isl: add new helper for format component compatibility

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Cc: mesa-stable
Reviewed-by: Nanley Chery <nanley.g.chery@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/17329>

src/intel/isl/isl.h

@@ -1872,6 +1872,9 @@ bool isl_formats_are_ccs_e_compatible(const struct intel_device_info *devinfo,
 uint8_t isl_format_get_aux_map_encoding(enum isl_format format);
 uint8_t isl_get_render_compression_format(enum isl_format format);
 
+bool isl_formats_have_same_bits_per_channel(enum isl_format format1,
+                                            enum isl_format format2);
+
 bool isl_format_has_unorm_channel(enum isl_format fmt) ATTRIBUTE_CONST;
 bool isl_format_has_snorm_channel(enum isl_format fmt) ATTRIBUTE_CONST;
 bool isl_format_has_ufloat_channel(enum isl_format fmt) ATTRIBUTE_CONST;

src/intel/isl/isl_format.c

@@ -948,6 +948,27 @@ isl_format_supports_multisampling(const struct intel_device_info *devinfo,
    }
 }
 
+/**
+ * Returns true if the two formats are component size compatible meaning that
+ * each component from one format has the same number of bits as the other
+ * format.
+ *
+ * This is useful to check whether an image used with 2 different formats can
+ * be fast cleared with a non 0 clear color.
+ */
+bool
+isl_formats_have_same_bits_per_channel(enum isl_format format1,
+                                       enum isl_format format2)
+{
+   const struct isl_format_layout *fmtl1 = isl_format_get_layout(format1);
+   const struct isl_format_layout *fmtl2 = isl_format_get_layout(format2);
+
+   return fmtl1->channels.r.bits == fmtl2->channels.r.bits &&
+          fmtl1->channels.g.bits == fmtl2->channels.g.bits &&
+          fmtl1->channels.b.bits == fmtl2->channels.b.bits &&
+          fmtl1->channels.a.bits == fmtl2->channels.a.bits;
+}
+
 /**
  * Returns true if the two formats are "CCS_E compatible" meaning that you can
  * render in one format with CCS_E enabled and then texture using the other
@@ -976,16 +997,10 @@ isl_formats_are_ccs_e_compatible(const struct intel_device_info *devinfo,
    if (format2 == ISL_FORMAT_A8_UNORM)
       format2 = ISL_FORMAT_R8_UNORM;
 
-   const struct isl_format_layout *fmtl1 = isl_format_get_layout(format1);
-   const struct isl_format_layout *fmtl2 = isl_format_get_layout(format2);
-
    /* The compression used by CCS is not dependent on the actual data encoding
     * of the format but only depends on the bit-layout of the channels.
     */
-   return fmtl1->channels.r.bits == fmtl2->channels.r.bits &&
+   return isl_formats_have_same_bits_per_channel(format1, format2);
-          fmtl1->channels.g.bits == fmtl2->channels.g.bits &&
-          fmtl1->channels.b.bits == fmtl2->channels.b.bits &&
-          fmtl1->channels.a.bits == fmtl2->channels.a.bits;
 }
 
 static bool