spirv: Add support for using derefs for UBO/SSBO access

For now, it's hidden behind a cap.  Hopefully, we can eventually drop
that along with all the manual offset code in spirv_to_nir.

Reviewed-by: Alejandro Piñeiro <apinheiro@igalia.com>
Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira@intel.com>
Tested-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>

src/amd/vulkan/radv_shader.c

@@ -219,6 +219,7 @@ radv_shader_compile_to_nir(struct radv_device *device,
 			}
 		}
 		const struct spirv_to_nir_options spirv_options = {
+			.lower_ubo_ssbo_access_to_offsets = true,
 			.caps = {
 				.device_group = true,
 				.draw_parameters = true,

src/compiler/nir/nir_intrinsics.py

@@ -364,6 +364,8 @@ def image(name, src_comp=[], **kwargs):
           flags=[CAN_ELIMINATE, CAN_REORDER])
 intrinsic("vulkan_resource_reindex", src_comp=[1, 1], dest_comp=1,
           indices=[DESC_TYPE], flags=[CAN_ELIMINATE, CAN_REORDER])
+intrinsic("load_vulkan_descriptor", src_comp=[1], dest_comp=0,
+          indices=[DESC_TYPE], flags=[CAN_ELIMINATE, CAN_REORDER])
 
 # variable atomic intrinsics
 #

src/compiler/spirv/nir_spirv.h

@@ -59,6 +59,9 @@ struct spirv_to_nir_options {
     */
    bool lower_workgroup_access_to_offsets;
 
+   /* Whether or not to lower all UBO/SSBO access to offsets up-front. */
+   bool lower_ubo_ssbo_access_to_offsets;
+
    struct spirv_supported_capabilities caps;
 
    /* Storage types for various kinds of pointers. */

src/compiler/spirv/spirv_to_nir.c

@@ -567,7 +567,7 @@ struct member_decoration_ctx {
  * Returns true if the given type contains a struct decorated Block or
  * BufferBlock
  */
-static bool
+bool
 vtn_type_contains_block(struct vtn_builder *b, struct vtn_type *type)
 {
    switch (type->base_type) {

src/compiler/spirv/vtn_private.h

@@ -378,6 +378,8 @@ struct vtn_type {
    };
 };
 
+bool vtn_type_contains_block(struct vtn_builder *b, struct vtn_type *type);
+
 bool vtn_types_compatible(struct vtn_builder *b,
                           struct vtn_type *t1, struct vtn_type *t2);