diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/compiler/src/beam_block.erl | 53 |
1 files changed, 52 insertions, 1 deletions
diff --git a/lib/compiler/src/beam_block.erl b/lib/compiler/src/beam_block.erl index af1bf8fd08..49e66b379b 100644 --- a/lib/compiler/src/beam_block.erl +++ b/lib/compiler/src/beam_block.erl @@ -183,7 +183,9 @@ opt_blocks([I|Is]) -> opt_blocks([]) -> []. opt_block(Is0) -> - Is = find_fixpoint(fun opt/1, Is0), + Is = find_fixpoint(fun(Is) -> + opt_tuple_element(opt(Is)) + end, Is0), opt_alloc(Is). find_fixpoint(OptFun, Is0) -> @@ -315,6 +317,55 @@ opt_move_1(R, [{set,_,_,_}=I|Is], Acc) -> opt_move_1(_, _, _) -> not_possible. +%% opt_tuple_element([Instruction]) -> [Instruction] +%% If possible, move get_tuple_element instructions forward +%% in the instruction stream to a move instruction, eliminating +%% the move instruction. Example: +%% +%% get_tuple_element Tuple Pos Dst1 +%% ... +%% move Dst1 Dst2 +%% +%% This code may be possible to rewrite to: +%% +%% %%(Moved get_tuple_element instruction) +%% ... +%% get_tuple_element Tuple Pos Dst2 +%% + +opt_tuple_element([{set,[D],[S],{get_tuple_element,_}}=I|Is0]) -> + case opt_tuple_element_1(Is0, I, {S,D}, []) of + no -> + [I|opt_tuple_element(Is0)]; + {yes,Is} -> + opt_tuple_element(Is) + end; +opt_tuple_element([I|Is]) -> + [I|opt_tuple_element(Is)]; +opt_tuple_element([]) -> []. + +opt_tuple_element_1([{set,_,_,{alloc,_,_}}|_], _, _, _) -> + no; +opt_tuple_element_1([{set,_,_,{'catch',_}}|_], _, _, _) -> + no; +opt_tuple_element_1([{set,[D],[S],move}|Is0], I0, {_,S}, Acc) -> + case eliminate_use_of_from_reg(Is0, S, D, []) of + no -> + no; + {yes,Is} -> + {set,[S],Ss,Op} = I0, + I = {set,[D],Ss,Op}, + {yes,reverse(Acc, [I|Is])} + end; +opt_tuple_element_1([{set,Ds,Ss,_}=I|Is], MovedI, {S,D}=Regs, Acc) -> + case member(S, Ds) orelse member(D, Ss) of + true -> + no; + false -> + opt_tuple_element_1(Is, MovedI, Regs, [I|Acc]) + end; +opt_tuple_element_1(_, _, _, _) -> no. + %% Reverse the instructions, while checking that there are no %% instructions that would interfere with using the new destination %% register (D). |