diff options
| -rw-r--r-- | lib/compiler/src/beam_jump.erl | 58 |
1 files changed, 5 insertions, 53 deletions
diff --git a/lib/compiler/src/beam_jump.erl b/lib/compiler/src/beam_jump.erl index 40a2211325..d3a618d211 100644 --- a/lib/compiler/src/beam_jump.erl +++ b/lib/compiler/src/beam_jump.erl @@ -128,7 +128,7 @@ %%% on the program state. %%% --import(lists, [dropwhile/2,foldl/3,mapfoldl/3,reverse/1,reverse/2]). +-import(lists, [foldl/3,mapfoldl/3,reverse/1,reverse/2]). -type instruction() :: beam_utils:instruction(). @@ -410,7 +410,7 @@ find_fixpoint(OptFun, Is0) -> Is -> find_fixpoint(OptFun, Is) end. -opt([{test,_,{f,L}=Lbl,_}=I|[{jump,{f,L}}|_]=Is], Acc0, St0) -> +opt([{test,_,{f,L}=Lbl,_}=I|[{jump,{f,L}}|_]=Is], Acc, St) -> %% We have %% Test Label Ops %% jump Label @@ -419,23 +419,20 @@ opt([{test,_,{f,L}=Lbl,_}=I|[{jump,{f,L}}|_]=Is], Acc0, St0) -> case beam_utils:is_pure_test(I) of false -> %% Test is not pure; we must keep it. - opt(Is, [I|Acc0], label_used(Lbl, St0)); + 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. - %% Check if any of the previous instructions could also be eliminated. - {Acc,St} = opt_useless_loads(Acc0, L, St0), opt(Is, Acc, St) end; -opt([{test,_,{f,L}=Lbl,_}=I|[{label,L}|_]=Is], Acc0, St0) -> +opt([{test,_,{f,L}=Lbl,_}=I|[{label,L}|_]=Is], Acc, St) -> %% Similar to the above, except we have a fall-through rather than jump %% Test Label Ops %% label Label case beam_utils:is_pure_test(I) of false -> - opt(Is, [I|Acc0], label_used(Lbl, St0)); + opt(Is, [I|Acc], label_used(Lbl, St)); true -> - {Acc,St} = opt_useless_loads(Acc0, L, St0), opt(Is, Acc, St) end; opt([{test,Test0,{f,L}=Lbl,Ops}=I|[{jump,To}|Is]=Is0], Acc, St) -> @@ -502,51 +499,6 @@ normalize_replace([{From,To0}|Rest], Replace, Acc) -> normalize_replace([], _Replace, Acc) -> maps:from_list(Acc). -%% After eliminating a test, it might happen, that a register was only used -%% in this test. Let's check if that was the case and if it was so, we can -%% eliminate the load into the register completely. -opt_useless_loads([{block,_}|_]=Is, L, #st{index={lazy,FIs}}=St) -> - opt_useless_loads(Is, L, St#st{index=beam_utils:index_labels(FIs)}); -opt_useless_loads([{block,Block0}|Is], L, #st{index=Index}=St) -> - case opt_useless_block_loads(Block0, L, Index) of - [] -> - opt_useless_loads(Is, L, St); - [_|_]=Block -> - {[{block,Block}|Is],St} - end; -%% After eliminating the test and useless blocks, it might happen, -%% that the previous test could also be eliminated. -%% It might be that the label was already marked as used, even if ultimately, -%% it never will be - we can't do much about it at that point, though -opt_useless_loads([{test,_,{f,L},_}=I|Is], L, St) -> - case beam_utils:is_pure_test(I) of - false -> - {[I|Is],St}; - true -> - opt_useless_loads(Is, L, St) - end; -opt_useless_loads(Is, _L, St) -> - {Is,St}. - -opt_useless_block_loads([{set,[Dst],_,_}=I|Is0], L, Index) -> - BlockJump = [{block,Is0},{jump,{f,L}}], - case beam_utils:is_killed(Dst, BlockJump, Index) of - true -> - %% The register is killed and not used, we can remove the load. - %% Remove any `put` instructions in case we just - %% removed a `put_tuple` instruction. - Is = dropwhile(fun({set,_,_,put}) -> true; - (_) -> false - end, Is0), - opt_useless_block_loads(Is, L, Index); - false -> - [I|opt_useless_block_loads(Is0, L, Index)] - end; -opt_useless_block_loads([I|Is], L, Index) -> - [I|opt_useless_block_loads(Is, L, Index)]; -opt_useless_block_loads([], _L, _Index) -> - []. - collect_labels(Is, Label, #st{entry=Entry,replace=Replace} = St) -> collect_labels_1(Is, Label, Entry, Replace, St). |