From ed7a03484ecf16a2af39c1306dfd68b46e067664 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= Date: Sun, 17 Feb 2019 13:15:18 +0100 Subject: Always make andalso/orelse right-associative Always rewriting left-associative andalso/orelse to right-associative will not change the code (except in very rare cases), but it will make sure that the transformation is tested. --- lib/compiler/src/v3_core.erl | 22 +++++++--------------- 1 file changed, 7 insertions(+), 15 deletions(-) diff --git a/lib/compiler/src/v3_core.erl b/lib/compiler/src/v3_core.erl index e2bcd25801..3699c9d22e 100644 --- a/lib/compiler/src/v3_core.erl +++ b/lib/compiler/src/v3_core.erl @@ -330,7 +330,7 @@ gexpr({protect,Line,Arg}, Bools0, St0) -> {#iprotect{anno=#a{anno=Anno},body=Eps++[E]},[],Bools0,St} end; gexpr({op,_,'andalso',_,_}=E0, Bools, St0) -> - {op,L,'andalso',E1,E2} = right_assoc(E0, 'andalso', St0), + {op,L,'andalso',E1,E2} = right_assoc(E0, 'andalso'), Anno = lineno_anno(L, St0), {#c_var{name=V0},St} = new_var(Anno, St0), V = {var,L,V0}, @@ -338,7 +338,7 @@ gexpr({op,_,'andalso',_,_}=E0, Bools, St0) -> E = make_bool_switch_guard(L, E1, V, E2, False), gexpr(E, Bools, St); gexpr({op,_,'orelse',_,_}=E0, Bools, St0) -> - {op,L,'orelse',E1,E2} = right_assoc(E0, 'orelse', St0), + {op,L,'orelse',E1,E2} = right_assoc(E0, 'orelse'), Anno = lineno_anno(L, St0), {#c_var{name=V0},St} = new_var(Anno, St0), V = {var,L,V0}, @@ -768,7 +768,7 @@ expr({op,_,'++',{lc,Llc,E,Qs0},More}, St0) -> {Y,Yps,St} = lc_tq(Llc, E, Qs, Mc, St2), {Y,Mps++Yps,St}; expr({op,_,'andalso',_,_}=E0, St0) -> - {op,L,'andalso',E1,E2} = right_assoc(E0, 'andalso', St0), + {op,L,'andalso',E1,E2} = right_assoc(E0, 'andalso'), Anno = lineno_anno(L, St0), {#c_var{name=V0},St} = new_var(Anno, St0), V = {var,L,V0}, @@ -776,7 +776,7 @@ expr({op,_,'andalso',_,_}=E0, St0) -> E = make_bool_switch(L, E1, V, E2, False, St0), expr(E, St); expr({op,_,'orelse',_,_}=E0, St0) -> - {op,L,'orelse',E1,E2} = right_assoc(E0, 'orelse', St0), + {op,L,'orelse',E1,E2} = right_assoc(E0, 'orelse'), Anno = lineno_anno(L, St0), {#c_var{name=V0},St} = new_var(Anno, St0), V = {var,L,V0}, @@ -2060,17 +2060,9 @@ fail_clause(Pats, Anno, Arg) -> args=[Arg]}]}. %% Optimization for Dialyzer. -right_assoc(E, Op, St) -> - case member(dialyzer, St#core.opts) of - true -> - right_assoc2(E, Op); - false -> - E - end. - -right_assoc2({op,L1,Op,{op,L2,Op,E1,E2},E3}, Op) -> - right_assoc2({op,L2,Op,E1,{op,L1,Op,E2,E3}}, Op); -right_assoc2(E, _Op) -> E. +right_assoc({op,L1,Op,{op,L2,Op,E1,E2},E3}, Op) -> + right_assoc({op,L2,Op,E1,{op,L1,Op,E2,E3}}, Op); +right_assoc(E, _Op) -> E. annotate_tuple(A, Es, St) -> case member(dialyzer, St#core.opts) of -- cgit v1.2.3 From eea819472238694d7a68b58663be6226d44b5bca Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= Date: Mon, 18 Feb 2019 07:04:03 +0100 Subject: Refactor optimization of Bool =:= true Refactor optimization of `Bool =:= true` to make the code somewhat simpler, as well as potentially apply the optimization in more cases. --- lib/compiler/src/beam_ssa_type.erl | 33 +++++++++++++++------------------ 1 file changed, 15 insertions(+), 18 deletions(-) diff --git a/lib/compiler/src/beam_ssa_type.erl b/lib/compiler/src/beam_ssa_type.erl index 3b5d25efce..a043f5a959 100644 --- a/lib/compiler/src/beam_ssa_type.erl +++ b/lib/compiler/src/beam_ssa_type.erl @@ -452,10 +452,19 @@ simplify(#b_set{op={bif,'=='},args=Args}=I, Ts) -> end; simplify(#b_set{op={bif,'=:='},args=[Same,Same]}, _Ts) -> #b_literal{val=true}; -simplify(#b_set{op={bif,'=:='},args=Args}=I, Ts) -> - case meet(get_types(Args, Ts)) of - none -> #b_literal{val=false}; - _ -> eval_bif(I, Ts) +simplify(#b_set{op={bif,'=:='},args=[A1,_A2]=Args}=I, Ts) -> + [T1,T2] = get_types(Args, Ts), + case meet(T1, T2) of + none -> + #b_literal{val=false}; + _ -> + case {t_is_boolean(T1),T2} of + {true,#t_atom{elements=[true]}} -> + %% Bool =:= true ==> Bool + A1; + {_,_} -> + eval_bif(I, Ts) + end end; simplify(#b_set{op={bif,Op},args=Args}=I, Ts) -> Types = get_types(Args, Ts), @@ -598,20 +607,8 @@ anno_float_arg(_) -> convert. opt_terminator(#b_br{bool=#b_literal{}}=Br, _Ts, _Ds) -> beam_ssa:normalize(Br); -opt_terminator(#b_br{bool=#b_var{}=V}=Br, Ts, Ds) -> - #{V:=Set} = Ds, - case Set of - #b_set{op={bif,'=:='},args=[Bool,#b_literal{val=true}]} -> - case t_is_boolean(get_type(Bool, Ts)) of - true -> - %% Bool =:= true ==> Bool - simplify_not(Br#b_br{bool=Bool}, Ts, Ds); - false -> - Br - end; - #b_set{} -> - simplify_not(Br, Ts, Ds) - end; +opt_terminator(#b_br{bool=#b_var{}}=Br, Ts, Ds) -> + simplify_not(Br, Ts, Ds); opt_terminator(#b_switch{arg=#b_literal{}}=Sw, _Ts, _Ds) -> beam_ssa:normalize(Sw); opt_terminator(#b_switch{arg=#b_var{}=V}=Sw0, Ts, Ds) -> -- cgit v1.2.3 From d96474de9d71705e4b68aa8b6f7e33657870873f Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= Date: Mon, 18 Feb 2019 07:19:11 +0100 Subject: Evaluate pure BIFs with literal arguments --- lib/compiler/src/beam_ssa_type.erl | 71 +++++++++++++++++++++++++++++++++----- 1 file changed, 62 insertions(+), 9 deletions(-) diff --git a/lib/compiler/src/beam_ssa_type.erl b/lib/compiler/src/beam_ssa_type.erl index a043f5a959..4b53848a74 100644 --- a/lib/compiler/src/beam_ssa_type.erl +++ b/lib/compiler/src/beam_ssa_type.erl @@ -260,22 +260,33 @@ opt_is([#b_set{op=phi,dst=Dst,args=Args0}=I0|Is], opt_is(Is, Ts, Ds, Fdb, D, Sub0, [I|Acc]) end; opt_is([#b_set{op=call,args=Args0,dst=Dst}=I0|Is], - Ts0, Ds0, Fdb0, D, Sub, Acc) -> - Args = simplify_args(Args0, Sub, Ts0), + Ts0, Ds0, Fdb0, D, Sub0, Acc) -> + Args = simplify_args(Args0, Sub0, Ts0), I1 = beam_ssa:normalize(I0#b_set{args=Args}), - {Ts,Ds,Fdb,I} = opt_call(I1, D, Ts0, Ds0, Fdb0), - case {map_get(Dst, Ts),Is} of - {none,[#b_set{op=succeeded}]} -> + {Ts1,Ds,Fdb,I2} = opt_call(I1, D, Ts0, Ds0, Fdb0), + case {map_get(Dst, Ts1),Is} of + {_,[#b_set{op=succeeded}]} -> %% This call instruction is inside a try/catch %% block. Don't attempt to optimize it. - opt_is(Is, Ts, Ds, Fdb, D, Sub, [I|Acc]); + opt_is(Is, Ts1, Ds, Fdb, D, Sub0, [I2|Acc]); {none,_} -> %% This call never returns. The rest of the %% instructions will not be executed. Ret = #b_ret{arg=Dst}, - {no_return,Ret,reverse(Acc, [I]),Ds,Fdb,Sub}; - _ -> - opt_is(Is, Ts, Ds, Fdb, D, Sub, [I|Acc]) + {no_return,Ret,reverse(Acc, [I2]),Ds,Fdb,Sub0}; + {_,_} -> + case simplify_call(I2) of + #b_set{}=I -> + opt_is(Is, Ts1, Ds, Fdb, D, Sub0, [I|Acc]); + #b_literal{}=Lit -> + Sub = Sub0#{Dst=>Lit}, + Ts = maps:remove(Dst, Ts1), + opt_is(Is, Ts, Ds0, Fdb, D, Sub, Acc); + #b_var{}=Var -> + Ts = maps:remove(Dst, Ts1), + Sub = Sub0#{Dst=>Var}, + opt_is(Is, Ts, Ds0, Fdb, D, Sub, Acc) + end end; opt_is([#b_set{op=succeeded,args=[Arg],dst=Dst}=I], Ts0, Ds0, Fdb, D, Sub0, Acc) -> @@ -328,6 +339,48 @@ opt_is([#b_set{args=Args0,dst=Dst}=I0|Is], opt_is([], Ts, Ds, Fdb, _D, Sub, Acc) -> {reverse(Acc), Ts, Ds, Fdb, Sub}. +simplify_call(#b_set{op=call,args=[#b_remote{}=Rem|Args]}=I) -> + case Rem of + #b_remote{mod=#b_literal{val=Mod}, + name=#b_literal{val=Name}} -> + case erl_bifs:is_pure(Mod, Name, length(Args)) of + true -> + simplify_remote_call(Mod, Name, Args, I); + false -> + I + end; + #b_remote{} -> + I + end; +simplify_call(I) -> I. + +%% Simplify a remote call to a pure BIF. +simplify_remote_call(erlang, '++', [#b_literal{val=[]},Tl], _I) -> + Tl; +simplify_remote_call(Mod, Name, Args0, I) -> + case make_literal_list(Args0) of + none -> + I; + Args -> + %% The arguments are literals. Try to evaluate the BIF. + try apply(Mod, Name, Args) of + Val -> + case cerl:is_literal_term(Val) of + true -> + #b_literal{val=Val}; + false -> + %% The value can't be expressed as a literal + %% (e.g. a pid). + I + end + catch + _:_ -> + %% Failed. Don't bother trying to optimize + %% the call. + I + end + end. + opt_call(#b_set{dst=Dst,args=[#b_local{}=Callee|Args]}=I0, D, Ts0, Ds0, Fdb0) -> {Ts, Ds, I} = opt_local_call(I0, Ts0, Ds0, Fdb0), case Fdb0 of -- cgit v1.2.3 From c5771f6d7adfbd0d8dd4202dce5d4a090d4ad50b Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= Date: Mon, 18 Feb 2019 11:43:51 +0100 Subject: Improve optimization of switches Part of the switch optimization done by `ssa_opt_sw` can be better done in `beam_ssa_type`. --- lib/compiler/src/beam_ssa_opt.erl | 93 ++++++++++---------------------------- lib/compiler/src/beam_ssa_type.erl | 79 ++++++++++++++++++++++---------- 2 files changed, 79 insertions(+), 93 deletions(-) diff --git a/lib/compiler/src/beam_ssa_opt.erl b/lib/compiler/src/beam_ssa_opt.erl index 0f03d0e736..f8e19d0aa7 100644 --- a/lib/compiler/src/beam_ssa_opt.erl +++ b/lib/compiler/src/beam_ssa_opt.erl @@ -164,12 +164,14 @@ repeated_passes(Opts) -> epilogue_passes(Opts) -> Ps = [?PASS(ssa_opt_type_finish), ?PASS(ssa_opt_float), - ?PASS(ssa_opt_live), %One last time to clean up the - %mess left by the float pass. + ?PASS(ssa_opt_sw), + + %% Run live one more time to clean up after the float and sw + %% passes. + ?PASS(ssa_opt_live), ?PASS(ssa_opt_bsm), ?PASS(ssa_opt_bsm_units), ?PASS(ssa_opt_bsm_shortcut), - ?PASS(ssa_opt_sw), ?PASS(ssa_opt_blockify), ?PASS(ssa_opt_sink), ?PASS(ssa_opt_merge_blocks), @@ -1830,12 +1832,16 @@ opt_tup_size_is([], _, _, _Acc) -> none. %%% ssa_opt_sw({#st{ssa=Linear0,cnt=Count0}=St, FuncDb}) -> - {Linear,Count} = opt_sw(Linear0, #{}, Count0, []), + {Linear,Count} = opt_sw(Linear0, Count0, []), {St#st{ssa=Linear,cnt=Count}, FuncDb}. -opt_sw([{L,#b_blk{is=Is,last=#b_switch{}=Last0}=Blk0}|Bs], Phis0, Count0, Acc) -> - Phis = opt_sw_phis(Is, Phis0), - case opt_sw_last(Last0, Phis) of +opt_sw([{L,#b_blk{is=Is,last=#b_switch{}=Sw0}=Blk0}|Bs], Count0, Acc) -> + %% Ensure that no label in the switch list is the same + %% as the failure label. + #b_switch{fail=Fail,list=List0} = Sw0, + List = [{Val,Lbl} || {Val,Lbl} <- List0, Lbl =/= Fail], + Sw1 = beam_ssa:normalize(Sw0#b_switch{list=List}), + case Sw1 of #b_switch{arg=Arg,fail=Fail,list=[{Lit,Lbl}]} -> %% Rewrite a single value switch to a br. Bool = #b_var{name={'@ssa_bool',Count0}}, @@ -1843,7 +1849,7 @@ opt_sw([{L,#b_blk{is=Is,last=#b_switch{}=Last0}=Blk0}|Bs], Phis0, Count0, Acc) - IsEq = #b_set{op={bif,'=:='},dst=Bool,args=[Arg,Lit]}, Br = #b_br{bool=Bool,succ=Lbl,fail=Fail}, Blk = Blk0#b_blk{is=Is++[IsEq],last=Br}, - opt_sw(Bs, Phis, Count, [{L,Blk}|Acc]); + opt_sw(Bs, Count, [{L,Blk}|Acc]); #b_switch{arg=Arg,fail=Fail, list=[{#b_literal{val=B1},Lbl},{#b_literal{val=B2},Lbl}]} when B1 =:= not B2 -> @@ -1853,71 +1859,18 @@ opt_sw([{L,#b_blk{is=Is,last=#b_switch{}=Last0}=Blk0}|Bs], Phis0, Count0, Acc) - IsBool = #b_set{op={bif,is_boolean},dst=Bool,args=[Arg]}, Br = #b_br{bool=Bool,succ=Lbl,fail=Fail}, Blk = Blk0#b_blk{is=Is++[IsBool],last=Br}, - opt_sw(Bs, Phis, Count, [{L,Blk}|Acc]); - Last0 -> - opt_sw(Bs, Phis, Count0, [{L,Blk0}|Acc]); - Last -> - Blk = Blk0#b_blk{last=Last}, - opt_sw(Bs, Phis, Count0, [{L,Blk}|Acc]) + opt_sw(Bs, Count, [{L,Blk}|Acc]); + Sw0 -> + opt_sw(Bs, Count0, [{L,Blk0}|Acc]); + Sw -> + Blk = Blk0#b_blk{last=Sw}, + opt_sw(Bs, Count0, [{L,Blk}|Acc]) end; -opt_sw([{L,#b_blk{is=Is}=Blk}|Bs], Phis0, Count, Acc) -> - Phis = opt_sw_phis(Is, Phis0), - opt_sw(Bs, Phis, Count, [{L,Blk}|Acc]); -opt_sw([], _Phis, Count, Acc) -> +opt_sw([{L,#b_blk{}=Blk}|Bs], Count, Acc) -> + opt_sw(Bs, Count, [{L,Blk}|Acc]); +opt_sw([], Count, Acc) -> {reverse(Acc),Count}. -opt_sw_phis([#b_set{op=phi,dst=Dst,args=Args}|Is], Phis) -> - case opt_sw_literals(Args, []) of - error -> - opt_sw_phis(Is, Phis); - Literals -> - opt_sw_phis(Is, Phis#{Dst=>Literals}) - end; -opt_sw_phis(_, Phis) -> Phis. - -opt_sw_last(#b_switch{arg=Arg,fail=Fail,list=List0}=Sw0, Phis) -> - case Phis of - #{Arg:=Values0} -> - Values = gb_sets:from_list(Values0), - - %% Prune the switch list to only contain the possible values. - List1 = [P || {Lit,_}=P <- List0, gb_sets:is_member(Lit, Values)], - - %% Now test whether the failure label can ever be reached. - Sw = case gb_sets:size(Values) =:= length(List1) of - true -> - %% The switch list has the same number of values as the phi node. - %% The values must be the same, because the values that were not - %% possible were pruned from the switch list. Therefore, the - %% failure label can't possibly be reached, and we can choose a - %% a new failure label by picking a value from the list. - case List1 of - [{#b_literal{},Lbl}|List] -> - Sw0#b_switch{fail=Lbl,list=List}; - [] -> - Sw0#b_switch{list=List1} - end; - false -> - %% There are some values in the phi node that are not in the - %% switch list; thus, the failure label can still be reached. - Sw0 - end, - beam_ssa:normalize(Sw); - #{} -> - %% Ensure that no label in the switch list is the same - %% as the failure label. - List = [{Val,Lbl} || {Val,Lbl} <- List0, Lbl =/= Fail], - Sw = Sw0#b_switch{list=List}, - beam_ssa:normalize(Sw) - end. - -opt_sw_literals([{#b_literal{}=Lit,_}|T], Acc) -> - opt_sw_literals(T, [Lit|Acc]); -opt_sw_literals([_|_], _Acc) -> - error; -opt_sw_literals([], Acc) -> Acc. - - %%% %%% Merge blocks. %%% diff --git a/lib/compiler/src/beam_ssa_type.erl b/lib/compiler/src/beam_ssa_type.erl index 4b53848a74..83f8a3cc56 100644 --- a/lib/compiler/src/beam_ssa_type.erl +++ b/lib/compiler/src/beam_ssa_type.erl @@ -23,7 +23,8 @@ -include("beam_ssa_opt.hrl"). -import(lists, [all/2,any/2,droplast/1,foldl/3,last/1,member/2, - partition/2,reverse/1,reverse/2,seq/2,sort/1]). + keyfind/3,partition/2,reverse/1,reverse/2, + seq/2,sort/1]). -define(UNICODE_INT, #t_integer{elements={0,16#10FFFF}}). @@ -664,25 +665,45 @@ opt_terminator(#b_br{bool=#b_var{}}=Br, Ts, Ds) -> simplify_not(Br, Ts, Ds); opt_terminator(#b_switch{arg=#b_literal{}}=Sw, _Ts, _Ds) -> beam_ssa:normalize(Sw); -opt_terminator(#b_switch{arg=#b_var{}=V}=Sw0, Ts, Ds) -> - Type = get_type(V, Ts), +opt_terminator(#b_switch{arg=#b_var{}=V}=Sw, Ts, Ds) -> + case get_type(V, Ts) of + any -> + beam_ssa:normalize(Sw); + Type -> + beam_ssa:normalize(opt_switch(Sw, Type, Ts, Ds)) + end; +opt_terminator(#b_ret{}=Ret, _Ts, _Ds) -> Ret. + + +opt_switch(#b_switch{fail=Fail,list=List0}=Sw0, Type, Ts, Ds) -> + List = prune_switch_list(List0, Fail, Type, Ts), + Sw1 = Sw0#b_switch{list=List}, case Type of #t_integer{elements={_,_}=Range} -> - simplify_switch_int(Sw0, Range); - _ -> + simplify_switch_int(Sw1, Range); + #t_atom{elements=[_|_]} -> case t_is_boolean(Type) of true -> - case simplify_switch_bool(Sw0, Ts, Ds) of - #b_br{}=Br -> - opt_terminator(Br, Ts, Ds); - Sw -> - beam_ssa:normalize(Sw) - end; + #b_br{} = Br = simplify_switch_bool(Sw1, Ts, Ds), + opt_terminator(Br, Ts, Ds); false -> - beam_ssa:normalize(Sw0) - end + simplify_switch_atom(Type, Sw1) + end; + _ -> + Sw1 + end. + +prune_switch_list([{_,Fail}|T], Fail, Type, Ts) -> + prune_switch_list(T, Fail, Type, Ts); +prune_switch_list([{Arg,_}=Pair|T], Fail, Type, Ts) -> + case meet(get_type(Arg, Ts), Type) of + none -> + %% Different types. This value can never match. + prune_switch_list(T, Fail, Type, Ts); + _ -> + [Pair|prune_switch_list(T, Fail, Type, Ts)] end; -opt_terminator(#b_ret{}=Ret, _Ts, _Ds) -> Ret. +prune_switch_list([], _, _, _) -> []. update_successors(#b_br{bool=#b_literal{val=true},succ=S}, Ts, D) -> update_successor(S, Ts, D); @@ -1079,6 +1100,17 @@ bs_match_type(utf16, _) -> bs_match_type(utf32, _) -> ?UNICODE_INT. +simplify_switch_atom(#t_atom{elements=Atoms}, #b_switch{list=List0}=Sw) -> + case sort([A || {#b_literal{val=A},_} <- List0]) of + Atoms -> + %% All possible atoms are included in the list. The + %% failure label will never be used. + [{_,Fail}|List] = List0, + Sw#b_switch{fail=Fail,list=List}; + _ -> + Sw + end. + simplify_switch_int(#b_switch{list=List0}=Sw, {Min,Max}) -> List1 = sort(List0), Vs = [V || {#b_literal{val=V},_} <- List1], @@ -1123,14 +1155,14 @@ simplify_is_record(I, any, _Size, _Tag, _Ts) -> simplify_is_record(_I, _Type, _Size, _Tag, _Ts) -> #b_literal{val=false}. -simplify_switch_bool(#b_switch{arg=B,list=List0}=Sw, Ts, Ds) -> - List = sort(List0), - case List of - [{#b_literal{val=false},Fail},{#b_literal{val=true},Succ}] -> - simplify_not(#b_br{bool=B,succ=Succ,fail=Fail}, Ts, Ds); - [_|_] -> - Sw - end. +simplify_switch_bool(#b_switch{arg=B,fail=Fail,list=List0}, Ts, Ds) -> + FalseVal = #b_literal{val=false}, + TrueVal = #b_literal{val=true}, + List1 = List0 ++ [{FalseVal,Fail},{TrueVal,Fail}], + {_,FalseLbl} = keyfind(FalseVal, 1, List1), + {_,TrueLbl} = keyfind(TrueVal, 1, List1), + Br = beam_ssa:normalize(#b_br{bool=B,succ=TrueLbl,fail=FalseLbl}), + simplify_not(Br, Ts, Ds). simplify_not(#b_br{bool=#b_var{}=V,succ=Succ,fail=Fail}=Br0, Ts, Ds) -> case Ds of @@ -1144,7 +1176,8 @@ simplify_not(#b_br{bool=#b_var{}=V,succ=Succ,fail=Fail}=Br0, Ts, Ds) -> end; #{} -> Br0 - end. + end; +simplify_not(#b_br{bool=#b_literal{}}=Br, _Ts, _Ds) -> Br. %%% %%% Calculate the set of variables that are only used once in the -- cgit v1.2.3 From 4d93f72435ae28c488499b99d37c3db9d4181056 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= Date: Wed, 20 Feb 2019 14:30:20 +0100 Subject: Correct confusing comment in beam_ssa_type --- lib/compiler/src/beam_ssa_type.erl | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/lib/compiler/src/beam_ssa_type.erl b/lib/compiler/src/beam_ssa_type.erl index 83f8a3cc56..5fbb679c6f 100644 --- a/lib/compiler/src/beam_ssa_type.erl +++ b/lib/compiler/src/beam_ssa_type.erl @@ -712,8 +712,8 @@ update_successors(#b_br{bool=#b_var{}=Bool,succ=Succ,fail=Fail}, Ts0, D0) -> true -> %% This variable is defined in this block and is only %% referenced by this br terminator. Therefore, there is - %% no need to include the type database passed on to the - %% successors of this block. + %% no need to include it in the type database passed on to + %% the successors of this block. Ts = maps:remove(Bool, Ts0), {SuccTs,FailTs} = infer_types_br(Bool, Ts, D0), D = update_successor(Fail, FailTs, D0), -- cgit v1.2.3 From 02de9d7de92298e807a0eef4816b36eab825e63a Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= Date: Wed, 20 Feb 2019 14:43:41 +0100 Subject: erl_bifs: Add a note to the comment for is_pure/3 --- lib/compiler/src/erl_bifs.erl | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/lib/compiler/src/erl_bifs.erl b/lib/compiler/src/erl_bifs.erl index d925decce6..94a5dfe012 100644 --- a/lib/compiler/src/erl_bifs.erl +++ b/lib/compiler/src/erl_bifs.erl @@ -32,6 +32,22 @@ %% Returns `true' if the function `Module:Name/Arity' does not %% affect the state, nor depend on the state, although its %% evaluation is not guaranteed to complete normally for all input. +%% +%% NOTE: There is no need to include every new pure BIF +%% here. Including it here means that the value of the function +%% will be evaluated at compile-time if the arguments are +%% constant. If that optimization is not useful/desired, there is +%% no need to include the new BIF here. +%% +%% Functions whose return value could conceivably change in a +%% future version of the runtime system must NOT be included here. +%% +%% Here are some example of functions that should not be +%% included: `term_to_binary/1', hashing functions, non-trivial +%% encode/decode functions. +%% +%% When unsure whether a new BIF should be included here, the +%% conservative safe choice is NOT to include it. -spec is_pure(atom(), atom(), arity()) -> boolean(). -- cgit v1.2.3