From 330629264c93535f352dc09b51d34f11ec791eb6 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= Date: Thu, 20 Sep 2018 15:57:09 +0200 Subject: beam_ssa_pre_codegen: Remove unused variable aliasing support Remove the variable aliasing support that was needed for the old beam_bsm pass. --- lib/compiler/src/beam_ssa_pre_codegen.erl | 120 ++++-------------------------- 1 file changed, 15 insertions(+), 105 deletions(-) (limited to 'lib/compiler/src/beam_ssa_pre_codegen.erl') diff --git a/lib/compiler/src/beam_ssa_pre_codegen.erl b/lib/compiler/src/beam_ssa_pre_codegen.erl index e949aab722..9b5f52d26b 100644 --- a/lib/compiler/src/beam_ssa_pre_codegen.erl +++ b/lib/compiler/src/beam_ssa_pre_codegen.erl @@ -107,7 +107,6 @@ functions([], _Ps, _UseBSM3) -> []. use_bsm3 :: boolean(), frames=[] :: [beam_ssa:label()], intervals=[] :: [{b_var(),[range()]}], - aliases=[] :: [{b_var(),b_var()}], res=[] :: [{b_var(),reservation()}] | #{b_var():=reservation()}, regs=#{} :: #{b_var():=ssa_register()}, extra_annos=[] :: [{atom(),term()}] @@ -141,9 +140,7 @@ passes(Opts) -> %% Calculate live intervals. ?PASS(number_instructions), ?PASS(live_intervals), - ?PASS(remove_unsuitable_aliases), ?PASS(reserve_regs), - ?PASS(merge_intervals), %% If needed for a .precg file, save the live intervals %% so they can be included in an annotation. @@ -154,7 +151,6 @@ passes(Opts) -> %% Allocate registers. ?PASS(linear_scan), - ?PASS(fix_aliased_regs), ?PASS(frame_size), ?PASS(turn_yregs)], [P || P <- Ps, P =/= ignore]. @@ -178,14 +174,6 @@ function(#b_function{anno=Anno,args=Args,bs=Blocks0,cnt=Count0}=F0, save_live_intervals(#st{intervals=Intervals}=St) -> St#st{extra_annos=[{live_intervals,Intervals}]}. -fix_aliased_regs(#st{aliases=Aliases,regs=Regs}=St) -> - St#st{regs=fix_aliased_regs(Aliases, Regs)}. - -fix_aliased_regs([{Alias,V}|Aliases], Regs) -> - #{V:=Reg} = Regs, - fix_aliased_regs(Aliases, Regs#{Alias=>Reg}); -fix_aliased_regs([], Regs) -> Regs. - %% Add extra annotations when a .precg listing file is being produced. add_extra_annos(F, Annos) -> foldl(fun({Name,Value}, Acc) -> @@ -1611,10 +1599,10 @@ live_intervals(#st{args=Args,ssa=Blocks}=St) -> Vars0 = [{V,{0,1}} || #b_var{}=V <- Args], F = fun(L, _, A) -> live_interval_blk(L, Blocks, A) end, LiveMap0 = #{}, - Acc0 = {[],[],LiveMap0}, - {Vars,Aliases,_} = beam_ssa:fold_po(F, Acc0, Blocks), + Acc0 = {[],LiveMap0}, + {Vars,_} = beam_ssa:fold_po(F, Acc0, Blocks), Intervals = merge_ranges(rel2fam(Vars0++Vars)), - St#st{intervals=Intervals,aliases=Aliases}. + St#st{intervals=Intervals}. merge_ranges([{V,Rs}|T]) -> [{V,merge_ranges_1(Rs)}|merge_ranges(T)]; @@ -1626,7 +1614,7 @@ merge_ranges_1([R|Rs]) -> [R|merge_ranges_1(Rs)]; merge_ranges_1([]) -> []. -live_interval_blk(L, Blocks, {Vars0,Aliases0,LiveMap0}) -> +live_interval_blk(L, Blocks, {Vars0,LiveMap0}) -> Live0 = [], Successors = beam_ssa:successors(L, Blocks), Live1 = update_successors(Successors, L, Blocks, LiveMap0, Live0), @@ -1638,8 +1626,7 @@ live_interval_blk(L, Blocks, {Vars0,Aliases0,LiveMap0}) -> %% Determine used and defined variables in this block. FirstNumber = first_number(Is, Last), - {UseDef0,Aliases} = live_interval_blk_1([Last|reverse(Is)], - FirstNumber, Aliases0, Use), + UseDef0 = live_interval_blk_1([Last|reverse(Is)], FirstNumber, Use), UseDef = rel2fam(UseDef0), %% Update what is live at the beginning of this block and @@ -1652,7 +1639,7 @@ live_interval_blk(L, Blocks, {Vars0,Aliases0,LiveMap0}) -> %% Construct the ranges for this block. Vars = make_block_ranges(UseDef, FirstNumber, Vars0), - {Vars,Aliases,LiveMap}. + {Vars,LiveMap}. make_block_ranges([{V,[{def,Def}]}|Vs], First, Acc) -> make_block_ranges(Vs, First, [{V,{Def,Def}}|Acc]); @@ -1664,18 +1651,17 @@ make_block_ranges([{V,[{use,_}|_]=Uses}|Vs], First, Acc) -> make_block_ranges(Vs, First, [{V,{First,Last}}|Acc]); make_block_ranges([], _, Acc) -> Acc. -live_interval_blk_1([#b_set{op=phi,dst=Dst}|Is], - FirstNumber, Aliases, Acc0) -> +live_interval_blk_1([#b_set{op=phi,dst=Dst}|Is], FirstNumber, Acc0) -> Acc = [{Dst,{def,FirstNumber}}|Acc0], - live_interval_blk_1(Is, FirstNumber, Aliases, Acc); -live_interval_blk_1([#b_set{op=bs_start_match}=I|Is], FirstNumber, - Aliases, Acc0) -> + live_interval_blk_1(Is, FirstNumber, Acc); +live_interval_blk_1([#b_set{op=bs_start_match}=I|Is], + FirstNumber, Acc0) -> N = beam_ssa:get_anno(n, I), #b_set{dst=Dst} = I, Acc1 = [{Dst,{def,N}}|Acc0], Acc = [{V,{use,N}} || V <- beam_ssa:used(I)] ++ Acc1, - live_interval_blk_1(Is, FirstNumber, Aliases, Acc); -live_interval_blk_1([I|Is], FirstNumber, Aliases, Acc0) -> + live_interval_blk_1(Is, FirstNumber, Acc); +live_interval_blk_1([I|Is], FirstNumber, Acc0) -> N = beam_ssa:get_anno(n, I), Acc1 = case I of #b_set{dst=Dst} -> @@ -1685,9 +1671,9 @@ live_interval_blk_1([I|Is], FirstNumber, Aliases, Acc0) -> end, Used = beam_ssa:used(I), Acc = [{V,{use,N}} || V <- Used] ++ Acc1, - live_interval_blk_1(Is, FirstNumber, Aliases, Acc); -live_interval_blk_1([], _FirstNumber, Aliases, Acc) -> - {Acc,Aliases}. + live_interval_blk_1(Is, FirstNumber, Acc); +live_interval_blk_1([], _FirstNumber, Acc) -> + Acc. %% first_number([#b_set{}]) -> InstructionNumber. %% Return the number for the first instruction for the block. @@ -2123,82 +2109,6 @@ res_xregs_prune(Xs, Used, Res) -> %% preferred registers. maps:filter(fun(_, {x,X}) -> X < NumSafe end, Xs). -%%% -%%% Remove unsuitable aliases. -%%% -%%% If a binary is matched more than once, we must not put the -%%% the match context in the same register as the binary to -%%% avoid the following situation: -%%% -%%% {test,bs_start_match2,{f,3},1,[{x,0},0],{x,0}}. -%%% . -%%% . -%%% . -%%% {test,bs_start_match2,{f,6},1,[{x,0},0],{x,1}}. %% ILLEGAL! -%%% -%%% The second instruction is illegal because a match context source -%%% is only allowed if source and destination registers are identical. -%%% - -remove_unsuitable_aliases(#st{aliases=[_|_]=Aliases0,ssa=Blocks}=St) -> - R = rem_unsuitable(maps:values(Blocks)), - Unsuitable0 = [V || {V,[_,_|_]} <- rel2fam(R)], - Unsuitable = gb_sets:from_list(Unsuitable0), - Aliases =[P || {_,V}=P <- Aliases0, - not gb_sets:is_member(V, Unsuitable)], - St#st{aliases=Aliases}; -remove_unsuitable_aliases(#st{aliases=[]}=St) -> St. - -rem_unsuitable([#b_blk{is=Is}|Bs]) -> - Vs = [{Var,Dst} || - #b_set{op=bs_start_match,dst=Dst, - args=[#b_var{}=Var]} <- Is], - Vs ++ rem_unsuitable(Bs); -rem_unsuitable([]) -> []. - -%%% -%%% Merge intervals. -%%% - -merge_intervals(#st{aliases=Aliases0,intervals=Intervals0, - res=Reserved}=St) -> - Aliases1 = [A || A <- Aliases0, - is_suitable_alias(A, Reserved)], - case Aliases1 of - [] -> - St#st{aliases=Aliases1}; - [_|_] -> - Intervals1 = maps:from_list(Intervals0), - {Intervals,Aliases} = - merge_intervals_1(Aliases1, Intervals1, []), - St#st{aliases=Aliases,intervals=Intervals} - end. - -merge_intervals_1([{Alias,V}|Vs], Intervals0, Acc) -> - #{Alias:=Int1,V:=Int2} = Intervals0, - Int3 = lists:merge(Int1, Int2), - Int = merge_intervals_2(Int3), - Intervals1 = maps:remove(Alias, Intervals0), - Intervals = Intervals1#{V:=Int}, - merge_intervals_1(Vs, Intervals, [{Alias,V}|Acc]); -merge_intervals_1([], Intervals, Acc) -> - {maps:to_list(Intervals),Acc}. - -merge_intervals_2([{A1,B1},{A2,B2}|Is]) when A2 =< B1 -> - merge_intervals_2([{min(A1, A2),max(B1, B2)}|Is]); -merge_intervals_2([{_A1,B1}=R|[{A2,_B2}|_]=Is]) when B1 < A2 -> - [R|merge_intervals_2(Is)]; -merge_intervals_2([_]=Is) -> Is. - -is_suitable_alias({V1,V2}, Reserved) -> - #{V1:=Res1,V2:=Res2} = Reserved, - case {Res1,Res2} of - {x,x} -> true; - {x,{x,_}} -> true; - {{x,_},x} -> true; - {_,_} -> false - end. - %%% %%% Register allocation using linear scan. %%% -- cgit v1.2.3