From 94517048c3dad66c6c6469088d174cefcbbdb552 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= Date: Wed, 31 Oct 2018 13:07:56 +0100 Subject: Fix bug when beam_jump removes put_tuple instructions `beam_jump` could remove a `put_tuple` instruction when the tuple would not be used, but it would leave the following `put` instructions. Make sure they are removed. https://bugs.erlang.org/browse/ERL-759 --- lib/compiler/src/beam_jump.erl | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) (limited to 'lib/compiler/src') diff --git a/lib/compiler/src/beam_jump.erl b/lib/compiler/src/beam_jump.erl index 9eee56d604..22974da398 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, [reverse/1,reverse/2,foldl/3]). +-import(lists, [dropwhile/2,reverse/1,reverse/2,foldl/3]). -type instruction() :: beam_utils:instruction(). @@ -411,14 +411,19 @@ opt_useless_loads([{test,_,{f,L},_}=I|Is], L, St) -> opt_useless_loads(Is, _L, St) -> {Is,St}. -opt_useless_block_loads([{set,[Dst],_,_}=I|Is], L, Index) -> - BlockJump = [{block,Is},{jump,{f,L}}], +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 + %% 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(Is, L, Index)] + [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)]; -- cgit v1.2.3