diff options
Diffstat (limited to 'lib/compiler/src/beam_jump.erl')
| -rw-r--r-- | lib/compiler/src/beam_jump.erl | 223 |
1 files changed, 139 insertions, 84 deletions
diff --git a/lib/compiler/src/beam_jump.erl b/lib/compiler/src/beam_jump.erl index 4365451356..0bcec9ce19 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 @@ -156,41 +156,46 @@ function({function,Name,Arity,CLabel,Asm0}) -> %%% share(Is0) -> - %% We will get more sharing if we never fall through to a label. - Is = eliminate_fallthroughs(Is0, []), - share_1(Is, #{}, [], []). + Is1 = eliminate_fallthroughs(Is0, []), + Is2 = find_fixpoint(fun(Is) -> + share_1(Is, #{}, #{}, [], []) + end, Is1), + reverse(Is2). -share_1([{label,L}=Lbl|Is], Dict0, [_|_]=Seq, Acc) -> +share_1([{label,L}=Lbl|Is], Dict0, Lbls0, [_|_]=Seq, Acc) -> case maps:find(Seq, Dict0) of error -> Dict = maps:put(Seq, L, Dict0), - share_1(Is, Dict, [], [Lbl|Seq ++ Acc]); + share_1(Is, Dict, Lbls0, [], [Lbl|Seq ++ Acc]); {ok,Label} -> - share_1(Is, Dict0, [], [Lbl,{jump,{f,Label}}|Acc]) + Lbls = maps:put(L, Label, Lbls0), + share_1(Is, Dict0, Lbls, [], [Lbl,{jump,{f,Label}}|Acc]) end; -share_1([{func_info,_,_,_}=I|Is], _, [], Acc) -> - reverse(Is, [I|Acc]); -share_1([{'catch',_,_}=I|Is], Dict0, Seq, Acc) -> - Dict = clean_non_sharable(Dict0), - share_1(Is, Dict, [I|Seq], Acc); -share_1([{'try',_,_}=I|Is], Dict0, Seq, Acc) -> - Dict = clean_non_sharable(Dict0), - share_1(Is, Dict, [I|Seq], Acc); -share_1([{try_case,_}=I|Is], Dict0, Seq, Acc) -> - Dict = clean_non_sharable(Dict0), - share_1(Is, Dict, [I|Seq], Acc); -share_1([{catch_end,_}=I|Is], Dict0, Seq, Acc) -> - Dict = clean_non_sharable(Dict0), - share_1(Is, Dict, [I|Seq], Acc); -share_1([I|Is], Dict, Seq, Acc) -> +share_1([{func_info,_,_,_}|_]=Is, _, Lbls, [], Acc) when Lbls =/= #{} -> + beam_utils:replace_labels(Acc, Is, Lbls, fun(Old) -> Old end); +share_1([{func_info,_,_,_}|_]=Is, _, Lbls, [], Acc) when Lbls =:= #{} -> + reverse(Acc, Is); +share_1([{'catch',_,_}=I|Is], Dict0, Lbls0, Seq, Acc) -> + {Dict,Lbls} = clean_non_sharable(Dict0, Lbls0), + share_1(Is, Dict, Lbls, [I|Seq], Acc); +share_1([{'try',_,_}=I|Is], Dict0, Lbls0, Seq, Acc) -> + {Dict,Lbls} = clean_non_sharable(Dict0, Lbls0), + share_1(Is, Dict, Lbls, [I|Seq], Acc); +share_1([{try_case,_}=I|Is], Dict0, Lbls0, Seq, Acc) -> + {Dict,Lbls} = clean_non_sharable(Dict0, Lbls0), + share_1(Is, Dict, Lbls, [I|Seq], Acc); +share_1([{catch_end,_}=I|Is], Dict0, Lbls0, Seq, Acc) -> + {Dict,Lbls} = clean_non_sharable(Dict0, Lbls0), + share_1(Is, Dict, Lbls, [I|Seq], Acc); +share_1([I|Is], Dict, Lbls, Seq, Acc) -> case is_unreachable_after(I) of false -> - share_1(Is, Dict, [I|Seq], Acc); + share_1(Is, Dict, Lbls, [I|Seq], Acc); true -> - share_1(Is, Dict, [I], Acc) + share_1(Is, Dict, Lbls, [I], Acc) end. -clean_non_sharable(Dict) -> +clean_non_sharable(Dict0, Lbls0) -> %% We are passing in or out of a 'catch' or 'try' block. Remove %% sequences that should not be shared over the boundaries of the %% block. Since the end of the sequence must match, the only @@ -198,7 +203,17 @@ clean_non_sharable(Dict) -> %% the 'catch'/'try' block is a sequence that ends with an %% instruction that causes an exception. Any sequence that causes %% an exception must contain a line/1 instruction. - maps:filter(fun(K, _V) -> sharable_with_try(K) end, Dict). + Dict1 = maps:to_list(Dict0), + Lbls1 = maps:to_list(Lbls0), + {Dict2,Lbls2} = foldl(fun({K, V}, {Dict,Lbls}) -> + case sharable_with_try(K) of + true -> + {[{K,V}|Dict],lists:keydelete(V, 2, Lbls)}; + false -> + {Dict,Lbls} + end + end, {[],Lbls1}, Dict1), + {maps:from_list(Dict2),maps:from_list(Lbls2)}. sharable_with_try([{line,_}|_]) -> %% This sequence may cause an exception and may potentially @@ -275,14 +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. - labels :: cerl_sets:set() %Set of referenced 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 built lazily only if needed }). opt(Is0, CLabel) -> find_fixpoint(fun(Is) -> Lbls = initial_labels(Is), - St = #st{entry=CLabel,mlbl=#{},labels=Lbls}, + St = #st{entry=CLabel,replace=#{},labels=Lbls,index={lazy,Is}}, opt(Is, [], St) end, Is0). @@ -292,7 +308,7 @@ find_fixpoint(OptFun, Is0) -> Is -> find_fixpoint(OptFun, Is) end. -opt([{test,_,{f,L}=Lbl,_}=I|[{jump,{f,L}}|_]=Is], Acc, St) -> +opt([{test,_,{f,L}=Lbl,_}=I|[{jump,{f,L}}|_]=Is], Acc0, St0) -> %% We have %% Test Label Ops %% jump Label @@ -301,10 +317,34 @@ opt([{test,_,{f,L}=Lbl,_}=I|[{jump,{f,L}}|_]=Is], Acc, St) -> case beam_utils:is_pure_test(I) of false -> %% Test is not pure; we must keep it. - opt(Is, [I|Acc], label_used(Lbl, St)); + opt(Is, [I|Acc0], label_used(Lbl, St0)); true -> %% The test is pure and its failure label is the same %% as in the jump that follows -- thus it is not needed. + %% Check if any of the previous instructions could also be eliminated. + {Acc,St} = opt_useless_loads(Acc0, L, St0), + opt(Is, Acc, St) + end; +opt([{test,_,{f,L}=Lbl,_}=I|[{label,L}|_]=Is], Acc0, St0) -> + %% Similar to the above, except we have a fall-through rather than jump + %% Test Label Ops + %% label Label + case beam_utils:is_pure_test(I) of + false -> + opt(Is, [I|Acc0], label_used(Lbl, St0)); + true -> + {Acc,St} = opt_useless_loads(Acc0, L, St0), + opt(Is, Acc, St) + end; +opt([{test,_,{f,L}=Lbl,_}=I|[{label,L}|_]=Is], Acc0, St0) -> + %% Similar to the above, except we have a fall-through rather than jump + %% Test Label Ops + %% label Label + case beam_utils:is_pure_test(I) of + false -> + opt(Is, [I|Acc0], label_used(Lbl, St0)); + true -> + {Acc,St} = opt_useless_loads(Acc0, L, St0), opt(Is, Acc, St) end; opt([{test,Test0,{f,L}=Lbl,Ops}=I|[{jump,To}|Is]=Is0], Acc, St) -> @@ -326,30 +366,16 @@ 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. @@ -369,36 +395,72 @@ 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. - -maps_append_list(K,Vs,M) -> - case M of - #{K:=Vs0} -> M#{K:=Vs0++Vs}; % same order as dict - _ -> M#{K => Vs} - end. +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 +%% eliminate the load into the register completely. +opt_useless_loads([{block,_}|_]=Is, L, #st{index={lazy,FIs}}=St) -> + opt_useless_loads(Is, L, St#st{index=beam_utils:index_labels(FIs)}); +opt_useless_loads([{block,Block0}|Is], L, #st{index=Index}=St) -> + case opt_useless_block_loads(Block0, L, Index) of + [] -> + opt_useless_loads(Is, L, St); + [_|_]=Block -> + {[{block,Block}|Is],St} + end; +%% After eliminating the test and useless blocks, it might happen, +%% that the previous test could also be eliminated. +%% It might be that the label was already marked as used, even if ultimately, +%% it never will be - we can't do much about it at that point, though +opt_useless_loads([{test,_,{f,L},_}=I|Is], L, St) -> + case beam_utils:is_pure_test(I) of + false -> + {[I|Is],St}; + true -> + opt_useless_loads(Is, L, St) + end; +opt_useless_loads(Is, _L, St) -> + {Is,St}. + +opt_useless_block_loads([{set,[Dst],_,_}=I|Is], L, Index) -> + BlockJump = [{block,Is},{jump,{f,L}}], + case beam_utils:is_killed(Dst, BlockJump, Index) of + true -> + %% The register is killed and not used, we can remove the load + opt_useless_block_loads(Is, L, Index); + false -> + [I|opt_useless_block_loads(Is, L, Index)] + end; +opt_useless_block_loads([I|Is], L, Index) -> + [I|opt_useless_block_loads(Is, L, Index)]; +opt_useless_block_loads([], _L, _Index) -> + []. -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 @@ -418,13 +480,6 @@ 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 |