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a49c6c6a65
The libctf dynhash hashtab abstraction supports per-hashtab arbitrary key/item freeing functions -- but it also has a constant slot type that holds both key and value requested by the user, so it needs to use its own freeing function to free that -- and it has nowhere to store the freeing functions the caller requested. So it copies them into every hash item, bloating every slot, even though all items in a given hash table must have the same key and value freeing functions. So point back to the owner using a back-pointer, but don't even spend space in the item or the hashtab allocating those freeing functions unless necessary: if none are needed, we can simply arrange to not pass in ctf_dynhash_item_free as a del_f to hashtab_create_alloc, and none of those fields will ever be accessed. The only downside is that this makes the code sensitive to the order of fields in the ctf_helem_t and ctf_hashtab_t: but the deduplicator allocates so many hash tables that doing this alone cuts memory usage during deduplication by about 10%. (libiberty hashtab itself has a lot of per-hashtab bloat: in the future we might trim that down, or make a trimmer version.) libctf/ * ctf-hash.c (ctf_helem_t) <key_free>: Remove. <value_free>: Likewise. <owner>: New. (ctf_dynhash_item_free): Indirect through the owner. (ctf_dynhash_create): Only pass in ctf_dynhash_item_free and allocate space for the key_free and value_free fields fields if necessary. (ctf_hashtab_insert): Likewise. Fix OOM errno value. (ctf_dynhash_insert): Only access ctf_hashtab's key_free and value_free if they will exist. Set the slot's owner, but only if it exists. (ctf_dynhash_remove): Adjust.