[Mesa-dev] [PATCH v2 06/21] intel/blorp_clear: Add gen8 HiZ clearing functions

[Nanley Chery]

Add an entry point for the optimized gen8 BLORP HiZ sequence. commit
c9eaf12de20ac4143fe79d42018bdbb5a391356f fixed a bug that was
unknowingly worked around by forcing additional clear rectangle
alignment restrictions not specified in the PRMs. Now that the bug is no
longer present, omit the additional alignment restrictions.

v2: Adjust code comment about padding

Signed-off-by: Nanley Chery <nanley.g.chery at intel.com>
---
 src/intel/blorp/blorp.h       | 12 +++++++
 src/intel/blorp/blorp_clear.c | 81 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 93 insertions(+)

diff --git a/src/intel/blorp/blorp.h b/src/intel/blorp/blorp.h
index 823475b607..ff60567fc4 100644
--- a/src/intel/blorp/blorp.h
+++ b/src/intel/blorp/blorp.h
@@ -155,8 +155,20 @@ blorp_clear_depth_stencil(struct blorp_batch *batch,
                           uint32_t x0, uint32_t y0, uint32_t x1, uint32_t y1,
                           bool clear_depth, float depth_value,
                           uint8_t stencil_mask, uint8_t stencil_value);
+bool
+blorp_can_hiz_clear_depth(uint8_t gen, enum isl_format format,
+                          uint32_t num_samples,
+                          uint32_t x0, uint32_t y0,
+                          uint32_t x1, uint32_t y1);
 
 void
+blorp_gen8_hiz_clear_attachments(struct blorp_batch *batch,
+                                 uint32_t num_samples,
+                                 uint32_t x0, uint32_t y0,
+                                 uint32_t x1, uint32_t y1,
+                                 bool clear_depth, bool clear_stencil,
+                                 uint8_t stencil_value);
+void
 blorp_clear_attachments(struct blorp_batch *batch,
                         uint32_t binding_table_offset,
                         enum isl_format depth_format,
diff --git a/src/intel/blorp/blorp_clear.c b/src/intel/blorp/blorp_clear.c
index d090408721..afc505d86c 100644
--- a/src/intel/blorp/blorp_clear.c
+++ b/src/intel/blorp/blorp_clear.c
@@ -470,6 +470,87 @@ blorp_clear_depth_stencil(struct blorp_batch *batch,
    }
 }
 
+bool
+blorp_can_hiz_clear_depth(uint8_t gen, enum isl_format format,
+                          uint32_t num_samples,
+                          uint32_t x0, uint32_t y0, uint32_t x1, uint32_t y1)
+{
+   /* This function currently doesn't support any gen prior to gen8 */
+   assert(gen >= 8);
+
+   if (gen == 8 && format == ISL_FORMAT_R16_UNORM) {
+      /* Apply the D16 alignment restrictions. On BDW, HiZ has an 8x4 sample
+       * block with the following property: as the number of samples increases,
+       * the number of pixels representable by this block decreases by a factor
+       * of the sample dimensions. Sample dimensions scale following the MSAA
+       * interleaved pattern.
+       *
+       * Sample|Sample|Pixel
+       * Count |Dim   |Dim
+       * ===================
+       *    1  | 1x1  | 8x4
+       *    2  | 2x1  | 4x4
+       *    4  | 2x2  | 4x2
+       *    8  | 4x2  | 2x2
+       *   16  | 4x4  | 2x1
+       *
+       * Table: Pixel Dimensions in a HiZ Sample Block Pre-SKL
+       */
+      const struct isl_extent2d sa_block_dim =
+         isl_get_interleaved_msaa_px_size_sa(num_samples);
+      const uint8_t align_px_w = 8 / sa_block_dim.w;
+      const uint8_t align_px_h = 4 / sa_block_dim.h;
+
+      /* Fast depth clears clear an entire sample block at a time. As a result,
+       * the rectangle must be aligned to the dimensions of the encompassing
+       * pixel block for a successful operation.
+       *
+       * Fast clears can still work if the upper-left corner is aligned and the
+       * bottom-rigtht corner touches the edge of a depth buffer whose extent
+       * is unaligned. This is because each miplevel in the depth buffer is
+       * padded by the Pixel Dim (similar to a standard compressed texture).
+       * In this case, the clear rectangle could be padded by to match the full
+       * depth buffer extent but to support multiple clearing techniques, we
+       * chose to be unaware of the depth buffer's extent and thus don't handle
+       * this case.
+       */
+      if (x0 % align_px_w || y0 % align_px_h ||
+          x1 % align_px_w || y1 % align_px_h)
+         return false;
+   }
+   return true;
+}
+
+/* Given a depth stencil attachment, this function performs a fast depth clear
+ * on a depth portion and a regular clear on the stencil portion. When
+ * performing a fast depth clear on the depth portion, the HiZ buffer is simply
+ * tagged as cleared so the depth clear value is not actually needed.
+ */
+void
+blorp_gen8_hiz_clear_attachments(struct blorp_batch *batch,
+                                 uint32_t num_samples,
+                                 uint32_t x0, uint32_t y0,
+                                 uint32_t x1, uint32_t y1,
+                                 bool clear_depth, bool clear_stencil,
+                                 uint8_t stencil_value)
+{
+   assert(batch->flags & BLORP_BATCH_NO_EMIT_DEPTH_STENCIL);
+
+   struct blorp_params params;
+   blorp_params_init(&params);
+   params.num_layers = 1;
+   params.hiz_op = BLORP_HIZ_OP_DEPTH_CLEAR;
+   params.x0 = x0;
+   params.y0 = y0;
+   params.x1 = x1;
+   params.y1 = y1;
+   params.num_samples = num_samples;
+   params.depth.enabled = clear_depth;
+   params.stencil.enabled = clear_stencil;
+   params.stencil_ref = stencil_value;
+   batch->blorp->exec(batch, &params);
+}
+
 /** Clear active color/depth/stencili attachments
  *
  * This function performs a clear operation on the currently bound
-- 
2.11.0