wt_icache: check the SpecDepth value

Signed-off-by: Alban Gruin <alban.gruin@irit.fr>

src/cache_subsystem/wt_icache.sv

@@ -614,6 +614,12 @@ end else begin : gen_piton_offset
 
   assert (ICACHE_SET_ASSOC==4)
     else $fatal(1,"[l1 icache] cache must be 4-associative");
+
+  assert (2 ** $clog2(SpecDepth) == SpecDepth)
+    else $fatal(1,"[l1 icache] SpecDepth is not a power of 2");
+
+  assert (SpecDepth >= 2)
+    else $fatal(1,"[l1 icache] SpecDepth is lower than 2");
  end
 `endif
 //pragma translate_on