nir: add has_txs flag

Some nir lowerings might need to know if txs is supported by
the backend.

Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8898>

src/compiler/nir/nir.h

@@ -3387,6 +3387,10 @@ typedef struct nir_shader_compiler_options {
     * iadd(x, ineg(y)). If true, driver should call nir_opt_algebraic_late(). */
    bool has_isub;
 
+   /** Backend supports txs, if not nir_lower_tex(..) uses txs-free variants
+    * for rect texture lowering. */
+   bool has_txs;
+
    /* Whether to generate only scoped_barrier intrinsics instead of the set of
     * memory and control barrier intrinsics based on GLSL.
     */

src/intel/compiler/brw_compiler.c

@@ -49,7 +49,8 @@
    .lower_base_vertex = true,                                                 \
    .use_scoped_barrier = true,                                                \
    .support_16bit_alu = true,                                                 \
-   .lower_uniforms_to_ubo = true
+   .lower_uniforms_to_ubo = true,                                             \
+   .has_txs = true
 
 #define COMMON_SCALAR_OPTIONS                                                 \
    .lower_to_scalar = true,                                                   \

src/microsoft/compiler/nir_to_dxil.c

@@ -104,6 +104,7 @@ nir_options = {
    .vertex_id_zero_based = true,
    .lower_base_vertex = true,
    .has_cs_global_id = true,
+   .has_txs = true,
 };
 
 const nir_shader_compiler_options*