Hi Bernd,
On 4 September 2017 at 16:52, Kyrill Tkachov <kyrylo.tkac...@foss.arm.com> wrote: > > On 29/04/17 18:45, Bernd Edlinger wrote: >> >> Ping... >> >> I attached a rebased version since there was a merge conflict in >> the xordi3 pattern, otherwise the patch is still identical. >> It splits adddi3, subdi3, anddi3, iordi3, xordi3 and one_cmpldi2 >> early when the target has no neon or iwmmxt. >> >> >> Thanks >> Bernd. >> >> >> >> On 11/28/16 20:42, Bernd Edlinger wrote: >>> >>> On 11/25/16 12:30, Ramana Radhakrishnan wrote: >>>> >>>> On Sun, Nov 6, 2016 at 2:18 PM, Bernd Edlinger >>>> <bernd.edlin...@hotmail.de> wrote: >>>>> >>>>> Hi! >>>>> >>>>> This improves the stack usage on the sha512 test case for the case >>>>> without hardware fpu and without iwmmxt by splitting all di-mode >>>>> patterns right while expanding which is similar to what the >>>>> shift-pattern >>>>> does. It does nothing in the case iwmmxt and fpu=neon or vfp as well >>>>> as >>>>> thumb1. >>>>> >>>> I would go further and do this in the absence of Neon, the VFP unit >>>> being there doesn't help with DImode operations i.e. we do not have 64 >>>> bit integer arithmetic instructions without Neon. The main reason why >>>> we have the DImode patterns split so late is to give a chance for >>>> folks who want to do 64 bit arithmetic in Neon a chance to make this >>>> work as well as support some of the 64 bit Neon intrinsics which IIRC >>>> map down to these instructions. Doing this just for soft-float doesn't >>>> improve the default case only. I don't usually test iwmmxt and I'm not >>>> sure who has the ability to do so, thus keeping this restriction for >>>> iwMMX is fine. >>>> >>>> >>> Yes I understand, thanks for pointing that out. >>> >>> I was not aware what iwmmxt exists at all, but I noticed that most >>> 64bit expansions work completely different, and would break if we split >>> the pattern early. >>> >>> I can however only look at the assembler outout for iwmmxt, and make >>> sure that the stack usage does not get worse. >>> >>> Thus the new version of the patch keeps only thumb1, neon and iwmmxt as >>> it is: around 1570 (thumb1), 2300 (neon) and 2200 (wimmxt) bytes stack >>> for the test cases, and vfp and soft-float at around 270 bytes stack >>> usage. >>> >>>>> It reduces the stack usage from 2300 to near optimal 272 bytes (!). >>>>> >>>>> Note this also splits many ldrd/strd instructions and therefore I will >>>>> post a followup-patch that mitigates this effect by enabling the >>>>> ldrd/strd >>>>> peephole optimization after the necessary reg-testing. >>>>> >>>>> >>>>> Bootstrapped and reg-tested on arm-linux-gnueabihf. >>>> >>>> What do you mean by arm-linux-gnueabihf - when folks say that I >>>> interpret it as --with-arch=armv7-a --with-float=hard >>>> --with-fpu=vfpv3-d16 or (--with-fpu=neon). >>>> >>>> If you've really bootstrapped and regtested it on armhf, doesn't this >>>> patch as it stand have no effect there i.e. no change ? >>>> arm-linux-gnueabihf usually means to me someone has configured with >>>> --with-float=hard, so there are no regressions in the hard float ABI >>>> case, >>>> >>> I know it proves little. When I say arm-linux-gnueabihf >>> I do in fact mean --enable-languages=all,ada,go,obj-c++ >>> --with-arch=armv7-a --with-tune=cortex-a9 --with-fpu=vfpv3-d16 >>> --with-float=hard. >>> >>> My main interest in the stack usage is of course not because of linux, >>> but because of eCos where we have very small task stacks and in fact >>> no fpu support by the O/S at all, so that patch is exactly what we need. >>> >>> >>> Bootstrapped and reg-tested on arm-linux-gnueabihf >>> Is it OK for trunk? > > > The code is ok. > AFAICS testing this with --with-fpu=vfpv3-d16 does exercise the new code as > the splits > will happen for !TARGET_NEON (it is of course !TARGET_IWMMXT and > TARGET_IWMMXT2 > is irrelevant here). > > So this is ok for trunk. > Thanks, and sorry again for the delay. > Kyrill > This patch (r251663) causes a regression on armeb-none-linux-gnueabihf --with-mode arm --with-cpu cortex-a9 --with-fpu vfpv3-d16-fp16 FAIL: gcc.dg/vect/vect-singleton_1.c (internal compiler error) FAIL: gcc.dg/vect/vect-singleton_1.c -flto -ffat-lto-objects (internal compiler error) the test passes if gcc is configured --with-fpu neon-fp16 Christophe >>> >>> Thanks >>> Bernd. > >
