WIP mul64 dlsym optimization

Change-Id: I4caf4f14deb7a106c17e3ca89bdff5cd89f9541b

diff --git a/elf/dl-lookup.c b/elf/dl-lookup.c
index 205d04371756d1d24327ed1476a612e10db47ab9..4d2f3b91f0b61ea2de228c12614e4515347b704d 100644 (file)
--- a/elf/dl-lookup.c
+++ b/elf/dl-lookup.c
@@ -396,16 +396,15 @@ do_lookup_x (const char *undef_name, uint_fast32_t new_hash,
                                & (bitmask_word >> hashbit2) & 1))
            {
              Elf32_Word bucket;
-             if (map->l_nbuckets > 1)
+             if (powerof2 (map->l_nbuckets))
+               bucket = map->l_gnu_buckets[new_hash & (map->l_nbuckets - 1)];
+             else
                {
                  uint32_t quotient
-                   = divopt_32 (new_hash, map->l_nbuckets_multiplier,
-                                map->l_nbuckets_multiplier_shift);
+                   = ((unsigned __int128) map->l_nbuckets_multiplier * ((uint64_t) new_hash + 1)) >> 64;
                  uint32_t remainder = new_hash - map->l_nbuckets * quotient;
                  bucket = map->l_gnu_buckets[remainder];
                }
-             else
-               bucket = map->l_gnu_buckets[0];
 
              if (bucket != 0)
                {
@@ -942,11 +941,10 @@ _dl_setup_hash (struct link_map *map)
       /* Initialize MIPS xhash translation table.  */
       ELF_MACHINE_XHASH_SETUP (hash32, symbias, map);
 
-      if (map->l_nbuckets >= 2)
-       map->l_nbuckets_multiplier_shift
-         = precompute_divopt_32 (map->l_nbuckets,
-                                 &map->l_nbuckets_multiplier);
-
+      if (powerof2 (map->l_nbuckets))
+       map->l_nbuckets_multiplier = __builtin_ctz (map->l_nbuckets);
+      else
+       map->l_nbuckets_multiplier = ((unsigned __int128) 1 << 64) / map->l_nbuckets;
       return;
     }
 

diff --git a/include/link.h b/include/link.h
index b09aa81bb42ac8ca77418739ac747cd71e651981..eec4c9ef6e87e17335be2feb9a5b6c48e4585988 100644 (file)
--- a/include/link.h
+++ b/include/link.h
@@ -153,8 +153,7 @@ struct link_map
 
     /* Symbol hash table.  */
     Elf_Symndx l_nbuckets;
-    uint32_t l_nbuckets_multiplier;
-    int l_nbuckets_multiplier_shift;
+    uint64_t l_nbuckets_multiplier;
     Elf32_Word l_gnu_bitmask_idxbits;
     Elf32_Word l_gnu_shift;
     const ElfW(Addr) *l_gnu_bitmask;