3 files changed, 39 insertions, 3 deletions
diff --git a/erts/emulator/beam/beam_emu.c b/erts/emulator/beam/beam_emu.c
index 8288eb9798..15591c3cad 100644
--- a/erts/emulator/beam/beam_emu.c
+++ b/erts/emulator/beam/beam_emu.c
@@ -6559,7 +6559,7 @@ new_map(Process* p, Eterm* reg, BeamInstr* I)
 
     ptr = &Arg(4);
 
-    if (n > MAP_SMALL_MAP_LIMIT) {
+    if (n > 2*MAP_SMALL_MAP_LIMIT) {
 	if (HeapWordsLeft(p) < n) {
 	    erts_garbage_collect(p, n, reg, Arg(2));
 	}
diff --git a/erts/emulator/beam/erl_map.c b/erts/emulator/beam/erl_map.c
index ea041e2303..0cf1c0e59d 100644
--- a/erts/emulator/beam/erl_map.c
+++ b/erts/emulator/beam/erl_map.c
@@ -422,6 +422,41 @@ static Eterm hashmap_from_validated_list(Process *p, Eterm list, Uint size) {
     erts_free(ERTS_ALC_T_TMP, (void *) hxns);
     ERTS_VERIFY_UNUSED_TEMP_ALLOC(p);
 
+    if (hashmap_size(res) <= MAP_SMALL_MAP_LIMIT) {
+        DECLARE_WSTACK(wstack);
+	Eterm *kv, *ks, *vs;
+	map_t *mp;
+	Eterm keys;
+        Uint n = hashmap_size(res);
+
+	/* build flat structure */
+	hp    = HAlloc(p, 3 + 1 + (2 * n));
+	keys  = make_tuple(hp);
+	*hp++ = make_arityval(n);
+	ks    = hp;
+	hp   += n;
+	mp    = (map_t*)hp;
+	hp   += MAP_HEADER_SIZE;
+	vs    = hp;
+
+	mp->thing_word = MAP_HEADER;
+	mp->size = n;
+	mp->keys = keys;
+
+	hashmap_iterator_init(&wstack, res);
+
+	while ((kv=hashmap_iterator_next(&wstack)) != NULL) {
+	    *ks++ = CAR(kv);
+	    *vs++ = CDR(kv);
+	}
+
+	/* it cannot have multiple keys */
+	erts_validate_and_sort_map(mp);
+
+	DESTROY_WSTACK(wstack);
+	return make_map(mp);
+    }
+
     return res;
 }
 
@@ -461,6 +496,7 @@ Eterm erts_hashmap_from_ks_and_vs_extra(Process *p, Eterm *ks, Eterm *vs, Uint n
     Eterm *hp, res;
 
     sz = (key == THE_NON_VALUE) ? n : (n + 1);
+    ASSERT(sz > MAP_SMALL_MAP_LIMIT);
     hp = HAlloc(p, 2 * sz);
 
     /* create tmp hx values and leaf ptrs */
diff --git a/erts/emulator/beam/erl_term.h b/erts/emulator/beam/erl_term.h
index 953525a45c..6d97344868 100644
--- a/erts/emulator/beam/erl_term.h
+++ b/erts/emulator/beam/erl_term.h
@@ -1110,8 +1110,8 @@ _ET_DECLARE_CHECKED(Uint,y_reg_index,Uint)
 #define BINARY_DEF		0x0
 #define LIST_DEF		0x1
 #define NIL_DEF			0x2
-#define MAP_DEF			0x3
-#define HASHMAP_DEF		0x4
+#define HASHMAP_DEF		0x3
+#define MAP_DEF			0x4
 #define TUPLE_DEF		0x5
 #define PID_DEF			0x6
 #define EXTERNAL_PID_DEF	0x7