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-rw-r--r--lib/compiler/test/bs_match_SUITE.erl19
1 files changed, 17 insertions, 2 deletions
diff --git a/lib/compiler/test/bs_match_SUITE.erl b/lib/compiler/test/bs_match_SUITE.erl
index 7557d6d57b..4bd5e8e2e1 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]).
+ beam_bsm/1,guard/1,is_ascii/1,non_opt_eq/1]).
-export([coverage_id/1,coverage_external_ignore/2]).
@@ -73,7 +73,7 @@ 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]}].
+ beam_bsm,guard,is_ascii,non_opt_eq]}].
init_per_suite(Config) ->
@@ -1654,6 +1654,21 @@ do_is_ascii(<<C,_/binary>>) when C >= 16#80 ->
do_is_ascii(<<_, T/binary>>) ->
do_is_ascii(T).
+non_opt_eq(_Config) ->
+ true = non_opt_eq([], <<>>),
+ true = non_opt_eq([$a], <<$a>>),
+ false = non_opt_eq([$a], <<$b>>),
+ ok.
+
+%% An example from the Efficiency Guide. It used to be not optimized,
+%% but now it can be optimized.
+
+non_opt_eq([H|T1], <<H,T2/binary>>) ->
+ non_opt_eq(T1, T2);
+non_opt_eq([_|_], <<_,_/binary>>) ->
+ false;
+non_opt_eq([], <<>>) ->
+ true.
check(F, R) ->
R = F().