[Mesa-dev] [PATCH RFC 2/2] nir/lower_tex: Update ->sampler_dim value before calling get_texture_size()

[Jason Ekstrand]

On Mon, Jun 17, 2019 at 5:21 AM Boris Brezillon <
boris.brezillon at collabora.com> wrote:

> get_texture_size() will create a txs instruction with ->sampler_dim set
> to the original tex->sampler_dim. The condition to call lower_rect()
> only checks the value of ->sampler_dim and whether lower_rect is
> requested or not. This leads to an infinite loop when calling
> nir_lower_tex() with the same options until it returns false.
>
> In order to avoid that, let's move the tex->sampler_dim patching before
> get_texture_size() is called. This way the txs instruction will have
> ->sampler_dim set to GLSL_SAMPLER_DIM_2D and nir_lower_tex() won't try
> to lower it on the subsequent passes.
>
> Signed-off-by: Boris Brezillon <boris.brezillon at collabora.com>
> ---
> Another option would be to not call lower_rect() when the instruction
> is a txs op.
> ---
>  src/compiler/nir/nir_lower_tex.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/src/compiler/nir/nir_lower_tex.c
> b/src/compiler/nir/nir_lower_tex.c
> index 73b26dbdb238..1ee961dbb90c 100644
> --- a/src/compiler/nir/nir_lower_tex.c
> +++ b/src/compiler/nir/nir_lower_tex.c
> @@ -266,6 +266,8 @@ lower_offset(nir_builder *b, nir_tex_instr *tex)
>  static void
>  lower_rect(nir_builder *b, nir_tex_instr *tex)
>  {
> +   tex->sampler_dim = GLSL_SAMPLER_DIM_2D;
>

Mind throwing in a short comment?

/* Set the sampler_dim to 2D here so that get_texture_size picks up the
right dimensionality */

With that,

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


> +
>     nir_ssa_def *txs = get_texture_size(b, tex);
>     nir_ssa_def *scale = nir_frcp(b, txs);
>
> @@ -280,8 +282,6 @@ lower_rect(nir_builder *b, nir_tex_instr *tex)
>                              &tex->src[i].src,
>                              nir_src_for_ssa(nir_fmul(b, coords, scale)));
>     }
> -
> -   tex->sampler_dim = GLSL_SAMPLER_DIM_2D;
>  }
>
>  static void
> --
> 2.20.1
>
>
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