[Bug target/65729] [5 Regression] ICE (in prohibited_class_reg_set_mode_p, at lra-constraints.c) on arm-linux-gnueabihf

["vmakarov at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65729

Vladimir Makarov <vmakarov at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P1
   Target Milestone|6.0                         |5.0
            Summary|[5/6 Regression] ICE (in    |[5 Regression] ICE (in
                   |prohibited_class_reg_set_mo |prohibited_class_reg_set_mo
                   |de_p, at lra-constraints.c) |de_p, at lra-constraints.c)
                   |on arm-linux-gnueabihf      |on arm-linux-gnueabihf

--- Comment #10 from Vladimir Makarov <vmakarov at gcc dot gnu.org> ---
(In reply to Jakub Jelinek from comment #6)
> (In reply to Vladimir Makarov from comment #5)
> > (In reply to Yvan Roux from comment #4)
> > > For me the assertion in prohibited_class_reg_set_mode_p is not right, it
> > > checks that set is a subset of reg_class_contents[rclass] and my
> > > understanding is that it should be the opposite:
> > > 
> > > lra_assert (hard_reg_set_subset_p (reg_class_contents[rclass],set));
> > > 
> > > With this modification the test is fixed (full validation is ongoing).
> > > 
> > > Do I miss something Vlad ?
> > 
> > After some investigation done, I believe you are right, Yvan. 
> > this_alternative_set is always not smaller than contents of this_alternative
> > as we use reg_class_subunion.  So you can submit your patch with swapping
> > arguments in the assert call, of course after testing on x86-64 at least.  I
> > am approving the patch.  If you don't respond it in a few hours, I'll do it
> > myself.  Thanks.
> > 
> > By the way, it is a bad practice for RA not define classes which are union
> > of classes can be used for the same operand.  In this case, we could use
> > GENERAL_REGS or VFP_LO_REGS but only VFP_LO_REGS will be used only as it is
> > a result of reg_class_subunion[GENERAL_REGS][VFP_LO_REGS].  But fixing it is
> > not a task for GCC-5.0 as we are at the very end of creation of a new
> > release.  Fixing RA bugs has a big chance introducing new ones until it is
> > stabilized.  This is a situation what we actually see now.
> 
> So, could we perhaps just comment out the lra_assert for GCC 5.1 release,
> then when stage1 reopens test the other order and if it works everywhere,
> after a few weeks backport that to the branch?  Not that it is very
> important, because the release will be --enable-checking=release for most
> users and thus the assert will be ignored anyway.
> Just commenting out the assert means that no further testing is needed on it
> right now, the patch would be obvious...

OK. I'll do it.  As I understand 
(In reply to Yvan Roux from comment #7)
> k, my validation is ok. I'll be off during ~3h and will submit it when I'm
> back (or the assertion commenting patch) if it's better for 5.1

I've just commented the assert.  We will fix it for 5.1.

So, Jakub, I did what you asked as it is important for your work on release
candidate.

Although I'd like to work on PR65710 but I am not sure it will be fixed soon as
it is a performance bug now and will take at least a few days to fix it.  So
the PR65710 is also work for 5.1.