nir: add nir_intrinsic_load_vrs_rates_amd

This intrinsic specific to RADV will be used to load VRS rates from
an user SGPR when RADV_FORCE_VRS is enabled by the application.

Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Timur Kristóf <timur.kristof@gmail.com>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/14713>

src/compiler/nir/nir_divergence_analysis.c

@@ -156,6 +156,7 @@ visit_intrinsic(nir_shader *shader, nir_intrinsic_instr *instr)
    case nir_intrinsic_load_cull_any_enabled_amd:
    case nir_intrinsic_load_cull_small_prim_precision_amd:
    case nir_intrinsic_load_user_data_amd:
+   case nir_intrinsic_load_force_vrs_rates_amd:
    case nir_intrinsic_load_tess_level_inner_default:
    case nir_intrinsic_load_tess_level_outer_default:
       is_divergent = false;

src/compiler/nir/nir_intrinsics.py

@@ -1275,6 +1275,9 @@ system_value("rt_arg_scratch_offset_amd", 1)
 # Whether to call the anyhit shader for an intersection in an intersection shader.
 system_value("intersection_opaque_amd", 1, bit_sizes=[1])
 
+# Load forced VRS rates.
+intrinsic("load_force_vrs_rates_amd", dest_comp=1, bit_sizes=[32], flags=[CAN_ELIMINATE, CAN_REORDER])
+
 # V3D-specific instrinc for tile buffer color reads.
 #
 # The hardware requires that we read the samples and components of a pixel