[PATCH] D11438: Part 2 to fix x86_64 fp128 calling convention.

[Chih-hung Hsieh via llvm-commits]

Indeed, it's nice to have __float128 in both clang and llvm.



On Fri, Dec 11, 2015 at 6:30 PM, Xinliang David Li <davidxl at google.com>
wrote:

> that is great!
>
> David
>
> On Fri, Dec 11, 2015 at 6:09 PM, Hal Finkel <hfinkel at anl.gov> wrote:
> > ----- Original Message -----
> >> From: "Xinliang David Li via llvm-commits" <llvm-commits at lists.llvm.org
> >
> >> To: "Chih-hung Hsieh" <chh at google.com>
> >> Cc: "llvm-commits" <llvm-commits at lists.llvm.org>,
> reviews+D11438+public+6e2ebe02f28cebc7 at reviews.llvm.org, "Elliott
> >> Hughes" <enh at google.com>
> >> Sent: Friday, December 11, 2015 8:06:11 PM
> >> Subject: Re: [PATCH] D11438: Part 2 to fix x86_64 fp128 calling
> convention.
> >>
> >> On Fri, Dec 11, 2015 at 4:41 PM, Chih-hung Hsieh <chh at google.com>
> >> wrote:
> >> >>
> >> >> > ================
> >> >> > Comment at: test/CodeGen/X86/fp128-i128.ll:44
> >> >> > @@ +43,3 @@
> >> >> > +; CHECK:       movaps %xmm0, -24(%rsp)
> >> >> > +; CHECK-NEXT:  movq -24(%rsp), %rax
> >> >> > +; CHECK-NEXT:  movabsq $281474976710655, %rcx
> >> >> > ----------------
> >> >> > davidxl wrote:
> >> >> >> The pattern checked is pretty long -- I worry it may break in
> >> >> >> the
> >> >> >> future. Is it possible to relax it some how?
> >> >> > I tried to reduce the C code, but any reduction won't trigger
> >> >> > the
> >> >> > complicated IL that reached a point that my partial fix core
> >> >> > dumped. Maybe
> >> >> > we can take out a few CHECK-NEXT requirements.
> >> >>
> >> >> Where does it core-dump? If it is in new code, it needs to be
> >> >> fixed :)
> >> >> Otherwise file a bug.
> >> >>
> >> >
> >> > Ah, I meant my incomplete fix at some time in the past.
> >> > My current patch passes these tests.
> >> > Adding these tests might catch future regression if anyone changes
> >> > f128
> >> > optimization.
> >> >
> >> >
> >> >>
> >> >> >
> >> >> > On the other hard, I was terrified by so many ad-hoc
> >> >> > optimizations of
> >> >> > floating points for the usage patterns in libm.
> >> >> > I guess llvm tried to match or do better then gcc and libm tried
> >> >> > to use
> >> >> > every possible bit operations.
> >> >> > So maybe it is better for Android or anyone depends on f128 type
> >> >> > to have
> >> >> > more check rules here.
> >> >> > Whoever changes float optimization in the future has better
> >> >> > fully
> >> >> > understand and update these tests.
> >> >>
> >> >> Maybe these complicated/fragile case do not belong here -- but
> >> >> somewhere downstream (libm).
> >> >
> >> >
> >> > Yes, AOSP bionic has already libm unit tests.
> >> > Most of my unit tests here are reduced from failed cases I hit with
> >> > my
> >> > incomplete work.
> >> > Now this patch passes all AOSP libm tests.
> >> >
> >> > It's difficult to expect all people changing LLVM floating points
> >> > run
> >> > through all libm tests for the Android target. So I do my best to
> >> > add more
> >> > unit tests here.
> >> >
> >>
> >> I suggest implementing __float128 in Clang as  follow up
> >
> > Nemanjai is already working on this (http://reviews.llvm.org/D15120).
> >
> >  -Hal
> >
> >> so that
> >> others can benefit from this feature other than Android.
> >>
> >> David
> >>
> >> > -- chh
> >> >
> >> >
> >> >>
> >> >>
> >> >> David
> >> >>
> >> >>
> >> >> >
> >> >> >
> >> >> >
> >> >> >
> >> >> > http://reviews.llvm.org/D11438
> >> >> >
> >> >> >
> >> >> >
> >> >
> >> >
> >> _______________________________________________
> >> llvm-commits mailing list
> >> llvm-commits at lists.llvm.org
> >> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
> >>
> >
> > --
> > Hal Finkel
> > Assistant Computational Scientist
> > Leadership Computing Facility
> > Argonne National Laboratory
>
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