diff options
Diffstat (limited to 'lib/compiler/src/sys_core_fold.erl')
| -rw-r--r-- | lib/compiler/src/sys_core_fold.erl | 27 |
1 files changed, 14 insertions, 13 deletions
diff --git a/lib/compiler/src/sys_core_fold.erl b/lib/compiler/src/sys_core_fold.erl index eeb3535936..72509947d6 100644 --- a/lib/compiler/src/sys_core_fold.erl +++ b/lib/compiler/src/sys_core_fold.erl @@ -2246,18 +2246,11 @@ make_var_name() -> list_to_atom("fol"++integer_to_list(N)). letify(Bs, Body) -> + Ann = cerl:get_ann(Body), foldr(fun({V,Val}, B) -> - letify(V, Val, B) + cerl:ann_c_let(Ann, [V], Val, B) end, Body, Bs). -letify(#c_var{name=Vname}=Var, Val, Body) -> - case core_lib:is_var_used(Vname, Body) of - true -> - A = element(2, Body), - #c_let{anno=A,vars=[Var],arg=Val,body=Body}; - false -> Body - end. - %% opt_case_in_let(LetExpr) -> LetExpr' opt_case_in_let(#c_let{vars=Vs,arg=Arg,body=B}=Let, Sub) -> @@ -2622,7 +2615,7 @@ opt_simple_let_2(Let0, Vs0, Arg0, Body0, effect, Sub) -> opt_case_in_let_arg(opt_case_in_let(Let, Sub), effect, Sub) end end; -opt_simple_let_2(Let, Vs0, Arg0, Body, value, Sub) -> +opt_simple_let_2(Let0, Vs0, Arg0, Body, value, Sub) -> case {Vs0,Arg0,Body} of {[#c_var{name=N1}],Arg,#c_var{name=N2}} -> case N1 =:= N2 of @@ -2641,9 +2634,17 @@ opt_simple_let_2(Let, Vs0, Arg0, Body, value, Sub) -> %% can be evaluated in effect context to simplify it. expr(#c_seq{arg=Arg,body=Body}, value, sub_new_preserve_types(Sub)); {Vs,Arg,Body} -> - opt_case_in_let_arg( - opt_case_in_let(Let#c_let{vars=Vs,arg=Arg,body=Body}, Sub), - value, Sub) + %% If none of the variables are used in the body, we can rewrite the + %% let to a sequence: + %% let <Var> = Arg in BodyWithoutVar ==> seq Arg BodyWithoutVar + case is_any_var_used(Vs, Body) of + false -> + expr(#c_seq{arg=Arg,body=Body}, value, + sub_new_preserve_types(Sub)); + true -> + Let = Let0#c_let{vars=Vs,arg=Arg,body=Body}, + opt_case_in_let_arg(opt_case_in_let(Let, Sub), value, Sub) + end end. move_case_into_arg(#c_case{arg=#c_let{vars=OuterVars0,arg=OuterArg, |