From 9b0122b65bdcafbae2a3cfd3299903da0948acab Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= <bjorn@erlang.org>
Date: Tue, 28 Nov 2017 07:28:25 +0100
Subject: 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.
---
 erts/emulator/beam/ops.tab | 1 +
 1 file changed, 1 insertion(+)

(limited to 'erts/emulator/beam/ops.tab')

diff --git a/erts/emulator/beam/ops.tab b/erts/emulator/beam/ops.tab
index fd1b3b9c74..1f4a8eadb0 100644
--- a/erts/emulator/beam/ops.tab
+++ b/erts/emulator/beam/ops.tab
@@ -1584,3 +1584,4 @@ i_recv_set
 #
 
 build_stacktrace
+raw_raise
-- 
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