Merge branch 'maint'

* maint:
  beam_ssa_bool: Fix miscompilation
  Fix crash when compiling is_list/1 call

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

lib/compiler/src/beam_ssa_codegen.erl

@@ -1266,9 +1266,22 @@ cg_block([#cg_set{op=is_tagged_tuple,anno=Anno,dst=Bool,args=Args0}], {Bool,Fail
             [Src,{integer,Arity},Tag] = typed_args(Args0, Anno, St),
             {[{test,is_tagged_tuple,ensure_label(Fail, St),[Src,Arity,Tag]}],St}
     end;
-cg_block([#cg_set{op=is_nonempty_list,dst=Bool,args=Args0}], {Bool,Fail}, St) ->
+cg_block([#cg_set{op=is_nonempty_list,dst=Bool0,args=Args0}=Set], {Bool0,Fail0}, St) ->
+    Fail = ensure_label(Fail0, St),
     Args = beam_args(Args0, St),
-    {[{test,is_nonempty_list,ensure_label(Fail, St),Args}],St};
+    case beam_args([Bool0|Args0], St) of
+        [{z,0}|Args] ->
+            {[{test,is_nonempty_list,Fail,Args}],St};
+        [Dst|Args] ->
+            %% This instruction was a call to is_list/1, which was
+            %% rewritten to an is_nonempty_list test by
+            %% beam_ssa_type. BEAM has no is_nonempty_list instruction
+            %% that will return a boolean, so we must revert it to an
+            %% is_list/1 call.
+            #cg_set{anno=#{was_bif_is_list := true}} = Set, %Assertion.
+            {[{bif,is_list,Fail0,Args,Dst},
+              {test,is_eq_exact,Fail,[Dst,{atom,true}]}],St}
+    end;
 cg_block([#cg_set{op=has_map_field,dst=Dst0,args=Args0}], {Dst0,Fail0}, St) ->
     Fail = ensure_label(Fail0, St),
     case beam_args([Dst0|Args0], St) of

lib/compiler/test/beam_type_SUITE.erl

@@ -1137,6 +1137,11 @@ cs_2({bar,baz}) ->
 is_list_opt(_Config) ->
     true = is_list_opt_1(id(<<"application/a2l">>)),
     false = is_list_opt_1(id(<<"">>)),
+
+    ok = is_list_opt_3(id([])),
+    true = is_list_opt_3(id([a])),
+    {'EXIT',{badarg,_}} = catch is_list_opt_3(id(no_list)),
+
     ok.
 
 is_list_opt_1(Type) ->
@@ -1148,6 +1153,16 @@ is_list_opt_1(Type) ->
 is_list_opt_2(<<"application/a2l">>) -> [<<"a2l">>];
 is_list_opt_2(_Type) -> nil.
 
+is_list_opt_3([]) ->
+    ok;
+is_list_opt_3(A) ->
+    %% The call to is_list/1 would be optimized to an is_nonempty_list
+    %% instruction, which only exists as a guard test that cannot
+    %% produce boolean value.
+    _ = (Bool = is_list(A)) orelse binary_to_integer(<<"">>),
+    Bool.
+
+
 %% We used to determine the type of `get_tuple_element` at the time of
 %% extraction, which is simple but sometimes throws away type information when 
 %% on tuple unions.

lib/compiler/test/guard_SUITE.erl

@@ -2636,6 +2636,7 @@ beam_bool_SUITE(_Config) ->
     gh_7252(),
     gh_7339(),
     gh_7370(),
+    gh_7517(),
     ok.
 
 before_and_inside_if() ->
@@ -3242,6 +3243,17 @@ 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.
 %%%