radeonsi: enable R600_DEBUG=nir for vertex and fragment shaders

Also, disable geometry and tessellation shaders. Mixing and matching NIR
and TGSI shaders should work (and I've tested it for the VS/PS interface),
but geometry and tessellation requires VS-as-ES/LS, which isn't implemented
yet for NIR.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>

src/gallium/drivers/radeon/r600_pipe_common.c

@@ -730,6 +730,7 @@ void r600_common_context_cleanup(struct r600_common_context *rctx)
 static const struct debug_named_value common_debug_options[] = {
 	/* logging */
 	{ "tex", DBG_TEX, "Print texture info" },
+	{ "nir", DBG_NIR, "Enable experimental NIR shaders" },
 	{ "compute", DBG_COMPUTE, "Print compute info" },
 	{ "vm", DBG_VM, "Print virtual addresses when creating resources" },
 	{ "info", DBG_INFO, "Print driver information" },

src/gallium/drivers/radeon/r600_pipe_common.h

@@ -67,7 +67,7 @@
 /* Debug flags. */
 /* logging */
 #define DBG_TEX			(1 << 0)
-/* gap - reuse */
+#define DBG_NIR			(1 << 1)
 #define DBG_COMPUTE		(1 << 2)
 #define DBG_VM			(1 << 3)
 /* gap - reuse */

src/gallium/drivers/radeonsi/si_pipe.c

@@ -556,6 +556,8 @@ static int si_get_param(struct pipe_screen* pscreen, enum pipe_cap param)
 		return 4;
 
 	case PIPE_CAP_GLSL_FEATURE_LEVEL:
+		if (sscreen->b.debug_flags & DBG_NIR)
+			return 140; /* no geometry and tessellation shaders yet */
 		if (si_have_tgsi_compute(sscreen))
 			return 450;
 		return 420;
@@ -753,6 +755,10 @@ static int si_get_shader_param(struct pipe_screen* pscreen,
 	case PIPE_SHADER_CAP_MAX_UNROLL_ITERATIONS_HINT:
 		return 32;
 	case PIPE_SHADER_CAP_PREFERRED_IR:
+		if (sscreen->b.debug_flags & DBG_NIR &&
+		    (shader == PIPE_SHADER_VERTEX ||
+		     shader == PIPE_SHADER_FRAGMENT))
+			return PIPE_SHADER_IR_NIR;
 		return PIPE_SHADER_IR_TGSI;
 	case PIPE_SHADER_CAP_LOWER_IF_THRESHOLD:
 		return 3;