diff options
Diffstat (limited to 'lib/compiler/src/beam_dead.erl')
| -rw-r--r-- | lib/compiler/src/beam_dead.erl | 57 |
1 files changed, 51 insertions, 6 deletions
diff --git a/lib/compiler/src/beam_dead.erl b/lib/compiler/src/beam_dead.erl index ead88b57e9..11129c39bc 100644 --- a/lib/compiler/src/beam_dead.erl +++ b/lib/compiler/src/beam_dead.erl @@ -239,11 +239,26 @@ backward([{test,is_eq_exact,Fail,[Dst,{integer,Arity}]}=I| backward([{label,Lbl}=L|Is], D, Acc) -> backward(Is, beam_utils:index_label(Lbl, Acc, D), [L|Acc]); backward([{select,select_val,Reg,{f,Fail0},List0}|Is], D, Acc) -> - List = shortcut_select_list(List0, Reg, D, []), + List1 = shortcut_select_list(List0, Reg, D, []), Fail1 = shortcut_label(Fail0, D), Fail = shortcut_bs_test(Fail1, Is, D), - Sel = {select,select_val,Reg,{f,Fail},List}, - backward(Is, D, [Sel|Acc]); + List = prune_redundant(List1, Fail), + case List of + [] -> + Jump = {jump,{f,Fail}}, + backward([Jump|Is], D, Acc); + [V,F] -> + Test = {test,is_eq_exact,{f,Fail},[Reg,V]}, + Jump = {jump,F}, + backward([Jump,Test|Is], D, Acc); + [{atom,B1},F,{atom,B2},F] when B1 =:= not B2 -> + Test = {test,is_boolean,{f,Fail},[Reg]}, + Jump = {jump,F}, + backward([Jump,Test|Is], D, Acc); + [_|_] -> + Sel = {select,select_val,Reg,{f,Fail},List}, + backward(Is, D, [Sel|Acc]) + end; backward([{jump,{f,To0}},{move,Src,Reg}=Move|Is], D, Acc) -> To = shortcut_select_label(To0, Reg, Src, D), Jump = {jump,{f,To}}, @@ -257,14 +272,17 @@ 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, +backward([{test,bs_start_match2,F,Live,[R,_]=Args,Ctxt}|Is], D, [{test,bs_match_string,F,[Ctxt,Bs]}, {test,bs_test_tail2,F,[Ctxt,0]}|Acc0]=Acc) -> + {f,To0} = F, + To = shortcut_bs_start_match(To0, R, D), case beam_utils:is_killed(Ctxt, Acc0, D) of true -> - Eq = {test,is_eq_exact,F,[R,{literal,Bs}]}, + Eq = {test,is_eq_exact,{f,To},[R,{literal,Bs}]}, backward(Is, D, [Eq|Acc0]); false -> + I = {test,bs_start_match2,{f,To},Live,Args,Ctxt}, backward(Is, D, [I|Acc]) end; backward([{test,bs_start_match2,{f,To0},Live,[Src|_]=Info,Dst}|Is], D, Acc) -> @@ -295,7 +313,28 @@ backward([{test,Op,{f,To0},Ops0}|Is], D, Acc) -> is_eq_exact -> combine_eqs(To, Ops0, D, Acc); _ -> {test,Op,{f,To},Ops0} end, - backward(Is, D, [I|Acc]); + case {I,Acc} of + {{test,is_atom,Fail,Ops0},[{test,is_boolean,Fail,Ops0}|_]} -> + %% An is_atom test before an is_boolean test (with the + %% same failure label) is redundant. + backward(Is, D, Acc); + {{test,is_atom,Fail,[R]}, + [{test,is_eq_exact,Fail,[R,{atom,_}]}|_]} -> + %% An is_atom test before a comparison with an atom (with + %% the same failure label) is redundant. + backward(Is, D, Acc); + {{test,is_integer,Fail,[R]}, + [{test,is_eq_exact,Fail,[R,{integer,_}]}|_]} -> + %% An is_integer test before a comparison with an integer + %% (with the same failure label) is redundant. + backward(Is, D, Acc); + {{test,_,_,_},_} -> + %% Still a test instruction. Done. + backward(Is, D, [I|Acc]); + {_,_} -> + %% Rewritten to a select_val. Rescan. + backward([I|Is], D, Acc) + end; backward([{test,Op,{f,To0},Live,Ops0,Dst}|Is], D, Acc) -> To1 = shortcut_bs_test(To0, Is, D), To2 = shortcut_label(To1, D), @@ -348,6 +387,12 @@ shortcut_label(To0, D) -> shortcut_select_label(To, Reg, Lit, D) -> shortcut_rel_op(To, is_ne_exact, [Reg,Lit], D). +prune_redundant([_,{f,Fail}|T], Fail) -> + prune_redundant(T, Fail); +prune_redundant([V,F|T], Fail) -> + [V,F|prune_redundant(T, Fail)]; +prune_redundant([], _) -> []. + %% Replace a comparison operator with a test instruction and a jump. %% For example, if we have this code: %% |