radv: start conditionalising vertex inputs. (v2)

In practice this will probably just drop draw id in a few places.

v2: just do draw_id for now. (Bas)
it might be possible to do something more if we need it in the
future. (nha)

Reviewed-by: Bas Nieuwenhuizen <[email protected]>
Signed-off-by: Dave Airlie <[email protected]>

3 files changed, 43 insertions, 8 deletions

diff --git a/src/amd/common/ac_nir_to_llvm.c b/src/amd/common/ac_nir_to_llvm.c
index dbb3b67b511..31b772f5669 100644
--- a/src/amd/common/ac_nir_to_llvm.c
+++ b/src/amd/common/ac_nir_to_llvm.c
@@ -614,10 +614,12 @@ static void create_function(struct nir_to_llvm_context *ctx)
 		break;
 	case MESA_SHADER_VERTEX:
 		if (!ctx->is_gs_copy_shader) {
-			arg_types[arg_idx++] = const_array(ctx->v16i8, 16); /* vertex buffers */
+			if (ctx->shader_info->info.vs.has_vertex_buffers)
+				arg_types[arg_idx++] = const_array(ctx->v16i8, 16); /* vertex buffers */
 			arg_types[arg_idx++] = ctx->i32; // base vertex
 			arg_types[arg_idx++] = ctx->i32; // start instance
-			arg_types[arg_idx++] = ctx->i32; // draw index
+			if (ctx->shader_info->info.vs.needs_draw_id)
+					arg_types[arg_idx++] = ctx->i32; // draw index
 		}
 		user_sgpr_count = arg_idx;
 		if (ctx->options->key.vs.as_es)
@@ -773,14 +775,22 @@ static void create_function(struct nir_to_llvm_context *ctx)
 		break;
 	case MESA_SHADER_VERTEX:
 		if (!ctx->is_gs_copy_shader) {
-			set_userdata_location_shader(ctx, AC_UD_VS_VERTEX_BUFFERS, user_sgpr_idx, 2);
-			user_sgpr_idx += 2;
-			ctx->vertex_buffers = LLVMGetParam(ctx->main_function, arg_idx++);
-			set_userdata_location_shader(ctx, AC_UD_VS_BASE_VERTEX_START_INSTANCE, user_sgpr_idx, 3);
-			user_sgpr_idx += 3;
+			if (ctx->shader_info->info.vs.has_vertex_buffers) {
+				set_userdata_location_shader(ctx, AC_UD_VS_VERTEX_BUFFERS, user_sgpr_idx, 2);
+				user_sgpr_idx += 2;
+				ctx->vertex_buffers = LLVMGetParam(ctx->main_function, arg_idx++);
+			}
+			unsigned vs_num = 2;
+			if (ctx->shader_info->info.vs.needs_draw_id)
+				vs_num++;
+
+			set_userdata_location_shader(ctx, AC_UD_VS_BASE_VERTEX_START_INSTANCE, user_sgpr_idx, vs_num);
+			user_sgpr_idx += vs_num;
+
 			ctx->base_vertex = LLVMGetParam(ctx->main_function, arg_idx++);
 			ctx->start_instance = LLVMGetParam(ctx->main_function, arg_idx++);
-			ctx->draw_index = LLVMGetParam(ctx->main_function, arg_idx++);
+			if (ctx->shader_info->info.vs.needs_draw_id)
+				ctx->draw_index = LLVMGetParam(ctx->main_function, arg_idx++);
 		}
 		if (ctx->options->key.vs.as_es)
 			ctx->es2gs_offset = LLVMGetParam(ctx->main_function, arg_idx++);
diff --git a/src/amd/common/ac_shader_info.c b/src/amd/common/ac_shader_info.c
index 85252fea146..6ad562505cf 100644
--- a/src/amd/common/ac_shader_info.c
+++ b/src/amd/common/ac_shader_info.c
@@ -30,6 +30,9 @@ gather_intrinsic_info(nir_intrinsic_instr *instr, struct ac_shader_info *info)
 	case nir_intrinsic_interp_var_at_sample:
 		info->ps.needs_sample_positions = true;
 		break;
+	case nir_intrinsic_load_draw_id:
+		info->vs.needs_draw_id = true;
+		break;
 	default:
 		break;
 	}
@@ -49,12 +52,30 @@ gather_info_block(nir_block *block, struct ac_shader_info *info)
 	}
 }
 
+static void
+gather_info_input_decl(nir_shader *nir,
+		       const struct ac_nir_compiler_options *options,
+		       nir_variable *var,
+		       struct ac_shader_info *info)
+{
+	switch (nir->stage) {
+	case MESA_SHADER_VERTEX:
+		info->vs.has_vertex_buffers = true;
+		break;
+	default:
+		break;
+	}
+}
+
 void
 ac_nir_shader_info_pass(struct nir_shader *nir,
 			const struct ac_nir_compiler_options *options,
 			struct ac_shader_info *info)
 {
 	struct nir_function *func = (struct nir_function *)exec_list_get_head(&nir->functions);
+	nir_foreach_variable(variable, &nir->inputs)
+		gather_info_input_decl(nir, options, variable, info);
+
 	nir_foreach_block(block, func->impl) {
 		gather_info_block(block, info);
 	}
diff --git a/src/amd/common/ac_shader_info.h b/src/amd/common/ac_shader_info.h
index 5576c3b4bac..7e2b6c885a6 100644
--- a/src/amd/common/ac_shader_info.h
+++ b/src/amd/common/ac_shader_info.h
@@ -29,6 +29,10 @@ struct ac_nir_compiler_options;
 
 struct ac_shader_info {
 	struct {
+		bool has_vertex_buffers; /* needs vertex buffers and base/start */
+		bool needs_draw_id;
+	} vs;
+	struct {
 		bool needs_sample_positions;
 	} ps;
 };