[Mesa-dev] [PATCH 32/59] intel/compiler: fix 16-bit float ddx and ddy for SIMD8

[Jason Ekstrand]

And here we are.... I think I'd still like byte_offset better but, either
way patches 31 and 32 are

Reviewed-by: Jason Ekstrand <jason at jlekstrand.net>

On Tue, Dec 4, 2018 at 1:18 AM Iago Toral Quiroga <itoral at igalia.com> wrote:

> In SIMD8 we pack 2 vector components in a single SIMD register, so
> for example, component Y of a 16-bit vec2 starts is at byte offset
> 16B. This means that when we compute the offset of the elements to
> be differentiated we should not stomp whatever base offset we have,
> but instead add to it.
> ---
>  src/intel/compiler/brw_fs_generator.cpp | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/src/intel/compiler/brw_fs_generator.cpp
> b/src/intel/compiler/brw_fs_generator.cpp
> index bffd9bc4787..d8e4bae17e0 100644
> --- a/src/intel/compiler/brw_fs_generator.cpp
> +++ b/src/intel/compiler/brw_fs_generator.cpp
> @@ -1259,7 +1259,7 @@ fs_generator::generate_ddx(const fs_inst *inst,
>     struct brw_reg src0 = src;
>     struct brw_reg src1 = src;
>
> -   src0.subnr   = type_sz(src.type);
> +   src0.subnr  += type_sz(src.type);
>     src0.vstride = vstride;
>     src0.width   = width;
>     src0.hstride = BRW_HORIZONTAL_STRIDE_0;
> @@ -1325,8 +1325,8 @@ fs_generator::generate_ddy(const fs_inst *inst,
>        /* replicate the derivative at the top-left pixel to other pixels */
>        struct brw_reg src0 = stride(src, 4, 4, 0);
>        struct brw_reg src1 = stride(src, 4, 4, 0);
> -      src0.subnr = 0 * type_size;
> -      src1.subnr = 2 * type_size;
> +      src0.subnr += 0 * type_size;
> +      src1.subnr += 2 * type_size;
>
>        brw_ADD(p, dst, negate(src0), src1);
>     }
> --
> 2.17.1
>
> _______________________________________________
> mesa-dev mailing list
> mesa-dev at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/mesa-dev
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.freedesktop.org/archives/mesa-dev/attachments/20181207/6b9ff434/attachment.html>