beam_utils: Correct is_killed/3, is_killed_at/3, is_used/3

is_killed/3 and is_killed_at/3 could return 'true' even if the
register was referenced by an allocation instruction. Somehow, that
does not seem to have caused any problems yet.

1 files changed, 3 insertions, 3 deletions

diff --git a/lib/compiler/src/beam_utils.erl b/lib/compiler/src/beam_utils.erl
index a57dbbbc2f..7031fe8bfe 100644
--- a/lib/compiler/src/beam_utils.erl
+++ b/lib/compiler/src/beam_utils.erl
@@ -118,7 +118,7 @@ is_killed(R, Is, D) ->
     St = #live{lbl=D,res=gb_trees:empty()},
     case check_liveness(R, Is, St) of
 	{killed,_} -> true;
-	{exit_not_used,_} -> true;
+	{exit_not_used,_} -> false;
 	{_,_} -> false
     end.
 
@@ -131,7 +131,7 @@ is_killed_at(R, Lbl, D) when is_integer(Lbl) ->
     St0 = #live{lbl=D,res=gb_trees:empty()},
     case check_liveness_at(R, Lbl, St0) of
 	{killed,_} -> true;
-	{exit_not_used,_} -> true;
+	{exit_not_used,_} -> false;
 	{_,_} -> false
     end.
 
@@ -148,7 +148,7 @@ is_not_used(R, Is, D) ->
     St = #live{lbl=D,res=gb_trees:empty()},
     case check_liveness(R, Is, St) of
 	{used,_} -> false;
-	{exit_not_used,_} -> false;
+	{exit_not_used,_} -> true;
 	{_,_} -> true
     end.