diff options
Diffstat (limited to 'lib/compiler/src/beam_dead.erl')
| -rw-r--r-- | lib/compiler/src/beam_dead.erl | 38 |
1 files changed, 22 insertions, 16 deletions
diff --git a/lib/compiler/src/beam_dead.erl b/lib/compiler/src/beam_dead.erl index 7cd07dc3be..5932d8ce1d 100644 --- a/lib/compiler/src/beam_dead.erl +++ b/lib/compiler/src/beam_dead.erl @@ -98,6 +98,12 @@ move_move_into_block([], Acc) -> reverse(Acc). forward(Is, Lc) -> forward(Is, gb_trees:empty(), Lc, []). +forward([{move,_,_}=Move|[{label,L}|_]=Is], D, Lc, Acc) -> + %% move/2 followed by jump/1 is optimized by backward/3. + forward([Move,{jump,{f,L}}|Is], D, Lc, Acc); +forward([{bif,_,_,_,_}=Bif|[{label,L}|_]=Is], D, Lc, Acc) -> + %% bif/4 followed by jump/1 is optimized by backward/3. + forward([Bif,{jump,{f,L}}|Is], D, Lc, Acc); forward([{block,[]}|Is], D, Lc, Acc) -> %% Empty blocks can prevent optimizations. forward(Is, D, Lc, Acc); @@ -124,6 +130,8 @@ forward([{label,Lbl}=LblI|[{move,Lit,Dst}|Is1]=Is0], D, Lc, Acc) -> _ -> Is0 %Keep move instruction. end, forward(Is, D, Lc, [LblI|Acc]); +forward([{test,is_eq_exact,_,[Same,Same]}|Is], D, Lc, Acc) -> + forward(Is, D, Lc, Acc); forward([{test,is_eq_exact,_,[Dst,Src]}=I, {block,[{set,[Dst],[Src],move}|Bl]}|Is], D, Lc, Acc) -> forward([I,{block,Bl}|Is], D, Lc, Acc); @@ -234,10 +242,8 @@ backward([{select,select_val,Reg,{f,Fail0},List0}|Is], D, Acc) -> Fail = shortcut_bs_test(Fail1, Is, D), Sel = {select,select_val,Reg,{f,Fail},List}, backward(Is, D, [Sel|Acc]); -backward([{jump,{f,To0}},{move,Src0,Reg}|Is], D, Acc) -> - To1 = shortcut_select_label(To0, Reg, Src0, D), - {To,Src} = shortcut_boolean_label(To1, Reg, Src0, D), - Move = {move,Src,Reg}, +backward([{jump,{f,To0}},{move,Src,Reg}=Move|Is], D, Acc) -> + To = shortcut_select_label(To0, Reg, Src, D), Jump = {jump,{f,To}}, case beam_utils:is_killed_at(Reg, To, D) of false -> backward([Move|Is], D, [Jump|Acc]); @@ -249,6 +255,16 @@ backward([{jump,{f,To}}=J|[{bif,Op,_,Ops,Reg}|Is]=Is0], D, Acc) -> catch throw:not_possible -> backward(Is0, D, [J|Acc]) end; +backward([{test,bs_start_match2,F,_,[R,_],Ctxt}=I|Is], D, + [{test,bs_match_string,F,[Ctxt,Bs]}, + {test,bs_test_tail2,F,[Ctxt,0]}|Acc0]=Acc) -> + case beam_utils:is_killed(Ctxt, Acc0, D) of + true -> + Eq = {test,is_eq_exact,F,[R,{literal,Bs}]}, + backward(Is, D, [Eq|Acc0]); + false -> + backward(Is, D, [I|Acc]) + end; backward([{test,bs_start_match2,{f,To0},Live,[Src|_]=Info,Dst}|Is], D, Acc) -> To = shortcut_bs_start_match(To0, Src, D), I = {test,bs_start_match2,{f,To},Live,Info,Dst}, @@ -330,16 +346,6 @@ shortcut_label(To0, D) -> shortcut_select_label(To, Reg, Lit, D) -> shortcut_rel_op(To, is_ne_exact, [Reg,Lit], D). -shortcut_boolean_label(To0, Reg, {atom,Bool0}=Lit, D) when is_boolean(Bool0) -> - case beam_utils:code_at(To0, D) of - [{line,_},{bif,'not',_,[Reg],Reg},{jump,{f,To}}|_] -> - Bool = {atom,not Bool0}, - {shortcut_select_label(To, Reg, Bool, D),Bool}; - _ -> - {To0,Lit} - end; -shortcut_boolean_label(To, _, Bool, _) -> {To,Bool}. - %% Replace a comparison operator with a test instruction and a jump. %% For example, if we have this code: %% @@ -463,8 +469,8 @@ count_bits_matched([{test,_,_,_,[_,Sz,U,{field_flags,_}],_}|Is], SavePoint, Bits {integer,N} -> count_bits_matched(Is, SavePoint, Bits+N*U); _ -> count_bits_matched(Is, SavePoint, Bits) end; -count_bits_matched([{test,bs_match_string,_,[_,Bits,_]}|Is], SavePoint, Bits0) -> - count_bits_matched(Is, SavePoint, Bits0+Bits); +count_bits_matched([{test,bs_match_string,_,[_,Bs]}|Is], SavePoint, Bits) -> + count_bits_matched(Is, SavePoint, Bits+bit_size(Bs)); count_bits_matched([{test,_,_,_}|Is], SavePoint, Bits) -> count_bits_matched(Is, SavePoint, Bits); count_bits_matched([{bs_save2,Reg,SavePoint}|_], {Reg,SavePoint}, Bits) -> |