[Mesa-dev] [PATCH RFC 1/2] nir/lower_tex: Actually report when projector lowering happened

[Jason Ekstrand]

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

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

> The code considers that projector lowering was done even if it's not
> really the case. Change the project_src() prototype to return a bool
> encoding whether projector lowering happened or not and update the
> progress var accordingly in nir_lower_tex_block().
>
> This prevents an infinite loop when doing:
>
>         do progress = nir_lower_tex(); while (progress);
>
> Signed-off-by: Boris Brezillon <boris.brezillon at collabora.com>
> ---
>  src/compiler/nir/nir_lower_tex.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/src/compiler/nir/nir_lower_tex.c
> b/src/compiler/nir/nir_lower_tex.c
> index c29581d9b048..73b26dbdb238 100644
> --- a/src/compiler/nir/nir_lower_tex.c
> +++ b/src/compiler/nir/nir_lower_tex.c
> @@ -39,13 +39,13 @@
>  #include "nir_builder.h"
>  #include "nir_format_convert.h"
>
> -static void
> +static bool
>  project_src(nir_builder *b, nir_tex_instr *tex)
>  {
>     /* Find the projector in the srcs list, if present. */
>     int proj_index = nir_tex_instr_src_index(tex, nir_tex_src_projector);
>     if (proj_index < 0)
> -      return;
> +      return false;
>
>     b->cursor = nir_before_instr(&tex->instr);
>
> @@ -100,6 +100,7 @@ project_src(nir_builder *b, nir_tex_instr *tex)
>     }
>
>     nir_tex_instr_remove_src(tex, proj_index);
> +   return true;
>  }
>
>  static nir_ssa_def *
> @@ -1049,8 +1050,7 @@ nir_lower_tex_block(nir_block *block, nir_builder *b,
>         * as clamping happens *after* projection:
>         */
>        if (lower_txp || sat_mask) {
> -         project_src(b, tex);
> -         progress = true;
> +         progress |= project_src(b, tex);
>        }
>
>        if ((tex->op == nir_texop_txf && options->lower_txf_offset) ||
> --
> 2.20.1
>
>
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