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-rw-r--r--lib/compiler/src/sys_core_fold.erl159
1 files changed, 95 insertions, 64 deletions
diff --git a/lib/compiler/src/sys_core_fold.erl b/lib/compiler/src/sys_core_fold.erl
index e28d48acf5..46816fe24a 100644
--- a/lib/compiler/src/sys_core_fold.erl
+++ b/lib/compiler/src/sys_core_fold.erl
@@ -145,14 +145,9 @@ find_fixpoint(OptFun, Core0, Max) ->
body(Body, Sub) ->
body(Body, value, Sub).
-body(#c_values{anno=A,es=Es0}, Ctxt, Sub) ->
- Es1 = expr_list(Es0, Ctxt, Sub),
- case Ctxt of
- value ->
- #c_values{anno=A,es=Es1};
- effect ->
- make_effect_seq(Es1, Sub)
- end;
+body(#c_values{anno=A,es=Es0}, value, Sub) ->
+ Es1 = expr_list(Es0, value, Sub),
+ #c_values{anno=A,es=Es1};
body(E, Ctxt, Sub) ->
?ASSERT(verify_scope(E, Sub)),
expr(E, Ctxt, Sub).
@@ -313,9 +308,15 @@ expr(#c_seq{arg=Arg0,body=B0}=Seq0, Ctxt, Sub) ->
false ->
%% Arg cannot be "values" here - only a single value
%% make sense here.
- case is_safe_simple(Arg, Sub) of
- true -> B1;
- false -> Seq0#c_seq{arg=Arg,body=B1}
+ case {Ctxt,is_safe_simple(Arg, Sub)} of
+ {effect,true} -> B1;
+ {effect,false} ->
+ case is_safe_simple(B1, Sub) of
+ true -> Arg;
+ false -> Seq0#c_seq{arg=Arg,body=B1}
+ end;
+ {value,true} -> B1;
+ {value,false} -> Seq0#c_seq{arg=Arg,body=B1}
end
end;
expr(#c_let{}=Let0, Ctxt, Sub) ->
@@ -379,10 +380,7 @@ expr(#c_case{}=Case0, Ctxt, Sub) ->
Case = Case1#c_case{arg=Arg2,clauses=Cs2},
warn_no_clause_match(Case1, Case),
Expr = eval_case(Case, Sub),
- case move_case_into_arg(Case, Sub) of
- impossible -> Expr;
- Other -> Other
- end;
+ move_case_into_arg(Expr, Sub);
Other ->
expr(Other, Ctxt, Sub)
end;
@@ -2664,53 +2662,93 @@ opt_simple_let_1(#c_let{vars=Vs0,body=B0}=Let, Arg0, Ctxt, Sub0) ->
%% Optimise let and add new substitutions.
{Vs,Args,Sub1} = let_substs(Vs0, Arg0, Sub0),
BodySub = update_let_types(Vs, Args, Sub1),
+ Sub = Sub1#sub{v=[],s=cerl_sets:new()},
B = body(B0, Ctxt, BodySub),
Arg = core_lib:make_values(Args),
- opt_simple_let_2(Let, Vs, Arg, B, B0, Ctxt, Sub1).
+ opt_simple_let_2(Let, Vs, Arg, B, B0, Sub).
+
+
+%% opt_simple_let_2(Let0, Vs0, Arg0, Body, PrevBody, Ctxt, Sub) -> Core.
+%% Do final simplifications of the let.
+%%
+%% Note that the substitutions and scope in Sub have been cleared
+%% and should not be used.
-opt_simple_let_2(Let0, Vs0, Arg0, Body, PrevBody, Ctxt, Sub) ->
+opt_simple_let_2(Let0, Vs0, Arg0, Body, PrevBody, Sub) ->
case {Vs0,Arg0,Body} of
- {[#c_var{name=N1}],Arg1,#c_var{name=N2}} ->
- case N1 =:= N2 of
- true ->
- %% let <Var> = Arg in <Var> ==> Arg
- Arg1;
- false ->
- %% let <Var> = Arg in <OtherVar> ==> seq Arg OtherVar
- Arg = maybe_suppress_warnings(Arg1, Vs0, PrevBody),
- #c_seq{arg=Arg,body=Body}
- end;
+ {[#c_var{name=V}],Arg1,#c_var{name=V}} ->
+ %% let <Var> = Arg in <Var> ==> Arg
+ Arg1;
{[],#c_values{es=[]},_} ->
%% No variables left.
Body;
- {Vs,Arg1,#c_literal{}} ->
- Arg = maybe_suppress_warnings(Arg1, Vs, PrevBody),
- case Ctxt of
- effect ->
- %% Throw away the literal body.
- Arg;
- value ->
- %% Since the variable is not used in the body, we
- %% can rewrite the let to a sequence.
- %% let <Var> = Arg in Literal ==> seq Arg Literal
- #c_seq{arg=Arg,body=Body}
- end;
- {Vs,Arg1,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 ->
- Arg = maybe_suppress_warnings(Arg1, Vs, PrevBody),
- #c_seq{arg=Arg,body=Body};
- true ->
- Let1 = Let0#c_let{vars=Vs,arg=Arg1,body=Body},
- opt_bool_case_in_let(Let1, Sub)
+ {[#c_var{name=V}=Var|Vars]=Vars0,Arg1,Body} ->
+ case core_lib:is_var_used(V, Body) of
+ false when Vars =:= [] ->
+ %% If the variable is not used in the body, we can
+ %% rewrite the let to a sequence:
+ %% let <Var> = Arg in BodyWithoutVar ==>
+ %% seq Arg BodyWithoutVar
+ Arg = maybe_suppress_warnings(Arg1, Var, PrevBody),
+ #c_seq{arg=Arg,body=Body};
+ false ->
+ %% There are multiple values returned by the argument
+ %% and the first value is not used (this is a 'case'
+ %% with exported variables, but the return value is
+ %% ignored). We can remove the first variable and the
+ %% the first value returned from the 'let' argument.
+ Arg2 = remove_first_value(Arg1, Sub),
+ Let1 = Let0#c_let{vars=Vars,arg=Arg2,body=Body},
+ post_opt_let(Let1, Sub);
+ true ->
+ Let1 = Let0#c_let{vars=Vars0,arg=Arg1,body=Body},
+ post_opt_let(Let1, Sub)
end
end.
-%% maybe_suppress_warnings(Arg, [#c_var{}], PreviousBody) -> Arg'
+%% post_opt_let(Let, Sub)
+%% Final optimizations of the let.
+%%
+%% Note that the substitutions and scope in Sub have been cleared
+%% and should not be used.
+
+post_opt_let(Let, Sub) ->
+ opt_bool_case_in_let(Let, Sub).
+
+
+%% remove_first_value(Core0, Sub) -> Core.
+%% Core0 is an expression that returns at least two values.
+%% Remove the first value returned from Core0.
+
+remove_first_value(#c_values{es=[V|Vs]}, Sub) ->
+ Values = core_lib:make_values(Vs),
+ case is_safe_simple(V, Sub) of
+ false ->
+ #c_seq{arg=V,body=Values};
+ true ->
+ Values
+ end;
+remove_first_value(#c_case{clauses=Cs0}=Core, Sub) ->
+ Cs = remove_first_value_cs(Cs0, Sub),
+ Core#c_case{clauses=Cs};
+remove_first_value(#c_receive{clauses=Cs0,action=Act0}=Core, Sub) ->
+ Cs = remove_first_value_cs(Cs0, Sub),
+ Act = remove_first_value(Act0, Sub),
+ Core#c_receive{clauses=Cs,action=Act};
+remove_first_value(#c_let{body=B}=Core, Sub) ->
+ Core#c_let{body=remove_first_value(B, Sub)};
+remove_first_value(#c_seq{body=B}=Core, Sub) ->
+ Core#c_seq{body=remove_first_value(B, Sub)};
+remove_first_value(#c_primop{}=Core, _Sub) ->
+ Core;
+remove_first_value(#c_call{}=Core, _Sub) ->
+ Core.
+
+remove_first_value_cs(Cs, Sub) ->
+ [C#c_clause{body=remove_first_value(B, Sub)} ||
+ #c_clause{body=B}=C <- Cs].
+
+%% maybe_suppress_warnings(Arg, #c_var{}, PreviousBody) -> Arg'
%% Try to suppress false warnings when a variable is not used.
%% For instance, we don't expect a warning for useless building in:
%%
@@ -2721,12 +2759,12 @@ opt_simple_let_2(Let0, Vs0, Arg0, Body, PrevBody, Ctxt, Sub) ->
%% referenced in the original unoptimized code. If they were, we will
%% consider the warning false and suppress it.
-maybe_suppress_warnings(Arg, Vs, PrevBody) ->
+maybe_suppress_warnings(Arg, #c_var{name=V}, PrevBody) ->
case should_suppress_warning(Arg) of
true ->
Arg; %Already suppressed.
false ->
- case is_any_var_used(Vs, PrevBody) of
+ case core_lib:is_var_used(V, PrevBody) of
true ->
suppress_warning([Arg]);
false ->
@@ -2815,7 +2853,7 @@ move_case_into_arg(#c_case{arg=#c_case{arg=OuterArg,
Outer#c_case{arg=OuterArg,
clauses=[OuterCa,OuterCb]};
false ->
- impossible
+ Inner0
end;
move_case_into_arg(#c_case{arg=#c_seq{arg=OuterArg,body=InnerArg}=Outer,
clauses=InnerClauses}=Inner, _Sub) ->
@@ -2831,15 +2869,8 @@ move_case_into_arg(#c_case{arg=#c_seq{arg=OuterArg,body=InnerArg}=Outer,
%%
Outer#c_seq{arg=OuterArg,
body=Inner#c_case{arg=InnerArg,clauses=InnerClauses}};
-move_case_into_arg(_, _) ->
- impossible.
-
-is_any_var_used([#c_var{name=V}|Vs], Expr) ->
- case core_lib:is_var_used(V, Expr) of
- false -> is_any_var_used(Vs, Expr);
- true -> true
- end;
-is_any_var_used([], _) -> false.
+move_case_into_arg(Expr, _) ->
+ Expr.
%%%
%%% Retrieving information about types.
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-05 11:56:18 +0000