hv.h: rework HEK_FLAGS to a proper member in struct hek

Move the store of HEK_FLAGS off the end of the allocated
hek_key into the hek struct, simplifying access and providing
clarity to the code.

What is not clear is why Nicholas or perhaps Jarkko did
not do this themselves. We use similar tricks elsewhere,
so perhaps it was just continuing a tradition...

One thought is that we often have do strcmp/memeq on these
strings, and having their start be aligned might improve
performance, wheras this patch changes them to be unaligned.
If so perhaps we should just make flags a U32 and let the
HEK's be larger. They are shared in PL_strtab, and are
probably often sitting in malloc blocks that are sufficiently
large enough that making them bigger would make no practical
difference. (All of this is worth checking.)

[with edits by Yves Orton]

1 files changed, 2 insertions, 3 deletions

diff --git a/hv.h b/hv.h
index ee536f08c8..16634b7e44 100644
--- a/hv.h
+++ b/hv.h
@@ -45,10 +45,9 @@ struct he {
 struct hek {
     U32		hek_hash;	/* hash of key */
     I32		hek_len;	/* length of hash key */
+    char        hek_flags;      /* The flags associated with this key */
     char	hek_key[1];	/* variable-length hash key */
     /* the hash-key is \0-terminated */
-    /* after the \0 there is a byte for flags, such as whether the key
-       is UTF-8 */
 };
 
 struct shared_he {
@@ -397,7 +396,7 @@ C<SV*>.
 #define HEK_HASH(hek)		(hek)->hek_hash
 #define HEK_LEN(hek)		(hek)->hek_len
 #define HEK_KEY(hek)		(hek)->hek_key
-#define HEK_FLAGS(hek)	(*((unsigned char *)(HEK_KEY(hek))+HEK_LEN(hek)+1))
+#define HEK_FLAGS(hek)                (hek)->hek_flags
 
 #define HVhek_UTF8	0x01 /* Key is utf8 encoded. */
 #define HVhek_WASUTF8	0x02 /* Key is bytes here, but was supplied as utf8. */