Don't build a stacktrace if it's only passed to erlang:raise/3

Consider the following function:

    function({function,Name,Arity,CLabel,Is0}, Lc0) ->
      try
        %% Optimize the code for the function.
      catch
        Class:Error:Stack ->
          io:format("Function: ~w/~w\n", [Name,Arity]),
          erlang:raise(Class, Error, Stack)
      end.

The stacktrace is retrieved, but it is only used in the call
to erlang:raise/3. There is no need to build a stacktrace
in this function. We can avoid the building if we introduce
an instruction called raw_raise/3 that works exactly like
the erlang:raise/3 BIF except that its third argument must
be a raw stacktrace.

1 files changed, 4 insertions, 0 deletions

diff --git a/lib/compiler/src/beam_utils.erl b/lib/compiler/src/beam_utils.erl
index 901588ee3b..5333925589 100644
--- a/lib/compiler/src/beam_utils.erl
+++ b/lib/compiler/src/beam_utils.erl
@@ -871,6 +871,8 @@ live_opt([{block,Bl0}|Is], Regs0, D, Acc) ->
     live_opt(Is, Regs, D, [{block,[Live|Bl]}|Acc]);
 live_opt([build_stacktrace=I|Is], _, D, Acc) ->
     live_opt(Is, live_call(1), D, [I|Acc]);
+live_opt([raw_raise=I|Is], _, D, Acc) ->
+    live_opt(Is, live_call(3), D, [I|Acc]);
 live_opt([{label,L}=I|Is], Regs, D0, Acc) ->
     D = gb_trees:insert(L, Regs, D0),
     live_opt(Is, Regs, D, [I|Acc]);
@@ -1142,6 +1144,8 @@ defs([{move,_,Dst}=I|Is], Regs0, D) ->
 defs([{put_map,{f,Fail},_,_,Dst,_,_}=I|Is], Regs0, D) ->
     Regs = def_regs([Dst], Regs0),
     [I|defs(Is, Regs, update_regs(Fail, Regs0, D))];
+defs([raw_raise=I|Is], _Regs, D) ->
+    [I|defs(Is, 1, D)];
 defs([return=I|Is], _Regs, D) ->
     [I|defs_unreachable(Is, D)];
 defs([{select,_,_Src,Fail,List}=I|Is], Regs, D0) ->