diff options
Diffstat (limited to 'lib/compiler/src')
| -rw-r--r-- | lib/compiler/src/sys_core_fold.erl | 37 |
1 files changed, 11 insertions, 26 deletions
diff --git a/lib/compiler/src/sys_core_fold.erl b/lib/compiler/src/sys_core_fold.erl index a13bdedaf9..47042c2393 100644 --- a/lib/compiler/src/sys_core_fold.erl +++ b/lib/compiler/src/sys_core_fold.erl @@ -1275,13 +1275,18 @@ let_subst_list([], [], _) -> {[],[],[]}. %%pattern(Pat, Sub) -> pattern(Pat, Sub, Sub). pattern(#c_var{}=Pat, Isub, Osub) -> - case sub_is_val(Pat, Isub) of + case sub_is_in_scope(Pat, Isub) of true -> + %% This variable either has a substitution or is used in + %% the variable list of an enclosing `let`. In either + %% case, it must be renamed to an unused name to avoid + %% name capture problems. V1 = make_var_name(), Pat1 = #c_var{name=V1}, {Pat1,sub_set_var(Pat, Pat1, sub_add_scope([V1], Osub))}; false -> - {Pat,sub_del_var(Pat, Osub)} + %% This variable has never been used. Add it to the scope. + {Pat,sub_add_scope([Pat#c_var.name], Osub)} end; pattern(#c_literal{}=Pat, _, Osub) -> {Pat,Osub}; pattern(#c_cons{anno=Anno,hd=H0,tl=T0}, Isub, Osub0) -> @@ -1460,8 +1465,8 @@ is_subst(_) -> false. %% sub_set_name(Name, Value, #sub{}) -> #sub{}. %% sub_del_var(Var, #sub{}) -> #sub{}. %% sub_subst_var(Var, Value, #sub{}) -> [{Name,Value}]. -%% sub_is_val(Var, #sub{}) -> boolean(). -%% sub_add_scope(#sub{}) -> #sub{} +%% sub_is_in_scope(Var, #sub{}) -> boolean(). +%% sub_add_scope([Var], #sub{}) -> #sub{} %% sub_subst_scope(#sub{}) -> #sub{} %% %% We use the variable name as key so as not have problems with @@ -1496,18 +1501,6 @@ sub_set_name(V, Val, #sub{v=S,s=Scope,t=Tdb0}=Sub) -> Tdb = copy_type(V, Val, Tdb1), Sub#sub{v=orddict:store(V, Val, S),s=cerl_sets:add_element(V, Scope),t=Tdb}. -sub_del_var(#c_var{name=V}, #sub{v=S,s=Scope,t=Tdb}=Sub) -> - %% Profiling shows that for programs with many record operations, - %% sub_del_var/2 is a bottleneck. Since the scope contains all - %% variables that are live, we know that V cannot be present in S - %% if it is not in the scope. - case cerl_sets:is_element(V, Scope) of - false -> - Sub#sub{s=cerl_sets:add_element(V, Scope)}; - true -> - Sub#sub{v=orddict:erase(V, S),t=kill_types(V, Tdb)} - end. - sub_subst_var(#c_var{name=V}, Val, #sub{v=S0}) -> %% Fold chained substitutions. [{V,Val}] ++ [ {K,Val} || {K,#c_var{name=V1}} <- S0, V1 =:= V]. @@ -1533,16 +1526,8 @@ sub_subst_scope_1([H|T], Key, Acc) -> sub_subst_scope_1(T, Key-1, [{Key,#c_var{name=H}}|Acc]); sub_subst_scope_1([], _, Acc) -> Acc. -sub_is_val(#c_var{name=V}, #sub{v=S,s=Scope}) -> - %% When the bottleneck in sub_del_var/2 was eliminated, this - %% became the new bottleneck. Since the scope contains all - %% live variables, a variable V can only be the target for - %% a substitution if it is in the scope. - cerl_sets:is_element(V, Scope) andalso v_is_value(V, S). - -v_is_value(Var, [{_,#c_var{name=Var}}|_]) -> true; -v_is_value(Var, [_|T]) -> v_is_value(Var, T); -v_is_value(_, []) -> false. +sub_is_in_scope(#c_var{name=V}, #sub{s=Scope}) -> + cerl_sets:is_element(V, Scope). %% warn_no_clause_match(CaseOrig, CaseOpt) -> ok %% Generate a warning if none of the user-specified clauses |