diff options
| -rw-r--r-- | lib/compiler/src/sys_core_fold.erl | 50 |
1 files changed, 15 insertions, 35 deletions
diff --git a/lib/compiler/src/sys_core_fold.erl b/lib/compiler/src/sys_core_fold.erl index c83dd3c0a1..7d1819ea15 100644 --- a/lib/compiler/src/sys_core_fold.erl +++ b/lib/compiler/src/sys_core_fold.erl @@ -2272,31 +2272,7 @@ opt_simple_let_1(#c_let{vars=Vs0,body=B0}=Let, Arg0, Ctxt, Sub0) -> Arg = core_lib:make_values(Args), opt_simple_let_2(Let, Vs, Arg, B, Ctxt, Sub1). -opt_simple_let_2(Let0, Vs0, Arg0, Body0, effect, Sub) -> - case {Vs0,Arg0,Body0} of - {[],#c_values{es=[]},Body} -> - %% No variables left (because of substitutions). - Body; - {[_|_],Arg,#c_literal{}} -> - %% The body is a literal. That means that we can ignore - %% it and that the return value is Arg revisited in - %% effect context. - body(Arg, effect, sub_new_preserve_types(Sub)); - {Vs,Arg,Body} -> - %% Since we are in effect context, there is a chance - %% that the body no longer references the variables. - %% In that case we can construct a sequence and visit - %% that in effect context: - %% let <Var> = Arg in BodyWithoutVar ==> seq Arg BodyWithoutVar - case is_any_var_used(Vs, Body) of - false -> - expr(#c_seq{arg=Arg,body=Body}, effect, 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), effect, Sub) - end - end; -opt_simple_let_2(Let0, Vs0, Arg0, Body, value, Sub) -> +opt_simple_let_2(Let0, Vs0, Arg0, Body, Ctxt, Sub) -> case {Vs0,Arg0,Body} of {[#c_var{name=N1}],Arg,#c_var{name=N2}} -> case N1 =:= N2 of @@ -2305,26 +2281,30 @@ opt_simple_let_2(Let0, Vs0, Arg0, Body, value, Sub) -> Arg; false -> %% let <Var> = Arg in <OtherVar> ==> seq Arg OtherVar - expr(#c_seq{arg=Arg,body=Body}, value, sub_new_preserve_types(Sub)) + expr(#c_seq{arg=Arg,body=Body}, Ctxt, + sub_new_preserve_types(Sub)) end; {[],#c_values{es=[]},_} -> %% No variables left. Body; {_,Arg,#c_literal{}} -> - %% The variable is not used in the body. The argument - %% 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} -> - %% If none of the variables are used in the body, we can rewrite the + %% Since the variable is not used in the body, we can rewrite the %% let to a sequence: - %% let <Var> = Arg in BodyWithoutVar ==> seq Arg BodyWithoutVar + %% let <Var> = Arg in Literal ==> seq Arg Literal + expr(#c_seq{arg=Arg,body=Body}, Ctxt, sub_new_preserve_types(Sub)); + {Vs,Arg,Body} -> + %% 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, + expr(#c_seq{arg=Arg,body=Body}, Ctxt, 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) + Let1 = Let0#c_let{vars=Vs,arg=Arg,body=Body}, + Let2 = opt_case_in_let(Let1, Sub), + opt_case_in_let_arg(Let2, Ctxt, Sub) end end. |