kernel: bypass unicode translation in group for latin1 putc_requests

user_drv knows whether the request should be converted to unicode.

lib/kernel/src/group.erl

@@ -609,9 +609,7 @@ putc_request({put_chars,unicode,M,F,As}, Drv, From) ->
             end
     end;
 putc_request({put_chars,latin1,Binary}, Drv, From) when is_binary(Binary) ->
-    send_drv(Drv, {put_chars_sync, unicode,
-                   unicode:characters_to_binary(Binary,latin1),
-                   From}),
+    send_drv(Drv, {put_chars_sync, latin1, Binary, From}),
     noreply;
 putc_request({put_chars,latin1,Chars}, Drv, From) ->
     case catch unicode:characters_to_binary(Chars,latin1) of

lib/kernel/src/user_drv.erl

@@ -52,6 +52,9 @@
         %% Same as put_chars/3, but sends Reply to From when the characters are
         %% guaranteed to have been written to the terminal
         {put_chars_sync, unicode, binary(), {From :: pid(), Reply :: term()}} |
+        %% When we receive latin1 binary output requests, and encoding is in latin1,
+        %% then we will output the binary without conversion to unicode.
+        {put_chars_sync, latin1, binary(), {From :: pid(), Reply :: term()}} |
         %% Put text in expansion area
         {put_expand, unicode, binary(), integer()} |
         {move_expand, -32768..32767} |
@@ -867,6 +870,16 @@ io_request(delete_line, TTY) ->
     write(prim_tty:handle_request(TTY, delete_line));
 io_request({put_chars, unicode, Chars}, TTY) ->
     write(prim_tty:handle_request(TTY, {putc, unicode:characters_to_binary(Chars)}));
+io_request({put_chars_sync, latin1, Bin, Reply}, TTY) when is_binary(Bin) ->
+    Unicode = prim_tty:unicode(TTY),
+    {Output, NewTTY} = if Unicode =:= false ->
+            prim_tty:handle_request(TTY, {putc_raw, Bin});
+       true ->
+            prim_tty:handle_request(TTY,
+                                    {putc, unicode:characters_to_binary(Bin, latin1)})
+    end,
+    {ok, MonitorRef} = prim_tty:write(NewTTY, Output, self()),
+    {Reply, MonitorRef, NewTTY};
 io_request({put_chars_sync, unicode, Chars, Reply}, TTY) ->
     {Output, NewTTY} = prim_tty:handle_request(TTY, {putc, unicode:characters_to_binary(Chars)}),
     {ok, MonitorRef} = prim_tty:write(NewTTY, Output, self()),

lib/stdlib/test/escript_SUITE.erl

@@ -39,7 +39,8 @@
 	 overflow/1,
 	 verify_sections/4,
          unicode/1,
-         bad_io_server/1
+         bad_io_server/1,
+     bypass_unicode_conversion/1
 	]).
 
 -include_lib("common_test/include/ct.hrl").
@@ -54,9 +55,10 @@ all() ->
      emulator_flags_no_shebang, two_lines,
      module_script, beam_script, archive_script, epp,
      create_and_extract, foldl, overflow,
-     archive_script_file_access, unicode, bad_io_server].
+     archive_script_file_access, unicode, bad_io_server,
+     bypass_unicode_conversion].
 
-groups() -> 
+groups() ->
     [].
 
 init_per_suite(Config) ->
@@ -978,6 +980,24 @@ bad_io_server(Config) when is_list(Config) ->
            "called as '\\x{400}' / 0\nExitCode:127">>]),
     ok.
 
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+bypass_unicode_conversion(Config) when is_list(Config) ->
+    Data = proplists:get_value(data_dir, Config),
+    Dir = filename:absname(Data),		%Get rid of trailing slash.
+    Cmd = fun(Enc) -> "bypass_unicode_conversion "++atom_to_list(Enc)++" 1> /dev/null" end,
+    {TimeLatin1, _} = timer:tc(
+        fun() -> run(Config, Dir, Cmd(latin1), [<<"ExitCode:0">>]) end),
+    {TimeUnicode, _} = timer:tc(
+        fun() -> run(Config, Dir, Cmd(unicode), [<<"ExitCode:0">>]) end),
+    %% Check that Time(latin1) is about the same as Time(unicode) with a maximum 10% difference
+    %% Without the bypass, the time difference would be about 5x.
+    io:format("Time(latin1) = ~p ~~= Time(unicode) = ~p~n", [TimeLatin1, TimeUnicode]),
+    true = TimeLatin1 =< TimeUnicode * 1.1,
+    ok.
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
 run(Config, Dir, Cmd, Expected) ->
     run_with_opts(Config, Dir, "", Cmd, Expected).
 

lib/stdlib/test/escript_SUITE_data/bypass_unicode_conversion

@@ -0,0 +1,7 @@
+#!/usr/bin/env escript
+
+main([Enc]) ->
+  Data = {tuple, {list, lists:seq(1,1000000)}},
+  io:setopts(erlang:group_leader(), [binary, {encoding, list_to_atom(Enc)}]),
+  file:write(erlang:group_leader(), term_to_binary(Data)),
+  ok.