qht: require a default comparison function

qht_lookup now uses the default cmp function. qht_lookup_custom is defined
to retain the old behaviour, that is a cmp function is explicitly provided.

qht_insert will gain use of the default cmp in the next patch.

Note that we move qht_lookup_custom's @func to be the last argument,
which makes the new qht_lookup as simple as possible.
Instead of this (i.e. keeping @func 2nd):
0000000000010750 <qht_lookup>:
   10750:       89 d1                   mov    %edx,%ecx
   10752:       48 89 f2                mov    %rsi,%rdx
   10755:       48 8b 77 08             mov    0x8(%rdi),%rsi
   10759:       e9 22 ff ff ff          jmpq   10680 <qht_lookup_custom>
   1075e:       66 90                   xchg   %ax,%ax

We get:
0000000000010740 <qht_lookup>:
   10740:       48 8b 4f 08             mov    0x8(%rdi),%rcx
   10744:       e9 37 ff ff ff          jmpq   10680 <qht_lookup_custom>
   10749:       0f 1f 80 00 00 00 00    nopl   0x0(%rax)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

1 files changed, 11 insertions, 3 deletions

diff --git a/util/qht.c b/util/qht.c
index 55b0738..487e923 100644
--- a/util/qht.c
+++ b/util/qht.c
@@ -351,11 +351,14 @@ static struct qht_map *qht_map_create(size_t n_buckets)
     return map;
 }
 
-void qht_init(struct qht *ht, size_t n_elems, unsigned int mode)
+void qht_init(struct qht *ht, qht_cmp_func_t cmp, size_t n_elems,
+              unsigned int mode)
 {
     struct qht_map *map;
     size_t n_buckets = qht_elems_to_buckets(n_elems);
 
+    g_assert(cmp);
+    ht->cmp = cmp;
     ht->mode = mode;
     qemu_mutex_init(&ht->lock);
     map = qht_map_create(n_buckets);
@@ -479,8 +482,8 @@ void *qht_lookup__slowpath(struct qht_bucket *b, qht_lookup_func_t func,
     return ret;
 }
 
-void *qht_lookup(struct qht *ht, qht_lookup_func_t func, const void *userp,
-                 uint32_t hash)
+void *qht_lookup_custom(struct qht *ht, const void *userp, uint32_t hash,
+                        qht_lookup_func_t func)
 {
     struct qht_bucket *b;
     struct qht_map *map;
@@ -502,6 +505,11 @@ void *qht_lookup(struct qht *ht, qht_lookup_func_t func, const void *userp,
     return qht_lookup__slowpath(b, func, userp, hash);
 }
 
+void *qht_lookup(struct qht *ht, const void *userp, uint32_t hash)
+{
+    return qht_lookup_custom(ht, userp, hash, ht->cmp);
+}
+
 /* call with head->lock held */
 static bool qht_insert__locked(struct qht *ht, struct qht_map *map,
                                struct qht_bucket *head, void *p, uint32_t hash,