beam_ssa_bool: Fix miscompilation

Fixes erlang#7517
bjorng · Jul 31, 2023 · 42e6979 · 42e6979
1 parent d051172
commit 42e6979
Show file tree

Hide file tree

Showing 2 changed files with 35 additions and 9 deletions.
diff --git a/lib/compiler/src/beam_ssa_bool.erl b/lib/compiler/src/beam_ssa_bool.erl
@@ -1040,15 +1040,11 @@ ensure_no_failing_instructions(First, Second, G, St) ->
 
 can_fail({succeeded,_}, V, G) -> not eaten_by_phi(V, G);
 can_fail(put_map, _, _) -> true;
-can_fail(_, _, _) -> false.
-
-eaten_by_phi(V, G) ->
-    {br,_,Fail} = get_targets(V, G),
-    case beam_digraph:vertex(G, Fail) of
-        br ->
-            [To] = beam_digraph:out_neighbours(G, Fail),
-            case beam_digraph:vertex(G, To) of
-                #b_set{op=phi} ->
+can_fail(_, V, G) ->
+    case get_targets(V, G) of
+        {br,_Succ,Fail} ->
+            case follow_branch(G, Fail) of
+                {external,_} ->
                     true;
                 _ ->
                     false
@@ -1057,6 +1053,24 @@ eaten_by_phi(V, G) ->
             false
     end.
 
+eaten_by_phi(V, G) ->
+    {br,_,Fail} = get_targets(V, G),
+    case follow_branch(G, Fail) of
+        #b_set{op=phi} ->
+            true;
+        _ ->
+            false
+    end.
+
+follow_branch(G, Br) ->
+    case beam_digraph:vertex(G, Br) of
+        br ->
+            [To] = beam_digraph:out_neighbours(G, Br),
+            beam_digraph:vertex(G, To);
+        _ ->
+            none
+    end.
+
 %% order_args([Arg1,Arg2], G, St) -> {First,Second}.
 %%  Order arguments for a boolean operator so that there is path in the
 %%  digraph from the instruction referered to by the first operand to

diff --git a/lib/compiler/test/guard_SUITE.erl b/lib/compiler/test/guard_SUITE.erl
@@ -2621,6 +2621,7 @@ beam_bool_SUITE(_Config) ->
     gh_7252(),
     gh_7339(),
     gh_7370(),
+    gh_7517(),
     ok.
 
 before_and_inside_if() ->
@@ -3216,6 +3217,17 @@ gh_7370(A) when (not (not is_float(A))) =/= ((ok and ok) or true) ->
 gh_7370(_) ->
     b.
 
+gh_7517() ->
+    ok = catch do_gh_7517([]),
+    ok = catch do_gh_7517([a,b,c]),
+    {'EXIT',{function_clause,_}} = catch do_gh_7517(ok),
+    {'EXIT',{function_clause,_}} = catch do_gh_7517(<<>>),
+    ok.
+
+do_gh_7517(A) when (ok /= A) or is_float(is_list(A) orelse ok andalso ok) ->
+    ok.
+
+
 %%%
 %%% End of beam_bool_SUITE tests.
 %%%