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-rw-r--r--lib/compiler/src/beam_bsm.erl13
-rw-r--r--lib/compiler/test/bs_match_SUITE.erl33
2 files changed, 43 insertions, 3 deletions
diff --git a/lib/compiler/src/beam_bsm.erl b/lib/compiler/src/beam_bsm.erl
index 1c8e0e9854..abc6e96c85 100644
--- a/lib/compiler/src/beam_bsm.erl
+++ b/lib/compiler/src/beam_bsm.erl
@@ -310,7 +310,18 @@ btb_reaches_match_2([{test,bs_start_match2,{f,F},Live,[Bin,_],Ctx}|Is],
end;
btb_reaches_match_2([{test,_,{f,F},Ss}=I|Is], Regs, D0) ->
btb_ensure_not_used(Ss, I, Regs),
- D = btb_follow_branch(F, Regs, D0),
+ D1 = btb_follow_branch(F, Regs, D0),
+ D = case Is of
+ [{bs_context_to_binary,_}|_] ->
+ %% bs_context_to_binary following a test instruction
+ %% probably needs the current position to be saved as
+ %% the new start position, but we can't be sure.
+ %% Therefore, conservatively disable the optimization
+ %% (instead of forcing a saving of the position).
+ D1#btb{must_save=true,must_not_save=true};
+ _ ->
+ D1
+ end,
btb_reaches_match_1(Is, Regs, D);
btb_reaches_match_2([{test,_,{f,F},_,Ss,_}=I|Is], Regs, D0) ->
btb_ensure_not_used(Ss, I, Regs),
diff --git a/lib/compiler/test/bs_match_SUITE.erl b/lib/compiler/test/bs_match_SUITE.erl
index e737839575..7814738449 100644
--- a/lib/compiler/test/bs_match_SUITE.erl
+++ b/lib/compiler/test/bs_match_SUITE.erl
@@ -40,7 +40,7 @@
map_and_binary/1,unsafe_branch_caching/1,
bad_literals/1,good_literals/1,constant_propagation/1,
parse_xml/1,get_payload/1,escape/1,num_slots_different/1,
- beam_bsm/1,guard/1,is_ascii/1,non_opt_eq/1]).
+ beam_bsm/1,guard/1,is_ascii/1,non_opt_eq/1,erl_689/1]).
-export([coverage_id/1,coverage_external_ignore/2]).
@@ -72,7 +72,7 @@ groups() ->
map_and_binary,unsafe_branch_caching,
bad_literals,good_literals,constant_propagation,parse_xml,
get_payload,escape,num_slots_different,
- beam_bsm,guard,is_ascii,non_opt_eq]}].
+ beam_bsm,guard,is_ascii,non_opt_eq,erl_689]}].
init_per_suite(Config) ->
@@ -1688,6 +1688,35 @@ non_opt_eq([_|_], <<_,_/binary>>) ->
non_opt_eq([], <<>>) ->
true.
+%% ERL-689
+
+erl_689(Config) ->
+ {{0, 0, 0}, <<>>} = do_erl_689_1(<<0>>, ?MODULE),
+ {{2018, 8, 7}, <<>>} = do_erl_689_1(<<4,2018:16/little,8,7>>, ?MODULE),
+ {{0, 0, 0}, <<>>} = do_erl_689_2(?MODULE, <<0>>),
+ {{2018, 8, 7}, <<>>} = do_erl_689_2(?MODULE, <<4,2018:16/little,8,7>>),
+ ok.
+
+do_erl_689_1(<<Length, Data/binary>>, _) ->
+ case {Data, Length} of
+ {_, 0} ->
+ %% bs_context_to_binary would incorrectly set Data to the original
+ %% binary (before matching in the function head).
+ {{0, 0, 0}, Data};
+ {<<Y:16/little, M, D, Rest/binary>>, 4} ->
+ {{Y, M, D}, Rest}
+ end.
+
+do_erl_689_2(_, <<Length, Data/binary>>) ->
+ case {Length, Data} of
+ {0, _} ->
+ %% bs_context_to_binary would incorrectly set Data to the original
+ %% binary (before matching in the function head).
+ {{0, 0, 0}, Data};
+ {4, <<Y:16/little, M, D, Rest/binary>>} ->
+ {{Y, M, D}, Rest}
+ end.
+
check(F, R) ->
R = F().