spirv: Implement the function portion of the Linkage capability

Acked-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/15486>

src/compiler/shader_info.h

@@ -72,6 +72,7 @@ struct spirv_supported_capabilities {
    bool kernel;
    bool kernel_image;
    bool kernel_image_read_write;
+   bool linkage;
    bool literal_sampler;
    bool mesh_shading_nv;
    bool min_lod;

src/compiler/spirv/spirv_to_nir.c

@@ -433,7 +433,7 @@ vtn_get_sampled_image(struct vtn_builder *b, uint32_t value_id)
    return si;
 }
 
-static const char *
+const char *
 vtn_string_literal(struct vtn_builder *b, const uint32_t *words,
                    unsigned word_count, unsigned *words_used)
 {
@@ -681,6 +681,7 @@ vtn_handle_decoration(struct vtn_builder *b, SpvOp opcode,
          unreachable("Invalid decoration opcode");
       }
       dec->decoration = *(w++);
+      dec->num_operands = w_end - w;
       dec->operands = w;
 
       /* Link into the list */
@@ -4482,6 +4483,8 @@ vtn_handle_preamble_instruction(struct vtn_builder *b, SpvOp opcode,
          if (!b->options->create_library)
             vtn_warn("Unsupported SPIR-V capability: %s",
                      spirv_capability_to_string(cap));
+         spv_check_supported(linkage, cap);
+         vtn_warn("The SPIR-V Linkage capability is not fully supported");
          break;
 
       case SpvCapabilitySparseResidency:

src/compiler/spirv/vtn_cfg.c

@@ -148,6 +148,29 @@ vtn_handle_function_call(struct vtn_builder *b, SpvOp opcode,
    }
 }
 
+static void
+function_decoration_cb(struct vtn_builder *b, struct vtn_value *val, int member,
+                       const struct vtn_decoration *dec, void *void_func)
+{
+   struct vtn_function *func = void_func;
+
+   switch (dec->decoration) {
+   case SpvDecorationLinkageAttributes: {
+      unsigned name_words;
+      const char *name =
+         vtn_string_literal(b, dec->operands, dec->num_operands, &name_words);
+      vtn_fail_if(name_words >= dec->num_operands,
+                  "Malformed LinkageAttributes decoration");
+      (void)name; /* TODO: What is this? */
+      func->linkage = dec->operands[name_words];
+      break;
+   }
+
+   default:
+      break;
+   }
+}
+
 static bool
 vtn_cfg_handle_prepass_instruction(struct vtn_builder *b, SpvOp opcode,
                                    const uint32_t *w, unsigned count)
@@ -160,12 +183,15 @@ vtn_cfg_handle_prepass_instruction(struct vtn_builder *b, SpvOp opcode,
       b->func->node.type = vtn_cf_node_type_function;
       b->func->node.parent = NULL;
       list_inithead(&b->func->body);
+      b->func->linkage = SpvLinkageTypeMax;
       b->func->control = w[3];
 
       UNUSED const struct glsl_type *result_type = vtn_get_type(b, w[1])->type;
       struct vtn_value *val = vtn_push_value(b, w[2], vtn_value_type_function);
       val->func = b->func;
 
+      vtn_foreach_decoration(b, val, function_decoration_cb, b->func);
+
       b->func->type = vtn_get_type(b, w[4]);
       const struct vtn_type *func_type = b->func->type;
 
@@ -221,10 +247,19 @@ vtn_cfg_handle_prepass_instruction(struct vtn_builder *b, SpvOp opcode,
    case SpvOpFunctionEnd:
       b->func->end = w;
       if (b->func->start_block == NULL) {
+         vtn_fail_if(b->func->linkage != SpvLinkageTypeImport,
+                     "A function declaration (an OpFunction with no basic "
+                     "blocks), must have a Linkage Attributes Decoration "
+                     "with the Import Linkage Type.");
+
          /* In this case, the function didn't have any actual blocks.  It's
           * just a prototype so delete the function_impl.
           */
          b->func->nir_func->impl = NULL;
+      } else {
+         vtn_fail_if(b->func->linkage == SpvLinkageTypeImport,
+                     "A function definition (an OpFunction with basic blocks) "
+                     "cannot be decorated with the Import Linkage Type.");
       }
       b->func = NULL;
       break;

src/compiler/spirv/vtn_opencl.c

@@ -812,8 +812,7 @@ handle_printf(struct vtn_builder *b, uint32_t opcode,
       glsl_struct_type(fields, num_srcs - 1, "printf", true);
 
    /* Step 3, create a variable of that type and populate its fields */
-   nir_variable *var = nir_local_variable_create(b->func->nir_func->impl,
-                                                 struct_type, NULL);
+   nir_variable *var = nir_local_variable_create(b->nb.impl, struct_type, NULL);
    nir_deref_instr *deref_var = nir_build_deref_var(&b->nb, var);
    size_t fmt_pos = 0;
    for (unsigned i = 1; i < num_srcs; ++i) {

src/compiler/spirv/vtn_private.h

@@ -274,6 +274,7 @@ struct vtn_function {
 
    const uint32_t *end;
 
+   SpvLinkageType linkage;
    SpvFunctionControlMask control;
 };
 
@@ -646,6 +647,7 @@ struct vtn_decoration {
     */
    int scope;
 
+   uint32_t num_operands;
    const uint32_t *operands;
    struct vtn_value *group;
 
@@ -743,6 +745,10 @@ struct vtn_builder {
    unsigned mem_model;
 };
 
+const char *
+vtn_string_literal(struct vtn_builder *b, const uint32_t *words,
+                   unsigned word_count, unsigned *words_used);
+
 nir_ssa_def *
 vtn_pointer_to_ssa(struct vtn_builder *b, struct vtn_pointer *ptr);
 struct vtn_pointer *