diff options
| -rw-r--r-- | lib/compiler/src/beam_block.erl | 53 |
1 files changed, 38 insertions, 15 deletions
diff --git a/lib/compiler/src/beam_block.erl b/lib/compiler/src/beam_block.erl index 39ae8d5347..7f6d3a75ae 100644 --- a/lib/compiler/src/beam_block.erl +++ b/lib/compiler/src/beam_block.erl @@ -289,7 +289,7 @@ opt_move(Dest, Is) -> opt_move_1(R, [{set,[D],[R],move}|Is0], Acc) -> %% Provided that the source register is killed by instructions %% that follow, the optimization is safe. - case eliminate_use_of_from_reg(Is0, R, D, []) of + case eliminate_use_of_from_reg(Is0, R, D) of {yes,Is} -> opt_move_rev(D, Acc, Is); no -> not_possible end; @@ -347,7 +347,7 @@ opt_tuple_element_1([{set,_,_,{alloc,_,_}}|_], _, _, _) -> opt_tuple_element_1([{set,_,_,{try_catch,_,_}}|_], _, _, _) -> no; opt_tuple_element_1([{set,[D],[S],move}|Is0], I0, {_,S}, Acc) -> - case eliminate_use_of_from_reg(Is0, S, D, []) of + case eliminate_use_of_from_reg(Is0, S, D) of no -> no; {yes,Is} -> @@ -389,6 +389,14 @@ is_killed_or_used(R, {set,Ss,Ds,_}) -> %% that FromRegister is still used and that the optimization is not %% possible. +eliminate_use_of_from_reg(Is, From, To) -> + try + eliminate_use_of_from_reg(Is, From, To, []) + catch + throw:not_possible -> + no + end. + eliminate_use_of_from_reg([{set,_,_,{alloc,Live,_}}|_]=Is0, {x,X}, _, Acc) -> if X < Live -> @@ -397,21 +405,32 @@ eliminate_use_of_from_reg([{set,_,_,{alloc,Live,_}}|_]=Is0, {x,X}, _, Acc) -> {yes,reverse(Acc, Is0)} end; eliminate_use_of_from_reg([{set,Ds,Ss0,Op}=I0|Is], From, To, Acc) -> + ensure_safe_tuple(I0, To), I = case member(From, Ss0) of - true -> - Ss = [case S of - From -> To; - _ -> S - end || S <- Ss0], - {set,Ds,Ss,Op}; - false -> - I0 - end, + true -> + Ss = [case S of + From -> To; + _ -> S + end || S <- Ss0], + {set,Ds,Ss,Op}; + false -> + I0 + end, case member(From, Ds) of - true -> - {yes,reverse(Acc, [I|Is])}; - false -> - eliminate_use_of_from_reg(Is, From, To, [I|Acc]) + true -> + {yes,reverse(Acc, [I|Is])}; + false -> + case member(To, Ds) of + true -> + case beam_utils:is_killed_block(From, Is) of + true -> + {yes,reverse(Acc, [I|Is])}; + false -> + no + end; + false -> + eliminate_use_of_from_reg(Is, From, To, [I|Acc]) + end end; eliminate_use_of_from_reg([I]=Is, From, _To, Acc) -> case beam_utils:is_killed_block(From, [I]) of @@ -421,6 +440,10 @@ eliminate_use_of_from_reg([I]=Is, From, _To, Acc) -> no end. +ensure_safe_tuple({set,[To],[],{put_tuple,_}}, To) -> + throw(not_possible); +ensure_safe_tuple(_, _) -> ok. + %% opt_allocs(Instructions) -> Instructions. Optimize allocate %% instructions inside blocks. If safe, replace an allocate_zero %% instruction with the slightly cheaper allocate instruction. |