Re: [RFC] Fix for PR driver/47785

[Richard Biener <richard dot guenther at gmail dot com>]

On Tue, Jan 22, 2013 at 5:00 PM, Ramana Radhakrishnan <ramrad01@arm.com> wrote:
> Hi,
>
> I ran into PR driver/47785 when doing some testing with an option passed to
> the testsuite and I chose to fix this by putting out COLLECT_AS_OPTIONS as
> though these are options for the driver by prepending them with a "'-Wa",
> and suffixing them with a "'" character and additionally providing spaces as
> duly required. I've chosen a simple implementation.
>
> Tested in the past with x86_64-linux-gnu and arm-none-eabi cross tests (with
> an additional -Wa option passed to the default flags in a site.exp)
>
> Thoughts ?
>
> Ok for trunk now or should I stage this for 4.9 ?

I don't think this fix will work reliably - it's probably desirable
anyway for other uses
of -Wa,... but providing a symbol definition is something that needs
to be understood
by LTO at WPA time, otherwise we will get confusing / wrong symbol
resolutions and
eventually wrong code generated in the end.  Thus with the patch you get some
false sense of security I think (consider -fno-fat-lto-objects, you'd
get x UNDEFed,
and with -ffat-lto-objects you'd get a prevailing IRONLY def but the
symbol wasn't
in the LTO symbol table and we don't find a prevailing definition at
WPA time ...)

Thus, I think it at least has to wait ;)

Richard.

> regards,
> Ramana
>
>
> gcc/
>
> <DATE>  Ramana Radhakrishnan  <ramana.radhakrishnan@arm.com>
>
>     PR driver/47785
>         * gcc.c (set_collect_as_options): New.
>          (main): Call this.
>         * lto-wrapper.c (run_gcc): Handle COLLECT_AS_OPTIONS.
>
>
> testsuite/
>
> <DATE>  Ramana Radhakrishnan  <ramana.radhakrishnan@arm.com>
>
>         PR driver/47785
>         * gcc.dg/pr47785.c: New test.
>
>
>