diff options
| -rw-r--r-- | lib/compiler/src/beam_jump.erl | 58 |
1 files changed, 28 insertions, 30 deletions
diff --git a/lib/compiler/src/beam_jump.erl b/lib/compiler/src/beam_jump.erl index db67d24514..79cdc8e179 100644 --- a/lib/compiler/src/beam_jump.erl +++ b/lib/compiler/src/beam_jump.erl @@ -260,38 +260,36 @@ find_fixpoint(OptFun, Is0) -> Is -> find_fixpoint(OptFun, Is) end. -opt([{test,Test0,{f,Lnum}=Lbl,Ops}=I|Is0], Acc, St) -> - case Is0 of - [{jump,{f,Lnum}}|Is] -> - %% We have - %% Test Label Ops - %% jump Label - %% The test instruction is definitely not needed. - %% The jump instruction is not needed if there is - %% a definition of Label following the jump instruction. - case is_label_defined(Is, Lnum) of - false -> - %% The jump instruction is still needed. - opt(Is0, [I|Acc], label_used(Lbl, St)); - true -> - %% Neither the test nor the jump are needed. - opt(Is, Acc, St) - end; - [{jump,To}|Is] -> - case is_label_defined(Is, Lnum) of - false -> +opt([{test,_,{f,L}=Lbl,_}=I|[{jump,{f,L}}|_]=Is], Acc, St) -> + %% We have + %% Test Label Ops + %% jump Label + %% The test instruction is not needed if the test is pure + %% (it modifies neither registers nor bit syntax state). + case beam_utils:is_pure_test(I) of + false -> + %% Test is not pure; we must keep it. + opt(Is, [I|Acc], label_used(Lbl, St)); + true -> + %% The test is pure and its failure label is the same + %% as in the jump that follows -- thus it is not needed. + opt(Is, Acc, St) + end; +opt([{test,Test0,{f,L}=Lbl,Ops}=I|[{jump,To}|Is]=Is0], Acc, St) -> + case is_label_defined(Is, L) of + false -> + opt(Is0, [I|Acc], label_used(Lbl, St)); + true -> + case invert_test(Test0) of + not_possible -> opt(Is0, [I|Acc], label_used(Lbl, St)); - true -> - case invert_test(Test0) of - not_possible -> - opt(Is0, [I|Acc], label_used(Lbl, St)); - Test -> - opt([{test,Test,To,Ops}|Is], Acc, St) - end - end; - _Other -> - opt(Is0, [I|Acc], label_used(Lbl, St)) + Test -> + %% Invert the test and remove the jump. + opt([{test,Test,To,Ops}|Is], Acc, St) + end end; +opt([{test,_,{f,_}=Lbl,_}=I|Is], Acc, St) -> + opt(Is, [I|Acc], label_used(Lbl, St)); opt([{test,_,{f,_}=Lbl,_,_,_}=I|Is], Acc, St) -> opt(Is, [I|Acc], label_used(Lbl, St)); opt([{select_val,_R,Fail,{list,Vls}}=I|Is], Acc, St) -> |