1 files changed, 28 insertions, 24 deletions

diff --git a/lib/compiler/src/beam_utils.erl b/lib/compiler/src/beam_utils.erl
index ac249e6672..45cdf8a659 100644
--- a/lib/compiler/src/beam_utils.erl
+++ b/lib/compiler/src/beam_utils.erl
@@ -1,19 +1,19 @@
 %%
 %% %CopyrightBegin%
-%% 
-%% Copyright Ericsson AB 2007-2009. All Rights Reserved.
-%% 
+%%
+%% Copyright Ericsson AB 2007-2010. All Rights Reserved.
+%%
 %% The contents of this file are subject to the Erlang Public License,
 %% Version 1.1, (the "License"); you may not use this file except in
 %% compliance with the License. You should have received a copy of the
 %% Erlang Public License along with this software. If not, it can be
 %% retrieved online at http://www.erlang.org/.
-%% 
+%%
 %% Software distributed under the License is distributed on an "AS IS"
 %% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
 %% the License for the specific language governing rights and limitations
 %% under the License.
-%% 
+%%
 %% %CopyrightEnd%
 %%
 %% Purpose : Common utilities used by several optimization passes.
@@ -407,16 +407,23 @@ check_liveness(R, [{bif,Op,{f,Fail},Ss,D}|Is], St0) ->
 	Other ->
 	    Other
     end;
-check_liveness(R, [{gc_bif,Op,{f,Fail},_,Ss,D}|Is], St0) ->
-    case check_liveness_fail(R, Op, Ss, Fail, St0) of
-	{killed,St} = Killed ->
-	    case member(R, Ss) of
-		true -> {used,St};
-		false when R =:= D -> Killed;
-		false -> check_liveness(R, Is, St)
-	    end;
-	Other ->
-	    Other
+check_liveness(R, [{gc_bif,Op,{f,Fail},Live,Ss,D}|Is], St0) ->
+    case R of
+	{x,X} when X >= Live ->
+	    {killed,St0};
+	{x,_} ->
+	    {used,St0};
+	_ ->
+	    case check_liveness_fail(R, Op, Ss, Fail, St0) of
+		{killed,St}=Killed ->
+		    case member(R, Ss) of
+			true -> {used,St};
+			false when R =:= D -> Killed;
+			false -> check_liveness(R, Is, St)
+		    end;
+		Other ->
+		    Other
+	    end
     end;
 check_liveness(R, [{bs_add,{f,0},Ss,D}|Is], St) ->
     case member(R, Ss) of
@@ -424,12 +431,6 @@ check_liveness(R, [{bs_add,{f,0},Ss,D}|Is], St) ->
 	false when R =:= D -> {killed,St};
 	false -> check_liveness(R, Is, St)
     end;
-check_liveness(R, [{bs_bits_to_bytes2,Src,Dst}|Is], St) ->
-    case R of
-	Src -> {used,St};
-	Dst -> {killed,St};
-	_ -> check_liveness(R, Is, St)
-    end;
 check_liveness(R, [{bs_put_binary,{f,0},Sz,_,_,Src}|Is], St) ->
     case member(R, [Sz,Src]) of
 	true -> {used,St};
@@ -488,10 +489,13 @@ check_liveness(R, [{bs_context_to_binary,S}|Is], St) ->
 	S -> {used,St};
 	_ -> check_liveness(R, Is, St)
     end;
-check_liveness(R, [{loop_rec,{f,_},{x,0}}|Is], St) ->
+check_liveness(R, [{loop_rec,{f,_},{x,0}}|_], St) ->
     case R of
-	{x,_} -> {killed,St};
-	_ -> check_liveness(R, Is, St)
+	{x,_} ->
+	    {killed,St};
+	_ ->
+	    %% y register. Rarely happens. Be very conversative.
+	    {unknown,St}
     end;
 check_liveness(R, [{loop_rec_end,{f,Fail}}|_], St) ->
     check_liveness_at(R, Fail, St);