anv: stop using 3DSTATE_WM::ForceThreadDispatchEnable

Documentation says we should leave this field to the default value
(Normal). Instead we set 3DSTATE_PS_EXTRA::PixelShaderHasUAV when we
see that a fragment shader has side effects.

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Tapani Pälli <tapani.palli@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/30408>

src/intel/vulkan/anv_private.h

@@ -1583,6 +1583,7 @@ struct anv_gfx_dynamic_state {
 
    /* 3DSTATE_PS_EXTRA */
    struct {
+      bool PixelShaderHasUAV;
       bool PixelShaderIsPerSample;
       bool PixelShaderKillsPixel;
       bool PixelShaderIsPerCoarsePixel;
@@ -1711,7 +1712,6 @@ struct anv_gfx_dynamic_state {
 
    /* 3DSTATE_WM */
    struct {
-      uint32_t ForceThreadDispatchEnable;
       bool     LineStippleEnable;
       uint32_t BarycentricInterpolationMode;
    } wm;
@@ -4707,7 +4707,6 @@ struct anv_graphics_pipeline {
    bool                                         rp_has_ds_self_dep;
 
    bool                                         kill_pixel;
-   bool                                         force_fragment_thread_dispatch;
    bool                                         uses_xfb;
    bool                                         sample_shading_enable;
    float                                        min_sample_shading;

src/intel/vulkan/genX_gfx_state.c

@@ -1012,19 +1012,6 @@ genX(cmd_buffer_flush_gfx_runtime_state)(struct anv_cmd_buffer *cmd_buffer)
         BITSET_TEST(dyn->dirty, MESA_VK_DYNAMIC_MS_SAMPLE_LOCATIONS_ENABLE)))
       BITSET_SET(hw_state->dirty, ANV_GFX_STATE_SAMPLE_PATTERN);
 
-   if ((gfx->dirty & ANV_CMD_DIRTY_PIPELINE) ||
-       (gfx->dirty & ANV_CMD_DIRTY_RENDER_TARGETS) ||
-       BITSET_TEST(dyn->dirty, MESA_VK_DYNAMIC_CB_COLOR_WRITE_ENABLES)) {
-      /* 3DSTATE_WM in the hope we can avoid spawning fragment shaders
-       * threads.
-       */
-      bool force_thread_dispatch =
-         anv_pipeline_has_stage(pipeline, MESA_SHADER_FRAGMENT) &&
-         (pipeline->force_fragment_thread_dispatch ||
-          anv_cmd_buffer_all_color_write_masked(cmd_buffer));
-      SET(WM, wm.ForceThreadDispatchEnable, force_thread_dispatch ? ForceON : 0);
-   }
-
    if ((cmd_buffer->state.gfx.dirty & ANV_CMD_DIRTY_PIPELINE) ||
        BITSET_TEST(dyn->dirty, MESA_VK_DYNAMIC_ATTACHMENT_FEEDBACK_LOOP_ENABLE)) {
       SET_STAGE(PS_EXTRA, ps_extra.PixelShaderKillsPixel,
@@ -1034,6 +1021,33 @@ genX(cmd_buffer_flush_gfx_runtime_state)(struct anv_cmd_buffer *cmd_buffer)
                 FRAGMENT);
    }
 
+#if GFX_VERx10 >= 125
+   if (cmd_buffer->state.gfx.dirty & ANV_CMD_DIRTY_PIPELINE) {
+      SET_STAGE(PS_EXTRA, ps_extra.PixelShaderHasUAV,
+                wm_prog_data && wm_prog_data->has_side_effects,
+                FRAGMENT);
+   }
+#else
+   if (cmd_buffer->state.gfx.dirty & (ANV_CMD_DIRTY_PIPELINE |
+                                      ANV_CMD_DIRTY_OCCLUSION_QUERY_ACTIVE)) {
+      /* Prior to Gfx12.5 the HW seems to avoid spawning fragment shaders even
+       * if 3DSTATE_PS_EXTRA::PixelShaderKillsPixel=true when
+       * 3DSTATE_PS_BLEND::HasWriteableRT=false. This is causing problems with
+       * occlusion queries with 0 attachments. There are no CTS tests
+       * exercising this but zink+anv fails a bunch of tests like piglit
+       * arb_framebuffer_no_attachments-query.
+       *
+       * Here we choose to tweak the PixelShaderHasUAV to make sure the
+       * fragment shaders are run properly.
+       */
+      SET_STAGE(PS_EXTRA, ps_extra.PixelShaderHasUAV,
+                wm_prog_data && (wm_prog_data->has_side_effects ||
+                                 (gfx->color_att_count == 0 &&
+                                  gfx->n_occlusion_queries > 0)),
+                FRAGMENT);
+   }
+#endif
+
    if ((gfx->dirty & ANV_CMD_DIRTY_PIPELINE) ||
        (gfx->dirty & ANV_CMD_DIRTY_RENDER_TARGETS) ||
        BITSET_TEST(dyn->dirty, MESA_VK_DYNAMIC_CB_LOGIC_OP) ||
@@ -1759,6 +1773,7 @@ cmd_buffer_gfx_state_emission(struct anv_cmd_buffer *cmd_buffer)
    if (BITSET_TEST(hw_state->dirty, ANV_GFX_STATE_PS_EXTRA)) {
       anv_batch_emit_merge(&cmd_buffer->batch, GENX(3DSTATE_PS_EXTRA),
                            pipeline, partial.ps_extra, pse) {
+         SET(pse, ps_extra, PixelShaderHasUAV);
          SET(pse, ps_extra, PixelShaderIsPerSample);
 #if GFX_VER >= 11
          SET(pse, ps_extra, PixelShaderIsPerCoarsePixel);
@@ -2136,7 +2151,6 @@ cmd_buffer_gfx_state_emission(struct anv_cmd_buffer *cmd_buffer)
    if (BITSET_TEST(hw_state->dirty, ANV_GFX_STATE_WM)) {
       anv_batch_emit_merge(&cmd_buffer->batch, GENX(3DSTATE_WM),
                            pipeline, partial.wm, wm) {
-         SET(wm, wm, ForceThreadDispatchEnable);
          SET(wm, wm, LineStippleEnable);
          SET(wm, wm, BarycentricInterpolationMode);
       }

src/intel/vulkan/genX_pipeline.c

@@ -1642,26 +1642,6 @@ emit_3dstate_wm(struct anv_graphics_pipeline *pipeline,
          } else {
             wm.EarlyDepthStencilControl         = EDSC_NORMAL;
          }
-
-         /* Gen8 hardware tries to compute ThreadDispatchEnable for us but
-          * doesn't take into account KillPixels when no depth or stencil
-          * writes are enabled. In order for occlusion queries to work
-          * correctly with no attachments, we need to force-enable PS thread
-          * dispatch.
-          *
-          * The BDW docs are pretty clear that that this bit isn't validated
-          * and probably shouldn't be used in production:
-          *
-          *    "This must always be set to Normal. This field should not be
-          *     tested for functional validation."
-          *
-          * Unfortunately, however, the other mechanism we have for doing this
-          * is 3DSTATE_PS_EXTRA::PixelShaderHasUAV which causes hangs on BDW.
-          * Given two bad options, we choose the one which works.
-          */
-         pipeline->force_fragment_thread_dispatch =
-            wm_prog_data->has_side_effects ||
-            wm_prog_data->uses_kill;
       }
    }
 }