mesa: Add a _mesa_active_fragment_shader_has_side_effects helper

Some drivers can disable the FS unit if there is nothing in the shader code
that writes to an output (i.e. color, depth, etc). Right now, mesa has
a function to check for atomic buffers and the i965 driver also checks for
images. Refactor this logic into a generic function that we can use for
any source of side effects in a fragment shader. Suggested by Jason.

v2:
- Use '_Shader', as suggested by Tapani, to fix the following CTS test:

ES31-CTS.shader_atomic_counters.advanced-usage-many-draw-calls2

Reviewed-by: Francisco Jerez <[email protected]>

2 files changed, 2 insertions, 7 deletions

diff --git a/src/mesa/drivers/dri/i965/gen7_wm_state.c b/src/mesa/drivers/dri/i965/gen7_wm_state.c
index 06d5e65786b..a6d1028dca1 100644
--- a/src/mesa/drivers/dri/i965/gen7_wm_state.c
+++ b/src/mesa/drivers/dri/i965/gen7_wm_state.c
@@ -77,13 +77,9 @@ upload_wm_state(struct brw_context *brw)
       dw1 |= GEN7_WM_KILL_ENABLE;
    }
 
-   if (_mesa_active_fragment_shader_has_atomic_ops(&brw->ctx)) {
-      dw1 |= GEN7_WM_DISPATCH_ENABLE;
-   }
-
    /* _NEW_BUFFERS | _NEW_COLOR */
    if (brw_color_buffer_write_enabled(brw) || writes_depth ||
-       prog_data->base.nr_image_params ||
+       _mesa_active_fragment_shader_has_side_effects(&brw->ctx) ||
        dw1 & GEN7_WM_KILL_ENABLE) {
       dw1 |= GEN7_WM_DISPATCH_ENABLE;
    }
diff --git a/src/mesa/drivers/dri/i965/gen8_ps_state.c b/src/mesa/drivers/dri/i965/gen8_ps_state.c
index 945f7106e3d..3cc8c68e132 100644
--- a/src/mesa/drivers/dri/i965/gen8_ps_state.c
+++ b/src/mesa/drivers/dri/i965/gen8_ps_state.c
@@ -90,8 +90,7 @@ gen8_upload_ps_extra(struct brw_context *brw,
     *
     * BRW_NEW_FS_PROG_DATA | BRW_NEW_FRAGMENT_PROGRAM | _NEW_BUFFERS | _NEW_COLOR
     */
-   if ((_mesa_active_fragment_shader_has_atomic_ops(&brw->ctx) ||
-        prog_data->base.nr_image_params) &&
+   if (_mesa_active_fragment_shader_has_side_effects(&brw->ctx) &&
        !brw_color_buffer_write_enabled(brw))
       dw1 |= GEN8_PSX_SHADER_HAS_UAV;