nvk: Use load_global_constant for ubo loads

and support load_global_constant in nak

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24998>

src/nouveau/compiler/nak_from_nir.rs

@@ -1567,15 +1567,21 @@ impl<'a> ShaderFromNir<'a> {
             nir_intrinsic_load_barycentric_centroid => (),
             nir_intrinsic_load_barycentric_pixel => (),
             nir_intrinsic_load_barycentric_sample => (),
-            nir_intrinsic_load_global => {
+            nir_intrinsic_load_global | nir_intrinsic_load_global_constant => {
                 let size_B =
                     (intrin.def.bit_size() / 8) * intrin.def.num_components();
                 assert!(u32::from(size_B) <= intrin.align());
+                let order =
+                    if intrin.intrinsic == nir_intrinsic_load_global_constant {
+                        MemOrder::Constant
+                    } else {
+                        MemOrder::Strong(MemScope::System)
+                    };
                 let access = MemAccess {
                     addr_type: MemAddrType::A64,
                     mem_type: MemType::from_size(size_B, false),
                     space: MemSpace::Global,
-                    order: MemOrder::Strong(MemScope::System),
+                    order: order,
                 };
                 let (addr, offset) = self.get_io_addr_offset(&srcs[0], 32);
                 let dst = b.alloc_ssa(RegFile::GPR, size_B.div_ceil(4));

src/nouveau/compiler/nak_nir.c

@@ -813,7 +813,7 @@ nak_postprocess_nir(nir_shader *nir,
    }
 
    nir_lower_mem_access_bit_sizes_options mem_bit_size_options = {
-      .modes = nir_var_mem_ubo | nir_var_mem_generic,
+      .modes = nir_var_mem_constant | nir_var_mem_ubo | nir_var_mem_generic,
       .callback = nak_mem_access_size_align,
    };
    OPT(nir, nir_lower_mem_access_bit_sizes, &mem_bit_size_options);

src/nouveau/vulkan/nvk_nir_lower_descriptors.c

@@ -586,9 +586,9 @@ lower_load_ssbo_descriptor(nir_builder *b, nir_intrinsic_instr *intrin,
    case nir_address_format_64bit_global:
       /* Mask off the binding stride */
       addr = nir_iand_imm(b, addr, BITFIELD64_MASK(56));
-      desc = nir_build_load_global(b, 1, 64, addr,
-                                   .access = ACCESS_NON_WRITEABLE,
-                                   .align_mul = 16, .align_offset = 0);
+      desc = nir_build_load_global_constant(b, 1, 64, addr,
+                                            .align_mul = 16,
+                                            .align_offset = 0);
       break;
 
    case nir_address_format_64bit_global_32bit_offset: {

src/nouveau/vulkan/nvk_shader.c

@@ -239,12 +239,11 @@ lower_load_global_constant_offset_instr(nir_builder *b,
    }
 
    nir_def *val =
-      nir_build_load_global(b, intrin->def.num_components,
-                            intrin->def.bit_size,
-                            nir_iadd(b, base_addr, nir_u2u64(b, offset)),
-                            .access = nir_intrinsic_access(intrin),
-                            .align_mul = nir_intrinsic_align_mul(intrin),
-                            .align_offset = nir_intrinsic_align_offset(intrin));
+      nir_build_load_global_constant(b, intrin->def.num_components,
+                                     intrin->def.bit_size,
+                                     nir_iadd(b, base_addr, nir_u2u64(b, offset)),
+                                     .align_mul = nir_intrinsic_align_mul(intrin),
+                                     .align_offset = nir_intrinsic_align_offset(intrin));
 
    if (intrin->intrinsic == nir_intrinsic_load_global_constant_bounded) {
       nir_pop_if(b, NULL);