[Mesa-dev] [v4 04/11] i965: Add helper for lossless compression support

[Ben Widawsky]

On Thu, Apr 21, 2016 at 02:58:59PM +0300, Topi Pohjolainen wrote:
> v2: Check explicitly against base type of GL_FLOAT instead of
>     using _mesa_is_format_integer_color(). Otherwise we miss
>     GL_UNSIGNED_NORMALIZED.
> 
> Signed-off-by: Topi Pohjolainen <topi.pohjolainen at intel.com>
> ---
>  src/mesa/drivers/dri/i965/intel_mipmap_tree.c | 22 ++++++++++++++++++++++
>  src/mesa/drivers/dri/i965/intel_mipmap_tree.h |  3 +++
>  2 files changed, 25 insertions(+)
> 
> diff --git a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
> index b68575f..78717df 100644
> --- a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
> +++ b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
> @@ -294,6 +294,28 @@ intel_miptree_is_lossless_compressed(const struct brw_context *brw,
>     return mt->num_samples <= 1;
>  }
>  
> +bool
> +intel_miptree_supports_lossless_compressed(mesa_format format)
> +{
> +   /* For now compression is only enabled for integer formats even though
> +    * there exist supported floating point formats also. This is a heuristic
> +    * decision based on current public benchmarks. In none of the cases these
> +    * formats provided any improvement but a few cases were seen to regress.
> +    * Hence these are left to to be enabled in the future when they are known
> +    * to improve things.
> +    */
> +   if (_mesa_get_format_datatype(format) == GL_FLOAT)
> +      return false;
> +
> +   /* In principle, fast clear mechanism and lossless compression go hand in
> +    * hand. However, fast clear can be also used to clear srgb surfaces by
> +    * using equivalent linear format. This trick, however, can't be extended
> +    * to be used with lossless compression and therefore a check is needed to
> +    * see if the format really is linear.
> +    */
> +   return _mesa_get_srgb_format_linear(format) == format;
> +}
> +

Picking nits here, but I don't like this function because it doesn't do what it
purports to do in it's name. It's really an ancillary function to MCS support.
How about?

diff --git a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
index 20c8a7f..17a6f7e 100644
--- a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
+++ b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
@@ -301,7 +301,9 @@ intel_miptree_is_lossless_compressed(const struct brw_context *brw,
 }
 
 bool
-intel_miptree_supports_lossless_compressed(mesa_format format)
+intel_miptree_supports_lossless_compressed(struct brw_context *brw,
+                                           const struct intel_mipmap_tree *mt,
+                                           mesa_format format)
 {
    /* For now compression is only enabled for integer formats even though
     * there exist supported floating point formats also. This is a heuristic
@@ -313,11 +315,14 @@ intel_miptree_supports_lossless_compressed(mesa_format format)
    if (_mesa_get_format_datatype(format) == GL_FLOAT)
       return false;
 
-   /* In principle, fast clear mechanism and lossless compression go hand in
-    * hand. However, fast clear can be also used to clear srgb surfaces by
-    * using equivalent linear format. This trick, however, can't be extended
-    * to be used with lossless compression and therefore a check is needed to
-    * see if the format really is linear.
+   /* Fast clear mechanism and lossless compression go hand in hand. */
+   if (!intel_miptree_supports_non_msrt_fast_clear(brw, mt))
+      return false;
+
+   /* Fast clear can be also used to clear srgb surfaces by using equivalent
+    * linear format. This trick, however, can't be extended to be used with
+    * lossless compression and therefore a check is needed to see if the format
+    * really is linear.
     */
    return _mesa_get_srgb_format_linear(format) == format;
 }
diff --git a/src/mesa/drivers/dri/i965/intel_mipmap_tree.h b/src/mesa/drivers/dri/i965/intel_mipmap_tree.h
index d4f8563..c859f6e 100644
--- a/src/mesa/drivers/dri/i965/intel_mipmap_tree.h
+++ b/src/mesa/drivers/dri/i965/intel_mipmap_tree.h
@@ -680,7 +680,9 @@ intel_miptree_supports_non_msrt_fast_clear(struct brw_context *brw,
                                            const struct intel_mipmap_tree *mt);
 
 bool
-intel_miptree_supports_lossless_compressed(mesa_format format);
+intel_miptree_supports_lossless_compressed(struct brw_context *brw,
+                                           const struct intel_mipmap_tree *mt,
+                                           mesa_format format);
 
 bool
 intel_miptree_alloc_non_msrt_mcs(struct brw_context *brw,

>  /**
>   * Determine depth format corresponding to a depth+stencil format,
>   * for separate stencil.
> diff --git a/src/mesa/drivers/dri/i965/intel_mipmap_tree.h b/src/mesa/drivers/dri/i965/intel_mipmap_tree.h
> index 7862152..6c143c3 100644
> --- a/src/mesa/drivers/dri/i965/intel_mipmap_tree.h
> +++ b/src/mesa/drivers/dri/i965/intel_mipmap_tree.h
> @@ -679,6 +679,9 @@ intel_miptree_supports_non_msrt_fast_clear(struct brw_context *brw,
>                                             const struct intel_mipmap_tree *mt);
>  
>  bool
> +intel_miptree_supports_lossless_compressed(mesa_format format);
> +
> +bool
>  intel_miptree_alloc_non_msrt_mcs(struct brw_context *brw,
>                                   struct intel_mipmap_tree *mt);
>