diff options
Diffstat (limited to 'lib/compiler/src/beam_dead.erl')
| -rw-r--r-- | lib/compiler/src/beam_dead.erl | 26 |
1 files changed, 25 insertions, 1 deletions
diff --git a/lib/compiler/src/beam_dead.erl b/lib/compiler/src/beam_dead.erl index 0cb5040177..fcd108bd89 100644 --- a/lib/compiler/src/beam_dead.erl +++ b/lib/compiler/src/beam_dead.erl @@ -239,10 +239,18 @@ 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), + 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}, @@ -307,6 +315,16 @@ backward([{test,Op,{f,To0},Ops0}|Is], D, Acc) -> %% 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]); @@ -366,6 +384,12 @@ 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: %% |