diff options
| -rw-r--r-- | lib/compiler/src/beam_block.erl | 10 | ||||
| -rw-r--r-- | lib/compiler/src/beam_utils.erl | 24 |
2 files changed, 26 insertions, 8 deletions
diff --git a/lib/compiler/src/beam_block.erl b/lib/compiler/src/beam_block.erl index 9543aa1355..7183381334 100644 --- a/lib/compiler/src/beam_block.erl +++ b/lib/compiler/src/beam_block.erl @@ -206,7 +206,7 @@ move_allocates([]) -> []. move_allocates_1([{'%anno',_}|Is], Acc) -> move_allocates_1(Is, Acc); -move_allocates_1([I|Is], [{set,[],[],{alloc,Live0,Info}}|Acc]=Acc0) -> +move_allocates_1([I|Is], [{set,[],[],{alloc,Live0,Info0}}|Acc]=Acc0) -> case alloc_may_pass(I) of false -> move_allocates_1(Is, [I|Acc0]); @@ -215,6 +215,7 @@ move_allocates_1([I|Is], [{set,[],[],{alloc,Live0,Info}}|Acc]=Acc0) -> not_possible -> move_allocates_1(Is, [I|Acc0]); Live when is_integer(Live) -> + Info = safe_info(Info0), A = {set,[],[],{alloc,Live,Info}}, move_allocates_1(Is, [A,I|Acc]) end @@ -230,6 +231,13 @@ alloc_may_pass({set,_,_,put_list}) -> false; alloc_may_pass({set,_,_,put}) -> false; alloc_may_pass({set,_,_,_}) -> true. +safe_info({nozero,Stack,Heap,_}) -> + %% nozero is not safe if the allocation instruction is moved + %% upwards past an instruction that may throw an exception + %% (such as element/2). + {zero,Stack,Heap,[]}; +safe_info(Info) -> Info. + %% opt([Instruction]) -> [Instruction] %% Optimize the instruction stream inside a basic block. diff --git a/lib/compiler/src/beam_utils.erl b/lib/compiler/src/beam_utils.erl index 4dcce30583..a57dbbbc2f 100644 --- a/lib/compiler/src/beam_utils.erl +++ b/lib/compiler/src/beam_utils.erl @@ -440,8 +440,11 @@ check_liveness(R, [{bs_init,_,_,Live,Ss,Dst}|Is], St) -> case member(R, Ss) of true -> {used,St}; false -> + %% If the exception is taken, the stack may + %% be scanned. Therefore the register is not + %% guaranteed to be killed. if - R =:= Dst -> {killed,St}; + R =:= Dst -> {not_used,St}; true -> not_used(check_liveness(R, Is, St)) end end @@ -735,8 +738,8 @@ check_liveness_block_1(R, Ss, Ds, Op, Is, St0) -> end end. -check_liveness_block_2(R, {gc_bif,_Op,{f,Lbl}}, _Ss, St) -> - check_liveness_block_3(R, Lbl, St); +check_liveness_block_2(R, {gc_bif,Op,{f,Lbl}}, Ss, St) -> + check_liveness_block_3(R, Lbl, {Op,length(Ss)}, St); check_liveness_block_2(R, {bif,Op,{f,Lbl}}, Ss, St) -> Arity = length(Ss), case erl_internal:comp_op(Op, Arity) orelse @@ -744,16 +747,23 @@ check_liveness_block_2(R, {bif,Op,{f,Lbl}}, Ss, St) -> true -> {killed,St}; false -> - check_liveness_block_3(R, Lbl, St) + check_liveness_block_3(R, Lbl, {Op,length(Ss)}, St) end; check_liveness_block_2(R, {put_map,_Op,{f,Lbl}}, _Ss, St) -> - check_liveness_block_3(R, Lbl, St); + check_liveness_block_3(R, Lbl, {unsafe,0}, St); check_liveness_block_2(_, _, _, St) -> {killed,St}. -check_liveness_block_3(_, 0, St) -> +check_liveness_block_3({x,_}, 0, _FA, St) -> {killed,St}; -check_liveness_block_3(R, Lbl, St0) -> +check_liveness_block_3({y,_}, 0, {F,A}, St) -> + %% If the exception is thrown, the stack may be scanned, + %% thus implicitly using the y register. + case erl_bifs:is_safe(erlang, F, A) of + true -> {killed,St}; + false -> {used,St} + end; +check_liveness_block_3(R, Lbl, _FA, St0) -> check_liveness_at(R, Lbl, St0). index_labels_1([{label,Lbl}|Is0], Acc) -> |