Correct transformation of put_map_assoc to new_map

A put_map_assoc instruction with an empty source map should be
converted to a simpler new_map instruction. The transformation
didn't happen because an empty source map is no longer represented
as a NIL term (as it was in the beginning before map literals
were implemented).

1 files changed, 17 insertions, 0 deletions

diff --git a/erts/emulator/beam/beam_load.c b/erts/emulator/beam/beam_load.c
index 02689e5b19..f140bb54cc 100644
--- a/erts/emulator/beam/beam_load.c
+++ b/erts/emulator/beam/beam_load.c
@@ -36,6 +36,7 @@
 #include "beam_catches.h"
 #include "erl_binary.h"
 #include "erl_zlib.h"
+#include "erl_map.h"
 
 #ifdef HIPE
 #include "hipe_bif0.h"
@@ -4051,6 +4052,22 @@ tuple_append_put(LoaderState* stp, GenOpArg Arity, GenOpArg Dst,
 }
 
 /*
+ * Predicate to test whether the given literal is an empty map.
+ */
+
+static int
+is_empty_map(LoaderState* stp, GenOpArg Lit)
+{
+    Eterm term;
+
+    if (Lit.type != TAG_q) {
+	return 0;
+    }
+    term = stp->literals[Lit.val].term;
+    return is_flatmap(term) && flatmap_get_size(flatmap_val(term)) == 0;
+}
+
+/*
  * Replace a get_map_elements with one key to an instruction with one
  * element
  */