[Mesa-dev] 3 element vectors in opencl 1.1+

[Tom Stellard]

On Mon, Apr 21, 2014 at 10:02:27PM -0400, Jan Vesely wrote:
> Hi,
> 
> I ran into a problem caused by this part of the OCL specs (6.1.5
> Alignment of Types):
> "For 3-component vector data types, the size of the data type is 4 *
> sizeof(component)."
> 
> and the corresponding part of Khronos cl_platform.h (with all types, not
> just float):
> /* cl_float3 is identical in size, alignment and behavior to cl_float4.
> See section 6.1.5. */
> typedef  cl_float4  cl_float3;
> 
> So when I try to run kernel that takes 3 element vectors as arguments I
> get 'invalid arg size' error.
> 
> Not sure whether this is best solved in clang, libclc or clover. I tried
> changing float3 to have 4 elements in libclc, it caused clang to
> complain in thousand places. I don't think this can be handled cleanly
> in clang, unless we add something like __attribute__((padding)).
> 
> I have attached a workaround that I use now.
> 

You may want to ask this question on the pocl mailing list as they
have likely solved this issue already.  Ideally, TD.getTypeStoreSize
would return the correct value.  Also, maybe look at the DataLayout
description for R600 and see if there is a way to specify the
correct type size.

-Tom

> any advice welcome,
> Jan
> 
> -- 
> Jan Vesely <jan.vesely at rutgers.edu>

> diff --git a/src/gallium/state_trackers/clover/llvm/invocation.cpp b/src/gallium/state_trackers/clover/llvm/invocation.cpp
> index a81bdf8..71ee01f 100644
> --- a/src/gallium/state_trackers/clover/llvm/invocation.cpp
> +++ b/src/gallium/state_trackers/clover/llvm/invocation.cpp
> @@ -62,6 +62,8 @@
>  #include <llvm/IR/DataLayout.h>
>  #endif
>  
> +#include <llvm/Support/Debug.h>
> +
>  #include "pipe/p_state.h"
>  #include "util/u_memory.h"
>  
> @@ -309,6 +311,13 @@ namespace {
>  
>              llvm::Type *arg_type = arg.getType();
>              unsigned arg_size = TD.getTypeStoreSize(arg_type);
> +            if (arg_type->isVectorTy() &&
> +               ::llvm::cast<::llvm::VectorType>(arg_type)->getNumElements() == 3) {
> +               ::llvm::dbgs() << "Fixing argument type: " << *arg_type
> +                              << " size: " << arg_size << "->"
> +                              << (arg_size / 3) * 4 << "\n";
> +               arg_size = (arg_size / 3) * 4;
> +            }
>  
>              llvm::Type *target_type = arg_type->isIntegerTy() ?
>                 TD.getSmallestLegalIntType(mod->getContext(), arg_size * 8) :




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