> -----Original Message----- > From: Prathamesh Kulkarni <prathamesh.kulka...@linaro.org> > Sent: 06 July 2021 08:06 > To: Christophe LYON <christophe.l...@foss.st.com> > Cc: Kyrylo Tkachov <kyrylo.tkac...@arm.com>; gcc Patches <gcc- > patc...@gcc.gnu.org> > Subject: Re: [ARM] PR98435: Missed optimization in expanding vector > constructor > > On Thu, 1 Jul 2021 at 16:26, Prathamesh Kulkarni > <prathamesh.kulka...@linaro.org> wrote: > > > > On Wed, 30 Jun 2021 at 20:51, Christophe LYON > > <christophe.l...@foss.st.com> wrote: > > > > > > > > > On 29/06/2021 12:46, Prathamesh Kulkarni wrote: > > > > On Mon, 28 Jun 2021 at 14:48, Christophe LYON > > > > <christophe.l...@foss.st.com> wrote: > > > >> > > > >> On 28/06/2021 10:40, Kyrylo Tkachov via Gcc-patches wrote: > > > >>>> -----Original Message----- > > > >>>> From: Prathamesh Kulkarni <prathamesh.kulka...@linaro.org> > > > >>>> Sent: 28 June 2021 09:38 > > > >>>> To: Kyrylo Tkachov <kyrylo.tkac...@arm.com> > > > >>>> Cc: Christophe Lyon <christophe.l...@linaro.org>; gcc Patches > <gcc- > > > >>>> patc...@gcc.gnu.org> > > > >>>> Subject: Re: [ARM] PR98435: Missed optimization in expanding > vector > > > >>>> constructor > > > >>>> > > > >>>> On Thu, 24 Jun 2021 at 22:01, Kyrylo Tkachov > <kyrylo.tkac...@arm.com> > > > >>>> wrote: > > > >>>>> > > > >>>>>> -----Original Message----- > > > >>>>>> From: Prathamesh Kulkarni <prathamesh.kulka...@linaro.org> > > > >>>>>> Sent: 14 June 2021 09:02 > > > >>>>>> To: Christophe Lyon <christophe.l...@linaro.org> > > > >>>>>> Cc: gcc Patches <gcc-patches@gcc.gnu.org>; Kyrylo Tkachov > > > >>>>>> <kyrylo.tkac...@arm.com> > > > >>>>>> Subject: Re: [ARM] PR98435: Missed optimization in expanding > vector > > > >>>>>> constructor > > > >>>>>> > > > >>>>>> On Wed, 9 Jun 2021 at 15:58, Prathamesh Kulkarni > > > >>>>>> <prathamesh.kulka...@linaro.org> wrote: > > > >>>>>>> On Fri, 4 Jun 2021 at 13:15, Christophe Lyon > > > >>>> <christophe.l...@linaro.org> > > > >>>>>> wrote: > > > >>>>>>>> On Fri, 4 Jun 2021 at 09:27, Prathamesh Kulkarni via Gcc- > patches > > > >>>>>>>> <gcc-patches@gcc.gnu.org> wrote: > > > >>>>>>>>> Hi, > > > >>>>>>>>> As mentioned in PR, for the following test-case: > > > >>>>>>>>> > > > >>>>>>>>> #include <arm_neon.h> > > > >>>>>>>>> > > > >>>>>>>>> bfloat16x4_t f1 (bfloat16_t a) > > > >>>>>>>>> { > > > >>>>>>>>> return vdup_n_bf16 (a); > > > >>>>>>>>> } > > > >>>>>>>>> > > > >>>>>>>>> bfloat16x4_t f2 (bfloat16_t a) > > > >>>>>>>>> { > > > >>>>>>>>> return (bfloat16x4_t) {a, a, a, a}; > > > >>>>>>>>> } > > > >>>>>>>>> > > > >>>>>>>>> Compiling with arm-linux-gnueabi -O3 -mfpu=neon -mfloat- > > > >>>> abi=softfp > > > >>>>>>>>> -march=armv8.2-a+bf16+fp16 results in f2 not being > vectorized: > > > >>>>>>>>> > > > >>>>>>>>> f1: > > > >>>>>>>>> vdup.16 d16, r0 > > > >>>>>>>>> vmov r0, r1, d16 @ v4bf > > > >>>>>>>>> bx lr > > > >>>>>>>>> > > > >>>>>>>>> f2: > > > >>>>>>>>> mov r3, r0 @ __bf16 > > > >>>>>>>>> adr r1, .L4 > > > >>>>>>>>> ldrd r0, [r1] > > > >>>>>>>>> mov r2, r3 @ __bf16 > > > >>>>>>>>> mov ip, r3 @ __bf16 > > > >>>>>>>>> bfi r1, r2, #0, #16 > > > >>>>>>>>> bfi r0, ip, #0, #16 > > > >>>>>>>>> bfi r1, r3, #16, #16 > > > >>>>>>>>> bfi r0, r2, #16, #16 > > > >>>>>>>>> bx lr > > > >>>>>>>>> > > > >>>>>>>>> This seems to happen because vec_init pattern in neon.md > has VDQ > > > >>>>>> mode > > > >>>>>>>>> iterator, which doesn't include V4BF. In attached patch, I > changed > > > >>>>>>>>> mode > > > >>>>>>>>> to VDQX which seems to work for the test-case, and the > compiler > > > >>>> now > > > >>>>>> generates: > > > >>>>>>>>> f2: > > > >>>>>>>>> vdup.16 d16, r0 > > > >>>>>>>>> vmov r0, r1, d16 @ v4bf > > > >>>>>>>>> bx lr > > > >>>>>>>>> > > > >>>>>>>>> However, the pattern is also gated on TARGET_HAVE_MVE > and I am > > > >>>>>> not > > > >>>>>>>>> sure if either VDQ or VDQX are correct modes for MVE since > MVE > > > >>>> has > > > >>>>>>>>> only 128-bit vectors ? > > > >>>>>>>>> > > > >>>>>>>> I think patterns common to both Neon and MVE should be > moved to > > > >>>>>>>> vec-common.md, I don't know why such patterns were left in > > > >>>> neon.md. > > > >>>>>>> Since we end up calling neon_expand_vector_init for both > NEON and > > > >>>> MVE, > > > >>>>>>> I am not sure if we should separate the pattern ? > > > >>>>>>> Would it make sense to FAIL if the mode size isn't 16 bytes for > MVE as > > > >>>>>>> in attached patch so > > > >>>>>>> it will call neon_expand_vector_init only for 128-bit vectors ? > > > >>>>>>> Altho hard-coding 16 in the pattern doesn't seem a good idea to > me > > > >>>> either. > > > >>>>>> ping https://gcc.gnu.org/pipermail/gcc-patches/2021- > June/572342.html > > > >>>>>> (attaching patch as text). > > > >>>>>> > > > >>>>> --- a/gcc/config/arm/neon.md > > > >>>>> +++ b/gcc/config/arm/neon.md > > > >>>>> @@ -459,10 +459,12 @@ > > > >>>>> ) > > > >>>>> > > > >>>>> (define_expand "vec_init<mode><V_elem_l>" > > > >>>>> - [(match_operand:VDQ 0 "s_register_operand") > > > >>>>> + [(match_operand:VDQX 0 "s_register_operand") > > > >>>>> (match_operand 1 "" "")] > > > >>>>> "TARGET_NEON || TARGET_HAVE_MVE" > > > >>>>> { > > > >>>>> + if (TARGET_HAVE_MVE && GET_MODE_SIZE (GET_MODE > > > >>>> (operands[0])) != 16) > > > >>>>> + FAIL; > > > >>>>> neon_expand_vector_init (operands[0], operands[1]); > > > >>>>> DONE; > > > >>>>> }) > > > >>>>> > > > >>>>> I think we should move this to vec-common.md like Christophe > said. > > > >>>>> Perhaps rather than making it FAIL for non-16 MVE sizes we just > disable it in > > > >>>> the expander condition? > > > >>>>> "TARGET_NEON || (TARGET_HAVE_MVE && GET_MODE_SIZE (< > > > >>>> VDQ>mode) != 16)" > > > >>>> Is it OK to use <MODE>mode ? Because using <VDQ>mode resulted > in lot > > > >>>> of build errors. > > > >>>> Also, I think the comparison should be inverted, ie, GET_MODE_SIZE > > > >>>> (<MODE>mode) == 16 since > > > >>>> we want to make the pattern pass if target is MVE and vector size is > 16 bytes ? > > > >>>> Do these changes in attached patch look OK ? > > > >>> Yes, you're right. > > > >> > > > >> Can't this be ARM_HAVE_<MODE>_ARITH like in most expanders in > vec-common.md? > > > >> > > > >> (maybe with a && !TARGET_REALLY_IWMMXT if needed) > > > > I wonder if this should be ARM_HAVE_<MODE>_LDST instead since > we're > > > > initializing the vector ? > > > > > > > > > Well, it really depends on which modes you want to enable. > > > > > > > > > Looks like your move VDQ -> VDQ adds V4BF, V8BF and DI. > > > > > > Are they all OK for Neon? > > > > > > They are not OK for MVE. > > > > > > Ideally you could add testcases to cover to the supported and > > > unsupported modes for both Neon and MVE.\ > > > > > > Before your patch, the expander is enabled for MVE for 64 bit modes > > > (V8QI, V4HI, V2SI): what happens in this case? Does the compiler crash > > > or is there something else preventing the match? > > Hi, > > Apparently there is VALID_MVE_MODE macro, so is it better to use: > > TARGET_NEON || (TARGET_HAVE_MVE && > VALID_MVE_MODE(<MODE>mode)) > > as in the attached patch ?
The change is ok. I would like to see some testcases like Christophe suggested, but this patch just moves the expander around rather than introducing new functionality. Thanks, Kyrill > ping https://gcc.gnu.org/pipermail/gcc-patches/2021-July/574206.html > > Thanks, > Prathamesh > > > > Thanks, > > Prathamesh > > > > > > > > > Thanks, > > > > > > > > > Christophe > > > > > > > > > > Thanks, > > > > Prathamesh > > > >> > > > >> Christophe > > > >> > > > >> > > > >>> Ok. > > > >>> Thanks, > > > >>> Kyrill > > > >>> > > > >>> > > > >>>> Thanks, > > > >>>> Prathamesh > > > >>>>> Thanks, > > > >>>>> Kyrill > > > >>>>> > > > >>>>>> Thanks, > > > >>>>>> Prathamesh > > > >>>>>>> Thanks, > > > >>>>>>> Prathamesh > > > >>>>>>>> That being said, I suggest you look at other similar patterns in > > > >>>>>>>> vec-common.md, most of which are gated on > > > >>>>>>>> ARM_HAVE_<MODE>_ARITH > > > >>>>>>>> and possibly beware of issues with iwmmxt :-) > > > >>>>>>>> > > > >>>>>>>> Christophe > > > >>>>>>>> > > > >>>>>>>>> Thanks, > > > >>>>>>>>> Prathamesh