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, 6 insertions, 1 deletions

diff --git a/lib/compiler/src/v3_codegen.erl b/lib/compiler/src/v3_codegen.erl
index 8f3399d133..a96d58a903 100644
--- a/lib/compiler/src/v3_codegen.erl
+++ b/lib/compiler/src/v3_codegen.erl
@@ -1855,7 +1855,12 @@ internal_cg(guard_error, [ExitCall], _Rs, Le, Vdb, Bef, St) ->
     {Ms,_} = cg_call_args(As, Bef, Le#l.i, Vdb),
     Call = {call_ext,Arity,{extfunc,Mod,Name,Arity}},
     Is = Ms++[line(Le),Call],
-    {Is,Bef,St}.
+    {Is,Bef,St};
+internal_cg(raw_raise=I, As, Rs, Le, Vdb, Bef, St) ->
+    %% This behaves like a function call.
+    {Sis,Int} = cg_setup_call(As, Bef, Le#l.i, Vdb),
+    Reg = load_vars(Rs, clear_regs(Int#sr.reg)),
+    {Sis++[I],clear_dead(Int#sr{reg=Reg}, Le#l.i, Vdb),St}.
 
 %% bif_cg(Bif, [Arg], [Ret], Le, Vdb, StackReg, State) ->
 %%      {[Ainstr],StackReg,State}.