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-rw-r--r--lib/compiler/src/sys_core_fold.erl174
1 files changed, 168 insertions, 6 deletions
diff --git a/lib/compiler/src/sys_core_fold.erl b/lib/compiler/src/sys_core_fold.erl
index a388960312..e2b9213891 100644
--- a/lib/compiler/src/sys_core_fold.erl
+++ b/lib/compiler/src/sys_core_fold.erl
@@ -246,6 +246,16 @@ expr(#c_tuple{anno=Anno,es=Es0}=Tuple, Ctxt, Sub) ->
value ->
ann_c_tuple(Anno, Es)
end;
+expr(#c_map{var=V0,es=Es0}=Map, Ctxt, Sub) ->
+ Es = pair_list(Es0, Ctxt, Sub),
+ case Ctxt of
+ effect ->
+ add_warning(Map, useless_building),
+ expr(make_effect_seq(Es, Sub), Ctxt, Sub);
+ value ->
+ V = expr(V0, Ctxt, Sub),
+ Map#c_map{var=V,es=Es}
+ end;
expr(#c_binary{segments=Ss}=Bin0, Ctxt, Sub) ->
%% Warn for useless building, but always build the binary
%% anyway to preserve a possible exception.
@@ -295,6 +305,10 @@ expr(#c_let{}=Let, Ctxt, Sub) ->
%% Now recursively re-process the new expression.
expr(Expr, Ctxt, sub_new_preserve_types(Sub))
end;
+expr(#c_letrec{body=#c_var{}}=Letrec, effect, _Sub) ->
+ %% This is named fun in an 'effect' context. Warn and ignore.
+ add_warning(Letrec, useless_building),
+ void();
expr(#c_letrec{defs=Fs0,body=B0}=Letrec, Ctxt, Sub) ->
Fs1 = map(fun ({Name,Fb}) ->
{Name,expr(Fb, {letrec,Ctxt}, Sub)}
@@ -339,7 +353,12 @@ 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),
- bsm_an(Expr);
+ case move_case_into_arg(Case, Sub) of
+ impossible ->
+ bsm_an(Expr);
+ Other ->
+ expr(Other, Ctxt, sub_new_preserve_types(Sub))
+ end;
Other ->
expr(Other, Ctxt, Sub)
end;
@@ -408,6 +427,16 @@ expr(#c_try{anno=A,arg=E0,vars=Vs0,body=B0,evars=Evs0,handler=H0}=Try, _, Sub0)
expr_list(Es, Ctxt, Sub) ->
[expr(E, Ctxt, Sub) || E <- Es].
+pair_list(Es, Ctxt, Sub) ->
+ [pair(E, Ctxt, Sub) || E <- Es].
+
+pair(#c_map_pair{key=K,val=V}, effect, Sub) ->
+ make_effect_seq([K,V], Sub);
+pair(#c_map_pair{key=K0,val=V0}=Pair, value=Ctxt, Sub) ->
+ K = expr(K0, Ctxt, Sub),
+ V = expr(V0, Ctxt, Sub),
+ Pair#c_map_pair{key=K,val=V}.
+
bitstr_list(Es, Sub) ->
[bitstr(E, Sub) || E <- Es].
@@ -578,6 +607,14 @@ eval_binary_1([#c_bitstr{val=#c_literal{val=Val},size=#c_literal{val=Sz},
error:_ ->
throw(impossible)
end;
+eval_binary_1([#c_bitstr{val=#c_literal{},size=#c_literal{},
+ unit=#c_literal{},type=#c_literal{},
+ flags=#c_cons{}=Flags}=Bitstr|Ss], Acc0) ->
+ case cerl:fold_literal(Flags) of
+ #c_literal{} = Flags1 ->
+ eval_binary_1([Bitstr#c_bitstr{flags=Flags1}|Ss], Acc0);
+ _ -> throw(impossible)
+ end;
eval_binary_1([], Acc) -> Acc;
eval_binary_1(_, _) -> throw(impossible).
@@ -677,7 +714,7 @@ useless_call(effect, #c_call{anno=Anno,
useless_call(_, _) -> no.
%% make_effect_seq([Expr], Sub) -> #c_seq{}|void()
-%% Convert a list of epressions evaluated in effect context to a chain of
+%% Convert a list of expressions evaluated in effect context to a chain of
%% #c_seq{}. The body in the innermost #c_seq{} will be void().
%% Anything that will not have any effect will be thrown away.
@@ -1500,6 +1537,9 @@ pattern(#c_cons{anno=Anno,hd=H0,tl=T0}, Isub, Osub0) ->
pattern(#c_tuple{anno=Anno,es=Es0}, Isub, Osub0) ->
{Es1,Osub1} = pattern_list(Es0, Isub, Osub0),
{ann_c_tuple(Anno, Es1),Osub1};
+pattern(#c_map{anno=Anno,es=Es0}=Map, Isub, Osub0) ->
+ {Es1,Osub1} = map_pair_pattern_list(Es0, Isub, Osub0),
+ {Map#c_map{anno=Anno,es=Es1},Osub1};
pattern(#c_binary{segments=V0}=Pat, Isub, Osub0) ->
{V1,Osub1} = bin_pattern_list(V0, Isub, Osub0),
{Pat#c_binary{segments=V1},Osub1};
@@ -1509,6 +1549,23 @@ pattern(#c_alias{var=V0,pat=P0}=Pat, Isub, Osub0) ->
Osub = update_types(V1, [P1], Osub2),
{Pat#c_alias{var=V1,pat=P1},Osub}.
+map_pair_pattern_list(Ps0, Isub, Osub0) ->
+ {Ps,{_,Osub}} = mapfoldl(fun map_pair_pattern/2, {Isub,Osub0}, Ps0),
+ {Ps,Osub}.
+
+map_pair_pattern(#c_map_pair{op=#c_literal{val=exact},key=K0,val=V0}=Pair,{Isub,Osub0}) ->
+ {K,Osub1} = case cerl:type(K0) of
+ binary ->
+ K1 = eval_binary(K0),
+ case cerl:type(K1) of
+ literal -> {K1,Osub0};
+ _ -> pattern(K0,Isub,Osub0)
+ end;
+ _ -> pattern(K0,Isub,Osub0)
+ end,
+ {V,Osub} = pattern(V0,Isub,Osub1),
+ {Pair#c_map_pair{key=K,val=V},{Isub,Osub}}.
+
bin_pattern_list(Ps0, Isub, Osub0) ->
{Ps,{_,Osub}} = mapfoldl(fun bin_pattern/2, {Isub,Osub0}, Ps0),
{Ps,Osub}.
@@ -1888,14 +1945,45 @@ opt_bool_case_guard(Arg, [#c_clause{pats=[#c_literal{val=false}]}=Fc,Tc]) ->
%% last clause is guaranteed to match so if there is only one clause
%% with a pattern containing only variables then rewrite to a let.
-eval_case(#c_case{arg=E,clauses=[#c_clause{pats=Ps0,body=B}]}, Sub) ->
+eval_case(#c_case{arg=E,clauses=[#c_clause{pats=Ps0,
+ guard=#c_literal{val=true},
+ body=B}]}=Case, Sub) ->
Es = case cerl:is_c_values(E) of
true -> cerl:values_es(E);
false -> [E]
end,
- {true,Bs} = cerl_clauses:match_list(Ps0, Es),
- {Ps,As} = unzip(Bs),
- expr(#c_let{vars=Ps,arg=core_lib:make_values(As),body=B}, sub_new(Sub));
+ %% Consider:
+ %%
+ %% case SomeSideEffect() of
+ %% X=Y -> ...
+ %% end
+ %%
+ %% We must not rewrite it to:
+ %%
+ %% let <X,Y> = <SomeSideEffect(),SomeSideEffect()> in ...
+ %%
+ %% because SomeSideEffect() would be evaluated twice.
+ %%
+ %% Instead we must evaluate the case expression in an outer let
+ %% like this:
+ %%
+ %% let NewVar = SomeSideEffect() in
+ %% let <X,Y> = <NewVar,NewVar> in ...
+ %%
+ Vs = make_vars([], length(Es)),
+ case cerl_clauses:match_list(Ps0, Vs) of
+ {false,_} ->
+ %% This can only happen if the Core Erlang code is
+ %% handwritten or generated by another code generator
+ %% than v3_core. Assuming that the Core Erlang program
+ %% is correct, the clause will always match at run-time.
+ Case;
+ {true,Bs} ->
+ {Ps,As} = unzip(Bs),
+ InnerLet = cerl:c_let(Ps, core_lib:make_values(As), B),
+ Let = cerl:c_let(Vs, E, InnerLet),
+ expr(Let, sub_new(Sub))
+ end;
eval_case(Case, _) -> Case.
%% case_opt(CaseArg, [Clause]) -> {CaseArg,[Clause]}.
@@ -2523,6 +2611,77 @@ opt_simple_let_2(Let, Vs0, Arg0, Body, value, Sub) ->
value, Sub)
end.
+move_case_into_arg(#c_case{arg=#c_let{vars=OuterVars0,arg=OuterArg,
+ body=InnerArg0}=Outer,
+ clauses=InnerClauses}=Inner, Sub) ->
+ %%
+ %% case let <OuterVars> = <OuterArg> in <InnerArg> of
+ %% <InnerClauses>
+ %% end
+ %%
+ %% ==>
+ %%
+ %% let <OuterVars> = <OuterArg>
+ %% in case <InnerArg> of <InnerClauses> end
+ %%
+ ScopeSub0 = sub_subst_scope(Sub#sub{t=[]}),
+ {OuterVars,ScopeSub} = pattern_list(OuterVars0, ScopeSub0),
+ InnerArg = body(InnerArg0, ScopeSub),
+ Outer#c_let{vars=OuterVars,arg=OuterArg,
+ body=Inner#c_case{arg=InnerArg,clauses=InnerClauses}};
+move_case_into_arg(#c_case{arg=#c_case{arg=OuterArg,
+ clauses=[OuterCa0,OuterCb]}=Outer,
+ clauses=InnerClauses}=Inner0, Sub) ->
+ case is_failing_clause(OuterCb) of
+ true ->
+ #c_clause{pats=OuterPats0,guard=OuterGuard0,
+ body=InnerArg0} = OuterCa0,
+ %%
+ %% case case <OuterArg> of
+ %% <OuterPats> when <OuterGuard> -> <InnerArg>
+ %% <OuterCb>
+ %% ...
+ %% end of
+ %% <InnerClauses>
+ %% end
+ %%
+ %% ==>
+ %%
+ %% case <OuterArg> of
+ %% <OuterPats> when <OuterGuard> ->
+ %% case <InnerArg> of <InnerClauses> end
+ %% <OuterCb>
+ %% end
+ %%
+ ScopeSub0 = sub_subst_scope(Sub#sub{t=[]}),
+ {OuterPats,ScopeSub} = pattern_list(OuterPats0, ScopeSub0),
+ OuterGuard = guard(OuterGuard0, ScopeSub),
+ InnerArg = body(InnerArg0, ScopeSub),
+ Inner = Inner0#c_case{arg=InnerArg,clauses=InnerClauses},
+ OuterCa = OuterCa0#c_clause{pats=OuterPats,guard=OuterGuard,
+ body=Inner},
+ Outer#c_case{arg=OuterArg,
+ clauses=[OuterCa,OuterCb]};
+ false ->
+ impossible
+ end;
+move_case_into_arg(#c_case{arg=#c_seq{arg=OuterArg,body=InnerArg}=Outer,
+ clauses=InnerClauses}=Inner, _Sub) ->
+ %%
+ %% case do <OuterArg> <InnerArg> of
+ %% <InnerClauses>
+ %% end
+ %%
+ %% ==>
+ %%
+ %% do <OuterArg>
+ %% case <InnerArg> of <InerClauses> end
+ %%
+ Outer#c_seq{arg=OuterArg,
+ body=Inner#c_case{arg=InnerArg,clauses=InnerClauses}};
+move_case_into_arg(_, _) ->
+ impossible.
+
%% In guards only, rewrite a case in a let argument like
%%
%% let <Var> = case <> of
@@ -2987,6 +3146,9 @@ format_error(result_ignored) ->
"(suppress the warning by assigning the expression to the _ variable)";
format_error(useless_building) ->
"a term is constructed, but never used";
+format_error({map_pair_key_overloaded,K}) ->
+ M = io_lib:format("the key ~p is used multiple times in map value association",[K]),
+ flatten(M);
format_error(bin_opt_alias) ->
"INFO: the '=' operator will prevent delayed sub binary optimization";
format_error(bin_partition) ->
generated by cgit v1.2.3 (git 2.25.1) at 2024-07-29 12:21:21 +0000