diff options
Diffstat (limited to 'lib/compiler/src/beam_dead.erl')
| -rw-r--r-- | lib/compiler/src/beam_dead.erl | 49 |
1 files changed, 33 insertions, 16 deletions
diff --git a/lib/compiler/src/beam_dead.erl b/lib/compiler/src/beam_dead.erl index da944f3ce6..dbbaae05eb 100644 --- a/lib/compiler/src/beam_dead.erl +++ b/lib/compiler/src/beam_dead.erl @@ -294,24 +294,25 @@ backward([{jump,{f,To}}=J|[{gc_bif,_,{f,To},_,_,_Dst}|Is]], D, Acc) -> %% register is initialized, and it is therefore no need to test %% for liveness of the destination register at label To. backward([J|Is], D, Acc); -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) -> +backward([{test,bs_start_match2,F,Live,[Src,_]=Args,Ctxt}|Is], D, Acc0) -> {f,To0} = F, - case beam_utils:is_killed(Ctxt, Acc0, D) of - true -> - To = shortcut_bs_context_to_binary(To0, R, D), - Eq = {test,is_eq_exact,{f,To},[R,{literal,Bs}]}, - backward(Is, D, [Eq|Acc0]); - false -> - To = shortcut_bs_start_match(To0, R, D), - I = {test,bs_start_match2,{f,To},Live,Args,Ctxt}, - backward(Is, D, [I|Acc]) + case test_bs_literal(F, Ctxt, D, Acc0) of + {none,Acc} -> + %% Ctxt killed immediately after bs_start_match2. + To = shortcut_bs_context_to_binary(To0, Src, D), + I = {test,is_bitstr,{f,To},[Src]}, + backward(Is, D, [I|Acc]); + {Literal,Acc} -> + %% Ctxt killed after matching a literal. + To = shortcut_bs_context_to_binary(To0, Src, D), + Eq = {test,is_eq_exact,{f,To},[Src,{literal,Literal}]}, + backward(Is, D, [Eq|Acc]); + not_killed -> + %% Ctxt not killed. Not much to do. + To = shortcut_bs_start_match(To0, Src, D), + I = {test,bs_start_match2,{f,To},Live,Args,Ctxt}, + backward(Is, D, [I|Acc0]) 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}, - backward(Is, D, [I|Acc]); backward([{test,Op,{f,To0},Ops0}|Is], D, Acc) -> To1 = shortcut_bs_test(To0, Is, D), To2 = shortcut_label(To1, D), @@ -511,6 +512,22 @@ remove_from_list(Lit, [Val,{f,_}=Fail|T]) -> [Val,Fail|remove_from_list(Lit, T)]; remove_from_list(_, []) -> []. + +test_bs_literal(F, Ctxt, D, + [{test,bs_match_string,F,[Ctxt,Bs]}, + {test,bs_test_tail2,F,[Ctxt,0]}|Acc]) -> + test_bs_literal_1(Ctxt, Acc, D, Bs); +test_bs_literal(F, Ctxt, D, [{test,bs_test_tail2,F,[Ctxt,0]}|Acc]) -> + test_bs_literal_1(Ctxt, Acc, D, <<>>); +test_bs_literal(_, Ctxt, D, Acc) -> + test_bs_literal_1(Ctxt, Acc, D, none). + +test_bs_literal_1(Ctxt, Is, D, Literal) -> + case beam_utils:is_killed(Ctxt, Is, D) of + true -> {Literal,Is}; + false -> not_killed + end. + %% shortcut_bs_test(TargetLabel, ReversedInstructions, D) -> TargetLabel' %% Try to shortcut the failure label for bit syntax matching. |