From 69bb7b21a552c6e7d0615d4ead0345370deec2a0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= <bjorn@erlang.org>
Date: Fri, 20 May 2016 15:18:53 +0200
Subject: beam_bool: Reject potentially unsafe optimization

When calculating the sets of registers that must be killed or
unused, registers set in a {protected,_,_,_} block were not
considered. That could result in a crash in the
assertion in beam_utils:live_opt_block/4.
---
 lib/compiler/src/beam_bool.erl        |  2 ++
 lib/compiler/test/beam_bool_SUITE.erl | 31 +++++++++++++++++++++++++++++--
 2 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/lib/compiler/src/beam_bool.erl b/lib/compiler/src/beam_bool.erl
index 359fdb6d3c..99e4ccb1e9 100644
--- a/lib/compiler/src/beam_bool.erl
+++ b/lib/compiler/src/beam_bool.erl
@@ -311,6 +311,8 @@ dst_regs([{set,[D],_,{bif,_,{f,_}}}|Is], Acc) ->
     dst_regs(Is, [D|Acc]);
 dst_regs([{set,[D],_,{alloc,_,{gc_bif,_,{f,_}}}}|Is], Acc) ->
     dst_regs(Is, [D|Acc]);
+dst_regs([{protected,_,Bl,_}|Is], Acc) ->
+    dst_regs(Bl, dst_regs(Is, Acc));
 dst_regs([_|Is], Acc) ->
     dst_regs(Is, Acc);
 dst_regs([], Acc) -> ordsets:from_list(Acc).
diff --git a/lib/compiler/test/beam_bool_SUITE.erl b/lib/compiler/test/beam_bool_SUITE.erl
index 84d634e5ca..a07d010879 100644
--- a/lib/compiler/test/beam_bool_SUITE.erl
+++ b/lib/compiler/test/beam_bool_SUITE.erl
@@ -22,7 +22,7 @@
 -export([all/0,suite/0,groups/0,init_per_suite/1,end_per_suite/1,
 	 init_per_group/2,end_per_group/2,
 	 before_and_inside_if/1,
-	 scotland/1,y_registers/1]).
+	 scotland/1,y_registers/1,protected/1]).
 
 suite() ->
     [{ct_hooks,[ts_install_cth]}].
@@ -35,7 +35,8 @@ groups() ->
     [{p,[parallel],
       [before_and_inside_if,
        scotland,
-       y_registers
+       y_registers,
+       protected
       ]}].
 
 init_per_suite(Config) ->
@@ -158,3 +159,29 @@ potter(Modes) ->
 		_ -> not_ok
 	    end,
     {Final,Raw}.
+
+protected(_Config) ->
+    {'EXIT',{if_clause,_}} = (catch photographs({1, surprise, true}, opinions)),
+
+    {{true}} = welcome({perfect, true}),
+    {'EXIT',{if_clause,_}} = (catch welcome({perfect, false})),
+    ok.
+
+photographs({_Violation, surprise, Deep}, opinions) ->
+    {if
+	 0; "here", Deep ->
+	     Deep = Deep
+     end}.
+
+welcome({perfect, Profit}) ->
+    if
+	Profit, Profit, Profit; 0 ->
+	    {id({Profit})}
+    end.
+
+%%%
+%%% Common utilities.
+%%%
+
+id(I) ->
+    I.
-- 
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