Re: PATCH: PR bootstrap/63784: [5 Regression] profiledbootstrap failure with bootstrap-lto

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

On Mon, Nov 10, 2014 at 2:43 PM, Jakub Jelinek <jakub@redhat.com> wrote:
> On Mon, Nov 10, 2014 at 05:32:32AM -0800, H.J. Lu wrote:
>> On Mon, Nov 10, 2014 at 4:05 AM, Jakub Jelinek <jakub@redhat.com> wrote:
>> > On Mon, Nov 10, 2014 at 12:50:44PM +0100, Richard Biener wrote:
>> >> On Sun, Nov 9, 2014 at 5:46 PM, H.J. Lu <hongjiu.lu@intel.com> wrote:
>> >> > Hi,
>> >> >
>> >> > r216964 disables bootstrap for libcc1 which exposed 2 things:
>> >> >
>> >> > 1. libcc1 isn't compiled with LTO even when GCC is configured with
>> >> > "--with-build-config=bootstrap-lto".  It may be intentional since
>> >> > libcc1 is disabled for bootstrap.
>> >> > 2. -fPIC isn't used to created libcc1.so, which is OK if libcc1 is
>> >> > compiled with LTO which remembers PIC option.
>> >>
>> >> Why is this any special to LTO?  If it is then it looks like a LTO
>> >> (driver) issue to me?  Why are we linking the pic libibterty into
>> >> a non-pic libcc1?
>> >
>> > I admit I haven't tried LTO bootstrap, but from normal bootstrap logs,
>> > libcc1 is built normally using libtool using -fPIC only, and linked into
>> > libcc1.so.0.0.0 and libcc1plugin.so.0.0.0, and of course against the
>> > pic/libiberty.a, because we need PIC code in the shared libraries.
>> > So, I don't understand the change at all.
>> >
>> >         Jakub
>>
>> This is the command line to build libcc1.la:
>
> Sure, but there was -fPIC used to compile all the *.o files that are being
> linked into libcc1.so, so LTO should know that.

And it does.  If not please file a bug with a smaller testcase than libcc1
and libiberty.

Richard.

>         Jakub