2 files changed, 40 insertions, 8 deletions

diff --git a/src/gallium/drivers/radeonsi/si_shader.c b/src/gallium/drivers/radeonsi/si_shader.c
index 7f771408a37..3af878b5c20 100644
--- a/src/gallium/drivers/radeonsi/si_shader.c
+++ b/src/gallium/drivers/radeonsi/si_shader.c
@@ -2393,8 +2393,8 @@ handle_semantic:
 	    shader->selector->info.writes_layer) {
 		pos_args[1].enabled_channels = shader->selector->info.writes_psize |
 					       (shader->selector->info.writes_edgeflag << 1) |
-					       (shader->selector->info.writes_layer << 2) |
-					       (shader->selector->info.writes_viewport_index << 3);
+					       (shader->selector->info.writes_layer << 2);
+
 		pos_args[1].valid_mask = 0; /* EXEC mask */
 		pos_args[1].done = 0; /* last export? */
 		pos_args[1].target = V_008DFC_SQ_EXP_POS + 1;
@@ -2423,11 +2423,34 @@ handle_semantic:
 							  ctx->f32, "");
 		}
 
-		if (shader->selector->info.writes_layer)
-			pos_args[1].out[2] = layer_value;
+		if (ctx->screen->b.chip_class >= GFX9) {
+			/* GFX9 has the layer in out.z[10:0] and the viewport
+			 * index in out.z[19:16].
+			 */
+			if (shader->selector->info.writes_layer)
+				pos_args[1].out[2] = layer_value;
+
+			if (shader->selector->info.writes_viewport_index) {
+				LLVMValueRef v = viewport_index_value;
+
+				v = bitcast(bld_base, TGSI_TYPE_UNSIGNED, v);
+				v = LLVMBuildShl(ctx->gallivm.builder, v,
+						 LLVMConstInt(ctx->i32, 16, 0), "");
+				v = LLVMBuildOr(ctx->gallivm.builder, v,
+						bitcast(bld_base, TGSI_TYPE_UNSIGNED,
+						        pos_args[1].out[2]), "");
+				pos_args[1].out[2] = bitcast(bld_base, TGSI_TYPE_FLOAT, v);
+				pos_args[1].enabled_channels |= 1 << 2;
+			}
+		} else {
+			if (shader->selector->info.writes_layer)
+				pos_args[1].out[2] = layer_value;
 
-		if (shader->selector->info.writes_viewport_index)
-			pos_args[1].out[3] = viewport_index_value;
+			if (shader->selector->info.writes_viewport_index) {
+				pos_args[1].out[3] = viewport_index_value;
+				pos_args[1].enabled_channels |= 1 << 3;
+			}
+		}
 	}
 
 	for (i = 0; i < 4; i++)
diff --git a/src/gallium/drivers/radeonsi/si_state_shaders.c b/src/gallium/drivers/radeonsi/si_state_shaders.c
index e4794220913..b80a3478caf 100644
--- a/src/gallium/drivers/radeonsi/si_state_shaders.c
+++ b/src/gallium/drivers/radeonsi/si_state_shaders.c
@@ -867,8 +867,17 @@ static void si_shader_vs(struct si_screen *sscreen, struct si_shader *shader,
 	 * not sent again.
 	 */
 	if (!gs) {
-		si_pm4_set_reg(pm4, R_028A40_VGT_GS_MODE,
-			       S_028A40_MODE(enable_prim_id ? V_028A40_GS_SCENARIO_A : 0));
+		unsigned mode = 0;
+
+		/* PrimID needs GS scenario A.
+		 * GFX9 also needs it when ViewportIndex is enabled.
+		 */
+		if (enable_prim_id ||
+		    (sscreen->b.chip_class >= GFX9 &&
+		     shader->selector->info.writes_viewport_index))
+			mode = V_028A40_GS_SCENARIO_A;
+
+		si_pm4_set_reg(pm4, R_028A40_VGT_GS_MODE, S_028A40_MODE(mode));
 		si_pm4_set_reg(pm4, R_028A84_VGT_PRIMITIVEID_EN, enable_prim_id);
 	} else {
 		si_pm4_set_reg(pm4, R_028A40_VGT_GS_MODE, si_vgt_gs_mode(gs));