erts: Add the size-testing guard BIF map_size/1

1 files changed, 23 insertions, 0 deletions

diff --git a/erts/emulator/beam/erl_bif_guard.c b/erts/emulator/beam/erl_bif_guard.c
index a715756c15..bbd8aa31d9 100644
--- a/erts/emulator/beam/erl_bif_guard.c
+++ b/erts/emulator/beam/erl_bif_guard.c
@@ -33,6 +33,7 @@
 #include "bif.h"
 #include "big.h"
 #include "erl_binary.h"
+#include "erl_map.h"
 
 static Eterm gc_double_to_integer(Process* p, double x, Eterm* reg, Uint live);
 
@@ -455,6 +456,28 @@ Eterm erts_gc_byte_size_1(Process* p, Eterm* reg, Uint live)
     }
 }
 
+Eterm erts_gc_map_size_1(Process* p, Eterm* reg, Uint live)
+{
+    Eterm arg = reg[live];
+    if (is_map(arg)) {
+	map_t *mp = (map_t*)map_val(arg);
+	Uint size = map_get_size(mp);
+	if (IS_USMALL(0, size)) {
+	    return make_small(size);
+	} else {
+	    Eterm* hp;
+	    if (ERTS_NEED_GC(p, BIG_UINT_HEAP_SIZE)) {
+		erts_garbage_collect(p, BIG_UINT_HEAP_SIZE, reg, live);
+	    }
+	    hp = p->htop;
+	    p->htop += BIG_UINT_HEAP_SIZE;
+	    return uint_to_big(size, hp);
+	}
+    } else {
+	BIF_ERROR(p, BADARG);
+    }
+}
+
 Eterm erts_gc_abs_1(Process* p, Eterm* reg, Uint live)
 {
     Eterm arg;