> Hi!
>
> On Sun, Mar 05, 2023 at 03:33:40PM -0600, Segher Boessenkool wrote:
> > On Sun, Mar 05, 2023 at 08:43:20PM +0000, Tamar Christina wrote:
> > Yes, *look* better: I have seen no proof or indication that this would
>
> ("looks", I cannot type, sorry)
>
> > actually generate better code, not even on just aarch, let alone on
> > the majority of targets. As I said I have a test running, you may be
> > lucky even :-) It has to run for about six hours more and after that
> > it needs analysis still (a few more hours if it isn't obviously always
> > better or worse), so expect results tomorrow night at the earliest.
>
> The results are in:
>
> $ perl sizes.pl --percent C[12]
> C1 C2
> alpha 7082243 100.066%
> arc 4207975 100.015%
> arm 11518624 100.008%
> arm64 24514565 100.067%
> armhf 16661684 100.098%
> csky 4031841 100.002%
> i386 0 0
> ia64 20354295 100.029%
> m68k 4394084 100.023%
> microblaze 6549965 100.014%
> mips 10684680 100.024%
> mips64 8171850 100.002%
> nios2 4356713 100.012%
> openrisc 5010570 100.003%
> parisc 8406294 100.002%
> parisc64 0 0
> powerpc 11104901 99.992%
> powerpc64 24532358 100.057%
> powerpc64le 21293219 100.062%
> riscv32 2028474 100.131%
> riscv64 9515453 100.120%
> s390 20519612 100.279%
> sh 0 0
> shnommu 1840960 100.012%
> sparc 5314422 100.004%
> sparc64 7964129 99.992%
> x86_64 0 0
> xtensa 2925723 100.070%
>
>
> C1 is the original, C2 with your patch. These numbers are the code sizes of a
> Linux kernel, some defconfig for every arch. This is a good measure of how
> effective combine was.
>
> The patch is a tiny win for sparc64 and classic powerpc32 only, but bad
> everywhere else. Look at that s390 number! Or riscv, or most of the arm
> variants (including aarch64).
>
> Do you want me to look in detail what causes this regression on some
> particular target, i.e. why we really still need the expand_compound
> functionality there?
>
Hi,
Thanks for having a look! I think the Richards are exploring a different
solution on the PR
so I don't think it's worth looking at now (maybe in stage-1?). Thanks for
checking though!
I Appreciate you all helping to get this fixed!
Kind Regards,
Tamar
> (Btw. "0" means the target did not build. For the x86 targets this is just
> more
> -Werror madness that seeped in it seems. For parisc64 and sh it is the choice
> of config. Will fix.)
>
>
> Segher
