[Libclc-dev] [PATCH] Add vstore_half helpers for ptx

Tue Oct 3 13:37:30 PDT 2017

> On 3 Oct 2017, at 22:20, Jan Vesely <jan.vesely at rutgers.edu> wrote:
> 
> On Tue, 2017-10-03 at 22:04 +0200, Jeroen Ketema via Libclc-dev wrote:
>> Hi Jan,
>> 
>>> On 3 Oct 2017, at 21:57, Jan Vesely <jan.vesely at rutgers.edu> wrote:
>>> 
>>> On Tue, 2017-10-03 at 20:26 +0200, Jeroen Ketema via Libclc-dev wrote:
>>>> Index: ptx/lib/SOURCES_4.0
>>>> ===================================================================
>>>> --- ptx/lib/SOURCES_4.0	(nonexistent)
>>>> +++ ptx/lib/SOURCES_4.0	(working copy)
>>>> @@ -0,0 +1 @@
>>>> +shared/vstore_half_helpers.ll
>>>> Index: ptx/lib/SOURCES_5.0
>>>> ===================================================================
>>>> --- ptx/lib/SOURCES_5.0	(nonexistent)
>>>> +++ ptx/lib/SOURCES_5.0	(working copy)
>>> 
>>> you probably need SOURCES_3.9 as well.
>>> or add a comment why it's not needed.
>> 
>> Yes, if we’re supporting that. I don’t know what the current policy/status is?
> 
> llvm-3.9 support was restored last week. I don't have a testing setup
> but the generated library is sane (there's even a travis CI to check
> that).

Ok, I’ll add that. Was there any particular reason it was restored? In the past
libclc generally only supported the tip of the Clang/LLVM tree.

> 
>> 
>>> 
>>>> @@ -0,0 +1 @@
>>>> +shared/vstore_half_helpers.ll
>>>> Index: ptx/lib/shared/vstore_half_helpers.ll
>>>> ===================================================================
>>>> --- ptx/lib/shared/vstore_half_helpers.ll	(nonexistent)
>>>> +++ ptx/lib/shared/vstore_half_helpers.ll	(working copy)
>>> 
>>> can you add datalayout, or would it prevent sharing the file between
>>> ptx and ptx64?
>> 
>> That would prevent sharing. I wonder if we might come up with some kind of solution
>> that adds the data layout at configuration or compilation time?
> 
> I was considering passing .ll files through c preprocessor (clang -E
> with the same options as .cl compilation), so that you can use things
> like #ifdef and #include.
> It should not be a lot of work, and it'd allow us to share .ll files
> without linker complaints.

I’m a bit hesitant about (ab)using the preprocessor. Although this is a simple
use case, I’ve seen more advanced uses lead to problems in the past, e.g.,
the ghc compiler at some point stopped working on MacOS, because
clang’s preprocessor diverged from gcc’s.

> 
>> 
>>> I assume GENERIC == private and SHARED == local?
>> 
>> Correct.
> 
> just out of curiosity. what's your use case for nvptx libclc?

GPUVerify: http://multicore.doc.ic.ac.uk/tools/GPUVerify/

We use clang to compile CUDA and OpenCL down to bitcode for the NVPTX
target (linking with libclc in the latter case) before feeding it to the tool proper.

Jeroen

> 
> Jan
> 
>> 
>> Thanks for the review,
>> 
>> Jeroen
>> 
>>> 
>>> other than that
>>> Reviewed-by: Jan Vesely <jan.vesely at rutgers.edu <mailto:jan.vesely at rutgers.edu> <mailto:jan.vesely at rutgers.edu <mailto:jan.vesely at rutgers.edu>>>
>>> 
>>> Jan
>>> 
>>>> @@ -0,0 +1,35 @@
>>>> +define void @__clc_vstore_half_float_helper__private(float %data, half addrspace(0)* nocapture %ptr) nounwind alwaysinline {
>>>> +  %res = fptrunc float %data to half
>>>> +  store half %res, half addrspace(0)* %ptr
>>>> +  ret void
>>>> +}
>>>> +
>>>> +define void @__clc_vstore_half_float_helper__global(float %data, half addrspace(1)* nocapture %ptr) nounwind alwaysinline {
>>>> +  %res = fptrunc float %data to half
>>>> +  store half %res, half addrspace(1)* %ptr
>>>> +  ret void
>>>> +}
>>>> +
>>>> +define void @__clc_vstore_half_float_helper__local(float %data, half addrspace(3)* nocapture %ptr) nounwind alwaysinline {
>>>> +  %res = fptrunc float %data to half
>>>> +  store half %res, half addrspace(3)* %ptr
>>>> +  ret void
>>>> +}
>>>> +
>>>> +define void @__clc_vstore_half_double_helper__private(double %data, half addrspace(0)* nocapture %ptr) nounwind alwaysinline {
>>>> +  %res = fptrunc double %data to half
>>>> +  store half %res, half addrspace(0)* %ptr
>>>> +  ret void
>>>> +}
>>>> +
>>>> +define void @__clc_vstore_half_double_helper__global(double %data, half addrspace(1)* nocapture %ptr) nounwind alwaysinline {
>>>> +  %res = fptrunc double %data to half
>>>> +  store half %res, half addrspace(1)* %ptr
>>>> +  ret void
>>>> +}
>>>> +
>>>> +define void @__clc_vstore_half_double_helper__local(double %data, half addrspace(3)* nocapture %ptr) nounwind alwaysinline {
>>>> +  %res = fptrunc double %data to half
>>>> +  store half %res, half addrspace(3)* %ptr
>>>> +  ret void
>>>> +}
>>>> 
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>>> 
>>> -- 
>>> Jan Vesely <jan.vesely at rutgers.edu <mailto:jan.vesely at rutgers.edu> <mailto:jan.vesely at rutgers.edu <mailto:jan.vesely at rutgers.edu>>>
>> 
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> 
> -- 
> Jan Vesely <jan.vesely at rutgers.edu <mailto:jan.vesely at rutgers.edu>>

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