diff options
Diffstat (limited to 'lib/compiler/src/beam_block.erl')
| -rw-r--r-- | lib/compiler/src/beam_block.erl | 484 |
1 files changed, 144 insertions, 340 deletions
diff --git a/lib/compiler/src/beam_block.erl b/lib/compiler/src/beam_block.erl index 0321b1c07b..10dbaf462c 100644 --- a/lib/compiler/src/beam_block.erl +++ b/lib/compiler/src/beam_block.erl @@ -23,14 +23,13 @@ -module(beam_block). -export([module/2]). --import(lists, [mapfoldl/3,reverse/1,reverse/2,foldl/3,member/2]). --define(MAXREG, 1024). +-import(lists, [reverse/1,reverse/2,foldl/3,member/2]). -module({Mod,Exp,Attr,Fs0,Lc0}, _Opt) -> - {Fs,Lc} = mapfoldl(fun function/2, Lc0, Fs0), +module({Mod,Exp,Attr,Fs0,Lc}, _Opt) -> + Fs = [function(F) || F <- Fs0], {ok,{Mod,Exp,Attr,Fs,Lc}}. -function({function,Name,Arity,CLabel,Is0}, Lc0) -> +function({function,Name,Arity,CLabel,Is0}) -> try %% Collect basic blocks and optimize them. Is1 = blockify(Is0), @@ -40,11 +39,8 @@ function({function,Name,Arity,CLabel,Is0}, Lc0) -> Is5 = opt_blocks(Is4), Is6 = beam_utils:delete_live_annos(Is5), - %% Optimize bit syntax. - {Is,Lc} = bsm_opt(Is6, Lc0), - %% Done. - {{function,Name,Arity,CLabel,Is},Lc} + {function,Name,Arity,CLabel,Is6} catch Class:Error -> Stack = erlang:get_stacktrace(), @@ -62,56 +58,15 @@ blockify(Is) -> blockify([{loop_rec,{f,Fail},{x,0}},{loop_rec_end,_Lbl},{label,Fail}|Is], Acc) -> %% Useless instruction sequence. blockify(Is, Acc); -blockify([{test,is_atom,{f,Fail},[Reg]}=I| - [{select,select_val,Reg,{f,Fail}, - [{atom,false},{f,_}=BrFalse, - {atom,true}=AtomTrue,{f,_}=BrTrue]}|Is]=Is0], - [{block,Bl}|_]=Acc) -> - case is_last_bool(Bl, Reg) of - false -> - blockify(Is0, [I|Acc]); - true -> - %% The last instruction is a boolean operator/guard BIF that can't fail. - %% We can convert the three-way branch to a two-way branch (eliminating - %% the reference to the failure label). - blockify(Is, [{jump,BrTrue}, - {test,is_eq_exact,BrFalse,[Reg,AtomTrue]}|Acc]) - end; -blockify([{test,is_atom,{f,Fail},[Reg]}=I| - [{select,select_val,Reg,{f,Fail}, - [{atom,true}=AtomTrue,{f,_}=BrTrue, - {atom,false},{f,_}=BrFalse]}|Is]=Is0], - [{block,Bl}|_]=Acc) -> - case is_last_bool(Bl, Reg) of - false -> - blockify(Is0, [I|Acc]); - true -> - blockify(Is, [{jump,BrTrue}, - {test,is_eq_exact,BrFalse,[Reg,AtomTrue]}|Acc]) - end; blockify([I|Is0]=IsAll, Acc) -> - case is_bs_put(I) of - true -> - {BsPuts0,Is} = collect_bs_puts(IsAll), - BsPuts = opt_bs_puts(BsPuts0), - blockify(Is, reverse(BsPuts, Acc)); - false -> - case collect(I) of - error -> blockify(Is0, [I|Acc]); - Instr when is_tuple(Instr) -> - {Block,Is} = collect_block(IsAll), - blockify(Is, [{block,Block}|Acc]) - end + case collect(I) of + error -> blockify(Is0, [I|Acc]); + Instr when is_tuple(Instr) -> + {Block,Is} = collect_block(IsAll), + blockify(Is, [{block,Block}|Acc]) end; blockify([], Acc) -> reverse(Acc). -is_last_bool([{set,[Reg],As,{bif,N,_}}], Reg) -> - Ar = length(As), - erl_internal:new_type_test(N, Ar) orelse erl_internal:comp_op(N, Ar) - orelse erl_internal:bool_op(N, Ar); -is_last_bool([_|Is], Reg) -> is_last_bool(Is, Reg); -is_last_bool([], _) -> false. - collect_block(Is) -> collect_block(Is, []). @@ -149,7 +104,10 @@ collect({put_map,F,Op,S,D,R,{list,Puts}}) -> collect({get_map_elements,F,S,{list,Gets}}) -> {Ss,Ds} = beam_utils:split_even(Gets), {set,Ds,[S|Ss],{get_map_elements,F}}; -collect({'catch',R,L}) -> {set,[R],[],{'catch',L}}; +collect({'catch'=Op,R,L}) -> + {set,[R],[],{try_catch,Op,L}}; +collect({'try'=Op,R,L}) -> + {set,[R],[],{try_catch,Op,L}}; collect(fclearerror) -> {set,[],[],fclearerror}; collect({fcheckerror,{f,0}}) -> {set,[],[],fcheckerror}; collect({fmove,S,D}) -> {set,[D],[S],fmove}; @@ -183,7 +141,9 @@ opt_blocks([I|Is]) -> opt_blocks([]) -> []. opt_block(Is0) -> - Is = find_fixpoint(fun opt/1, Is0), + Is = find_fixpoint(fun(Is) -> + opt_tuple_element(opt(Is)) + end, Is0), opt_alloc(Is). find_fixpoint(OptFun, Is0) -> @@ -279,76 +239,151 @@ opt_moves([X0,Y0], Is0) -> not_possible -> {[X,Y0],Is2}; {X,_} -> {[X,Y0],Is2}; {Y,Is} -> {[X,Y],Is} - end; -opt_moves(Ds, Is) -> - %% multiple destinations -> pass through - {Ds,Is}. - + end. %% opt_move(Dest, [Instruction]) -> {UpdatedDest,[Instruction]} | not_possible %% If there is a {move,Dest,FinalDest} instruction %% in the instruction stream, remove the move instruction %% and let FinalDest be the destination. -%% -%% For this optimization to be safe, we must be sure that -%% Dest will not be referenced in any other by other instructions -%% in the rest of the instruction stream. Not even the indirect -%% reference by an instruction that may allocate (such as -%% test_heap/2 or a GC Bif) is allowed. opt_move(Dest, Is) -> - opt_move_1(Dest, Is, ?MAXREG, []). - -opt_move_1(R, [{set,_,_,{alloc,Live,_}}|_]=Is, SafeRegs, Acc) when Live < SafeRegs -> - %% Downgrade number of safe regs and rescan the instruction, as it most probably - %% is a gc_bif instruction. - opt_move_1(R, Is, Live, Acc); -opt_move_1(R, [{set,[{x,X}=D],[R],move}|Is], SafeRegs, Acc) -> - case X < SafeRegs andalso beam_utils:is_killed_block(R, Is) of - true -> opt_move_2(D, Acc, Is); - false -> not_possible + opt_move_1(Dest, Is, []). + +opt_move_1(R, [{set,[D],[R],move}|Is0], Acc) -> + %% Provided that the source register is killed by instructions + %% that follow, the optimization is safe. + case eliminate_use_of_from_reg(Is0, R, D, []) of + {yes,Is} -> opt_move_rev(D, Acc, Is); + no -> not_possible end; -opt_move_1(R, [{set,[D],[R],move}|Is], _SafeRegs, Acc) -> - case beam_utils:is_killed_block(R, Is) of - true -> opt_move_2(D, Acc, Is); - false -> not_possible +opt_move_1({x,_}, [{set,_,_,{alloc,_,_}}|_], _) -> + %% The optimization is not possible. If the X register is not + %% killed by allocation, the optimization would not be safe. + %% If the X register is killed, it means that there cannot + %% follow a 'move' instruction with this X register as the + %% source. + not_possible; +opt_move_1(R, [{set,_,_,_}=I|Is], Acc) -> + %% If the source register is either killed or used by this + %% instruction, the optimimization is not possible. + case is_killed_or_used(R, I) of + true -> not_possible; + false -> opt_move_1(R, Is, [I|Acc]) end; -opt_move_1(R, [I|Is], SafeRegs, Acc) -> - case is_transparent(R, I) of - false -> not_possible; - true -> opt_move_1(R, Is, SafeRegs, [I|Acc]) - end. +opt_move_1(_, _, _) -> + not_possible. + +%% opt_tuple_element([Instruction]) -> [Instruction] +%% If possible, move get_tuple_element instructions forward +%% in the instruction stream to a move instruction, eliminating +%% the move instruction. Example: +%% +%% get_tuple_element Tuple Pos Dst1 +%% ... +%% move Dst1 Dst2 +%% +%% This code may be possible to rewrite to: +%% +%% %%(Moved get_tuple_element instruction) +%% ... +%% get_tuple_element Tuple Pos Dst2 +%% -%% Reverse the instructions, while checking that there are no instructions that -%% would interfere with using the new destination register chosen. +opt_tuple_element([{set,[D],[S],{get_tuple_element,_}}=I|Is0]) -> + case opt_tuple_element_1(Is0, I, {S,D}, []) of + no -> + [I|opt_tuple_element(Is0)]; + {yes,Is} -> + opt_tuple_element(Is) + end; +opt_tuple_element([I|Is]) -> + [I|opt_tuple_element(Is)]; +opt_tuple_element([]) -> []. + +opt_tuple_element_1([{set,_,_,{alloc,_,_}}|_], _, _, _) -> + no; +opt_tuple_element_1([{set,_,_,{try_catch,_,_}}|_], _, _, _) -> + no; +opt_tuple_element_1([{set,[D],[S],move}|Is0], I0, {_,S}, Acc) -> + case eliminate_use_of_from_reg(Is0, S, D, []) of + no -> + no; + {yes,Is} -> + {set,[S],Ss,Op} = I0, + I = {set,[D],Ss,Op}, + {yes,reverse(Acc, [I|Is])} + end; +opt_tuple_element_1([{set,Ds,Ss,_}=I|Is], MovedI, {S,D}=Regs, Acc) -> + case member(S, Ds) orelse member(D, Ss) of + true -> + no; + false -> + opt_tuple_element_1(Is, MovedI, Regs, [I|Acc]) + end; +opt_tuple_element_1(_, _, _, _) -> no. + +%% Reverse the instructions, while checking that there are no +%% instructions that would interfere with using the new destination +%% register (D). -opt_move_2(D, [I|Is], Acc) -> - case is_transparent(D, I) of - false -> not_possible; - true -> opt_move_2(D, Is, [I|Acc]) +opt_move_rev(D, [I|Is], Acc) -> + case is_killed_or_used(D, I) of + true -> not_possible; + false -> opt_move_rev(D, Is, [I|Acc]) + end; +opt_move_rev(D, [], Acc) -> {D,Acc}. + +%% is_killed_or_used(Register, {set,_,_,_}) -> bool() +%% Test whether the register is used by the instruction. + +is_killed_or_used(R, {set,Ss,Ds,_}) -> + member(R, Ds) orelse member(R, Ss). + +%% eliminate_use_of_from_reg([Instruction], FromRegister, ToRegister, Acc) -> +%% {yes,Is} | no +%% Eliminate any use of FromRegister in the instruction sequence +%% by replacing uses of FromRegister with ToRegister. If FromRegister +%% is referenced by an allocation instruction, return 'no' to indicate +%% that FromRegister is still used and that the optimization is not +%% possible. + +eliminate_use_of_from_reg([{set,_,_,{alloc,Live,_}}|_]=Is0, {x,X}, _, Acc) -> + if + X < Live -> + no; + true -> + {yes,reverse(Acc, Is0)} end; -opt_move_2(D, [], Acc) -> {D,Acc}. - -%% is_transparent(Register, Instruction) -> true | false -%% Returns true if Instruction does not in any way references Register -%% (even indirectly by an allocation instruction). -%% Returns false if Instruction does reference Register, or we are -%% not sure. - -is_transparent({x,X}, {set,_,_,{alloc,Live,_}}) when X < Live -> - false; -is_transparent(R, {set,Ds,Ss,_Op}) -> - case member(R, Ds) of - true -> false; - false -> not member(R, Ss) +eliminate_use_of_from_reg([{set,Ds,Ss0,Op}=I0|Is], From, To, Acc) -> + I = case member(From, Ss0) of + true -> + Ss = [case S of + From -> To; + _ -> S + end || S <- Ss0], + {set,Ds,Ss,Op}; + false -> + I0 + end, + case member(From, Ds) of + true -> + {yes,reverse(Acc, [I|Is])}; + false -> + eliminate_use_of_from_reg(Is, From, To, [I|Acc]) end; -is_transparent(_, _) -> false. +eliminate_use_of_from_reg([I]=Is, From, _To, Acc) -> + case beam_utils:is_killed_block(From, [I]) of + true -> + {yes,reverse(Acc, Is)}; + false -> + no + end. %% opt_alloc(Instructions) -> Instructions' %% Optimises all allocate instructions. opt_alloc([{set,[],[],{alloc,R,{_,Ns,Nh,[]}}}|Is]) -> - [{set,[],[],opt_alloc(Is, Ns, Nh, R)}|opt(Is)]; + [{set,[],[],opt_alloc(Is, Ns, Nh, R)}|Is]; opt_alloc([I|Is]) -> [I|opt_alloc(Is)]; opt_alloc([]) -> []. @@ -414,234 +449,3 @@ x_dead([], Regs) -> Regs. x_live([{x,N}|Rs], Regs) -> x_live(Rs, Regs bor (1 bsl N)); x_live([_|Rs], Regs) -> x_live(Rs, Regs); x_live([], Regs) -> Regs. - -%%% -%%% Evaluation of constant bit fields. -%%% - -is_bs_put({bs_put,_,{bs_put_integer,_,_},_}) -> true; -is_bs_put({bs_put,_,{bs_put_float,_,_},_}) -> true; -is_bs_put(_) -> false. - -collect_bs_puts(Is) -> - collect_bs_puts_1(Is, []). - -collect_bs_puts_1([I|Is]=Is0, Acc) -> - case is_bs_put(I) of - false -> {reverse(Acc),Is0}; - true -> collect_bs_puts_1(Is, [I|Acc]) - end. - -opt_bs_puts(Is) -> - opt_bs_1(Is, []). - -opt_bs_1([{bs_put,Fail, - {bs_put_float,1,Flags0},[{integer,Sz},Src]}=I0|Is], Acc) -> - try eval_put_float(Src, Sz, Flags0) of - <<Int:Sz>> -> - Flags = force_big(Flags0), - I = {bs_put,Fail,{bs_put_integer,1,Flags}, - [{integer,Sz},{integer,Int}]}, - opt_bs_1([I|Is], Acc) - catch - error:_ -> - opt_bs_1(Is, [I0|Acc]) - end; -opt_bs_1([{bs_put,_,{bs_put_integer,1,_},[{integer,8},{integer,_}]}|_]=IsAll, - Acc0) -> - {Is,Acc} = bs_collect_string(IsAll, Acc0), - opt_bs_1(Is, Acc); -opt_bs_1([{bs_put,Fail,{bs_put_integer,1,F},[{integer,Sz},{integer,N}]}=I|Is0], - Acc) when Sz > 8 -> - case field_endian(F) of - big -> - %% We can do this optimization for any field size without risk - %% for code explosion. - case bs_split_int(N, Sz, Fail, Is0) of - no_split -> opt_bs_1(Is0, [I|Acc]); - Is -> opt_bs_1(Is, Acc) - end; - little when Sz < 128 -> - %% We only try to optimize relatively small fields, to avoid - %% an explosion in code size. - <<Int:Sz>> = <<N:Sz/little>>, - Flags = force_big(F), - Is = [{bs_put,Fail,{bs_put_integer,1,Flags}, - [{integer,Sz},{integer,Int}]}|Is0], - opt_bs_1(Is, Acc); - _ -> %native or too wide little field - opt_bs_1(Is0, [I|Acc]) - end; -opt_bs_1([{bs_put,Fail,{Op,U,F},[{integer,Sz},Src]}|Is], Acc) when U > 1 -> - opt_bs_1([{bs_put,Fail,{Op,1,F},[{integer,U*Sz},Src]}|Is], Acc); -opt_bs_1([I|Is], Acc) -> - opt_bs_1(Is, [I|Acc]); -opt_bs_1([], Acc) -> reverse(Acc). - -eval_put_float(Src, Sz, Flags) when Sz =< 256 -> %Only evaluate if Sz is reasonable. - Val = value(Src), - case field_endian(Flags) of - little -> <<Val:Sz/little-float-unit:1>>; - big -> <<Val:Sz/big-float-unit:1>> - %% native intentionally not handled here - we can't optimize it. - end. - -value({integer,I}) -> I; -value({float,F}) -> F. - -bs_collect_string(Is, [{bs_put,_,{bs_put_string,Len,{string,Str}},[]}|Acc]) -> - bs_coll_str_1(Is, Len, reverse(Str), Acc); -bs_collect_string(Is, Acc) -> - bs_coll_str_1(Is, 0, [], Acc). - -bs_coll_str_1([{bs_put,_,{bs_put_integer,U,_},[{integer,Sz},{integer,V}]}|Is], - Len, StrAcc, IsAcc) when U*Sz =:= 8 -> - Byte = V band 16#FF, - bs_coll_str_1(Is, Len+1, [Byte|StrAcc], IsAcc); -bs_coll_str_1(Is, Len, StrAcc, IsAcc) -> - {Is,[{bs_put,{f,0},{bs_put_string,Len,{string,reverse(StrAcc)}},[]}|IsAcc]}. - -field_endian({field_flags,F}) -> field_endian_1(F). - -field_endian_1([big=E|_]) -> E; -field_endian_1([little=E|_]) -> E; -field_endian_1([native=E|_]) -> E; -field_endian_1([_|Fs]) -> field_endian_1(Fs). - -force_big({field_flags,F}) -> - {field_flags,force_big_1(F)}. - -force_big_1([big|_]=Fs) -> Fs; -force_big_1([little|Fs]) -> [big|Fs]; -force_big_1([F|Fs]) -> [F|force_big_1(Fs)]. - -bs_split_int(0, Sz, _, _) when Sz > 64 -> - %% We don't want to split in this case because the - %% string will consist of only zeroes. - no_split; -bs_split_int(-1, Sz, _, _) when Sz > 64 -> - %% We don't want to split in this case because the - %% string will consist of only 255 bytes. - no_split; -bs_split_int(N, Sz, Fail, Acc) -> - FirstByteSz = case Sz rem 8 of - 0 -> 8; - Rem -> Rem - end, - bs_split_int_1(N, FirstByteSz, Sz, Fail, Acc). - -bs_split_int_1(-1, _, Sz, Fail, Acc) when Sz > 64 -> - I = {bs_put,Fail,{bs_put_integer,1,{field_flags,[big]}}, - [{integer,Sz},{integer,-1}]}, - [I|Acc]; -bs_split_int_1(0, _, Sz, Fail, Acc) when Sz > 64 -> - I = {bs_put,Fail,{bs_put_integer,1,{field_flags,[big]}}, - [{integer,Sz},{integer,0}]}, - [I|Acc]; -bs_split_int_1(N, ByteSz, Sz, Fail, Acc) when Sz > 0 -> - Mask = (1 bsl ByteSz) - 1, - I = {bs_put,Fail,{bs_put_integer,1,{field_flags,[big]}}, - [{integer,ByteSz},{integer,N band Mask}]}, - bs_split_int_1(N bsr ByteSz, 8, Sz-ByteSz, Fail, [I|Acc]); -bs_split_int_1(_, _, _, _, Acc) -> Acc. - - -%%% -%%% Optimization of new bit syntax matching: get rid -%%% of redundant bs_restore2/2 instructions across select_val -%%% instructions, as well as a few other simple peep-hole optimizations. -%%% - -bsm_opt(Is0, Lc0) -> - {Is1,D0,Lc} = bsm_scan(Is0, [], Lc0, []), - Is2 = case D0 of - [] -> - Is1; - _ -> - D = gb_trees:from_orddict(orddict:from_list(D0)), - bsm_reroute(Is1, D, none, []) - end, - Is = beam_clean:bs_clean_saves(Is2), - {bsm_opt_2(Is, []),Lc}. - -bsm_scan([{label,L}=Lbl,{bs_restore2,_,Save}=R|Is], D0, Lc, Acc0) -> - D = [{{L,Save},Lc}|D0], - Acc = [{label,Lc},R,Lbl|Acc0], - bsm_scan(Is, D, Lc+1, Acc); -bsm_scan([I|Is], D, Lc, Acc) -> - bsm_scan(Is, D, Lc, [I|Acc]); -bsm_scan([], D, Lc, Acc) -> - {reverse(Acc),D,Lc}. - -bsm_reroute([{bs_save2,Reg,Save}=I|Is], D, _, Acc) -> - bsm_reroute(Is, D, {Reg,Save}, [I|Acc]); -bsm_reroute([{bs_restore2,Reg,Save}=I|Is], D, _, Acc) -> - bsm_reroute(Is, D, {Reg,Save}, [I|Acc]); -bsm_reroute([{label,_}=I|Is], D, S, Acc) -> - bsm_reroute(Is, D, S, [I|Acc]); -bsm_reroute([{select,select_val,Reg,F0,Lbls0}|Is], D, {_,Save}=S, Acc0) -> - [F|Lbls] = bsm_subst_labels([F0|Lbls0], Save, D), - Acc = [{select,select_val,Reg,F,Lbls}|Acc0], - bsm_reroute(Is, D, S, Acc); -bsm_reroute([{test,TestOp,F0,TestArgs}=I|Is], D, {_,Save}=S, Acc0) -> - F = bsm_subst_label(F0, Save, D), - Acc = [{test,TestOp,F,TestArgs}|Acc0], - case bsm_not_bs_test(I) of - true -> - %% The test instruction will not update the bit offset for the - %% binary being matched. Therefore the save position can be kept. - bsm_reroute(Is, D, S, Acc); - false -> - %% The test instruction might update the bit offset. Kill our - %% remembered Save position. - bsm_reroute(Is, D, none, Acc) - end; -bsm_reroute([{test,TestOp,F0,Live,TestArgs,Dst}|Is], D, {_,Save}, Acc0) -> - F = bsm_subst_label(F0, Save, D), - Acc = [{test,TestOp,F,Live,TestArgs,Dst}|Acc0], - %% The test instruction will update the bit offset. Kill our - %% remembered Save position. - bsm_reroute(Is, D, none, Acc); -bsm_reroute([{block,[{set,[],[],{alloc,_,_}}]}=Bl, - {bs_context_to_binary,_}=I|Is], D, S, Acc) -> - %% To help further bit syntax optimizations. - bsm_reroute([I,Bl|Is], D, S, Acc); -bsm_reroute([I|Is], D, _, Acc) -> - bsm_reroute(Is, D, none, [I|Acc]); -bsm_reroute([], _, _, Acc) -> reverse(Acc). - -bsm_opt_2([{test,bs_test_tail2,F,[Ctx,Bits]}|Is], - [{test,bs_skip_bits2,F,[Ctx,{integer,I},Unit,_Flags]}|Acc]) -> - bsm_opt_2(Is, [{test,bs_test_tail2,F,[Ctx,Bits+I*Unit]}|Acc]); -bsm_opt_2([{test,bs_skip_bits2,F,[Ctx,{integer,I1},Unit1,_]}|Is], - [{test,bs_skip_bits2,F,[Ctx,{integer,I2},Unit2,Flags]}|Acc]) -> - bsm_opt_2(Is, [{test,bs_skip_bits2,F, - [Ctx,{integer,I1*Unit1+I2*Unit2},1,Flags]}|Acc]); -bsm_opt_2([I|Is], Acc) -> - bsm_opt_2(Is, [I|Acc]); -bsm_opt_2([], Acc) -> reverse(Acc). - -%% bsm_not_bs_test({test,Name,_,Operands}) -> true|false. -%% Test whether is the test is a "safe", i.e. does not move the -%% bit offset for a binary. -%% -%% 'true' means that the test is safe, 'false' that we don't know or -%% that the test moves the offset (e.g. bs_get_integer2). - -bsm_not_bs_test({test,bs_test_tail2,_,[_,_]}) -> true; -bsm_not_bs_test(Test) -> beam_utils:is_pure_test(Test). - -bsm_subst_labels(Fs, Save, D) -> - bsm_subst_labels_1(Fs, Save, D, []). - -bsm_subst_labels_1([F|Fs], Save, D, Acc) -> - bsm_subst_labels_1(Fs, Save, D, [bsm_subst_label(F, Save, D)|Acc]); -bsm_subst_labels_1([], _, _, Acc) -> - reverse(Acc). - -bsm_subst_label({f,Lbl0}=F, Save, D) -> - case gb_trees:lookup({Lbl0,Save}, D) of - {value,Lbl} -> {f,Lbl}; - none -> F - end; -bsm_subst_label(Other, _, _) -> Other. |