[Mesa-dev] [PATCH 4/6] nir/lower_tex: support for lowering RECT textures

[Kenneth Graunke]

On Friday, September 18, 2015 10:55:07 AM Rob Clark wrote:
> From: Rob Clark <robclark at freedesktop.org>
> 
> v2: comments/suggestions from Ilia and Eric, split out get_texture_size()
> helper so we can use it in the next commit for clamping RECT textures.
> 
> Signed-off-by: Rob Clark <robclark at freedesktop.org>
> ---
>  src/glsl/nir/nir.h           |  7 +++++
>  src/glsl/nir/nir_lower_tex.c | 62 +++++++++++++++++++++++++++++++++++++++++---
>  2 files changed, 66 insertions(+), 3 deletions(-)
> 
> diff --git a/src/glsl/nir/nir.h b/src/glsl/nir/nir.h
> index 4600fb0..3c908b9 100644
> --- a/src/glsl/nir/nir.h
> +++ b/src/glsl/nir/nir.h
> @@ -1843,6 +1843,13 @@ typedef struct nir_lower_tex_options {
>      * sampler types a texture projector is lowered.
>      */
>     unsigned lower_txp;
> +
> +   /**
> +    * If true, lower rect textures to 2D, using txs to fetch the
> +    * texture dimensions and dividing the texture coords by the
> +    * texture dims to normalize.
> +    */
> +   bool lower_rect;
>  } nir_lower_tex_options;
>  
>  void nir_lower_tex(nir_shader *shader,
> diff --git a/src/glsl/nir/nir_lower_tex.c b/src/glsl/nir/nir_lower_tex.c
> index 281fc9f..a71a5c5 100644
> --- a/src/glsl/nir/nir_lower_tex.c
> +++ b/src/glsl/nir/nir_lower_tex.c
> @@ -22,9 +22,13 @@
>   */
>  
>  /*
> - * This lowering pass converts the coordinate division for texture projection
> - * to be done in ALU instructions instead of asking the texture operation to
> - * do so.
> + * This lowering pass supports (as configured via nir_lower_tex_options)
> + * various texture related conversions:
> + *   + texture projector lowering: converts the coordinate division for
> + *     texture projection to be done in ALU instructions instead of
> + *     asking the texture operation to do so.
> + *   + lowering RECT: converts the un-normalized RECT texture coordinates
> + *     to normalized coordinates with txs plus ALU instructions
>   */
>  
>  #include "nir.h"
> @@ -111,6 +115,55 @@ project_src(nir_builder *b, nir_tex_instr *tex)
>     tex->num_srcs--;
>  }
>  
> +static nir_ssa_def *
> +get_texture_size(nir_builder *b, nir_tex_instr *tex)
> +{
> +   b->cursor = nir_before_instr(&tex->instr);
> +
> +   /* RECT textures should not be array: */
> +   assert(!tex->is_array);
> +
> +   nir_tex_instr *txs;
> +
> +   txs = nir_tex_instr_create(b->shader, 1);
> +   txs->op = nir_texop_txs;
> +   txs->sampler_dim = GLSL_SAMPLER_DIM_RECT;
> +   txs->sampler_index = tex->sampler_index;
> +
> +   /* only single src, the lod: */
> +   txs->src[0].src = nir_src_for_ssa(nir_imm_int(b, 0));
> +   txs->src[0].src_type = nir_tex_src_lod;
> +
> +   nir_ssa_dest_init(&txs->instr, &txs->dest, 3, NULL);

Shouldn't this be 2? textureSize of 2DRect returns an ivec2...

> +   nir_builder_instr_insert(b, &txs->instr);
> +
> +   return nir_i2f(b, &txs->dest.ssa);
> +}
> +
> +static void
> +lower_rect(nir_builder *b, nir_tex_instr *tex)
> +{
> +   nir_ssa_def *txs = get_texture_size(b, tex);
> +
> +   nir_ssa_def *scalex = nir_frcp(b, nir_channel(b, txs, 0));
> +   nir_ssa_def *scaley = nir_frcp(b, nir_channel(b, txs, 1));
> +   nir_ssa_def *scale  = nir_vec2(b, scalex, scaley);

Why not just do 1 / txs.xy directly?

unsigned swizzle[4] = { SWIZZLE_X, SWIZZLE_Y, SWIZZLE_Y, SWIZZLE_Y };
nir_ssa_def *scale = nir_frcp(b, nir_swizzle(b, txs, swizzle, 2, false);

> +
> +   /* Walk through the sources normalizing the requested arguments. */
> +   for (unsigned i = 0; i < tex->num_srcs; i++) {
> +      if (tex->src[i].src_type != nir_tex_src_coord)
> +         continue;
> +
> +      nir_ssa_def *coords =
> +         nir_ssa_for_src(b, tex->src[i].src, tex->coord_components);
> +      nir_instr_rewrite_src(&tex->instr,
> +                            &tex->src[i].src,
> +                            nir_src_for_ssa(nir_fmul(b, coords, scale)));
> +   }
> +
> +   tex->sampler_dim = GLSL_SAMPLER_DIM_2D;
> +}
> +
>  static bool
>  nir_lower_tex_block(nir_block *block, void *void_state)
>  {
> @@ -127,6 +180,9 @@ nir_lower_tex_block(nir_block *block, void *void_state)
>        if (lower_txp)
>           project_src(b, tex);
>  
> +      if ((tex->sampler_dim == GLSL_SAMPLER_DIM_RECT) &&

Please remove the bonus parens.

> +          state->options->lower_rect)
> +         lower_rect(b, tex);
>     }
>  
>     return true;
> 

With the ivec2/ivec3 thing fixed, this would be:
Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 819 bytes
Desc: This is a digitally signed message part.
URL: <http://lists.freedesktop.org/archives/mesa-dev/attachments/20150918/74f98805/attachment.sig>