strings: revert caching of hash value.

Research indicates that this is something useful in
languages that abuse strings for implementing symbols.
We have interned symbols.

* lib.h (struct string): Remove hash member.

* lib.c (string_own, string, string_utf8, mkustring,
string_extend, replace_str, chr_str_set): Remove
all initializations and updates of the removed
hash member.

* hash.c (equal_hash): Do not cache string hash value.

3 files changed, 4 insertions, 34 deletions

diff --git a/hash.c b/hash.c
index 2f99a5ce..d71f0e20 100644
--- a/hash.c
+++ b/hash.c
@@ -315,13 +315,6 @@ ucnum equal_hash(val obj, int *count, ucnum seed)
     return equal_hash(obj->c.car, count, seed)
             + equal_hash(obj->c.cdr, count, seed + (CONS << 8));
   case STR:
-#if HAVE_MALLOC_USABLE_SIZE
-    if (seed == 0) {
-      return if3(obj->st.hash != 0,
-                 obj->st.hash,
-                 obj->st.hash = hash_c_str(obj->st.str, 0, count));
-    }
-#endif
     return hash_c_str(obj->st.str, seed, count);
   case CHR:
     return c_ch(obj);
diff --git a/lib.c b/lib.c
index 1bca83ef..07cae971 100644
--- a/lib.c
+++ b/lib.c
@@ -4859,9 +4859,7 @@ val string_own(wchar_t *str)
   obj->st.type = STR;
   obj->st.str = str;
   obj->st.len = nil;
-#if HAVE_MALLOC_USABLE_SIZE
-  obj->st.hash = 0;
-#else
+#if !HAVE_MALLOC_USABLE_SIZE
   obj->st.alloc = 0;
 #endif
   return obj;
@@ -4873,9 +4871,7 @@ val string(const wchar_t *str)
   obj->st.type = STR;
   obj->st.str = chk_strdup(str);
   obj->st.len = nil;
-#if HAVE_MALLOC_USABLE_SIZE
-  obj->st.hash = 0;
-#else
+#if !HAVE_MALLOC_USABLE_SIZE
   obj->st.alloc = 0;
 #endif
   return obj;
@@ -4887,9 +4883,7 @@ val string_utf8(const char *str)
   obj->st.type = STR;
   obj->st.str = utf8_dup_from(str);
   obj->st.len = nil;
-#if HAVE_MALLOC_USABLE_SIZE
-  obj->st.hash = 0;
-#else
+#if !HAVE_MALLOC_USABLE_SIZE
   obj->st.alloc = 0;
 #endif
   return obj;
@@ -4953,9 +4947,6 @@ val mkustring(val len)
 val init_str(val str, const wchar_t *data, val self)
 {
   wmemcpy(str->st.str, data, c_num(str->st.len, self));
-#if HAVE_MALLOC_USABLE_SIZE
-  str->st.hash = 0;
-#endif
   return str;
 }
 
@@ -5083,9 +5074,6 @@ val string_extend(val str, val tail, val finish_in)
       str->st.str[len] = c_chr(tail);
       str->st.str[len + 1] = 0;
     }
-#if HAVE_MALLOC_USABLE_SIZE
-    str->st.hash = 0;
-#endif
   }
 
   return str;
@@ -5596,11 +5584,6 @@ val replace_str(val str_in, val items, val from, val to)
   from = max2(zero, min2(from, len));
   to = max2(zero, min2(to, len));
 
-
-#if HAVE_MALLOC_USABLE_SIZE
-  str_in->st.hash = 0;
-#endif
-
   {
     val len_rep = minus(to, from);
     val len_it = length(items);
@@ -6885,10 +6868,6 @@ val chr_str_set(val str, val ind, val chr)
               self, str, nao);
   }
 
-#if HAVE_MALLOC_USABLE_SIZE
-  str->st.hash = 0;
-#endif
-
   if (index < 0) {
     ind = plus(length_str(str), ind);
     index = c_num(ind, self);
diff --git a/lib.h b/lib.h
index 48320174..34f00c09 100644
--- a/lib.h
+++ b/lib.h
@@ -154,9 +154,7 @@ struct string {
   obj_common;
   wchar_t *str;
   val len;
-#if HAVE_MALLOC_USABLE_SIZE
-  ucnum hash;
-#else
+#if !HAVE_MALLOC_USABLE_SIZE
   cnum alloc;
 #endif
 };