blorp: Assert 8x4 alignment for a HiZ op on Gen8-9

On BDW and SKL, assert that render target dimensions are 8x4-aligned
when performing HiZ ambiguates on LOD1+. Testing indicates that the
assertion should hold in order to achieve consistent/correct ambiguate
operations on gen9.

v2. Account for the relaxed restrictions on ICL+. (Ken)

Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/3788
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8853>

src/intel/blorp/blorp.c

@@ -323,6 +323,8 @@ blorp_hiz_op(struct blorp_batch *batch, struct blorp_surf *surf,
              uint32_t level, uint32_t start_layer, uint32_t num_layers,
              enum isl_aux_op op)
 {
+   const struct gen_device_info *devinfo = batch->blorp->isl_dev->info;
+
    struct blorp_params params;
    blorp_params_init(&params);
 
@@ -386,6 +388,41 @@ blorp_hiz_op(struct blorp_batch *batch, struct blorp_surf *surf,
          /* TODO: What about MSAA? */
          params.depth.surf.logical_level0_px.width = params.x1;
          params.depth.surf.logical_level0_px.height = params.y1;
+      } else if (devinfo->gen >= 8 && devinfo->gen <= 9 &&
+                 op == ISL_AUX_OP_AMBIGUATE) {
+         /* On some platforms, it's not enough to just adjust the clear
+          * rectangle when the LOD is greater than 0.
+          *
+          * From the BDW and SKL PRMs, Vol 7, "Optimized Hierarchical Depth
+          * Buffer Resolve":
+          *
+          *    The following is required when performing a hierarchical depth
+          *    buffer resolve:
+          *
+          *    - A rectangle primitive covering the full render target must be
+          *      programmed on Xmin, Ymin, Xmax, and Ymax in the
+          *      3DSTATE_WM_HZ_OP command.
+          *
+          *    - The rectangle primitive size must be aligned to 8x4 pixels.
+          *
+          * And from the Clear Rectangle programming note in 3DSTATE_WM_HZ_OP
+          * (Vol 2a):
+          *
+          *    Hence the max values must be less than or equal to: ( Surface
+          *    Width » LOD ) and ( Surface Height » LOD ) for X Max and Y Max
+          *    respectively.
+          *
+          * This means that the extent of the LOD must be naturally
+          * 8x4-aligned after minification of the base LOD. Since the base LOD
+          * dimensions affect the placement of smaller LODs, it's not trivial
+          * (nor possible, at times) to satisfy the requirement by adjusting
+          * the base LOD extent. Just assert that the caller is accessing an
+          * LOD that satisfies this requirement.
+          */
+         assert(minify(params.depth.surf.logical_level0_px.width,
+                       params.depth.view.base_level) == params.x1);
+         assert(minify(params.depth.surf.logical_level0_px.height,
+                       params.depth.view.base_level) == params.y1);
       }
 
       params.dst.surf.samples = params.depth.surf.samples;