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-rw-r--r--lib/compiler/src/beam_utils.erl5
-rw-r--r--lib/compiler/test/beam_utils_SUITE.erl23
2 files changed, 25 insertions, 3 deletions
diff --git a/lib/compiler/src/beam_utils.erl b/lib/compiler/src/beam_utils.erl
index 6e23003fc7..6b2ab5a2a4 100644
--- a/lib/compiler/src/beam_utils.erl
+++ b/lib/compiler/src/beam_utils.erl
@@ -745,8 +745,11 @@ check_liveness_block_2(R, {gc_bif,Op,{f,Lbl}}, Ss, St) ->
check_liveness_block_3(R, Lbl, {Op,length(Ss)}, St);
check_liveness_block_2(R, {bif,Op,{f,Lbl}}, Ss, St) ->
Arity = length(Ss),
+
+ %% Note that is_function/2 is a type test but is not safe.
case erl_internal:comp_op(Op, Arity) orelse
- erl_internal:new_type_test(Op, Arity) of
+ (erl_internal:new_type_test(Op, Arity) andalso
+ erl_bifs:is_safe(erlang, Op, Arity)) of
true ->
{killed,St};
false ->
diff --git a/lib/compiler/test/beam_utils_SUITE.erl b/lib/compiler/test/beam_utils_SUITE.erl
index ac19305d69..ff0f72d519 100644
--- a/lib/compiler/test/beam_utils_SUITE.erl
+++ b/lib/compiler/test/beam_utils_SUITE.erl
@@ -26,7 +26,7 @@
select/1,y_catch/1,otp_8949_b/1,liveopt/1,coverage/1,
y_registers/1,user_predef/1,scan_f/1,cafu/1,
receive_label/1,read_size_file_version/1,not_used/1,
- is_used_fr/1]).
+ is_used_fr/1,unsafe_is_function/1]).
-export([id/1]).
suite() -> [{ct_hooks,[ts_install_cth]}].
@@ -53,7 +53,8 @@ groups() ->
cafu,
read_size_file_version,
not_used,
- is_used_fr
+ is_used_fr,
+ unsafe_is_function
]}].
init_per_suite(Config) ->
@@ -570,6 +571,24 @@ is_used_fr(X, Y) ->
end,
X ! 1.
+%% ERL-778.
+unsafe_is_function(Config) ->
+ {undefined,any} = unsafe_is_function(undefined, any),
+ {ok,any} = unsafe_is_function(fun() -> ok end, any),
+ {'EXIT',{{case_clause,_},_}} = (catch unsafe_is_function(fun(_) -> ok end, any)),
+ ok.
+
+unsafe_is_function(F, M) ->
+ %% There would be an internal consistency failure:
+ %% Instruction: {bif,is_function,{f,0},[{x,0},{integer,0}],{x,2}}
+ %% Error: {uninitialized_reg,{y,0}}:
+
+ NewValue = case is_function(F, 0) of
+ true -> F();
+ false when F =:= undefined -> undefined
+ end,
+ {NewValue,M}.
+
%% The identity function.
id(I) -> I.