diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/compiler/src/sys_core_fold.erl | 24 | ||||
| -rw-r--r-- | lib/compiler/test/core_fold_SUITE.erl | 21 |
2 files changed, 37 insertions, 8 deletions
diff --git a/lib/compiler/src/sys_core_fold.erl b/lib/compiler/src/sys_core_fold.erl index 620b4e8847..c92ee86e07 100644 --- a/lib/compiler/src/sys_core_fold.erl +++ b/lib/compiler/src/sys_core_fold.erl @@ -150,14 +150,26 @@ guard(Expr, Sub) -> opt_guard_try(#c_seq{arg=Arg,body=Body0}=Seq) -> Body = opt_guard_try(Body0), case {Arg,Body} of - {#c_call{},#c_literal{val=false}} -> - %% We have sequence consisting of a call (evaluted - %% for a possible exception only), followed by 'false'. - %% Since the sequence is inside a try block that will + {#c_call{module=#c_literal{val=Mod}, + name=#c_literal{val=Name}, + args=Args},#c_literal{val=false}} -> + %% We have sequence consisting of a call (evaluated + %% for a possible exception and/or side effect only), + %% followed by 'false'. + %% Since the sequence is inside a try block that will %% default to 'false' if any exception occurs, not %% evalutating the call will not change the behaviour - %% of the guard. - Body; + %% provided that the call has no side effects. + case erl_bifs:is_pure(Mod, Name, length(Args)) of + false -> + %% Not a pure BIF (meaning that this is not + %% a guard and that we must keep the call). + Seq#c_seq{body=Body}; + true -> + %% The BIF has no side effects, so it can + %% be safely removed. + Body + end; {_,_} -> Seq#c_seq{body=Body} end; diff --git a/lib/compiler/test/core_fold_SUITE.erl b/lib/compiler/test/core_fold_SUITE.erl index fb5ec88c9f..54bd52947e 100644 --- a/lib/compiler/test/core_fold_SUITE.erl +++ b/lib/compiler/test/core_fold_SUITE.erl @@ -21,7 +21,7 @@ -export([all/0, suite/0,groups/0,init_per_suite/1, end_per_suite/1, init_per_group/2,end_per_group/2, t_element/1,setelement/1,t_length/1,append/1,t_apply/1,bifs/1, - eq/1,nested_call_in_case/1,coverage/1]). + eq/1,nested_call_in_case/1,guard_try_catch/1,coverage/1]). -export([foo/0,foo/1,foo/2,foo/3]). @@ -32,7 +32,7 @@ suite() -> [{ct_hooks,[ts_install_cth]}]. all() -> test_lib:recompile(?MODULE), [t_element, setelement, t_length, append, t_apply, bifs, - eq, nested_call_in_case, coverage]. + eq, nested_call_in_case, guard_try_catch, coverage]. groups() -> []. @@ -207,6 +207,23 @@ nested_call_in_case(Config) when is_list(Config) -> ?line {'EXIT',_} = (catch Mod:a(not_a_list, 42)), ok. +guard_try_catch(_Config) -> + false = do_guard_try_catch(key, value), + value = get(key), + ok. + +do_guard_try_catch(K, V) -> + %% This try...catch block looks like a guard. + %% Make sure that it is not optimized like a guard + %% (the put/2 call must not be optimized away). + try + put(K, V), + false + catch + _:_ -> + false + end. + coverage(Config) when is_list(Config) -> ?line {'EXIT',{{case_clause,{a,b,c}},_}} = (catch cover_will_match_list_type({a,b,c})), |