diff options
Diffstat (limited to 'lib/compiler/src/sys_core_fold.erl')
-rw-r--r-- | lib/compiler/src/sys_core_fold.erl | 143 |
1 files changed, 135 insertions, 8 deletions
diff --git a/lib/compiler/src/sys_core_fold.erl b/lib/compiler/src/sys_core_fold.erl index 1cdbac5693..e2b9213891 100644 --- a/lib/compiler/src/sys_core_fold.erl +++ b/lib/compiler/src/sys_core_fold.erl @@ -305,6 +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)} @@ -349,7 +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; @@ -598,6 +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). @@ -1536,9 +1553,17 @@ 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} = pattern(K0, Isub, Osub0), - {V,Osub} = pattern(V0, Isub, Osub1), +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) -> @@ -1920,14 +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]}. @@ -2555,6 +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 |