Fix crash in beam_bool

The following code crashes beam_bool:

bad(XDo1, XDo2, Do3) ->
    Do1 = (XDo1 =/= []),
    Do2 = (XDo2 =/= []),
    if Do1 =:= true;
       Do1 =:= false, Do2 =:= false, Do3 =:= delete ->
	    no
    end.

(Reported by Simon Cornish; minimized by Kostis Sagonas.)

For the moment fix the bug in the simplest and safest way possible
(basically, instead of crashing just don't do the optimization).

In a future major release (e.g. R14), the following improvements
could be considered:

* In beam_bool, it should be possible to move the Do1 and Do2
  expressions to the pre-block and still optimize the expression
  in the 'if' statement.

* In sys_core_fold, it should be possible to eliminate the
  try/catch around the guard expression in the 'if', because
  none of the guard tests can actually fail.

1 files changed, 10 insertions, 5 deletions

diff --git a/lib/compiler/src/beam_bool.erl b/lib/compiler/src/beam_bool.erl
index d8c201a194..ffe5cdb501 100644
--- a/lib/compiler/src/beam_bool.erl
+++ b/lib/compiler/src/beam_bool.erl
@@ -123,6 +123,12 @@ bopt_block(Reg, Fail, OldIs, [{block,Bl0}|Acc0], St0) ->
 		throw:mixed ->
 		    failed;
 
+		%% There was a reference to a boolean expression
+		%% from inside a protected block (try/catch), to
+		%% a boolean expression outside.
+		  throw:protected_barrier ->
+		    failed;
+
 		  %% The 'xor' operator was used. We currently don't
 		  %% find it worthwile to translate 'xor' operators
 		  %% (the code would be clumsy).
@@ -414,11 +420,10 @@ bopt_good_args([A|As], Regs) ->
 bopt_good_args([], _) -> ok.
 
 bopt_good_arg({Tag,_}=X, Regs) when Tag =:= x; Tag =:= tmp ->
-    case gb_trees:get(X, Regs) of
-	any -> ok;
-	_Other ->
-	    %%io:format("not any: ~p: ~p\n", [X,_Other]),
-	    throw(mixed)
+    case gb_trees:lookup(X, Regs) of
+	{value,any} -> ok;
+	{value,_} -> throw(mixed);
+	none -> throw(protected_barrier)
     end;
 bopt_good_arg(_, _) -> ok.