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-rw-r--r--lib/compiler/test/core_fold_SUITE.erl31
1 files changed, 29 insertions, 2 deletions
diff --git a/lib/compiler/test/core_fold_SUITE.erl b/lib/compiler/test/core_fold_SUITE.erl
index bca8afb1b0..b45874433c 100644
--- a/lib/compiler/test/core_fold_SUITE.erl
+++ b/lib/compiler/test/core_fold_SUITE.erl
@@ -23,7 +23,8 @@
t_element/1,setelement/1,t_length/1,append/1,t_apply/1,bifs/1,
eq/1,nested_call_in_case/1,guard_try_catch/1,coverage/1,
unused_multiple_values_error/1,unused_multiple_values/1,
- multiple_aliases/1,redundant_boolean_clauses/1,mixed_matching_clauses/1]).
+ multiple_aliases/1,redundant_boolean_clauses/1,
+ mixed_matching_clauses/1,unnecessary_building/1]).
-export([foo/0,foo/1,foo/2,foo/3]).
@@ -40,7 +41,8 @@ groups() ->
[t_element,setelement,t_length,append,t_apply,bifs,
eq,nested_call_in_case,guard_try_catch,coverage,
unused_multiple_values_error,unused_multiple_values,
- multiple_aliases,redundant_boolean_clauses,mixed_matching_clauses]}].
+ multiple_aliases,redundant_boolean_clauses,
+ mixed_matching_clauses,unnecessary_building]}].
init_per_suite(Config) ->
@@ -403,4 +405,29 @@ mixed_matching_clauses(Config) when is_list(Config) ->
end,
ok.
+unnecessary_building(Config) when is_list(Config) ->
+ Term1 = do_unnecessary_building_1(test_lib:id(a)),
+ [{a,a},{a,a}] = Term1,
+ 7 = erts_debug:size(Term1),
+
+ %% The Input term should not be rebuilt (thus, it should
+ %% only be counted once in the size of the combined term).
+ Input = test_lib:id({a,b,c}),
+ Term2 = test_lib:id(do_unnecessary_building_2(Input)),
+ {b,[{a,b,c},none],x} = Term2,
+ 4+4+4+2 = erts_debug:size([Term2|Input]),
+
+ ok.
+
+do_unnecessary_building_1(S) ->
+ %% The tuple must only be built once.
+ F0 = F1 = {S,S},
+ [F0,F1].
+
+do_unnecessary_building_2({a,_,_}=T) ->
+ %% The T term should not be rebuilt.
+ {b,
+ [_,_] = [T,none],
+ x}.
+
id(I) -> I.