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authorBjörn Gustavsson <[email protected]>2018-06-27 12:51:22 +0200
committerBjörn Gustavsson <[email protected]>2018-06-27 13:22:20 +0200
commit81ce942d77826dd7219f1226866ffb2fa71c1d28 (patch)
tree1763b4bb4dde689878c4be55de3ae6c0521629f8 /lib
parenta0ae44f324576104760a63fe6cf63e0ca31756fc (diff)
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beam_type: Fix unsafe optimization
beam_type assumed that the operand for the bs_context_to_binary instruction must be a binary. That is not correct; bs_context_to_binary accepts anything. Based on the incorrect assumption, beam_type would remove other test instructions. The bug was introduced in eee8655788d2, which was supposed to be just a refactoring commit. https://bugs.erlang.org/browse/ERL-655
Diffstat (limited to 'lib')
-rw-r--r--lib/compiler/src/beam_type.erl2
-rw-r--r--lib/compiler/test/beam_type_SUITE.erl32
2 files changed, 31 insertions, 3 deletions
diff --git a/lib/compiler/src/beam_type.erl b/lib/compiler/src/beam_type.erl
index b8c3ca1325..b5c979e529 100644
--- a/lib/compiler/src/beam_type.erl
+++ b/lib/compiler/src/beam_type.erl
@@ -559,7 +559,7 @@ update({bs_save2,_,_}, Ts) ->
update({bs_restore2,_,_}, Ts) ->
Ts;
update({bs_context_to_binary,Dst}, Ts) ->
- tdb_store(Dst, {binary,1}, Ts);
+ tdb_store(Dst, any, Ts);
update({test,bs_start_match2,_,_,[Src,_],Dst}, Ts0) ->
Ts = tdb_meet(Src, {binary,1}, Ts0),
tdb_copy(Src, Dst, Ts);
diff --git a/lib/compiler/test/beam_type_SUITE.erl b/lib/compiler/test/beam_type_SUITE.erl
index 499b9b41df..1355f9f862 100644
--- a/lib/compiler/test/beam_type_SUITE.erl
+++ b/lib/compiler/test/beam_type_SUITE.erl
@@ -23,7 +23,7 @@
init_per_group/2,end_per_group/2,
integers/1,coverage/1,booleans/1,setelement/1,cons/1,
tuple/1,record_float/1,binary_float/1,float_compare/1,
- arity_checks/1,elixir_binaries/1]).
+ arity_checks/1,elixir_binaries/1,find_best/1]).
suite() -> [{ct_hooks,[ts_install_cth]}].
@@ -43,7 +43,8 @@ groups() ->
binary_float,
float_compare,
arity_checks,
- elixir_binaries
+ elixir_binaries,
+ find_best
]}].
init_per_suite(Config) ->
@@ -292,6 +293,33 @@ elixir_bitstring_3(Bar) when is_bitstring(Bar) ->
list_to_bitstring(Rewrite)
end/bitstring>>.
+find_best(_Config) ->
+ ok = find_best([a], nil),
+ ok = find_best([<<"a">>], nil),
+ {error,_} = find_best([], nil),
+ ok.
+
+%% Failed because beam_type assumed that the operand
+%% for bs_context_binary must be a binary. Not true!
+find_best([a|Tail], Best) ->
+ find_best(Tail,
+ case Best of
+ X when X =:= nil orelse X =:= false -> a;
+ X -> X
+ end);
+find_best([<<"a">>|Tail], Best) ->
+ find_best(Tail,
+ case Best of
+ X when X =:= nil orelse X =:= false -> <<"a">>;
+ X -> X
+ end);
+find_best([], a) ->
+ ok;
+find_best([], <<"a">>) ->
+ ok;
+find_best([], nil) ->
+ {error,<<"should not get here">>}.
+
id(I) ->
I.