Free bit 7 of GC 'marked' field

Tables were using this bit to indicate their array sizes were real
('isrealasize'), but this bit can be useful for tests. Instead, they
can use bit 7 of their 'flag' field for that purpose. (There are only
six fast-access metamethods.) This 'flag' field only exists in tables,
so this use does not affect other types.

1 files changed, 9 insertions, 0 deletions

diff --git a/ltm.h b/ltm.h
index 99b545e7..73b833c6 100644
--- a/ltm.h
+++ b/ltm.h
@@ -46,6 +46,15 @@ typedef enum {
 
 
 /*
+** Mask with 1 in all fast-access methods. A 1 in any of these bits
+** in the flag of a (meta)table means the metatable does not have the
+** corresponding metamethod field. (Bit 7 of the flag is used for
+** 'isrealasize'.)
+*/
+#define maskflags       (~(~0u << (TM_EQ + 1)))
+
+
+/*
 ** Test whether there is no tagmethod.
 ** (Because tagmethods use raw accesses, the result may be an "empty" nil.)
 */