[Mesa-stable] [PATCH] intel/compiler: do not copy-propagate strided regions to ddx/ddy arguments

[Jason Ekstrand]

On Tue, Dec 11, 2018 at 5:22 AM Iago Toral Quiroga <itoral at igalia.com>
wrote:

> The implementation of these opcodes in the generator assumes that their
> arguments are packed, and it generates register regions based on that
> assumption.
>
> Reviewed-by: Jason Ekstrand <jason at jlekstrand.net>
> ---
> Although this patch hasn't landed in master yet (it is part of a larger
> series
> that is still in review), Jason suggested to backport it to stable. I
> guess it
> might be a good idea to land it early in master too if we are doing this
> though.
>

No reason it can't land in master early.  Probably best to land in master
before stable anyway.

--Jason


>  .../compiler/brw_fs_copy_propagation.cpp      | 21 +++++++++++++++++++
>  1 file changed, 21 insertions(+)
>
> diff --git a/src/intel/compiler/brw_fs_copy_propagation.cpp
> b/src/intel/compiler/brw_fs_copy_propagation.cpp
> index ab34b63748..a8ec1c3463 100644
> --- a/src/intel/compiler/brw_fs_copy_propagation.cpp
> +++ b/src/intel/compiler/brw_fs_copy_propagation.cpp
> @@ -361,6 +361,20 @@ can_take_stride(fs_inst *inst, unsigned arg, unsigned
> stride,
>     return true;
>  }
>
> +static bool
> +instruction_requires_packed_data(fs_inst *inst)
> +{
> +   switch (inst->opcode) {
> +   case FS_OPCODE_DDX_FINE:
> +   case FS_OPCODE_DDX_COARSE:
> +   case FS_OPCODE_DDY_FINE:
> +   case FS_OPCODE_DDY_COARSE:
> +      return true;
> +   default:
> +      return false;
> +   }
> +}
> +
>  bool
>  fs_visitor::try_copy_propagate(fs_inst *inst, int arg, acp_entry *entry)
>  {
> @@ -407,6 +421,13 @@ fs_visitor::try_copy_propagate(fs_inst *inst, int
> arg, acp_entry *entry)
>         inst->opcode == SHADER_OPCODE_GEN4_SCRATCH_WRITE)
>        return false;
>
> +   /* Some instructions implemented in the generator backend, such as
> +    * derivatives, assume that their operands are packed so we can't
> +    * generally propagate strided regions to them.
> +    */
> +   if (instruction_requires_packed_data(inst) && entry->src.stride > 1)
> +      return false;
> +
>     /* Bail if the result of composing both strides would exceed the
>      * hardware limit.
>      */
> --
> 2.17.1
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.freedesktop.org/archives/mesa-stable/attachments/20181211/a563e610/attachment.html>