[i386] Scalar DImode instructions on XMM registers

Jakub Jelinek jakub@redhat.com
Thu May 21 20:28:00 GMT 2015

On Thu, May 21, 2015 at 02:23:47PM -0600, Jeff Law wrote:
> On 05/21/2015 01:08 PM, Vladimir Makarov wrote:
> >On 05/21/2015 05:54 AM, Ilya Enkovich wrote:
> >>>Thanks.  For me it looks like an inheritance bug.  It is really hard
> >>>>to fix the bug w/o the source code.  Could you send me your patch in
> >>>>order I can debug RA with it to investigate more.
> >>>>
> >>Sure! Here is a patch and a testcase.  I applied patch to r222125.
> >>Cmd to reproduce:
> >>
> >>gcc -m32 -msse4.2 -O2 pr65105.c -S -march=slm -fPIE
> >The problem is in sharing a subreg in different insns.  Pseudo should be
> >shared but not their subregs.
> [ ... ]
> >
> >So, Ilya, to solve the problem you need to avoid sharing subregs for the
> >correct LRA/reload work.
> If their code is sharing subregs, then most definitely that code is wrong.
> GCC has very well defined rtx sharing rules that are defined in the
> developer documentation.

Shouldn't --enable-checking=rtl catch such bugs?


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