isl: round format alignment to nearest power of 2

A few inline asserts in anv assume alignments are power of 2, but with
formats like R8G8B8 we have odd alignments.

v2: round up to power of 2 (Ilia)

v3: reuse util_next_power_of_two() from gallium/aux/util/u_math.h (Ilia)

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>

src/intel/isl/isl.c

@@ -1201,6 +1201,7 @@ isl_surf_init_s(const struct isl_device *dev,
             base_alignment = MAX(base_alignment, fmtl->bpb / 8);
          }
       }
+      base_alignment = isl_round_up_to_power_of_two(base_alignment);
    } else {
       assert(phys_slice0_sa.w % fmtl->bw == 0);
       const uint32_t total_w_el = phys_slice0_sa.width / fmtl->bw;

src/intel/isl/isl_priv.h

@@ -98,6 +98,15 @@ isl_log2u(uint32_t n)
    return 31 - __builtin_clz(n);
 }
 
+static inline uint32_t
+isl_round_up_to_power_of_two(uint32_t value)
+{
+   if (value <= 1)
+      return value;
+
+   return 1 << (32 - __builtin_clz(value - 1));
+}
+
 static inline uint32_t
 isl_minify(uint32_t n, uint32_t levels)
 {