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

[Xinliang David Li via llvm-commits]

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 so that
others can benefit from this feature other than Android.

David

> -- chh
>
>
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>> David
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>> >
>> > http://reviews.llvm.org/D11438
>> >
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