Avoid repeated hash computation, reduce irept::dt size

tautschnig · tautschnig · commit 23fea45c2f26 · 2018-04-03T14:42:24.000+01:00
On SV-COMP benchmarks, hashing accounts for &gt;22% of CPU time (with
profiling enabled).
diff --git a/src/util/irep.h b/src/util/irep.h
@@ -18,8 +18,8 @@ Author: Daniel Kroening, kroening@kroening.com
 #include "irep_ids.h"
 
 #define SHARING
-// #define HASH_CODE
-// #define SUB_IS_LIST
+#define HASH_CODE
+#define SUB_IS_LIST
 
 #ifdef SHARING
 #include "cow.h"
