diff options
Diffstat (limited to 'lib/compiler/src/beam_dead.erl')
| -rw-r--r-- | lib/compiler/src/beam_dead.erl | 24 |
1 files changed, 10 insertions, 14 deletions
diff --git a/lib/compiler/src/beam_dead.erl b/lib/compiler/src/beam_dead.erl index 7cd07dc3be..f4515ba2a7 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]); @@ -330,16 +336,6 @@ 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: %% |