diff options
Diffstat (limited to 'lib/compiler/src')
| -rw-r--r-- | lib/compiler/src/beam_dead.erl | 42 |
1 files changed, 24 insertions, 18 deletions
diff --git a/lib/compiler/src/beam_dead.erl b/lib/compiler/src/beam_dead.erl index 9c1c60a92e..aaad7f4095 100644 --- a/lib/compiler/src/beam_dead.erl +++ b/lib/compiler/src/beam_dead.erl @@ -453,31 +453,26 @@ remove_from_list(Lit, [Val,{f,_}=Fail|T]) -> [Val,Fail|remove_from_list(Lit, T)]; remove_from_list(_, []) -> []. -%% shortcut_bs_test(TargetLabel, [Instruction], D) -> TargetLabel' -%% Try to shortcut the failure label for a bit syntax matching. -%% We know that the binary contains at least Bits bits after -%% the latest save point. +%% 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}|Is], PrevIs, To, D) -> - shortcut_bs_test_2(Is, {Reg,SavePoint}, PrevIs, To, D); -shortcut_bs_test_1([_|_], _, To, _) -> To. - -shortcut_bs_test_2([{label,_}|Is], Save, PrevIs, To, D) -> - shortcut_bs_test_2(Is, Save, PrevIs, To, D); -shortcut_bs_test_2([{test,bs_test_tail2,{f,To},[_,TailBits]}|_], - {Reg,_Point} = RP, PrevIs, To0, D) -> - case count_bits_matched(PrevIs, RP, 0) of +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. + %% 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. + %% 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 @@ -485,8 +480,19 @@ shortcut_bs_test_2([{test,bs_test_tail2,{f,To},[_,TailBits]}|_], _Bits -> To0 end; -shortcut_bs_test_2([_|_], _, _, To, _) -> To. +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); |