Use a set to store ref registers in beam_receive

In some circumstances, as when inlining code, when some optimization
passes are disabled or with hand-written but semantically correct Core
Erlang or BEAM assembly, a fresh reference may be live in more than one
register:

    ...
    {allocate_zero,2,2}.
    ...
    {call_ext,0,{extfunc,erlang,make_ref,0}}. % Ref in [x0]
    ...
    {move,{x,0},{y,0}}. % Ref in [x0,y0]
    {move,{y,1},{x,0}}. % Ref in [y0]
    ...
    {move,{y,0},{x,0}}. % Ref in [x0,y0]
    {move,{x,0},{y,1}}. % Ref in [x0,y0,y1]
  {label,5}.
    {loop_rec,{f,6},{x,0}}. % Ref in [y0,y1]
    ...
    {loop_rec_end,{f,5}}.
  {label,6}.
    {wait,{f,5}}.
    ...

Pass beam_receive expects a single live register for the ref when it
encounters the loop_rec instruction and crashes with the following
reason:

$ erlc t.S
...
crash reason: {{case_clause,
                   {'EXIT',
                       {{case_clause,[{y,1},{y,0}]},
                        [{beam_receive,opt_recv,5,
                             [{file,"beam_receive.erl"},{line,154}]},
                         ...]}}},
               ...}

This commit teaches beam_receive how to use a set of registers instead
of a single one when tracking fresh references, thus avoiding the crash.

1 files changed, 71 insertions, 0 deletions

diff --git a/lib/compiler/test/receive_SUITE_data/ref_opt/yes_14.S b/lib/compiler/test/receive_SUITE_data/ref_opt/yes_14.S
new file mode 100644
index 0000000000..fd14228135
--- /dev/null
+++ b/lib/compiler/test/receive_SUITE_data/ref_opt/yes_14.S
@@ -0,0 +1,71 @@
+{module, yes_14}.  %% version = 0
+
+{exports, [{f,2},{module_info,0},{module_info,1},{yes_14,0}]}.
+
+{attributes, []}.
+
+{labels, 12}.
+
+
+{function, yes_14, 0, 2}.
+  {label,1}.
+    {func_info,{atom,yes_14},{atom,yes_14},0}.
+  {label,2}.
+    {move,{atom,ok},{x,0}}.
+    return.
+
+
+{function, f, 2, 4}.
+  {label,3}.
+    {func_info,{atom,yes_14},{atom,f},2}.
+  {label,4}.
+    {allocate_heap,2,3,2}.
+    {move,{x,0},{y,1}}.
+    {put_tuple,2,{y,0}}.
+    {put,{atom,data}}.
+    {put,{x,1}}.
+    {call_ext,0,{extfunc,erlang,make_ref,0}}. % Ref in [x0]
+    {test_heap,4,1}.
+    {put_tuple,3,{x,1}}.
+    {put,{atom,request}}.
+    {put,{x,0}}.
+    {put,{y,0}}.
+    {move,{x,0},{y,0}}. % Ref in [x0,y0]
+    {move,{y,1},{x,0}}. % Ref in [y0]
+    {kill,{y,1}}.
+    send.
+    {move,{y,0},{x,0}}. % Ref in [x0,y0]
+    {move,{x,0},{y,1}}. % Ref in [x0,y0,y1]
+  {label,5}.
+    {loop_rec,{f,7},{x,0}}. % Ref in [y0,y1]
+    {test,is_tuple,{f,6},[{x,0}]}.
+    {test,test_arity,{f,6},[{x,0},2]}.
+    {get_tuple_element,{x,0},0,{x,1}}.
+    {get_tuple_element,{x,0},1,{x,2}}.
+    {test,is_eq_exact,{f,6},[{x,1},{atom,reply}]}.
+    {test,is_eq_exact,{f,6},[{x,2},{y,1}]}.
+    remove_message.
+    {move,{atom,ok},{x,0}}.
+    {deallocate,2}.
+    return.
+  {label,6}.
+    {loop_rec_end,{f,5}}.
+  {label,7}.
+    {wait,{f,5}}.
+
+
+{function, module_info, 0, 9}.
+  {label,8}.
+    {func_info,{atom,yes_14},{atom,module_info},0}.
+  {label,9}.
+    {move,{atom,yes_14},{x,0}}.
+    {call_ext_only,1,{extfunc,erlang,get_module_info,1}}.
+
+
+{function, module_info, 1, 11}.
+  {label,10}.
+    {func_info,{atom,yes_14},{atom,module_info},1}.
+  {label,11}.
+    {move,{x,0},{x,1}}.
+    {move,{atom,yes_14},{x,0}}.
+    {call_ext_only,2,{extfunc,erlang,get_module_info,2}}.