Re: [match.pd] Fix for PR35691

[Prathamesh Kulkarni <prathamesh dot kulkarni at linaro dot org>]

On 8 November 2016 at 16:46, Richard Biener <rguenther@suse.de> wrote:
> On Tue, 8 Nov 2016, Prathamesh Kulkarni wrote:
>
>> On 8 November 2016 at 13:23, Richard Biener <rguenther@suse.de> wrote:
>> > On Mon, 7 Nov 2016, Prathamesh Kulkarni wrote:
>> >
>> >> On 7 November 2016 at 23:06, Prathamesh Kulkarni
>> >> <prathamesh.kulkarni@linaro.org> wrote:
>> >> > On 7 November 2016 at 15:43, Richard Biener <rguenther@suse.de> wrote:
>> >> >> On Fri, 4 Nov 2016, Prathamesh Kulkarni wrote:
>> >> >>
>> >> >>> On 4 November 2016 at 13:41, Richard Biener <rguenther@suse.de> wrote:
>> >> >>> > On Thu, 3 Nov 2016, Marc Glisse wrote:
>> >> >>> >
>> >> >>> >> On Thu, 3 Nov 2016, Richard Biener wrote:
>> >> >>> >>
>> >> >>> >> > > > > The transform would also work for vectors (element_precision for
>> >> >>> >> > > > > the test but also a value-matching zero which should ensure the
>> >> >>> >> > > > > same number of elements).
>> >> >>> >> > > > Um sorry, I didn't get how to check vectors to be of equal length by a
>> >> >>> >> > > > matching zero.
>> >> >>> >> > > > Could you please elaborate on that ?
>> >> >>> >> > >
>> >> >>> >> > > He may have meant something like:
>> >> >>> >> > >
>> >> >>> >> > >   (op (cmp @0 integer_zerop@2) (cmp @1 @2))
>> >> >>> >> >
>> >> >>> >> > I meant with one being @@2 to allow signed vs. Unsigned @0/@1 which was the
>> >> >>> >> > point of the pattern.
>> >> >>> >>
>> >> >>> >> Oups, that's what I had written first, and then I somehow managed to confuse
>> >> >>> >> myself enough to remove it so as to remove the call to types_match :-(
>> >> >>> >>
>> >> >>> >> > > So the last operand is checked with operand_equal_p instead of
>> >> >>> >> > > integer_zerop. But the fact that we could compute bit_ior on the
>> >> >>> >> > > comparison results should already imply that the number of elements is the
>> >> >>> >> > > same.
>> >> >>> >> >
>> >> >>> >> > Though for equality compares we also allow scalar results IIRC.
>> >> >>> >>
>> >> >>> >> Oh, right, I keep forgetting that :-( And I have no idea how to generate one
>> >> >>> >> for a testcase, at least until the GIMPLE FE lands...
>> >> >>> >>
>> >> >>> >> > > On platforms that have IOR on floats (at least x86 with SSE, maybe some
>> >> >>> >> > > vector mode on s390?), it would be cool to do the same for floats (most
>> >> >>> >> > > likely at the RTL level).
>> >> >>> >> >
>> >> >>> >> > On GIMPLE view-converts could come to the rescue here as well.  Or we cab
>> >> >>> >> > just allow bit-and/or on floats as much as we allow them on pointers.
>> >> >>> >>
>> >> >>> >> Would that generate sensible code on targets that do not have logic insns for
>> >> >>> >> floats? Actually, even on x86_64 that generates inefficient code, so there
>> >> >>> >> would be some work (for instance grep finds no gen_iordf3, only gen_iorv2df3).
>> >> >>> >>
>> >> >>> >> I am also a bit wary of doing those obfuscating optimizations too early...
>> >> >>> >> a==0 is something that other optimizations might use. long
>> >> >>> >> c=(long&)a|(long&)b; (double&)c==0; less so...
>> >> >>> >>
>> >> >>> >> (and I am assuming that signaling NaNs don't make the whole transformation
>> >> >>> >> impossible, which might be wrong)
>> >> >>> >
>> >> >>> > Yeah.  I also think it's not so much important - I just wanted to mention
>> >> >>> > vectors...
>> >> >>> >
>> >> >>> > Btw, I still think we need a more sensible infrastructure for passes
>> >> >>> > to gather, analyze and modify complex conditions.  (I'm always pointing
>> >> >>> > to tree-affine.c as an, albeit not very good, example for handling
>> >> >>> > a similar problem)
>> >> >>> Thanks for mentioning the value-matching capture @@, I wasn't aware of
>> >> >>> this match.pd feature.
>> >> >>> The current patch keeps it restricted to only bitwise operators on integers.
>> >> >>> Bootstrap+test running on x86_64-unknown-linux-gnu.
>> >> >>> OK to commit if passes ?
>> >> >>
>> >> >> +/* PR35691: Transform
>> >> >> +   (x == 0 & y == 0) -> (x | typeof(x)(y)) == 0.
>> >> >> +   (x != 0 | y != 0) -> (x | typeof(x)(y)) != 0.  */
>> >> >> +
>> >> >>
>> >> >> Please omit the vertical space
>> >> >>
>> >> >> +(for bitop (bit_and bit_ior)
>> >> >> +     cmp (eq ne)
>> >> >> + (simplify
>> >> >> +  (bitop (cmp @0 integer_zerop) (cmp @1 integer_zerop))
>> >> >>
>> >> >> if you capture the first integer_zerop as @2 then you can re-use it...
>> >> >>
>> >> >> +   (if (INTEGRAL_TYPE_P (TREE_TYPE (@0))
>> >> >> +       && INTEGRAL_TYPE_P (TREE_TYPE (@1))
>> >> >> +       && TYPE_PRECISION (TREE_TYPE (@0)) == TYPE_PRECISION (TREE_TYPE
>> >> >> (@1)))
>> >> >> +    (cmp (bit_ior @0 (convert @1)) { build_zero_cst (TREE_TYPE (@0));
>> >> >>
>> >> >> ... here inplace of the { build_zero_cst ... }.
>> >> >>
>> >> >> Ok with that changes.
>> >> > Thanks, committed the attached version as r241915.
>> >> ugh, the svn commit message has:
>> >>
>> >> testsuite/
>> >> * gcc.dg/pr35691-1.c: New test-case.
>> >> * gcc.dg/pr35691-4.c: Likewise.
>> >>
>> >> pr35691-4.c was a typo, should be pr35691-2.c :/
>> >> However testsuite/ChangeLog correctly has entry for pr35691-2.c
>> >> Is it possible to edit the commit message for r241915 ?
>> >> Sorry about this.
>> >
>> > No, just leave it as-is.
>> Hi,
>> Chritstophe reported to me that the commit caused test-cases
>> pr35691-1.c and pr35691-2.c (which were added by the commit)
>> to FAIL for cortex-a5:
>> http://people.linaro.org/~christophe.lyon/cross-validation/gcc/trunk/241915/arm-none-linux-gnueabihf/diff-gcc-rh60-arm-none-linux-gnueabihf-arm-cortex-a5-vfpv3-d16-fp16.txt
>>
>> It seems truth_andif_expr is not simplified to bit_and_expr on
>> cortex-a5 as for x86_64 (and other arm variants).
>> The differences in dumps start from 004t.gimple for pr35691-1.c:
>>
>> x86_64 gimple dump:
>> foo (int z0, unsigned int z1)
>> {
>>   int D.1800;
>>   int t0;
>>   int t1;
>>   int t2;
>>
>>   _1 = z0 == 0;
>>   t0 = (int) _1;
>>   _2 = z1 == 0;
>>   t1 = (int) _2;
>>   _3 = t0 != 0;
>>   _4 = t1 != 0;
>>   _5 = _3 & _4;
>>   t2 = (int) _5;
>>   D.1800 = t2;
>>   return D.1800;
>> }
>>
>> cortex-a5 gimple dump:
>> foo (int z0, unsigned int z1)
>> {
>>   int iftmp.0;
>>   int D.4176;
>>   int t0;
>>   int t1;
>>   int t2;
>>
>>   _1 = z0 == 0;
>>   t0 = (int) _1;
>>   _2 = z1 == 0;
>>   t1 = (int) _2;
>>   if (t0 != 0) goto <D.4174>; else goto <D.4172>;
>>   <D.4174>:
>>   if (t1 != 0) goto <D.4175>; else goto <D.4172>;
>>   <D.4175>:
>>   iftmp.0 = 1;
>>   goto <D.4173>;
>>   <D.4172>:
>>   iftmp.0 = 0;
>>   <D.4173>:
>>   t2 = iftmp.0;
>>   D.4176 = t2;
>>   return D.4176;
>> }
>>
>> Since the pattern expects truth_andif_expr to be converted to bit_and_expr,
>> it fails to match for cortex-a5.
>> This seems to happen only for cortex-a5 (the other variants a9, a15,
>> a57 are OK).
>>
>> Is my assumption that truth_andif_expr would be always converted to bit_and_expr
>> for above case incorrect ?
>
> Yes, it depends on LOGICAL_OP_SHORT_CIRCUIT.
Thanks, I wasn't aware of that. I adjusted the test-case in the attached patch,
to always contain bit_and_expr/bit_ior_expr, which passes on cortex-a5
and powerpc.
I will update PR35691 with the comment that it's partially fixed, for
targets when LOGICAL_OP_NON_SHORT_CIRCUIT is true.
Cross-testing on arm*-*-* in progress.
Ok to commit if passes ?

Thanks,
Prathamesh
>
> Richard.
>
>> Thanks,
>> Prathamesh
>> >
>> > Richard.
>> >
>> >> Regards,
>> >> Prathamesh
>> >> >
>> >> >>
>> >> >> Richard.
>> >>
>> >>
>> >
>> > --
>> > Richard Biener <rguenther@suse.de>
>> > SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nuernberg)
>>
>>
>
> --
> Richard Biener <rguenther@suse.de>
> SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nuernberg)

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