[Mesa-dev] [PATCH] nir: special hack for TGSI vs indirect inputs

[Ilia Mirkin]

Are you looking for PIPE_SHADER_CAP_TGSI_ANY_INOUT_DECL_RANGE perchance?

On Mon, Jan 11, 2016 at 11:44 AM, Rob Clark <robdclark at gmail.com> wrote:
> From: Rob Clark <robclark at freedesktop.org>
>
> TGSI doesn't know about array input (or output[*]) variables.  If the
> INPUT file is addressed indirectly, we must treat the entire INPUT
> "register file" as one contiguous array.  However tgsi_to_nir cannot
> declare all the inputs as a single array var, as this would loose
> varying slot and interpolation info.
>
> This hack provides the extra information that the compiler backend
> needs so that all the N inputs can be organized as a single array for
> direct and indirect access.
>
> [*] tgsi_to_nir does not generate indirect output stores, otherwise we
> would need a similar hack for outputs
>
> Signed-off-by: Rob Clark <robclark at freedesktop.org>
> ---
> Yes, sorry, I know, TGSI is horrible.  But I don't really have any
> better ideas about how to handle this.
>
>  src/gallium/auxiliary/nir/tgsi_to_nir.c |  3 +++
>  src/glsl/nir/nir.h                      | 14 ++++++++++++++
>  2 files changed, 17 insertions(+)
>
> diff --git a/src/gallium/auxiliary/nir/tgsi_to_nir.c b/src/gallium/auxiliary/nir/tgsi_to_nir.c
> index 94d992b..4a57f9e 100644
> --- a/src/gallium/auxiliary/nir/tgsi_to_nir.c
> +++ b/src/gallium/auxiliary/nir/tgsi_to_nir.c
> @@ -1973,6 +1973,9 @@ tgsi_to_nir(const void *tgsi_tokens,
>                                    options);
>     s = c->build.shader;
>
> +   if (c->scan->indirect_files & (1 << TGSI_FILE_INPUT))
> +      s->info.tgsi_hack_indirect_inputs = true;
> +
>     s->num_inputs = scan.file_max[TGSI_FILE_INPUT] + 1;
>     s->num_uniforms = scan.const_file_max[0] + 1;
>     s->num_outputs = scan.file_max[TGSI_FILE_OUTPUT] + 1;
> diff --git a/src/glsl/nir/nir.h b/src/glsl/nir/nir.h
> index bedcc0d..629c32f 100644
> --- a/src/glsl/nir/nir.h
> +++ b/src/glsl/nir/nir.h
> @@ -1510,6 +1510,20 @@ typedef struct nir_shader_info {
>     /** Was this shader linked with any transform feedback varyings? */
>     bool has_transform_feedback_varyings;
>
> +   /**
> +    * Special hack for tgsi_to_nir.  Due to limitations in TGSI, when
> +    * there is indirect addressing of the input file, we don't actually
> +    * know which inputs are part of an array and which are not.  We
> +    * cannot convert all the inputs to a single array (which maps to
> +    * TGSI's IN[ADDR[0].x+n] semantics), since we need the varying-slot
> +    * and interpolation information still.
> +    *
> +    * NOTE that tgsi_to_nir doesn't generate indirect output_store's,
> +    * otherwise we would need a similar flag to indicate indirect
> +    * output file addressing.
> +    */
> +   bool tgsi_hack_indirect_inputs;
> +
>     union {
>        struct {
>           /** The number of vertices recieves per input primitive */
> --
> 2.5.0
>
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