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authorBjörn Gustavsson <[email protected]>2018-10-31 13:07:56 +0100
committerBjörn Gustavsson <[email protected]>2018-10-31 13:18:42 +0100
commit94517048c3dad66c6c6469088d174cefcbbdb552 (patch)
tree5e56189b9fd8ed7fb6e9d542feb23fdd621b494a /lib/compiler/src
parent3094642858ec071f9e98cfa666b82e06648b5266 (diff)
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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
Diffstat (limited to 'lib/compiler/src')
-rw-r--r--lib/compiler/src/beam_jump.erl15
1 files changed, 10 insertions, 5 deletions
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)];