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RE: New patch: [AArch64] [BE] [1/2] Make large opaque integer modes endianness-safe.
- From: "David Sherwood" <david dot sherwood at arm dot com>
- To: "'Christophe Lyon'" <christophe dot lyon at linaro dot org>
- Cc: <gcc-patches at gcc dot gnu dot org>, "Marcus Shawcroft" <Marcus dot Shawcroft at arm dot com>, "Alan Hayward" <Alan dot Hayward at arm dot com>, "Tejas Belagod" <Tejas dot Belagod at arm dot com>, "Richard Sandiford" <Richard dot Sandiford at arm dot com>
- Date: Mon, 15 Dec 2014 09:56:14 -0000
- Subject: RE: New patch: [AArch64] [BE] [1/2] Make large opaque integer modes endianness-safe.
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> -----Original Message-----
> From: Christophe Lyon [mailto:christophe.lyon@linaro.org]
> Sent: 11 December 2014 13:47
> To: David Sherwood
> Cc: gcc-patches@gcc.gnu.org; Marcus Shawcroft; Alan Hayward; Tejas Belagod; Richard Sandiford
> Subject: Re: New patch: [AArch64] [BE] [1/2] Make large opaque integer modes endianness-safe.
>
> On 11 December 2014 at 11:16, David Sherwood <david.sherwood@arm.com> wrote:
> > Hi Christophe,
> >
> > Sorry to bother you again. After my clarification email below are you now
> > happy for these patches to go in?
> >
> > Kind Regards,
> > David Sherwood.
> >
> >> -----Original Message-----
> >> From: David Sherwood [mailto:david.sherwood@arm.com]
> >> Sent: 27 November 2014 14:53
> >> To: 'Christophe Lyon'
> >> Cc: gcc-patches@gcc.gnu.org; Marcus Shawcroft; Alan Hayward; 'Tejas Belagod'; Richard Sandiford
> >> Subject: RE: New patch: [AArch64] [BE] [1/2] Make large opaque integer modes endianness-safe.
> >>
> >> > On 18 November 2014 10:14, David Sherwood <david.sherwood@arm.com> wrote:
> >> > > Hi Christophe,
> >> > >
> >> > > Ah sorry. My mistake - it fixes this in bugzilla:
> >> > >
> >> > > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59810
> >> >
> >> > I did look at that PR, but since it has no testcase attached, I was unsure.
> >> > And I am still not :-)
> >> > PR 59810 is "[AArch64] LDn/STn implementations are not ABI-conformant
> >> > for bigendian."
> >> > but the advsimd-intrinsics/vldX.c and vldX_lane.c now PASS with Alan's
> >> > patches on aarch64_be, so I thought Alan's patches solve PR59810.
> >> >
> >> > What am I missing?
> >>
> >> Hi Christophe,
> >>
> >> I think probably this is our fault for making our lives way too difficult and
> >> artificially splitting all these patches up. :)
> >>
> >> Alan's patch:
> >>
> >> https://gcc.gnu.org/ml/gcc-patches/2014-10/msg00952.html
> >>
> >> fixes some issues on aarch64_be, but also causes regressions. For example,
> >>
> >> ====
> >> Tests that now fail, but worked before:
> >>
> >> aarch64_be-elf-aem: gcc.dg/vect/slp-perm-8.c -flto -ffat-lto-objects execution test
> >> aarch64_be-elf-aem: gcc.dg/vect/slp-perm-8.c execution test
> >> aarch64_be-elf-aem: gcc.dg/vect/vect-over-widen-1-big-array.c -flto -ffat-lto-objects execution test
> >> ...
> >>
> >> Tests that now work, but didn't before:
> >>
> >> aarch64_be-elf-aem: gcc.dg/vect/fast-math-vect-complex-3.c execution test
> >> aarch64_be-elf-aem: gcc.dg/vect/if-cvt-stores-vect-ifcvt-18.c execution test
> >> aarch64_be-elf-aem: gcc.dg/vect/no-scevccp-outer-10a.c execution test
> >> ...
> >> ====
> I didn't notice that because I tested Alan's patch only against the
> advsimd-intrinsics tests.
> In this respect, I don't understand why your ChangeLog entry says
> * config/aarch64/aarch64-simd.md (vec_store_lanes(o/c/x)i,
> vec_load_lanes(o/c/x)i): Fixed to work for Big Endian.
> since the existing advsimd-intrinsics tests already pass with Alan's patch alone
> or is vld1_lane still broken (for which I haven't posted a test yet)?
>
Yes, I think the change log is unclear and I will change it. The only thing that was
broken was not adhering to the ABI, but we don't have any specific regression tests
that prove this.
> >> His patch is only half of the story and must be applied at the same time as the
> >> "[AArch64] [BE] [1/2] Make large opaque integer modes endianness-safe."
> >> patch. With both patches applied the result looks much healthier:
> >>
> >> ====
> >> # Comparing 1 common sum files
> >> ## /bin/sh ./src/gcc/contrib/compare_tests /tmp/gxx-sum1.10051 /tmp/gxx-sum2.10051
> >> Tests that now work, but didn't before:
> >>
> >> aarch64_be-elf-aem: gcc.dg/torture/pr52028.c -O3 -fomit-frame-pointer execution test
> >> aarch64_be-elf-aem: gcc.dg/torture/pr52028.c -O3 -fomit-frame-pointer -funroll-all-loops -finline-
> >> functions execution test
> >> aarch64_be-elf-aem: gcc.dg/torture/pr52028.c -O3 -fomit-frame-pointer -funroll-loops execution
> test
> >> ...
> >> ====
> >>
> >> with no new regressions. After applying both patches the aarch64_be gcc testsuite is
> >> on a parity with the aarch64 testsuite. Furthermore, after applying both of these patches:
> >>
> >> "[AArch64] [BE] [1/2] Make large opaque integer modes endianness-safe"
> >> "[AArch64] [BE] Fix vector load/stores to not use ld1/st1"
> >>
> >> it then becomes safe for us to remove the CCMC macro, which is the cause of
> >> unnecessary spills to the stack for certain auto-vectorised code. So really I
> >> suppose when I posted my second patch
> >>
> >> "[AArch64] [BE] [2/2] Make large opaque integer modes endianness-safe"
> >>
> >> I should have really just called this
> >>
> >> "[AArch64] [BE] Remove CCMC for aarch64"
> >>
> >> in order to make it clear exactly what the purpose of these patches is.
> well, not yet since this very does not remove it :-)
>
Again, this is my fault as I made a mistake in the change log. If you look at the
actual patch the CCMC macro is removed. Let me re-post corrected, more
sensible change logs for both of those changes here:
"[AArch64] [BE] [1/2] Make large opaque integer modes endianness-safe"
ChangeLog:
gcc/:
2014-10-10 David Sherwood <david.sherwood@arm.com>
2014-10-10 Tejas Belagod <Tejas.Belagod@arm.com>
* config/aarch64/aarch64-protos.h (aarch64_simd_attr_length_rglist,
aarch64_reverse_mask): New decls.
* config/aarch64/iterators.md (UNSPEC_REV_REGLIST): New enum.
* config/aarch64/iterators.md (insn_count): New mode_attr.
* config/aarch64/aarch64-simd.md (vec_store_lanesoi, vec_store_lanesci,
vec_store_lanesxi, vec_load_lanesoi, vec_load_lanesci, vec_load_lanesxi)
: Made ABI compliant for Big Endian targets.
* config/aarch64/aarch64-simd.md (aarch64_rev_reglist, aarch64_simd_ld2,
aarch64_simd_ld3, aarch64_simd_ld4, aarch64_simd_st2, aarch64_simd_st3,
aarch64_simd_st4): Added.
* config/aarch64/aarch64.c (aarch64_simd_attr_length_rglist,
aarch64_reverse_mask): Added.
"[AArch64] [BE] [2/2] Make large opaque integer modes endianness-safe"
ChangeLog:
gcc/:
2014-13-10 David Sherwood <david.sherwood@arm.com>
2014-13-10 Tejas Belagod <Tejas.Belagod@arm.com>
* config/aarch64/aarch64.h (CANNOT_CHANGE_MODE_CLASS): Removed.
* config/aarch64/aarch64.c (aarch64_cannot_change_mode_class): Removed.
* config/aarch64/aarch64-protos.h (aarch64_cannot_change_mode_class):
Removed.
Again, apologies for the confusion,
David.
> >>
> >> Kind Regards,
> >> David Sherwood.
> >
> >
> >
> >