Re: [vta, graphite?] propagate degenerate phi nodes into debug stmts

[Richard Guenther <richard.guenther@gmail.com>]

On Fri, Jun 3, 2011 at 4:33 PM, Alexandre Oliva <aoliva@redhat.com> wrote:
> According to http://gcc.gnu.org/ml/gcc-patches/2009-11/msg00999.html
> on Nov 19, 2009, Richard Guenther <richard.guenther@gmail.com> wrote:
>
>> On Thu, Nov 19, 2009 at 4:05 AM, Alexandre Oliva <aoliva@redhat.com> wrote:
>>> On Nov 17, 2009, Richard Guenther <richard.guenther@gmail.com> wrote:
>>>
>>>>>> This looks odd.  SSA DEF operand iteration should walk the PHI defs
>>>>>> as well, so the change should not be necessary.
>>>
>>>>> I thought so, too, but by the time we get there, the operands of the PHI
>>>>> stmt have already been disconnected.
>>>
>>>> It shouldn't be.  Please try to figure out why instead.
>>>
>>> Gotta use a different FOR_EACH macro to handle PHI nodes.
>>>
>>> s/FOR_EACH_SSA_DEF_OPERAND/FOR_EACH_PHI_OR_STMT_DEF/ fixed it.
>>>
>>> In order to make sure no other such mistakes had been made in GCC, I
>>> added an assertion check in the iterator initializer and adjusted the
>>> uses of GIMPLE_PHI nodes that triggered the assertion, but that would
>>> have done nothing whatsoever in its absence.  I haven't looked into
>>> whether doing nothing is correct.
>>>
>>> Should I check this in?
>
>> I think we should rather let num_ssa_operands and delink_stmt_imm_use
>> ICE on PHIs, but I'd rather do this in stage1 - can you queue this
>> patch until then?
>
> You meant 4.6 stage1, but I missed it.  How's it for 4.7 stage1?
> Regstrapped on x86_64-linux-gnu and i686-linux-gnu.

Isn't exactly ICEing for num_ssa_operands/delink_stmt_imm_use.

So, the op_iter_init change is ok, the other two not - they should
either ICE or work for PHIs (by using FOR_EACH_PHI_OR_STMT_USE
in them).

Thanks,
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
>
>