On Thu, Feb 10, 2022 at 4:17 PM Bill Schmidt <wschm...@linux.ibm.com> wrote:
>
> Hi!
>
> On 2/10/22 2:50 PM, Segher Boessenkool wrote:
> > On Thu, Feb 10, 2022 at 12:22:28PM -0600, Bill Schmidt wrote:
> >> This is a backport from mainline 3f30f2d1dbb3228b8468b26239fe60c2974ce2ac.
> >> These built-ins were misimplemented as always having big-endian semantics.
> >>
> >> Because the built-in infrastructure has changed, the modifications to the
> >> source are different but achieve the same purpose. The modifications to
> >> the test suite are identical (after fixing the issue with -mbig that David
> >> pointed out with the original patch).
> >> /* 1 argument vector functions added in ISA 3.0 (power9). */
> >> -BU_P9V_AV_1 (VCLZLSBB_V16QI, "vclzlsbb_v16qi", CONST,
> >> vclzlsbb_v16qi)
> >> -BU_P9V_AV_1 (VCLZLSBB_V8HI, "vclzlsbb_v8hi", CONST, vclzlsbb_v8hi)
> >> -BU_P9V_AV_1 (VCLZLSBB_V4SI, "vclzlsbb_v4si", CONST, vclzlsbb_v4si)
> >> -BU_P9V_AV_1 (VCTZLSBB_V16QI, "vctzlsbb_v16qi", CONST,
> >> vctzlsbb_v16qi)
> >> -BU_P9V_AV_1 (VCTZLSBB_V8HI, "vctzlsbb_v8hi", CONST, vctzlsbb_v8hi)
> >> -BU_P9V_AV_1 (VCTZLSBB_V4SI, "vctzlsbb_v4si", CONST, vctzlsbb_v4si)
> >> +BU_P9V_AV_1 (VCLZLSBB_V16QI, "vclzlsbb_v16qi", CONST,
> >> vctzlsbb_v16qi)
> >> +BU_P9V_AV_1 (VCLZLSBB_V8HI, "vclzlsbb_v8hi", CONST, vctzlsbb_v8hi)
> >> +BU_P9V_AV_1 (VCLZLSBB_V4SI, "vclzlsbb_v4si", CONST, vctzlsbb_v4si)
> >> +BU_P9V_AV_1 (VCTZLSBB_V16QI, "vctzlsbb_v16qi", CONST,
> >> vclzlsbb_v16qi)
> >> +BU_P9V_AV_1 (VCTZLSBB_V8HI, "vctzlsbb_v8hi", CONST, vclzlsbb_v8hi)
> >> +BU_P9V_AV_1 (VCTZLSBB_V4SI, "vctzlsbb_v4si", CONST, vclzlsbb_v4si)
> > Please change the default to be equal to the builtin name, so, the BE
> > version. We do that everywhere else as well, and it makes a lot more
> > sense (since everything in Power has BE numbering).
> >
> > The trunk version has this correct afaics?
>
> No, trunk has this, for example:
>
> const signed int __builtin_altivec_vclzlsbb_v16qi (vsc);
> VCLZLSBB_V16QI vctzlsbb_v16qi {endian}
>
> So the backport matches what is on trunk.
>
> Throughout the new builtin infrastructure, the defaults are set for
> little-endian, and the "endian" flag changes behavior for big-endian.
>
> >
> >> --- a/gcc/testsuite/gcc.target/powerpc/vsu/vec-cntlz-lsbb-0.c
> >> +++ b/gcc/testsuite/gcc.target/powerpc/vsu/vec-cntlz-lsbb-0.c
> >> @@ -1,6 +1,7 @@
> >> /* { dg-do compile { target { powerpc*-*-* } } } */
> > (Delete the redundant target clause when modifying any testcase, please).
>
> Okay.
> >
> >> /* { dg-require-effective-target powerpc_p9vector_ok } */
> >> /* { dg-options "-mdejagnu-cpu=power9" } */
> >> +/* { dg-additional-options "-mbig" { target powerpc64le-*-* } } */
> > You don't need the target clause, if it already is BE by default it does
> > not do anything to add it redundantly.
> >
> > But this is wrong anyway: the name of the target triple does not say
> > whether we are BE or LE. Instead you should use the be or le selectors.
> > But again, just add -mbig always.
>
> This was added by David Edelsohn to the trunk version of the patch, because
> -mbig actually is not supported on all subtargets. (I found that quite
> surprising also.) Apparently this doesn't work on AIX, for example. But
> -mlittle works everywhere. Go figure.
-mbig/-mlittle only applies to Linux, not AIX and not Darwin.
I changed the BE testcases to add "-mbig" for little endian default
targets because the compiler implicitly should be operating in big
endian mode for other targets and the testcases should succeed.
For the LE testcases, I changed the target selector to
"powrpc*-*-linux*" because that is the only PowerPC target that can
operate as little endian. I could not find a generic "le" target
selector. powerpc*-*-linux* understands "-mlittle", so I left the
dg-options clause because there is no need to separate out "-mlittle"
for that subset of PowerPC targets.
Thanks, David
>
> That's something that should be fixed, I guess, but it's orthogonal
> to this patch.
>
> Thanks!
> Bill
>
> >
> >> --- /dev/null
> >> +++ b/gcc/testsuite/gcc.target/powerpc/vsu/vec-cntlz-lsbb-3.c
> >> @@ -0,0 +1,15 @@
> >> +/* { dg-do compile { target { powerpc*-*-* } } } */
> >> +/* { dg-require-effective-target powerpc_p9vector_ok } */
> >> +/* { dg-options "-mdejagnu-cpu=power9 -mlittle" } */
> > And here you do it correctly :-)
> >
> > Okay with those fixes (all happen a few times). Thanks!
> >
> >
> > Segher
