[testsuite] don't use lto plugin if it doesn't work

[Richard Guenther]

On Thu, Jun 28, 2012 at 1:39 PM, Alexandre Oliva <aoliva@redhat.com> wrote:
> On Jun 28, 2012, Jakub Jelinek <jakub@redhat.com> wrote:
>
>> On Thu, Jun 28, 2012 at 04:16:55AM -0300, Alexandre Oliva wrote:
>>> I'd very be surprised if I asked for an i686 native build to package and
>>> install elsewhere, and didn't get a plugin just because the build-time
>>> linker wouldn't have been able to run the plugin.
>
>> Not disable plugin support altogether, but disable assuming the linker
>> supports the plugin.
>
> That still doesn't sound right to me: why should the compiler refrain
> from using a perfectly functional linker plugin on the machine where
> it's installed (not where it's built)?
>
> Also, this scenario of silently deciding whether or not to use the
> linker plugin could bring us to different test results for the same
> command lines.  I don't like that.

I don't like that we derive the default setting this way either.  In the end
I would like us to arrive at the point that LTO does not work at all without
a linker plugin.

Richard.

> --
> Alexandre Oliva, freedom fighter    http://FSFLA.org/~lxoliva/
> You must be the change you wish to see in the world. -- Gandhi
> Be Free! -- http://FSFLA.org/   FSF Latin America board member
> Free Software Evangelist      Red Hat Brazil Compiler Engineer