explicit does (assuming OVERRIDE_OPTIONS handles it)
is allow the user to not worry about the order of general and specific
-m options.  Really, what we want is to impose a partial ordering on
the -m options, so that general ones (-march= e.g.) are processed
before specific ones (-mgp64 e.g.)  I wonder if you have any ideas how
to handle that...?

zw