diff options
| -rw-r--r-- | lib/compiler/src/beam_dead.erl | 94 |
1 files changed, 15 insertions, 79 deletions
diff --git a/lib/compiler/src/beam_dead.erl b/lib/compiler/src/beam_dead.erl index eb5652b69a..1004f6048b 100644 --- a/lib/compiler/src/beam_dead.erl +++ b/lib/compiler/src/beam_dead.erl @@ -233,8 +233,7 @@ 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) -> List1 = shortcut_select_list(List0, Reg, D, []), - Fail1 = shortcut_label(Fail0, D), - Fail = shortcut_bs_test(Fail1, Is, D), + Fail = shortcut_label(Fail0, D), List = prune_redundant(List1, Fail), case List of [] -> @@ -304,9 +303,8 @@ backward([{test,bs_start_match2,F,Live,[Src,_]=Args,Ctxt}|Is], D, Acc0) -> backward(Is, D, [I|Acc0]) end; backward([{test,Op,{f,To0},Ops0}|Is], D, Acc) -> - To1 = shortcut_bs_test(To0, Is, D), - To2 = shortcut_label(To1, D), - To3 = shortcut_rel_op(To2, Op, Ops0, D), + To1 = shortcut_label(To0, D), + To2 = shortcut_rel_op(To1, Op, Ops0, D), %% Try to shortcut a repeated test: %% @@ -314,14 +312,14 @@ backward([{test,Op,{f,To0},Ops0}|Is], D, Acc) -> %% . . . ==> ... %% Fail1: test Op {f,Fail2} Operands Fail1: test Op {f,Fail2} Operands %% - To = case beam_utils:code_at(To3, D) of - [{test,Op,{f,To4},Ops}|_] -> + To = case beam_utils:code_at(To2, D) of + [{test,Op,{f,To3},Ops}|_] -> case equal_ops(Ops0, Ops) of - true -> To4; - false -> To3 + true -> To3; + false -> To2 end; _Code -> - To3 + To2 end, I = case Op of is_eq_exact -> combine_eqs(To, Ops0, D, Acc); @@ -350,22 +348,22 @@ backward([{test,Op,{f,To0},Ops0}|Is], D, Acc) -> 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), + To1 = shortcut_label(To0, D), + %% Try to shortcut a repeated test: %% %% test Op {f,Fail1} _ Ops _ test Op {f,Fail2} _ Ops _ %% . . . ==> ... %% Fail1: test Op {f,Fail2} _ Ops _ Fail1: test Op {f,Fail2} _ Ops _ %% - To = case beam_utils:code_at(To2, D) of - [{test,Op,{f,To3},_,Ops,_}|_] -> + To = case beam_utils:code_at(To1, D) of + [{test,Op,{f,To2},_,Ops,_}|_] -> case equal_ops(Ops0, Ops) of - true -> To3; - false -> To2 + true -> To2; + false -> To1 end; _Code -> - To2 + To1 end, I = {test,Op,{f,To},Live,Ops0,Dst}, backward(Is, D, [I|Acc]); @@ -538,68 +536,6 @@ test_bs_literal_1(Ctxt, Is, D, Literal) -> false -> not_killed end. -%% shortcut_bs_test(TargetLabel, ReversedInstructions, D) -> TargetLabel' -%% Try to shortcut the failure label for bit syntax matching. - -shortcut_bs_test(To, Is, D) -> - shortcut_bs_test_1(beam_utils:code_at(To, D), Is, To, D). - -shortcut_bs_test_1([{bs_restore2,Reg,SavePoint}, - {label,_}, - {test,bs_test_tail2,{f,To},[_,TailBits]}|_], - PrevIs, To0, D) -> - case count_bits_matched(PrevIs, {Reg,SavePoint}, 0) of - Bits when Bits > TailBits -> - %% This instruction will fail. We know because a restore has been - %% done from the previous point SavePoint in the binary, and we - %% also know that the binary contains at least Bits bits from - %% SavePoint. - %% - %% Since we will skip a bs_restore2 if we shortcut to label To, - %% we must now make sure that code at To does not depend on - %% the position in the context in any way. - case shortcut_bs_pos_used(To, Reg, D) of - false -> To; - true -> To0 - end; - _Bits -> - To0 - end; -shortcut_bs_test_1([_|_], _, To, _) -> To. - -%% counts_bits_matched(ReversedInstructions, SavePoint, Bits) -> Bits' -%% Given a reversed instruction stream, determine the minimum number -%% of bits that will be matched by bit syntax instructions up to the -%% given save point. - -count_bits_matched([{test,bs_get_utf8,{f,_},_,_,_}|Is], SavePoint, Bits) -> - count_bits_matched(Is, SavePoint, Bits+8); -count_bits_matched([{test,bs_get_utf16,{f,_},_,_,_}|Is], SavePoint, Bits) -> - count_bits_matched(Is, SavePoint, Bits+16); -count_bits_matched([{test,bs_get_utf32,{f,_},_,_,_}|Is], SavePoint, Bits) -> - count_bits_matched(Is, SavePoint, Bits+32); -count_bits_matched([{test,_,_,_,[_,Sz,U,{field_flags,_}],_}|Is], SavePoint, Bits) -> - case Sz of - {integer,N} -> count_bits_matched(Is, SavePoint, Bits+N*U); - _ -> count_bits_matched(Is, SavePoint, Bits) - end; -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) -> - %% The save point we are looking for - we are done. - Bits; -count_bits_matched([_|_], _, Bits) -> Bits. - -shortcut_bs_pos_used(To, Reg, D) -> - shortcut_bs_pos_used_1(beam_utils:code_at(To, D), Reg, D). - -shortcut_bs_pos_used_1([{bs_context_to_binary,Reg}|_], Reg, _) -> - false; -shortcut_bs_pos_used_1(Is, Reg, D) -> - not beam_utils:is_killed(Reg, Is, D). - %% shortcut_bs_start_match(TargetLabel, Reg) -> TargetLabel %% A failing bs_start_match2 instruction means that the source (Reg) %% cannot be a binary. That means that it is safe to skip |