py: Convert hash API to use MP_UNARY_OP_HASH instead of ad-hoc function.

Hashing is now done using mp_unary_op function with MP_UNARY_OP_HASH as
the operator argument.  Hashing for int, str and bytes still go via
fast-path in mp_unary_op since they are the most common objects which
need to be hashed.

This lead to quite a bit of code cleanup, and should be more efficient
if anything.  It saves 176 bytes code space on Thumb2, and 360 bytes on
x86.

The only loss is that the error message "unhashable type" is now the
more generic "unsupported type for __hash__".

1 files changed, 7 insertions, 0 deletions

diff --git a/py/runtime.c b/py/runtime.c
index a6cf7e0177..4f2d5a1600 100644
--- a/py/runtime.c
+++ b/py/runtime.c
@@ -32,6 +32,7 @@
 #include "py/nlr.h"
 #include "py/parsenum.h"
 #include "py/compile.h"
+#include "py/objstr.h"
 #include "py/objtuple.h"
 #include "py/objlist.h"
 #include "py/objmodule.h"
@@ -200,6 +201,8 @@ mp_obj_t mp_unary_op(mp_uint_t op, mp_obj_t arg) {
         switch (op) {
             case MP_UNARY_OP_BOOL:
                 return MP_BOOL(val != 0);
+            case MP_UNARY_OP_HASH:
+                return arg;
             case MP_UNARY_OP_POSITIVE:
                 return arg;
             case MP_UNARY_OP_NEGATIVE:
@@ -215,6 +218,10 @@ mp_obj_t mp_unary_op(mp_uint_t op, mp_obj_t arg) {
                 assert(0);
                 return arg;
         }
+    } else if (op == MP_UNARY_OP_HASH && MP_OBJ_IS_STR_OR_BYTES(arg)) {
+        // fast path for hashing str/bytes
+        GET_STR_HASH(arg, h);
+        return MP_OBJ_NEW_SMALL_INT(h);
     } else {
         mp_obj_type_t *type = mp_obj_get_type(arg);
         if (type->unary_op != NULL) {