diff options
| -rw-r--r-- | lib/hipe/main/hipe.erl | 4 | ||||
| -rw-r--r-- | lib/hipe/regalloc/hipe_regalloc_loop.erl | 9 | ||||
| -rw-r--r-- | lib/hipe/regalloc/hipe_regalloc_prepass.erl | 714 |
3 files changed, 580 insertions, 147 deletions
diff --git a/lib/hipe/main/hipe.erl b/lib/hipe/main/hipe.erl index 4e6de2e0dc..6be522f430 100644 --- a/lib/hipe/main/hipe.erl +++ b/lib/hipe/main/hipe.erl @@ -1354,6 +1354,8 @@ opt_keys() -> pp_rtl_lcm, pp_rtl_ssapre, pp_rtl_linear, + ra_partitioned, + ra_prespill, regalloc, remove_comments, rtl_ssa, @@ -1458,6 +1460,8 @@ opt_negations() -> {no_pp_native, pp_native}, {no_pp_rtl_lcm, pp_rtl_lcm}, {no_pp_rtl_ssapre, pp_rtl_ssapre}, + {no_ra_partitioned, ra_partitioned}, + {no_ra_prespill, ra_prespill}, {no_remove_comments, remove_comments}, {no_rtl_ssa, rtl_ssa}, {no_rtl_ssa_const_prop, rtl_ssa_const_prop}, diff --git a/lib/hipe/regalloc/hipe_regalloc_loop.erl b/lib/hipe/regalloc/hipe_regalloc_loop.erl index 33a7130ff1..4a933a890c 100644 --- a/lib/hipe/regalloc/hipe_regalloc_loop.erl +++ b/lib/hipe/regalloc/hipe_regalloc_loop.erl @@ -43,8 +43,13 @@ ra_common(Defun, SpillIndex, Options, RegAllocMod, TargetMod) -> alloc(Defun, CFG, SpillLimit, SpillIndex, Options, RegAllocMod, TargetMod) -> ?inc_counter(ra_iteration_counter, 1), {Coloring, _NewSpillIndex, Liveness} = - hipe_regalloc_prepass:regalloc( - RegAllocMod, CFG, SpillIndex, SpillLimit, TargetMod, Options), + case proplists:get_bool(ra_prespill, Options) of + true -> + hipe_regalloc_prepass:regalloc( + RegAllocMod, CFG, SpillIndex, SpillLimit, TargetMod, Options); + false -> + RegAllocMod:regalloc(CFG, SpillIndex, SpillLimit, TargetMod, Options) + end, {NewDefun, DidSpill} = TargetMod:check_and_rewrite(Defun, Coloring), case DidSpill of false -> %% No new temps, we are done. diff --git a/lib/hipe/regalloc/hipe_regalloc_prepass.erl b/lib/hipe/regalloc/hipe_regalloc_prepass.erl index f9df3a68de..60318fd080 100644 --- a/lib/hipe/regalloc/hipe_regalloc_prepass.erl +++ b/lib/hipe/regalloc/hipe_regalloc_prepass.erl @@ -31,21 +31,38 @@ %% * Spills trivially unallocatable temps %% This relies on the fact that calls intentionally clobber all registers. %% Since this is the case, any temp that is alive over a call can't possibly -%% be allocated to a +%% be allocated to anything but a spill slot. %% -%% TODO: Partition the IG (without constructing it) into connected components -%% and call the actual register allocator on them individually. - +%% * Partitions the program at points where no pseudos that were not spiled are +%% live, and then do register allocation on these partitions independently. +%% These program points are commonly, but not exclusively, the call +%% instructions. +%% +%% TODO +%% * This module seems very successful at finding every single spill; register +%% allocation performance should be improved if we short-circuit the first +%% hipe_regalloc_loop iteration, skipping directly to rewrite without ever +%% calling RegAllocMod. -module(hipe_regalloc_prepass). -export([regalloc/6]). -%% -ifndef(DEBUG). -%% -compile(inline). -%% -endif. +-ifndef(DEBUG). +-compile(inline). +-endif. %%-define(DO_ASSERT, 1). -include("../main/hipe.hrl"). +%%% TUNABLES + +%% Partitions with fewer than ?TUNE_TOO_FEW_BBS basic block halves are merged +%% together before register allocation. +-define(TUNE_TOO_FEW_BBS, 256). + +%% Ignore the ra_partitioned option (and do whole function RA instead) when +%% there are fewer than ?TUNE_MIN_SPLIT_PSEUDOS non-spilled used pseudos. +-define(TUNE_MIN_SPLIT_PSEUDOS, 1024). + %% We present a "pseudo-target" to the register allocator we wrap. %% Note: all arities are +1 as we're currently using the parameterised module %% facility to store context data. @@ -54,7 +71,6 @@ allocatable/1, args/2, bb/3, - breadthorder/2, def_use/2, defines/2, is_fixed/2, % used by hipe_graph_coloring_regalloc @@ -86,28 +102,35 @@ }). -record(cfg, - {cfg :: target_cfg() - ,bbs :: #{label() => hipe_bb:bb(instr())} - ,max_reg :: temp() % Exclusive upper bound on temp numbers - ,live :: target_liveness() + {cfg :: target_cfg() + ,bbs :: transformed_bbs() + ,max_reg :: temp() % Exclusive upper bound on temp numbers + ,rpostorder :: undefined % Only precomputed with partitioned cfg + | [label()] + }). + +-type bb() :: hipe_bb:bb(). % containing instr() +-type liveset() :: ordsets:ordset(temp()). +-record(transformed_bb, + {bb :: bb() + ,livein :: liveset() + ,liveout :: liveset() }). +-type transformed_bb() :: #transformed_bb{}. +-type transformed_bbs() :: #{label() => transformed_bb()}. -record(instr, - {tgt_instr :: target_instr() % Not used, for debugging - ,defuse :: {[temp()], [temp()]} + {defuse :: {[temp()], [temp()]} ,is_move :: boolean() }). -%% -record(label, -%% {no :: label() -%% }). --type instr() :: #instr{} %% | #label{} - . +-type instr() :: #instr{}. -type target_cfg() :: any(). -type target_instr() :: any(). -type target_temp() :: any(). -type target_reg() :: non_neg_integer(). -type target_liveness() :: any(). +-type target_liveset() :: ordsets:ordset(target_reg()). -type spillno() :: non_neg_integer(). -type temp() :: non_neg_integer(). -type label() :: non_neg_integer(). @@ -117,47 +140,127 @@ -> {hipe_map(), spillno(), target_liveness()}. regalloc(RegAllocMod, CFG, SpillIndex0, SpillLimit, Target, Options) -> Liveness = Target:analyze(CFG), - {BBs0, LivePseudos, _Unused, SpilledPseudos, SpillIndex} = + {ScanBBs, Seen, SpillMap, SpillIndex1} = scan_cfg(CFG, Liveness, SpillIndex0, Target), - {SubMap, InvMap, MaxPhys, MaxR, SubSpillLimit} = - number_and_map(Target:all_precoloured(), LivePseudos, SpillLimit), - BBs = transform_cfg(BBs0, SubMap), - SubMod = #cfg{cfg=CFG, bbs=BBs, max_reg=MaxR, live=Liveness}, - SubTarget = #?MODULE{target=Target, max_phys=MaxPhys, inv=InvMap, sub=SubMap}, - case - RegAllocMod:regalloc(SubMod, SpillIndex, SubSpillLimit, SubTarget, Options) - of - {SubColoring, NewSpillIndex} -> ok; - {SubColoring, NewSpillIndex, _SubLiveness} -> ok - end, - ?ASSERT(check_coloring(SubColoring, SubMod, SubTarget)), % blame the RA ;) - SpillColors = [{T, {spill, S}} || {T, S} <- maps:to_list(SpilledPseudos)], - Coloring = translate_coloring(SubColoring, InvMap) ++ SpillColors, + AllPrecoloured = Target:all_precoloured(), + + {PartColoring, SpillIndex} = + case proplists:get_bool(ra_partitioned, Options) of + true when map_size(Seen) - map_size(SpillMap) - length(AllPrecoloured) + > ?TUNE_MIN_SPLIT_PSEUDOS -> + regalloc_partitioned(SpillMap, SpillIndex1, SpillLimit, ScanBBs, + CFG, Target, RegAllocMod, Options); + _ -> + regalloc_whole(Seen, SpillMap, SpillIndex1, SpillLimit, ScanBBs, + CFG, Target, RegAllocMod, Options) + end, + + SpillColors = [{T, {spill, S}} || {T, S} <- maps:to_list(SpillMap)], + Coloring = SpillColors ++ PartColoring, + + ?ASSERT(begin + MaxPhys = lists:max(AllPrecoloured) + 1, + Unused = unused(live_pseudos(Seen, SpillMap, MaxPhys), + SpillMap, CFG, Target), + unused_unused(Unused, CFG, Target) + end), ?ASSERT(check_coloring(Coloring, CFG, Target)), % Sanity-check ?ASSERT(just_as_good_as(RegAllocMod, CFG, SpillIndex0, SpillLimit, Target, - Options, Coloring, _Unused)), - {Coloring, NewSpillIndex, Liveness}. - + Options, Coloring, Unused)), + {Coloring, SpillIndex, Liveness}. + +regalloc_whole(Seen, SpillMap, SpillIndex0, SpillLimit, ScanBBs, + CFG, Target, RegAllocMod, Options) -> + AllPrecoloured = Target:all_precoloured(), + MaxPhys = lists:max(AllPrecoloured) + 1, + LivePseudos = live_pseudos(Seen, SpillMap, MaxPhys), + {SubMap, InvMap, MaxPhys, MaxR, SubSpillLimit} = + number_and_map(AllPrecoloured, LivePseudos, SpillLimit), + BBs = transform_whole_cfg(ScanBBs, SubMap), + SubMod = #cfg{cfg=CFG, bbs=BBs, max_reg=MaxR}, + SubTarget = #?MODULE{target=Target, max_phys=MaxPhys, inv=InvMap, sub=SubMap}, + {SubColoring, SpillIndex, _} = + RegAllocMod:regalloc(SubMod, SpillIndex0, SubSpillLimit, SubTarget, + Options), + ?ASSERT(check_coloring(SubColoring, SubMod, SubTarget)), + {translate_coloring(SubColoring, InvMap), SpillIndex}. + +regalloc_partitioned(SpillMap, SpillIndex0, SpillLimit, ScanBBs, + CFG, Target, RegAllocMod, Options) -> + AllPrecoloured = Target:all_precoloured(), + MaxPhys = lists:max(AllPrecoloured) + 1, + + DSets0 = initial_dsets(CFG, Target), + PartBBList = part_cfg(ScanBBs, SpillMap, MaxPhys), + DSets1 = join_whole_blocks(PartBBList, DSets0), + {PartBBsRLList, DSets2} = merge_small_parts(DSets1), + {PartBBs, DSets3} = merge_pointless_splits(PartBBList, ScanBBs, DSets2), + SeenMap = collect_seenmap(PartBBsRLList, PartBBs), + {RPostMap, _DSets4} = part_order(Target:reverse_postorder(CFG), DSets3), + + {Allocations, SpillIndex} = + lists:mapfoldl( + fun({Root, Elems}, SpillIndex1) -> + #{Root := Seen} = SeenMap, + #{Root := RPost} = RPostMap, + LivePseudos = live_pseudos(Seen, SpillMap, MaxPhys), + {SubMap, InvMap, MaxPhys, MaxR, SubSpillLimit} = + number_and_map(AllPrecoloured, LivePseudos, SpillLimit), + BBs = transform_cfg(Elems, PartBBs, SubMap), + SubMod = #cfg{cfg=CFG, bbs=BBs, max_reg=MaxR, rpostorder=RPost}, + SubTarget = #?MODULE{target=Target, max_phys=MaxPhys, inv=InvMap, + sub=SubMap}, + {SubColoring, SpillIndex2, _} = + RegAllocMod:regalloc(SubMod, SpillIndex1, SubSpillLimit, SubTarget, + Options), + ?ASSERT(check_coloring(SubColoring, SubMod, SubTarget)), + {translate_coloring(SubColoring, InvMap), SpillIndex2} + end, SpillIndex0, PartBBsRLList), + {combine_allocations(Allocations, MaxPhys), SpillIndex}. + +-spec number_and_map([target_reg()], target_liveset(), target_reg()) + -> {sub_map(), inv_map(), temp(), temp(), temp()}. number_and_map(Phys, Pseud, SpillLimit) -> MaxPhys = lists:max(Phys) + 1, - case Pseud of [] -> ok; _ -> - case lists:min(Pseud) of % Assertion - FirstPseudo when FirstPseudo >= MaxPhys -> ok - end end, + ?ASSERT(Pseud =:= [] orelse lists:min(Pseud) >= MaxPhys), NrPseuds = length(Pseud), MaxR = MaxPhys+NrPseuds, PseudNrs = lists:zip(Pseud, lists:seq(MaxPhys, MaxR-1)), MapList = lists:zip(Phys, Phys) % Physicals are identity-mapped ++ PseudNrs, - SubMap = maps:from_list(MapList), - InvMap = maps:from_list([{Fake, Real} || {Real, Fake} <- MapList]), - LastPseudo = case Pseud of [] -> MaxPhys-1; _ -> lists:max(Pseud) end, - SubSpillLimit = if SpillLimit > LastPseudo -> MaxR; - true -> map_get(SpillLimit, SubMap) - end, + ?ASSERT(MapList =:= lists:ukeysort(1, MapList)), + SubMap = {s,maps:from_list(MapList)}, + InvMap = {i,maps:from_list([{Fake, Real} || {Real, Fake} <- MapList])}, + SubSpillLimit = translate_spill_limit(MapList, SpillLimit), {SubMap, InvMap, MaxPhys, MaxR, SubSpillLimit}. +-spec translate_spill_limit([{target_reg(), temp()}], target_reg()) -> temp(). +translate_spill_limit([{Real,Fake}], SpillLimit) when Real < SpillLimit -> + Fake + 1; +translate_spill_limit([{Real,_}|Ps], SpillLimit) when Real < SpillLimit -> + translate_spill_limit(Ps, SpillLimit); +translate_spill_limit([{Real,Fake}|_], SpillLimit) when Real >= SpillLimit -> + Fake. + +-spec live_pseudos(seen(), spill_map(), target_reg()) -> target_liveset(). +live_pseudos(Seen, SpillMap, MaxPhys) -> + %% When SpillMap is much larger than Seen (which is typical in the partitioned + %% case), it is much more efficient doing it like this than making an ordset + %% of the spills and subtracting. + ordsets:from_list( + lists:filter(fun(R) -> R >= MaxPhys andalso not maps:is_key(R, SpillMap) + end, maps:keys(Seen))). + +-spec translate_coloring(hipe_map(), inv_map()) -> hipe_map(). +translate_coloring(SubColoring, InvMap) -> + lists:map(fun({T, P}) -> {imap_get(T, InvMap), P} end, SubColoring). + +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +%% First pass +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +%% Spill trivially unallocatable temps, create internal target-independent +%% program representation, and collect a set of all used temps. -record(spill_state, {map :: spill_map() ,ix :: spillno() @@ -166,9 +269,8 @@ number_and_map(Phys, Pseud, SpillLimit) -> -type spill_map() :: #{target_reg() => spillno()}. -spec scan_cfg(target_cfg(), target_liveness(), spillno(), module()) - -> {#{label() => [instr()]} - ,ordsets:set(target_reg()) - ,ordsets:set(target_reg()) + -> {scan_bbs() + ,seen() ,spill_map() ,spillno() }. @@ -176,28 +278,53 @@ scan_cfg(CFG, Liveness, SpillIndex0, Target) -> State0 = #spill_state{map=#{}, ix=SpillIndex0}, {BBs, Seen, #spill_state{map=Spill, ix=SpillIndex}} = scan_bbs(Target:labels(CFG), CFG, Liveness, #{}, State0, #{}, Target), - SeenOSet = ordsets:from_list(maps:keys(Seen)), - SpillOSet = ordsets:from_list(maps:keys(Spill)), - PhysOSet = ordsets:from_list(Target:all_precoloured()), - Dead = ordsets:union(SpillOSet, PhysOSet), - LivePseudos = ordsets:subtract(SeenOSet, Dead), - {_TMin, _TMax} = Target:var_range(CFG), - _Unused = ordsets:subtract(lists:seq(_TMin, _TMax), - ordsets:union(SeenOSet, PhysOSet)), - {BBs, LivePseudos, _Unused, Spill, SpillIndex}. + {BBs, Seen, Spill, SpillIndex}. -type seen() :: #{target_reg() => []}. % set +-type scan_bb() :: {[instr()], target_liveset(), target_liveset()}. +-type scan_bbs() :: #{label() => scan_bb()}. -spec scan_bbs([label()], target_cfg(), target_liveness(), seen(), - spill_state(), #{label() => [instr()]}, module()) - -> {#{label() => [instr()]}, seen(), spill_state()}. -scan_bbs([], _CFG, _Liveness, Seen, State, BBs, _Target) -> {BBs, Seen, State}; + spill_state(), scan_bbs(), module()) + -> {scan_bbs(), seen(), spill_state()}. +scan_bbs([], _CFG, _Liveness, Seen, State, BBs, _Target) -> + {BBs, Seen, State}; scan_bbs([L|Ls], CFG, Liveness, Seen0, State0, BBs, Target) -> - {Code, _, Seen, State} = scan_bb(hipe_bb:code(Target:bb(CFG, L)), - t_liveout(Liveness, L, Target), - Seen0, State0, Target), - scan_bbs(Ls, CFG, Liveness, Seen, State, BBs#{L=>Code}, Target). + Liveout = t_liveout(Liveness, L, Target), + {Code, Livein, Seen, State} = + scan_bb(lists:reverse(hipe_bb:code(Target:bb(CFG, L))), Liveout, Seen0, + State0, [], Target), + BB = {Code, Livein, Liveout}, + scan_bbs(Ls, CFG, Liveness, Seen, State, BBs#{L=>BB}, Target). + +-spec scan_bb([target_instr()], target_liveset(), seen(), spill_state(), + [instr()], module()) + -> {[instr()] + ,target_liveset() + ,seen() + ,spill_state() + }. +scan_bb([], Live, Seen, State, IAcc, _Target) -> + {IAcc, Live, Seen, State}; +scan_bb([I|Is], Live0, Seen0, State0, IAcc0, Target) -> + {TDef, TUse} = Target:def_use(I), + ?ASSERT(TDef =:= Target:defines(I)), + ?ASSERT(TUse =:= Target:uses(I)), + Def = ordsets:from_list(reg_names(TDef, Target)), + Use = ordsets:from_list(reg_names(TUse, Target)), + Live = ordsets:union(Use, ToSpill = ordsets:subtract(Live0, Def)), + Seen = add_seen(Def, add_seen(Use, Seen0)), + NewI = #instr{defuse={Def, Use}, is_move=Target:is_move(I)}, + IAcc = [NewI|IAcc0], + State = + case Target:defines_all_alloc(I) of + false -> State0; + true -> spill_all(ToSpill, Target, State0) + end, + %% We can drop "no-ops" here; where (if anywhere) is it worth it? + scan_bb(Is, Live, Seen, State, IAcc, Target). +-spec t_liveout(target_liveness(), label(), module()) -> target_liveset(). t_liveout(Liveness, L, Target) -> %% FIXME: unnecessary sort; liveout is sorted, reg_names(...) should be sorted %% or consist of a few sorted subsequences (per type) @@ -207,27 +334,11 @@ t_liveout(Liveness, L, Target) -> reg_names(Regs, Target) -> [Target:reg_nr(X) || X <- Regs]. -scan_bb([], Live, Seen, State, _Target) -> {[], Live, Seen, State}; -scan_bb([I|Is0], Live0, Seen0, State0, Target) -> - %% We could pass Target in the return tuple to make the stack frames - %% smaller, but without multireturn opt, it's probably not worth it. - {Is1, Live1, Seen1, State1} = scan_bb(Is0, Live0, Seen0, State0, Target), - {TDef, TUse} = Target:def_use(I), - Def = ordsets:from_list(reg_names(TDef, Target)), - Use = ordsets:from_list(reg_names(TUse, Target)), - Live = ordsets:union(Use, ToSpill = ordsets:subtract(Live1, Def)), - Seen = add_seen(Def, add_seen(Use, Seen1)), - State = - case Target:defines_all_alloc(I) of - false -> State1; - true -> spill_all(ToSpill, Target, State1) - end, - NewI = #instr{tgt_instr=I, defuse={Def, Use}, is_move=Target:is_move(I)}, - {[NewI|Is1], Live, Seen, State}. - +-spec add_seen([target_reg()], seen()) -> seen(). add_seen([], Seen) -> Seen; add_seen([R|Rs], Seen) -> add_seen(Rs, Seen#{R=>[]}). +-spec spill_all([target_reg()], module(), spill_state()) -> spill_state(). spill_all([], _Target, State) -> State; spill_all([R|Rs], Target, State=#spill_state{map=Map, ix=Ix}) -> case Target:is_precoloured(R) or maps:is_key(R, Map) of @@ -235,17 +346,165 @@ spill_all([R|Rs], Target, State=#spill_state{map=Map, ix=Ix}) -> false -> spill_all(Rs, Target, State#spill_state{map=Map#{R=>Ix}, ix=Ix+1}) end. -transform_cfg(BBs0, SubMap) -> - maps:map(fun(_, BB) -> transform_bb(BB, SubMap) end, BBs0). +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +%% Second pass (without split) +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +%% Rewrite CFG to the new temp names. +-spec transform_whole_cfg(scan_bbs(), sub_map()) -> transformed_bbs(). +transform_whole_cfg(BBs0, SubMap) -> + maps:map(fun(_, BB) -> transform_whole_bb(BB, SubMap) end, BBs0). + +-spec transform_whole_bb(scan_bb(), sub_map()) -> transformed_bb(). +transform_whole_bb({Code, Livein, Liveout}, SubMap) -> + #transformed_bb{ + bb=hipe_bb:mk_bb([I#instr{defuse={smap_get_all_partial(Def, SubMap), + smap_get_all_partial(Use, SubMap)}} + || I = #instr{defuse={Def,Use}} <- Code]) + %% Assume mapping preserves monotonicity + ,livein=smap_get_all_partial(Livein, SubMap) + ,liveout=smap_get_all_partial(Liveout, SubMap) + }. -transform_bb(BB, SubMap) -> - hipe_bb:mk_bb([I#instr{defuse={map_get_all_partial(Def, SubMap), - map_get_all_partial(Use, SubMap)}} - || I = #instr{defuse={Def,Use}} <- BB]). +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +%% Second pass (with split) +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +%% Discover program partitioning +%% Regretfully, this needs to be a separate pass, as having the global live set +%% is crucial to get a useful partitioning. + +%% Single-block parts are merged if there are multiple in a single block, as it +%% is judged to not be beneficial to make them too small. + +-type part_bb_part() :: {[instr()], target_liveset(), target_liveset()}. +-type part_bb() :: {single, part_bb_part()} + | {split, part_bb_part(), part_bb_part()}. +-type part_bb_list() :: [{label(), part_bb()}]. +-type part_bbs() :: #{label() => part_bb()}. +-type part_bb_sofar() :: single + | {split, [instr()], target_liveset()}. % , target_liveset() + +-spec part_cfg(scan_bbs(), spill_map(), target_reg()) -> part_bb_list(). +part_cfg(ScanBBs, SpillMap, MaxPhys) -> + Liveset = mk_part_liveset(SpillMap, MaxPhys), + lists:map(fun(BB) -> part_bb(BB, Liveset) end, maps:to_list(ScanBBs)). + +-spec part_bb({label(), scan_bb()}, part_liveset()) -> {label(), part_bb()}. +part_bb({L, BB0={Code0, Livein, Liveout}}, Liveset) -> + {Sofar, NewCode} = part_bb_1(lists:reverse(Code0), Liveset, Liveout, []), + BB = case Sofar of + single -> + ?ASSERT(Code0 =:= NewCode), + {single, BB0}; + {split, ExitCode, ExitLivein = EntryLiveout} -> + {split, {NewCode, Livein, EntryLiveout}, + {ExitCode, ExitLivein, Liveout}} + end, + {L, BB}. + +-spec part_bb_1([instr()], part_liveset(), target_liveset(), [instr()]) + -> {part_bb_sofar(), [instr()]}. +part_bb_1([], _Liveset, _Livein, IAcc) -> {single, IAcc}; +part_bb_1([I=#instr{defuse={Def,Use}}|Is], Liveset, Live0, IAcc0) -> + Live = ordsets:union(Use, ordsets:subtract(Live0, Def)), + IAcc = [I|IAcc0], + case part_none_live(Live, Liveset) of + false -> part_bb_1(Is, Liveset, Live, IAcc); + %% One split point will suffice + true -> {{split, IAcc, Live}, lists:reverse(Is)} + end. --spec translate_coloring(hipe_map(), _) -> hipe_map(). -translate_coloring(SubColoring, InvMap) -> - lists:map(fun({T, P}) -> {map_get(T, InvMap), P} end, SubColoring). +-spec part_none_live(target_liveset(), part_liveset()) -> boolean(). +part_none_live(Live, Liveset) -> + not lists:any(fun(R) -> part_liveset_is_live(R, Liveset) end, Live). + +-type part_liveset() :: {spill_map(), target_reg()}. + +-spec mk_part_liveset(spill_map(), target_reg()) -> part_liveset(). +mk_part_liveset(SpillMap, MaxPhys) -> {SpillMap, MaxPhys}. + +-spec part_liveset_is_live(target_reg(), part_liveset()) -> boolean(). +part_liveset_is_live(R, {SpillMap, MaxPhys}) when is_integer(R) -> + R >= MaxPhys andalso not maps:is_key(R, SpillMap). + +%% @doc Merges split blocks where entry and exit belong to the same DSet. +%% Does not change DSets +-spec merge_pointless_splits(part_bb_list(), scan_bbs(), bb_dsets()) + -> {part_bbs(), bb_dsets()}. +merge_pointless_splits(PartBBList0, ScanBBs, DSets0) -> + {PartBBList, DSets} = + merge_pointless_splits_1(PartBBList0, ScanBBs, DSets0, []), + {maps:from_list(PartBBList), DSets}. + +-spec merge_pointless_splits_1( + part_bb_list(), scan_bbs(), bb_dsets(), part_bb_list()) + -> {part_bb_list(), bb_dsets()}. +merge_pointless_splits_1([], _ScanBBs, DSets, Acc) -> {Acc, DSets}; +merge_pointless_splits_1([P={_,{single,_}}|Ps], ScanBBs, DSets, Acc) -> + merge_pointless_splits_1(Ps, ScanBBs, DSets, [P|Acc]); +merge_pointless_splits_1([P0={L,{split,_,_}}|Ps], ScanBBs, DSets0, Acc) -> + {EntryRoot, DSets1} = dsets_find({entry,L}, DSets0), + {ExitRoot, DSets} = dsets_find({exit,L}, DSets1), + case EntryRoot =:= ExitRoot of + false -> merge_pointless_splits_1(Ps, ScanBBs, DSets, [P0|Acc]); + true -> + %% Reuse the code list from ScanBBs rather than concatenating the split + %% parts + #{L := BB} = ScanBBs, + ?ASSERT(begin + {L,{split,{_EntryCode,_,_},{_ExitCode,_,_}}}=P0, % [_| + {_Code,_,_}=BB, + _Code =:= (_EntryCode ++ _ExitCode) + end), + merge_pointless_splits_1(Ps, ScanBBs, DSets, [{L,{single, BB}}|Acc]) + end. + +-spec merge_small_parts(bb_dsets()) -> {bb_dsets_rllist(), bb_dsets()}. +merge_small_parts(DSets0) -> + {RLList, DSets1} = dsets_to_rllist(DSets0), + RLLList = [{R, length(Elems), Elems} || {R, Elems} <- RLList], + merge_small_parts_1(RLLList, DSets1, []). + +-spec merge_small_parts_1( + [{bb_dset_key(), non_neg_integer(), [bb_dset_key()]}], + bb_dsets(), bb_dsets_rllist() + ) -> {bb_dsets_rllist(), bb_dsets()}. +merge_small_parts_1([], DSets, Acc) -> {Acc, DSets}; +merge_small_parts_1([{R, _, Es}], DSets, Acc) -> {[{R, Es}|Acc], DSets}; +merge_small_parts_1([{R, L, Es}|Ps], DSets, Acc) when L >= ?TUNE_TOO_FEW_BBS -> + merge_small_parts_1(Ps, DSets, [{R,Es}|Acc]); +merge_small_parts_1([Fst,{R, L, Es}|Ps], DSets, Acc) + when L >= ?TUNE_TOO_FEW_BBS -> + merge_small_parts_1([Fst|Ps], DSets, [{R,Es}|Acc]); +merge_small_parts_1([{R1,L1,Es1},{R2,L2,Es2}|Ps], DSets0, Acc) -> + ?ASSERT(L1 < ?TUNE_TOO_FEW_BBS andalso L2 < ?TUNE_TOO_FEW_BBS), + DSets1 = dsets_union(R1, R2, DSets0), + {R, DSets} = dsets_find(R1, DSets1), + merge_small_parts_1([{R,L2+L1,Es2++Es1}|Ps], DSets, Acc). + +%% @doc Partition an ordering over BBs into subsequences for the dsets that +%% contain them. +%% Does not change dsets. +-spec part_order([label()], bb_dsets()) + -> {#{bb_dset_key() => [label()]}, bb_dsets()}. +part_order(Lbs, DSets) -> part_order(Lbs, DSets, #{}). + +part_order([], DSets, Acc) -> {Acc, DSets}; +part_order([L|Ls], DSets0, Acc0) -> + {EntryRoot, DSets1} = dsets_find({entry,L}, DSets0), + {ExitRoot, DSets2} = dsets_find({exit,L}, DSets1), + Acc1 = map_append(EntryRoot, L, Acc0), + %% Only include the label once if both entry and exit is in same partition + Acc2 = case EntryRoot =:= ExitRoot of + true -> Acc1; + false -> map_append(ExitRoot, L, Acc1) + end, + part_order(Ls, DSets2, Acc2). + +map_append(Key, Elem, Map) -> + case Map of + #{Key := List} -> Map#{Key := [Elem|List]}; + #{} -> Map#{Key => [Elem]} + end. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %% Interference graph partitioning @@ -257,22 +516,163 @@ translate_coloring(SubColoring, InvMap) -> %% to at most two non-local components; one from the beginning to the first %% split point, and one from the end to the last split point. +-type bb_dset_key() :: {entry | exit, label()}. +-type bb_dsets() :: dsets(bb_dset_key()). +-type bb_dsets_rllist() :: [{bb_dset_key(), [bb_dset_key()]}]. + +-spec initial_dsets(target_cfg(), module()) -> bb_dsets(). +initial_dsets(CFG, Target) -> + Labels = Target:labels(CFG), + DSets0 = dsets_new(lists:append([[{entry,L},{exit,L}] || L <- Labels])), + Edges = lists:append([[{L, S} || S <- hipe_gen_cfg:succ(CFG, L)] + || L <- Labels]), + lists:foldl(fun({X, Y}, DS) -> dsets_union({exit,X}, {entry,Y}, DS) end, + DSets0, Edges). + +-spec join_whole_blocks(part_bb_list(), bb_dsets()) -> bb_dsets(). +join_whole_blocks(PartBBList, DSets0) -> + lists:foldl(fun({L, {single, _}}, DS) -> dsets_union({entry,L}, {exit,L}, DS); + ({_, {split, _, _}}, DS) -> DS + end, DSets0, PartBBList). + +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +%% The disjoint set forests data structure, for elements of arbitrary types. +%% Note that the find operation mutates the set. +%% +%% We could do this more efficiently if we restricted the elements to integers, +%% and used the (mutable) hipe arrays. For arbitrary terms ETS could be used, +%% for a persistent interface (which isn't that nice when even accessors return +%% modified copies), the array module could be used. +-type dsets(X) :: #{X => {node, X} | {root, non_neg_integer()}}. + +-spec dsets_new([E]) -> dsets(E). +dsets_new(Elems) -> maps:from_list([{E,{root,0}} || E <- Elems]). + +-spec dsets_find(E, dsets(E)) -> {E, dsets(E)}. +dsets_find(E, DS0) -> + case DS0 of + #{E := {root,_}} -> {E, DS0}; + #{E := {node,N}} -> + case dsets_find(N, DS0) of + {N, _}=T -> T; + {R, DS1} -> {R, DS1#{E := {node,R}}} + end + ;_ -> error(badarg, [E, DS0]) + end. + +-spec dsets_union(E, E, dsets(E)) -> dsets(E). +dsets_union(X, Y, DS0) -> + {XRoot, DS1} = dsets_find(X, DS0), + case dsets_find(Y, DS1) of + {XRoot, DS2} -> DS2; + {YRoot, DS2} -> + #{XRoot := {root,XRR}, YRoot := {root,YRR}} = DS2, + if XRR < YRR -> DS2#{XRoot := {node,YRoot}}; + XRR > YRR -> DS2#{YRoot := {node,XRoot}}; + true -> DS2#{YRoot := {node,XRoot}, XRoot := {root,XRR+1}} + end + end. + +-spec dsets_to_rllist(dsets(E)) -> {[{Root::E, Elems::[E]}], dsets(E)}. +dsets_to_rllist(DS0) -> + {Lists, DS} = dsets_to_rllist(maps:keys(DS0), #{}, DS0), + {maps:to_list(Lists), DS}. + +dsets_to_rllist([], Acc, DS) -> {Acc, DS}; +dsets_to_rllist([E|Es], Acc, DS0) -> + {ERoot, DS} = dsets_find(E, DS0), + dsets_to_rllist(Es, map_append(ERoot, E, Acc), DS). + +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +%% Third pass +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +%% Collect all referenced temps in each partition. + +%% Note: The temps could be collected during the partition pass for each +%% half-bb, and then combined here. Would that be beneficial? + +collect_seenmap(PartBBsRLList, PartBBs) -> + collect_seenmap(PartBBsRLList, #{}, PartBBs). + +collect_seenmap([], Acc, _PartBBs) -> Acc; +collect_seenmap([{R,Elems}|Ps], Acc, PartBBs) -> + Seen = collect_seen_part(Elems, #{}, PartBBs), + collect_seenmap(Ps, Acc#{R => Seen}, PartBBs). + +collect_seen_part([], Acc, _PartBBs) -> Acc; +collect_seen_part([{Half,L}|Es], Acc0, PartBBs) -> + BB = maps:get(L, PartBBs), + Code = case {Half, BB} of + {entry, {single, {C,_,_}}} -> C; + {entry, {split, {C,_,_}, _}} -> C; + {exit, {split, _, {C,_,_}}} -> C; + {exit, {single, _}} -> [] % Ignore; was collected by its entry half + end, + Acc = collect_seen_code(Code, Acc0), + collect_seen_part(Es, Acc, PartBBs). + +collect_seen_code([], Acc) -> Acc; +collect_seen_code([#instr{defuse={Def,Use}}|Is], Acc) -> + collect_seen_code(Is, add_seen(Def, add_seen(Use, Acc))). + +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +%% Fourth pass +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +%% Rewrite CFG to the new temp names. +-spec transform_cfg([bb_dset_key()], part_bbs(), sub_map()) -> transformed_bbs(). + +transform_cfg(Elems, PartBBs, SubMap) -> + transform_cfg(Elems, PartBBs, SubMap, #{}). + +transform_cfg([], _PartBBs, _SubMap, Acc) -> Acc; +transform_cfg([{Half,L}|Es], PartBBs, SubMap, Acc0) -> + #{L := PBB} = PartBBs, + Acc = case {Half, PBB} of + {entry, {single,BB}} -> Acc0#{L=>transform_bb(BB, SubMap)}; + {entry, {split,BB,_}} -> Acc0#{L=>transform_bb(BB, SubMap)}; + {exit, {split,_,BB}} -> Acc0#{L=>transform_bb(BB, SubMap)}; + {exit, {single, _}} -> Acc0 % Was included by the entry half + end, + transform_cfg(Es, PartBBs, SubMap, Acc). + +-spec transform_bb(part_bb_part(), sub_map()) -> transformed_bb(). +transform_bb(BB, SubMap) -> + %% For now, part_bb_part() and split_bb() share representation + transform_whole_bb(BB, SubMap). + +%% +combine_allocations([A|As], MaxPhys) -> + {Phys, Pseuds} = lists:partition(fun({R,_}) -> R < MaxPhys end, A), + combine_allocations_1(As, MaxPhys, Phys, Pseuds). + +combine_allocations_1([], _MaxPhys, Phys, Pseuds) -> Phys ++ Pseuds; +combine_allocations_1([A|As], MaxPhys, Phys, Acc) -> + {Phys, Pseuds} = lists:partition(fun({R,_}) -> R < MaxPhys end, A), + combine_allocations_1(As, MaxPhys, Phys, Pseuds ++ Acc). + %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %% Temp map ADT %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% --type sub_map() :: #{target_temp() => temp()}. --type inv_map() :: #{temp() => target_temp()}. -map_get(Temp, Map) when is_integer(Temp) -> maps:get(Temp, Map). +-type sub_map() :: {s,#{target_reg() => temp()}}. +-type inv_map() :: {i,#{temp() => target_reg()}}. + +-spec smap_get(target_reg(), sub_map()) -> temp(). +smap_get(Temp, {s,Map}) when is_integer(Temp) -> maps:get(Temp, Map). -%% map_get_all(Ts, Map) -> [map_get(T, Map) || T <- Ts]. +-spec imap_get(temp(), inv_map()) -> target_reg(). +imap_get(Temp, {i,Map}) when is_integer(Temp) -> maps:get(Temp, Map). -map_get_all_partial([], _) -> []; -map_get_all_partial([T|Ts], Map) when is_integer(T) -> +-spec smap_get_all_partial([target_reg()], sub_map()) -> [temp()]. +smap_get_all_partial([], _) -> []; +smap_get_all_partial([T|Ts], SMap={s,Map}) when is_integer(T) -> case Map of - #{T := R} -> [R|map_get_all_partial(Ts, Map)]; - #{} -> map_get_all_partial(Ts, Map) + #{T := R} -> [R|smap_get_all_partial(Ts, SMap)]; + #{} -> smap_get_all_partial(Ts, SMap) end. +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +%% Validation +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% -ifdef(DO_ASSERT). %%%%%%%%%%%%%%%%%%%% %% Check that the coloring is correct (if the IG is correct): @@ -286,7 +686,7 @@ map_get_all_partial([T|Ts], Map) when is_integer(T) -> check_coloring(Coloring, CFG, Target) -> ?report0("checking coloring ~p~n",[Coloring]), - IG = hipe_ig:build(CFG, Target), + IG = hipe_ig:build(CFG, Target:analyze(CFG), Target), check_cols(hipe_vectors:list(hipe_ig:adj_list(IG)), init_coloring(Coloring, Target)). @@ -294,13 +694,8 @@ init_coloring(Xs, Target) -> hipe_temp_map:cols2tuple(Xs, Target). check_color_of(X, Cols) -> -%% if -%% is_precoloured(X) -> -%% phys_reg_color(X,Cols); -%% true -> case hipe_temp_map:find(X, Cols) of unknown -> - ?WARNING_MSG("node ~p: color not found~n", [X]), uncolored; C -> C @@ -330,71 +725,100 @@ valid_coloring(X, C, [{Y,C}|Ys]) -> valid_coloring(X, C, [_|Ys]) -> valid_coloring(X, C, Ys). +unused_unused(Unused, CFG, Target) -> + IG = hipe_ig:build(CFG, Target:analyze(CFG), Target), + lists:all(fun(R) -> case hipe_ig:get_node_degree(R, IG) of + 0 -> true; + Deg -> + ?msg("Temp ~w is in unused but has degree ~w~n", + [R, Deg]), + false + end end, Unused). + %%%%%%%%%%%%%%%%%%%% -%% Check that no register allocation opportinities were missed due to ?MODULE +%% Check that no register allocation opportunities were missed due to ?MODULE %% just_as_good_as(RegAllocMod, CFG, SpillIndex0, SpillLimit, Target, Options, Coloring, Unused) -> - {CheckColoring, _} = RegAllocMod:regalloc(CFG, SpillIndex0, SpillLimit, - Target, Options), - Now = lists:sort([vt(C) || C <- Coloring]), - Check = lists:sort([vt(C) || C={R,_} <- CheckColoring, - not ordsets:is_element(R, Unused)]), - case Now of - Check -> true; - _ -> - io:fwrite(standard_error, "Colorings differ (~w, sub: ~w, full: ~w)!~n" - %% "Sub:~w~n" + {CheckColoring, _, _} = RegAllocMod:regalloc(CFG, SpillIndex0, SpillLimit, + Target, Options), + Now = lists:sort([{R,Kind} || {R,{Kind,_}} <- Coloring, + not ordsets:is_element(R, Unused)]), + Check = lists:sort([{R,Kind} || {R,{Kind,_}} <- CheckColoring, + not ordsets:is_element(R, Unused)]), + CheckMap = maps:from_list(Check), + case lists:all(fun({R, spill}) -> maps:get(R, CheckMap) =:= spill; + ({_,reg}) -> true + end, Now) + of + true -> true; + false -> + {NowRegs, _} = _NowCount = count(Now), + {CheckRegs, _} = _CheckCount = count(Check), + io:fwrite(standard_error, "Colorings differ (~w, ~w)!~n" "Unused: ~w~n" "Now:~w~nCorrect:~w~n", - [Target, count(Coloring), count(CheckColoring), - %% SubColoring, + [Target, RegAllocMod, Unused, Now -- Check, Check -- Now]), - false + NowRegs >= CheckRegs end. -count(C) -> {length([[] || {_, {reg, _}} <- C]), - length([[] || {_, {spill, _}} <- C])}. +count(C) -> {length([[] || {_, reg} <- C]), + length([[] || {_, spill} <- C])}. -vt({R, {reg, _}}) -> {R, reg}; -vt({R, {spill, _}}) -> {R, spill}. --endif. +unused(LivePseudos, SpillMap, CFG, Target) -> + {TMin, TMax} = Target:var_range(CFG), + SpillOSet = ordsets:from_list(maps:keys(SpillMap)), + PhysOSet = ordsets:from_list(Target:all_precoloured()), + Used = ordsets:union(LivePseudos, ordsets:union(PhysOSet, SpillOSet)), + ordsets:subtract(lists:seq(TMin, TMax), Used). +-endif. % DO_ASSERT %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %% Pseudo-target interface %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% analyze(Cfg, _ModRec) -> Cfg. -bb(#cfg{bbs=BBs}, Ix, _ModRec) -> maps:get(Ix, BBs). +bb(Cfg=#cfg{bbs=BBs}, Ix, _ModRec) -> + case BBs of + #{Ix := #transformed_bb{bb=BB}} -> BB; + _ -> error(badarg, [Cfg, Ix]) + end. args(Arity, #?MODULE{target=Target, sub=SubM}) -> - map_get(Target:args(Arity), SubM). -labels(#cfg{cfg=CFG}, #?MODULE{target=Target}) -> Target:labels(CFG). -livein(#cfg{live=Live}, Lb, #?MODULE{target=Target, sub=SubM}) -> - map_get_all_partial(reg_names(Target:livein(Live, Lb), Target), SubM). % Should we precompute? -liveout(#cfg{live=Live}, Lb, #?MODULE{target=Target, sub=SubM}) -> - map_get_all_partial(reg_names(Target:liveout(Live, Lb), Target), SubM). % dito + smap_get(Target:args(Arity), SubM). +labels(#cfg{bbs=BBs}, _ModRec) -> maps:keys(BBs). +livein(#cfg{bbs=BBs}, Lb, _SubMod) -> + #{Lb := #transformed_bb{livein=Livein}} = BBs, + Livein. +liveout(#cfg{bbs=BBs}, Lb, _SubMod) -> + #{Lb := #transformed_bb{liveout=Liveout}} = BBs, + Liveout. uses(I, MR) -> element(2, def_use(I, MR)). defines(I, MR) -> element(1, def_use(I, MR)). def_use(#instr{defuse=DefUse}, _ModRec) -> DefUse. is_move(#instr{is_move=IM}, _ModRec) -> IM. is_fixed(Reg, #?MODULE{target=Target,inv=InvM}) -> - Target:is_fixed(map_get(Reg, InvM)). % XXX: Is this hot? + Target:is_fixed(imap_get(Reg, InvM)). % XXX: Is this hot? is_global(Reg, #?MODULE{target=Target,max_phys=MaxPhys}) when Reg < MaxPhys -> Target:is_global(Reg). % assume id-map is_precoloured(Reg, #?MODULE{max_phys=MaxPhys}) -> Reg < MaxPhys. reg_nr(Reg, _ModRec) -> Reg. % After mapping (naturally) non_alloc(#cfg{cfg=CFG}, #?MODULE{target=Target,sub=SubM}) -> - map_get_all_partial(reg_names(Target:non_alloc(CFG), Target), SubM). + smap_get_all_partial(reg_names(Target:non_alloc(CFG), Target), SubM). number_of_temporaries(#cfg{max_reg=MaxR}, _ModRec) -> MaxR. allocatable(#?MODULE{target=Target}) -> Target:allocatable(). % assume id-map -physical_name(Reg, _ModRec) -> Reg. % XXX: is this correct? +physical_name(Reg, _ModRec) -> Reg. all_precoloured(#?MODULE{target=Target}) -> Target:all_precoloured(). % dito -var_range(#cfg{cfg=CFG, max_reg=MaxReg}, #?MODULE{target=Target}) -> - {0, _} = Target:var_range(CFG), - {0, MaxReg-1}. % What is the correct answer? - -breadthorder(#cfg{cfg=CFG}, #?MODULE{target=Target}) -> - Target:breadthorder(CFG). -postorder(#cfg{cfg=CFG}, #?MODULE{target=Target}) -> Target:postorder(CFG). -reverse_postorder(#cfg{cfg=CFG}, #?MODULE{target=Target}) -> - Target:reverse_postorder(CFG). +var_range(#cfg{cfg=_CFG, max_reg=MaxReg}, #?MODULE{target=_Target}) -> + ?ASSERT(begin {TgtMin, _} = _Target:var_range(_CFG), TgtMin =:= 0 end), + {0, MaxReg-1}. + +postorder(#cfg{cfg=CFG,rpostorder=undefined}, #?MODULE{target=Target}) -> + Target:postorder(CFG); +postorder(#cfg{rpostorder=Labels}, _ModRec) when is_list(Labels) -> + lists:reverse(Labels). + +reverse_postorder(#cfg{cfg=CFG,rpostorder=undefined}, #?MODULE{target=Target}) -> + Target:reverse_postorder(CFG); +reverse_postorder(#cfg{rpostorder=Labels}, _ModRec) when is_list(Labels) -> + Labels. |