3 files changed, 44 insertions, 1 deletions
diff --git a/erts/emulator/beam/beam_emu.c b/erts/emulator/beam/beam_emu.c
index 1166b32a3b..c753e57ddc 100644
--- a/erts/emulator/beam/beam_emu.c
+++ b/erts/emulator/beam/beam_emu.c
@@ -6781,8 +6781,19 @@ update_map_assoc(Process* p, Eterm* reg, Eterm map, BeamInstr* I)
 
     n = kp - p->htop - 1;	/* Actual number of keys/values */
     *p->htop = make_arityval(n);
+    p->htop  = hp;
     mp->size = n;
-    p->htop = hp;
+
+    /* The expensive case, need to build a hashmap */
+    if (n > MAP_SMALL_MAP_LIMIT) {
+	res = erts_hashmap_from_ks_and_vs(p,map_get_keys(mp),map_get_values(mp),n);
+	if (p->mbuf) {
+	    Uint live = Arg(3);
+	    reg[live] = res;
+	    erts_garbage_collect(p, 0, reg, live+1);
+	    res       = reg[live];
+	}
+    }
     return res;
 }
 
diff --git a/erts/emulator/beam/erl_map.c b/erts/emulator/beam/erl_map.c
index 1703f86b0e..e26b97d75c 100644
--- a/erts/emulator/beam/erl_map.c
+++ b/erts/emulator/beam/erl_map.c
@@ -452,6 +452,37 @@ Eterm erts_hashmap_from_array(Process *p, Eterm *leafs, Uint n) {
     return res;
 }
 
+
+Eterm erts_hashmap_from_ks_and_vs(Process *p, Eterm *ks, Eterm *vs, Uint n) {
+    Uint32 sw, hx;
+    Uint i;
+    hxnode_t *hxns;
+    Eterm *hp, res;
+
+    ASSERT(n > 0);
+
+    hp = HAlloc(p, (2 * n));
+
+    /* create tmp hx values and leaf ptrs */
+    hxns = (hxnode_t *)erts_alloc(ERTS_ALC_T_TMP, n * sizeof(hxnode_t));
+
+    for(i = 0; i < n; i++) {
+	hx = hashmap_make_hash(ks[i]);
+	swizzle32(sw,hx);
+	hxns[i].hx   = sw;
+	hxns[i].val  = CONS(hp, ks[i], vs[i]); hp += 2;
+	hxns[i].skip = 1; /* will be reassigned in from_array */
+	hxns[i].i    = i;
+    }
+
+    res = hashmap_from_unsorted_array(p, hxns, n);
+
+    erts_free(ERTS_ALC_T_TMP, (void *) hxns);
+    ERTS_VERIFY_UNUSED_TEMP_ALLOC(p);
+
+    return res;
+}
+
 static Eterm hashmap_from_unsorted_array(Process *p, hxnode_t *hxns, Uint n) {
     Uint jx = 0, ix = 0, lx, cx;
     Eterm res;
diff --git a/erts/emulator/beam/erl_map.h b/erts/emulator/beam/erl_map.h
index 3544189936..6a7b29fe86 100644
--- a/erts/emulator/beam/erl_map.h
+++ b/erts/emulator/beam/erl_map.h
@@ -103,6 +103,7 @@ void   hashmap_iterator_init(struct ErtsWStack_* s, Eterm node);
 Eterm* hashmap_iterator_next(struct ErtsWStack_* s);
 int    hashmap_key_hash_cmp(Eterm* ap, Eterm* bp);
 Eterm  erts_hashmap_from_array(Process *p, Eterm *leafs, Uint n);
+Eterm  erts_hashmap_from_ks_and_vs(Process *p, Eterm *ks, Eterm *vs, Uint n);
 const  Eterm *erts_hashmap_get(Uint32 hx, Eterm key, Eterm map);
 
 #if HALFWORD_HEAP