Cover code in beam_trim

2 files changed, 45 insertions, 2 deletions

diff --git a/lib/compiler/test/bs_match_SUITE.erl b/lib/compiler/test/bs_match_SUITE.erl
index 9a0d4cfd26..2cfcb841a7 100644
--- a/lib/compiler/test/bs_match_SUITE.erl
+++ b/lib/compiler/test/bs_match_SUITE.erl
@@ -743,9 +743,19 @@ coverage(Config) when is_list(Config) ->
     bitstring = coverage_bitstring(<<7:4>>),
     other = coverage_bitstring([a]),
 
+    %% Cover code in beam_trim.
+
     {done,<<17,53>>,[253,155,200]} =
         coverage_trim(<<253,155,200,17,53>>, e0, e1, e2, e3, []),
 
+    <<"(right|linux)">> = coverage_trim_1(<<"">>, <<"right">>, <<"linux">>),
+    <<"/(right|linux)">> = coverage_trim_1(<<"/">>, <<"right">>, <<"linux">>),
+    <<"(left|linux)/(right|linux)">> =
+        coverage_trim_1(<<"left">>, <<"right">>, <<"linux">>),
+
+    {10,<<"-">>,""} = coverage_trim_2(<<"-">>, 10, []),
+    {8,<<"-">>,"aa"} = coverage_trim_2(<<"aa-">>, 10, []),
+
     ok.
 
 coverage_fold(Fun, Acc, <<H,T/binary>>) ->
@@ -848,6 +858,29 @@ coverage_trim(<<C:8,T/binary>> = Bin, E0, E1, E2, E3, Acc) ->
             {done,Bin,lists:reverse(Acc)}
     end.
 
+coverage_trim_1(<<>>, Right, OsType) ->
+    do_coverage_trim_1(Right, OsType);
+coverage_trim_1(<<"/">>, Right, OsType) ->
+    <<"/",(do_coverage_trim_1(Right, OsType))/binary>>;
+coverage_trim_1(Left, Right, OsType) ->
+    <<(do_coverage_trim_1(Left, OsType))/binary,
+      "/",
+      (do_coverage_trim_1(Right, OsType))/binary>>.
+
+do_coverage_trim_1(A, OsType) ->
+    <<"(",A/binary,"|",OsType/binary,")">>.
+
+coverage_trim_2(<<C/utf8,R/binary>> = Bin, I, L) ->
+    case printable_char(C) of
+        true ->
+            coverage_trim_2(R, I - 1, [C | L]);
+        false ->
+            {I,Bin,lists:reverse(L)}
+    end.
+
+printable_char($a) -> true;
+printable_char(_) -> false.
+
 multiple_uses(Config) when is_list(Config) ->
     {344,62879,345,<<245,159,1,89>>} = multiple_uses_1(<<1,88,245,159,1,89>>),
     true = multiple_uses_2(<<0,0,197,18>>),
diff --git a/lib/compiler/test/map_SUITE.erl b/lib/compiler/test/map_SUITE.erl
index 3d7a4e445a..440b632381 100644
--- a/lib/compiler/test/map_SUITE.erl
+++ b/lib/compiler/test/map_SUITE.erl
@@ -73,7 +73,7 @@
         t_reused_key_variable/1,
 
         %% new in OTP 22
-        t_mixed_clause/1
+        t_mixed_clause/1,cover_beam_trim/1
     ]).
 
 suite() -> [].
@@ -130,7 +130,7 @@ all() ->
         t_reused_key_variable,
 
         %% new in OTP 22
-        t_mixed_clause
+        t_mixed_clause,cover_beam_trim
     ].
 
 groups() -> [].
@@ -2182,6 +2182,16 @@ t_mixed_clause(_Config) ->
               end,
     ok.
 
+cover_beam_trim(_Config) ->
+    val = do_cover_beam_trim(id, max, max, id, #{id=>val}),
+    ok.
+
+do_cover_beam_trim(Id, OldMax, Max, Id, M) ->
+    OldMax = id(Max),
+    #{Id:=Val} = id(M),
+    Val.
+
+
 %% aux
 
 rand_terms(0) -> [];