i965: Refactor brw_is_hiz_depth_format()

Every caller of this function uses it to determine if the current
miptree needs a hiz buffer to be allocated. Strangely, the function
doesn't take a miptree argument. So, this function effectively decides
if and when a miptree's hiz buffer gets allocated without inspecting the
miptree itself.  Luckily, the driver behaves correctly despite the
brw_is_hiz_depth_format's quirk.

I will soon make some changes to the miptree that will require
inspecting the miptree to determine if it needs a hiz buffer. So this
patch renames
    brw_is_hiz_depth_format -> intel_miptree_wants_hiz_buffer
and gives it a miptree parameter.

This patch shouldn't change any behavior.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Tapani Pälli <tapani.palli@intel.com>
Reviewed-by: Topi Pohjolainen <topi.pohjolainen@intel.com>

src/mesa/drivers/dri/i965/brw_context.h

@@ -1681,7 +1681,6 @@ void brw_upload_abo_surfaces(struct brw_context *brw,
                              struct brw_stage_prog_data *prog_data);
 
 /* brw_surface_formats.c */
-bool brw_is_hiz_depth_format(struct brw_context *ctx, mesa_format format);
 bool brw_render_target_supported(struct brw_context *brw,
                                  struct gl_renderbuffer *rb);
 uint32_t brw_depth_format(struct brw_context *brw, mesa_format format);

src/mesa/drivers/dri/i965/brw_surface_formats.c

@@ -798,22 +798,3 @@ brw_depth_format(struct brw_context *brw, mesa_format format)
       unreachable("Unexpected depth format.");
    }
 }
-
-/** Can HiZ be enabled on a depthbuffer of the given format? */
-bool
-brw_is_hiz_depth_format(struct brw_context *brw, mesa_format format)
-{
-   if (!brw->has_hiz)
-      return false;
-
-   switch (format) {
-   case MESA_FORMAT_Z_FLOAT32:
-   case MESA_FORMAT_Z32_FLOAT_S8X24_UINT:
-   case MESA_FORMAT_Z24_UNORM_X8_UINT:
-   case MESA_FORMAT_Z24_UNORM_S8_UINT:
-   case MESA_FORMAT_Z_UNORM16:
-      return true;
-   default:
-      return false;
-   }
-}

src/mesa/drivers/dri/i965/intel_fbo.c

@@ -561,7 +561,7 @@ intel_renderbuffer_update_wrapper(struct brw_context *brw,
 
    intel_renderbuffer_set_draw_offset(irb);
 
-   if (mt->hiz_buf == NULL && brw_is_hiz_depth_format(brw, rb->Format)) {
+   if (intel_miptree_wants_hiz_buffer(brw, mt)) {
       intel_miptree_alloc_hiz(brw, mt);
       if (!mt->hiz_buf)
 	 return false;
@@ -1032,7 +1032,7 @@ intel_renderbuffer_move_to_temp(struct brw_context *brw,
                                  INTEL_MIPTREE_TILING_ANY,
                                  false);
 
-   if (brw_is_hiz_depth_format(brw, new_mt->format)) {
+   if (intel_miptree_wants_hiz_buffer(brw, new_mt)) {
       intel_miptree_alloc_hiz(brw, new_mt);
    }
 

src/mesa/drivers/dri/i965/intel_mipmap_tree.c

@@ -403,7 +403,8 @@ intel_miptree_create_layout(struct brw_context *brw,
    if (!for_bo &&
        _mesa_get_format_base_format(format) == GL_DEPTH_STENCIL &&
        (brw->must_use_separate_stencil ||
-	(brw->has_separate_stencil && brw_is_hiz_depth_format(brw, format)))) {
+	(brw->has_separate_stencil &&
+         intel_miptree_wants_hiz_buffer(brw, mt)))) {
       const bool force_all_slices_at_each_lod = brw->gen == 6;
       mt->stencil_mt = intel_miptree_create(brw,
                                             mt->target,
@@ -843,7 +844,7 @@ intel_miptree_create_for_renderbuffer(struct brw_context *brw,
    if (!mt)
       goto fail;
 
-   if (brw_is_hiz_depth_format(brw, format)) {
+   if (intel_miptree_wants_hiz_buffer(brw, mt)) {
       ok = intel_miptree_alloc_hiz(brw, mt);
       if (!ok)
          goto fail;
@@ -1681,6 +1682,27 @@ intel_hiz_miptree_buf_create(struct brw_context *brw,
    return buf;
 }
 
+bool
+intel_miptree_wants_hiz_buffer(struct brw_context *brw,
+                               struct intel_mipmap_tree *mt)
+{
+   if (!brw->has_hiz)
+      return false;
+
+   if (mt->hiz_buf != NULL)
+      return false;
+
+   switch (mt->format) {
+   case MESA_FORMAT_Z_FLOAT32:
+   case MESA_FORMAT_Z32_FLOAT_S8X24_UINT:
+   case MESA_FORMAT_Z24_UNORM_X8_UINT:
+   case MESA_FORMAT_Z24_UNORM_S8_UINT:
+   case MESA_FORMAT_Z_UNORM16:
+      return true;
+   default:
+      return false;
+   }
+}
 
 bool
 intel_miptree_alloc_hiz(struct brw_context *brw,

src/mesa/drivers/dri/i965/intel_mipmap_tree.h

@@ -632,12 +632,15 @@ intel_miptree_copy_teximage(struct brw_context *brw,
  * functions on a miptree without HiZ. In that case, each function is a no-op.
  */
 
+bool
+intel_miptree_wants_hiz_buffer(struct brw_context *brw,
+			       struct intel_mipmap_tree *mt);
+
 /**
  * \brief Allocate the miptree's embedded HiZ miptree.
  * \see intel_mipmap_tree:hiz_mt
  * \return false if allocation failed
  */
-
 bool
 intel_miptree_alloc_hiz(struct brw_context *brw,
 			struct intel_mipmap_tree *mt);