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authorBjörn Gustavsson <[email protected]>2010-11-26 09:22:44 +0100
committerBjörn Gustavsson <[email protected]>2010-11-26 10:25:07 +0100
commit8836ebccae92886decf5645944ae4ce8a2f99947 (patch)
tree797dfafe3ca5173d9ffb5bfba68bb2fe7959062a
parent99a28d961d2d760e98353b55991f1fc51dee06b0 (diff)
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beam_utils: Fix liveness analysis for gc_bif instructions
When gc_bif instructions occurred outside of a block, beam_utils:check_liveness/3 did not take into account that the instruction could do a garbage collection, and could falsely report that an x register would be killed. That could cause the beam_dead pass to make the code unsafe by removing the assignment to an x register that would subsequently be referenced by the garbage collector. Reported-by: Christopher Williams
-rw-r--r--lib/compiler/src/beam_utils.erl27
-rw-r--r--lib/compiler/test/compilation_SUITE.erl26
2 files changed, 41 insertions, 12 deletions
diff --git a/lib/compiler/src/beam_utils.erl b/lib/compiler/src/beam_utils.erl
index 761d4ffec0..dc8079d0b7 100644
--- a/lib/compiler/src/beam_utils.erl
+++ b/lib/compiler/src/beam_utils.erl
@@ -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
diff --git a/lib/compiler/test/compilation_SUITE.erl b/lib/compiler/test/compilation_SUITE.erl
index 9c06740816..7b6975f912 100644
--- a/lib/compiler/test/compilation_SUITE.erl
+++ b/lib/compiler/test/compilation_SUITE.erl
@@ -1,7 +1,7 @@
%%
%% %CopyrightBegin%
%%
-%% Copyright Ericsson AB 1997-2009. All Rights Reserved.
+%% Copyright Ericsson AB 1997-2010. 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
@@ -46,7 +46,7 @@ all(suite) ->
trycatch_4, opt_crash,
otp_5404,otp_5436,otp_5481,otp_5553,otp_5632,
otp_5714,otp_5872,otp_6121,otp_6121a,otp_6121b,
- otp_7202,otp_7345,on_load,string_table
+ otp_7202,otp_7345,on_load,string_table,otp_8949_a
].
-define(comp(N),
@@ -606,5 +606,27 @@ string_table(Config) when is_list(Config) ->
?line {"StrT", <<"stringabletringtable">>} = StringTableChunk,
ok.
+otp_8949_a(Config) when is_list(Config) ->
+ value = otp_8949_a(),
+ ok.
+
+-record(cs, {exs,keys = [],flags = 1}).
+-record(exs, {children = []}).
+
+otp_8949_a() ->
+ case id([#cs{}]) of
+ [#cs{}=Cs] ->
+ SomeVar = id(value),
+ if
+ Cs#cs.flags band 1 =/= 0 ->
+ id(SomeVar);
+ (((Cs#cs.exs)#exs.children /= [])
+ and
+ (Cs#cs.flags band (1 bsl 0 bor (1 bsl 22)) == 0));
+ Cs#cs.flags band (1 bsl 22) =/= 0 ->
+ ok
+ end
+ end.
+
id(I) -> I.