Fix receive support in erl_eval with a BEAM module

Using the low-level BEAM instructions, we can loop over each message in
the process queue and removes the first message that matches, without
receiving them all to later send them back to itself.

The function prim_eval:'receive'/2 is equivalent to the
following pseudo-code:

  'receive'(F, T) ->
    RESET MESSAGE QUEUE POINTER,
    LOOP:
      case PEEK CURRENT MESSAGE WITH TIMEOUT T of
        {ok,Msg} ->
          case F(Msg) of
            nomatch ->
              DECREMENT TIMEOUT T,
              ADVANCE MESSAGE QUEUE POINTER,
              GOTO LOOP;
            Result ->
              RESET MESSAGE QUEUE POINTER,
              Result
          end;
        timeout ->
          RESET MESSAGE QUEUE POINTER,
          timeout
      end.

To not break Dialyzer and other tools, we use a stub Erlang module which
abstract code is forcefully inserted into prim_inet.erl afterwards
compilation.

1 files changed, 70 insertions, 0 deletions

diff --git a/erts/preloaded/src/prim_eval.S b/erts/preloaded/src/prim_eval.S
new file mode 100644
index 0000000000..958a79a1da
--- /dev/null
+++ b/erts/preloaded/src/prim_eval.S
@@ -0,0 +1,70 @@
+%%
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 2013. All Rights Reserved.
+%%
+%% The contents of this file are subject to the Erlang Public License,
+%% Version 1.1, (the "License"); you may not use this file except in
+%% compliance with the License. You should have received a copy of the
+%% Erlang Public License along with this software. If not, it can be
+%% retrieved online at http://www.erlang.org/.
+%%
+%% Software distributed under the License is distributed on an "AS IS"
+%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+%% the License for the specific language governing rights and limitations
+%% under the License.
+%%
+%% %CopyrightEnd%
+%%
+{module, prim_eval}.
+
+%% This module uses low-level BEAM instructions for the message queue facility
+%% to allow erl_eval to evaluate receive expressions correctly.
+
+{exports, [{'receive',2},{module_info,0},{module_info,1}]}.
+
+{attributes, []}.
+
+{labels, 10}.
+
+
+{function, 'receive', 2, 2}.
+  {label,1}.
+    {func_info,{atom,prim_eval},{atom,'receive'},2}.
+  {label,2}.
+    {allocate,2,2}.
+    {move,{x,1},{y,0}}.
+    {move,{x,0},{y,1}}.
+  {label,3}.
+    {loop_rec,{f,5},{x,0}}.
+    {move,{y,1},{x,1}}.
+    {call_fun,1}.
+    {test,is_ne_exact,{f,4},[{x,0},{atom,nomatch}]}.
+    remove_message.
+    {deallocate,2}.
+    return.
+  {label,4}.
+    {loop_rec_end,{f,3}}.
+  {label,5}.
+    {wait_timeout,{f,3},{y,0}}.
+    timeout.
+    {move,{atom,timeout},{x,0}}.
+    {deallocate,2}.
+    return.
+
+
+{function, module_info, 0, 8}.
+  {label,6}.
+    {func_info,{atom,prim_eval},{atom,module_info},0}.
+  {label,7}.
+    {move,{atom,prim_eval},{x,0}}.
+    {call_ext_only,1,{extfunc,erlang,get_module_info,1}}.
+
+
+{function, module_info, 1, 10}.
+  {label,8}.
+    {func_info,{atom,prim_eval},{atom,module_info},1}.
+  {label,9}.
+    {move,{x,0},{x,1}}.
+    {move,{atom,prim_eval},{x,0}}.
+    {call_ext_only,2,{extfunc,erlang,get_module_info,2}}.