[Mesa-dev] [PATCH] radeonsi: fix isolines tess factor writes to control ring

[Nicolai Hähnle]

From: Nicolai Hähnle <nicolai.haehnle at amd.com>

Fixes piglit arb_tessellation_shader/execution/isoline{_no_tcs}.shader_test.

Cc: mesa-stable at lists.freedesktop.org
---
 src/gallium/drivers/radeonsi/si_shader.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/src/gallium/drivers/radeonsi/si_shader.c b/src/gallium/drivers/radeonsi/si_shader.c
index 44a4dd2..271b8d0 100644
--- a/src/gallium/drivers/radeonsi/si_shader.c
+++ b/src/gallium/drivers/radeonsi/si_shader.c
@@ -2561,24 +2561,32 @@ static void si_write_tess_factors(struct lp_build_tgsi_context *bld_base,
 	tess_outer_index = si_shader_io_get_unique_index(TGSI_SEMANTIC_TESSOUTER, 0);
 
 	lds_base = tcs_out_current_patch_data_offset;
 	lds_inner = LLVMBuildAdd(gallivm->builder, lds_base,
 				 lp_build_const_int32(gallivm,
 						      tess_inner_index * 4), "");
 	lds_outer = LLVMBuildAdd(gallivm->builder, lds_base,
 				 lp_build_const_int32(gallivm,
 						      tess_outer_index * 4), "");
 
-	for (i = 0; i < outer_comps; i++)
-		out[i] = lds_load(bld_base, TGSI_TYPE_SIGNED, i, lds_outer);
-	for (i = 0; i < inner_comps; i++)
-		out[outer_comps+i] = lds_load(bld_base, TGSI_TYPE_SIGNED, i, lds_inner);
+	if (shader->key.part.tcs.epilog.prim_mode == PIPE_PRIM_LINES) {
+		/* For isolines, the hardware expects tess factors in the
+		 * reverse order from what GLSL / TGSI specify.
+		 */
+		out[0] = lds_load(bld_base, TGSI_TYPE_SIGNED, 1, lds_outer);
+		out[1] = lds_load(bld_base, TGSI_TYPE_SIGNED, 0, lds_outer);
+	} else {
+		for (i = 0; i < outer_comps; i++)
+			out[i] = lds_load(bld_base, TGSI_TYPE_SIGNED, i, lds_outer);
+		for (i = 0; i < inner_comps; i++)
+			out[outer_comps+i] = lds_load(bld_base, TGSI_TYPE_SIGNED, i, lds_inner);
+	}
 
 	/* Convert the outputs to vectors for stores. */
 	vec0 = lp_build_gather_values(gallivm, out, MIN2(stride, 4));
 	vec1 = NULL;
 
 	if (stride > 4)
 		vec1 = lp_build_gather_values(gallivm, out+4, stride - 4);
 
 	/* Get the buffer. */
 	rw_buffers = LLVMGetParam(ctx->main_fn,
-- 
2.7.4