[Mesa-dev] [PATCH 4/8] r600: workaround empty geom shader.

[Dave Airlie]

From: Dave Airlie <airlied at redhat.com>

We need to emit at least one cut/emit in every
geometry shader, the easiest workaround it to
stick a single CUT at the top of each geom shader.

Signed-off-by: Dave Airlie <airlied at redhat.com>
---
 src/gallium/drivers/r600/r600_shader.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/gallium/drivers/r600/r600_shader.c b/src/gallium/drivers/r600/r600_shader.c
index fc6335a..6646a7e 100644
--- a/src/gallium/drivers/r600/r600_shader.c
+++ b/src/gallium/drivers/r600/r600_shader.c
@@ -2205,6 +2205,11 @@ static int r600_shader_from_tgsi(struct r600_context *rctx,
 		if (ctx.type == TGSI_PROCESSOR_GEOMETRY) {
 			struct r600_bytecode_alu alu;
 			int r;
+
+			/* GS thread with no output workaround - emit a cut at start of GS */
+			if (ctx.bc->chip_class == R600)
+				r600_bytecode_add_cfinst(ctx.bc, CF_OP_CUT_VERTEX);
+
 			for (j = 0; j < 4; j++) {
 				memset(&alu, 0, sizeof(struct r600_bytecode_alu));
 				alu.op = ALU_OP1_MOV;
-- 
2.1.0