From 104c69e2153c41d5fb4eea86d18852d065258083 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Micha=C5=82=20Muska=C5=82a?= Date: Sun, 13 Aug 2017 17:42:09 +0200 Subject: Replace labels instead of inserting duplicates in beam_jump This makes other optimisations more efficient since we have less labels overall. --- lib/compiler/src/beam_jump.erl | 89 +++++++++++++++--------------------------- 1 file changed, 32 insertions(+), 57 deletions(-) (limited to 'lib/compiler/src') diff --git a/lib/compiler/src/beam_jump.erl b/lib/compiler/src/beam_jump.erl index 72bf1e21dd..c33de217bd 100644 --- a/lib/compiler/src/beam_jump.erl +++ b/lib/compiler/src/beam_jump.erl @@ -71,9 +71,9 @@ %%% %%% jump L2 %%% . . . -%%% L1: %%% L2: ... %%% +%%% and all preceding uses of L1 renamed to L2. %%% If the jump is unreachable, it will be removed according to (1). %%% %%% (5) In @@ -290,15 +290,15 @@ extract_seq_1(_, _) -> no. -record(st, { entry :: beam_asm:label(), %Entry label (must not be moved). - mlbl :: #{beam_asm:label() := [beam_asm:label()]}, %Moved labels. + replace :: #{beam_asm:label() := beam_asm:label()}, %Labels to replace. labels :: cerl_sets:set(), %Set of referenced labels. - index :: beam_utils:code_index() | {lazy,[beam_utils:instruction()]} %Index build lazily only if needed + index :: beam_utils:code_index() | {lazy,[beam_utils:instruction()]} %Index built lazily only if needed }). opt(Is0, CLabel) -> find_fixpoint(fun(Is) -> Lbls = initial_labels(Is), - St = #st{entry=CLabel,mlbl=#{},labels=Lbls,index={lazy,Is}}, + St = #st{entry=CLabel,replace=#{},labels=Lbls,index={lazy,Is}}, opt(Is, [], St) end, Is0). @@ -355,30 +355,16 @@ opt([{test,_,{f,_}=Lbl,_,_,_}=I|Is], Acc, St) -> opt(Is, [I|Acc], label_used(Lbl, St)); opt([{select,_,_R,Fail,Vls}=I|Is], Acc, St) -> skip_unreachable(Is, [I|Acc], label_used([Fail|Vls], St)); -opt([{label,Lbl}=I|Is], Acc, #st{mlbl=Mlbl}=St0) -> - case maps:find(Lbl, Mlbl) of - {ok,Lbls} -> - %% Essential to remove the list of labels from the dictionary, - %% since we will rescan the inserted labels. We MUST rescan. - St = St0#st{mlbl=maps:remove(Lbl, Mlbl)}, - insert_labels([Lbl|Lbls], Is, Acc, St); - error -> - opt(Is, [I|Acc], St0) - end; +opt([{label,From}=I,{label,To}|Is], Acc, #st{replace=Replace}=St) -> + opt([I|Is], Acc, St#st{replace=Replace#{To => From}}); opt([{jump,{f,_}=X}|[{label,_},{jump,X}|_]=Is], Acc, St) -> opt(Is, Acc, St); opt([{jump,{f,Lbl}}|[{label,Lbl}|_]=Is], Acc, St) -> opt(Is, Acc, St); -opt([{jump,{f,L}=Lbl}=I|Is], Acc0, #st{mlbl=Mlbl0}=St0) -> - %% All labels before this jump instruction should now be - %% moved to the location of the jump's target. - {Lbls,Acc} = collect_labels(Acc0, St0), - St = case Lbls of - [] -> St0; - [_|_] -> - Mlbl = maps_append_list(L, Lbls, Mlbl0), - St0#st{mlbl=Mlbl} - end, +opt([{jump,{f,L}=Lbl}=I|Is], Acc0, St0) -> + %% Replace all labels before this jump instruction into the + %% location of the jump's target. + {Acc,St} = collect_labels(Acc0, L, St0), skip_unreachable(Is, [I|Acc], label_used(Lbl, St)); %% Optimization: quickly handle some common instructions that don't %% have any failure labels and where is_unreachable_after(I) =:= false. @@ -398,19 +384,21 @@ opt([I|Is], Acc, #st{labels=Used0}=St0) -> true -> skip_unreachable(Is, [I|Acc], St); false -> opt(Is, [I|Acc], St) end; -opt([], Acc, #st{mlbl=Mlbl}) -> - Code = reverse(Acc), - insert_fc_labels(Code, Mlbl). - -insert_fc_labels([{label,L}=I|Is0], Mlbl) -> - case maps:find(L, Mlbl) of - error -> - [I|insert_fc_labels(Is0, Mlbl)]; - {ok,Lbls} -> - Is = [{label,Lb} || Lb <- Lbls] ++ Is0, - [I|insert_fc_labels(Is, maps:remove(L, Mlbl))] +opt([], Acc, #st{replace=Replace0}) when Replace0 =/= #{} -> + Replace = normalize_replace(maps:to_list(Replace0), Replace0, []), + beam_utils:replace_labels(Acc, [], Replace, fun(Old) -> Old end); +opt([], Acc, #st{replace=Replace}) when Replace =:= #{} -> + reverse(Acc). + +normalize_replace([{From,To0}|Rest], Replace, Acc) -> + case Replace of + #{To0 := To} -> + normalize_replace([{From,To}|Rest], Replace, Acc); + _ -> + normalize_replace(Rest, Replace, [{From,To0}|Acc]) end; -insert_fc_labels([_|_]=Is, _) -> Is. +normalize_replace([], _Replace, Acc) -> + maps:from_list(Acc). %% After eliminating a test, it might happen, that a register was only used %% in this test. Let's check if that was the case and if it was so, we can @@ -452,22 +440,16 @@ opt_useless_block_loads([I|Is], L, Index) -> opt_useless_block_loads([], _L, _Index) -> []. -maps_append_list(K,Vs,M) -> - case M of - #{K:=Vs0} -> M#{K:=Vs0++Vs}; % same order as dict - _ -> M#{K => Vs} - end. - -collect_labels(Is, #st{entry=Entry}) -> - collect_labels_1(Is, Entry, []). +collect_labels(Is, Label, #st{entry=Entry,replace=Replace} = St) -> + collect_labels_1(Is, Label, Entry, Replace, St). -collect_labels_1([{label,Entry}|_]=Is, Entry, Acc) -> +collect_labels_1([{label,Entry}|_]=Is, _Label, Entry, Acc, St) -> %% Never move the entry label. - {Acc,Is}; -collect_labels_1([{label,L}|Is], Entry, Acc) -> - collect_labels_1(Is, Entry, [L|Acc]); -collect_labels_1(Is, _Entry, Acc) -> - {Acc,Is}. + {Is,St#st{replace=Acc}}; +collect_labels_1([{label,L}|Is], Label, Entry, Acc, St) -> + collect_labels_1(Is, Label, Entry, Acc#{L => Label}, St); +collect_labels_1(Is, _Label, _Entry, Acc, St) -> + {Is,St#st{replace=Acc}}. %% label_defined(Is, Label) -> true | false. %% Test whether the label Label is defined at the start of the instruction @@ -487,13 +469,6 @@ invert_test(is_eq_exact) -> is_ne_exact; invert_test(is_ne_exact) -> is_eq_exact; invert_test(_) -> not_possible. -insert_labels([L|Ls], Is, [{jump,{f,L}}|Acc], St) -> - insert_labels(Ls, [{label,L}|Is], Acc, St); -insert_labels([L|Ls], Is, Acc, St) -> - insert_labels(Ls, [{label,L}|Is], Acc, St); -insert_labels([], Is, Acc, St) -> - opt(Is, Acc, St). - %% skip_unreachable([Instruction], St). %% Remove all instructions (including definitions of labels %% that have not been referenced yet) up to the next -- cgit v1.2.3