Ping...
On 04/29/17 19:45, 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? >> >> >> Thanks >> Bernd.
