1 files changed, 51 insertions, 4 deletions

diff --git a/lib/compiler/test/beam_ssa_SUITE.erl b/lib/compiler/test/beam_ssa_SUITE.erl
index dd1b7ddcd3..3b510f3528 100644
--- a/lib/compiler/test/beam_ssa_SUITE.erl
+++ b/lib/compiler/test/beam_ssa_SUITE.erl
@@ -23,7 +23,7 @@
 	 init_per_group/2,end_per_group/2,
          calls/1,tuple_matching/1,recv/1,maps/1,
          cover_ssa_dead/1,combine_sw/1,share_opt/1,
-         beam_ssa_dead_crash/1]).
+         beam_ssa_dead_crash/1,stack_init/1]).
 
 suite() -> [{ct_hooks,[ts_install_cth]}].
 
@@ -39,7 +39,8 @@ groups() ->
        cover_ssa_dead,
        combine_sw,
        share_opt,
-       beam_ssa_dead_crash
+       beam_ssa_dead_crash,
+       stack_init
       ]}].
 
 init_per_suite(Config) ->
@@ -524,9 +525,11 @@ do_comb_sw_2(X) ->
     erase(?MODULE).
 
 share_opt(_Config) ->
-    ok = do_share_opt(0).
+    ok = do_share_opt_1(0),
+    ok = do_share_opt_2(),
+    ok.
 
-do_share_opt(A) ->
+do_share_opt_1(A) ->
     %% The compiler would be stuck in an infinite loop in beam_ssa_share.
     case A of
         0 -> a;
@@ -535,6 +538,26 @@ do_share_opt(A) ->
     end,
     receive after 1 -> ok end.
 
+do_share_opt_2() ->
+    ok = sopt_2({[pointtopoint], [{dstaddr,any}]}, ok),
+    ok = sopt_2({[broadcast], [{broadaddr,any}]}, ok),
+    ok = sopt_2({[], []}, ok),
+    ok.
+
+sopt_2({Flags, Opts}, ok) ->
+    Broadcast = lists:member(broadcast, Flags),
+    P2P = lists:member(pointtopoint, Flags),
+    case Opts of
+        %% The following two clauses would be combined to one, silently
+        %% discarding the guard test of the P2P variable.
+        [{broadaddr,_}|Os] when Broadcast ->
+            sopt_2({Flags, Os}, ok);
+        [{dstaddr,_}|Os] when P2P ->
+            sopt_2({Flags, Os}, ok);
+        [] ->
+            ok
+    end.
+    
 beam_ssa_dead_crash(_Config) ->
     not_A_B = do_beam_ssa_dead_crash(id(false), id(true)),
     not_A_not_B = do_beam_ssa_dead_crash(false, false),
@@ -589,6 +612,30 @@ do_beam_ssa_dead_crash(A, B) ->
             end
     end.
 
+stack_init(_Config) ->
+    6 = stack_init(a, #{a => [1,2,3]}),
+    0 = stack_init(missing, #{}),
+    ok.
+
+stack_init(Key, Map) ->
+    %% beam_ssa_codegen would wrongly assume that y(0) would always be
+    %% initialized by the `get_map_elements` instruction that follows, and
+    %% would set up the stack frame using an `allocate` instruction and
+    %% would not generate an `init` instruction to initialize y(0).
+    Res = case Map of
+              #{Key := Elements} ->
+                  %% Elements will be assigned to y(0) if the key Key exists.
+                  lists:foldl(fun(El, Acc) ->
+                                      Acc + El
+                              end, 0, Elements);
+              #{} ->
+                  %% y(0) will be left uninitialized when the key is not
+                  %% present in the map.
+                  0
+          end,
+    %% y(0) would be uninitialized here if the key was not present in the map
+    %% (if the second clause was executed).
+    id(Res).
 
 %% The identity function.
 id(I) -> I.