diff options
Diffstat (limited to 'lib/compiler/src/beam_utils.erl')
| -rw-r--r-- | lib/compiler/src/beam_utils.erl | 409 |
1 files changed, 213 insertions, 196 deletions
diff --git a/lib/compiler/src/beam_utils.erl b/lib/compiler/src/beam_utils.erl index 249d9395ca..e39fbdc3b7 100644 --- a/lib/compiler/src/beam_utils.erl +++ b/lib/compiler/src/beam_utils.erl @@ -22,18 +22,37 @@ -module(beam_utils). -export([is_killed_block/2,is_killed/3,is_killed_at/3, - is_not_used/3,is_not_used_at/3, + is_not_used/3, empty_label_index/0,index_label/3,index_labels/1, code_at/2,bif_to_test/3,is_pure_test/1, live_opt/1,delete_live_annos/1,combine_heap_needs/2, split_even/1]). +-export_type([code_index/0,module_code/0,instruction/0]). + -import(lists, [member/2,sort/1,reverse/1,splitwith/2]). +%% instruction() describes all instructions that are used during optimzation +%% (from beam_a to beam_z). +-type instruction() :: atom() | tuple(). + +-type code_index() :: gb_trees:tree(beam_asm:label(), [instruction()]). + +-type int_function() :: {'function',beam_asm:function_name(),arity(), + beam_asm:label(),[instruction()]}. + +-type module_code() :: + {module(),[_],[_],[int_function()],pos_integer()}. + +%% Internal types. +-type fail() :: beam_asm:fail() | 'fail'. +-type test() :: {'test',atom(),fail(),[beam_asm:src()]} | + {'test',atom(),fail(),integer(),list(),beam_asm:reg()}. +-type result_cache() :: gb_trees:tree(beam_asm:label(), 'killed' | 'used'). + -record(live, - {bl, %Block check fun. - lbl, %Label to code index. - res}). %Result cache for each label. + {lbl :: code_index(), %Label to code index. + res :: result_cache()}). %Result cache for each label. %% is_killed_block(Register, [Instruction]) -> true|false @@ -45,12 +64,18 @@ %% i.e. it is OK to enter the instruction sequence with Register %% containing garbage. -is_killed_block(R, Is) -> - case check_killed_block(R, Is) of - killed -> true; - used -> false; - transparent -> false - end. +-spec is_killed_block(beam_asm:reg(), [instruction()]) -> boolean(). + +is_killed_block({x,X}, [{set,_,_,{alloc,Live,_}}|_]) -> + X >= Live; +is_killed_block(R, [{set,Ds,Ss,_Op}|Is]) -> + not member(R, Ss) andalso (member(R, Ds) orelse is_killed_block(R, Is)); +is_killed_block(R, [{'%live',_,Regs}|Is]) -> + case R of + {x,X} when (Regs bsr X) band 1 =:= 0 -> true; + _ -> is_killed_block(R, Is) + end; +is_killed_block(_, []) -> false. %% is_killed(Register, [Instruction], State) -> true|false %% Determine whether a register is killed by the instruction sequence. @@ -62,21 +87,25 @@ is_killed_block(R, Is) -> %% The state (constructed by index_instructions/1) is used to allow us %% to determine the kill state across branches. +-spec is_killed(beam_asm:reg(), [instruction()], code_index()) -> boolean(). + is_killed(R, Is, D) -> - St = #live{bl=check_killed_block_fun(),lbl=D,res=gb_trees:empty()}, + St = #live{lbl=D,res=gb_trees:empty()}, case check_liveness(R, Is, St) of {killed,_} -> true; - {used,_} -> false + {_,_} -> false end. %% is_killed_at(Reg, Lbl, State) -> true|false %% Determine whether Reg is killed at label Lbl. +-spec is_killed_at(beam_asm:reg(), beam_asm:label(), code_index()) -> boolean(). + is_killed_at(R, Lbl, D) when is_integer(Lbl) -> - St0 = #live{bl=check_killed_block_fun(),lbl=D,res=gb_trees:empty()}, + St0 = #live{lbl=D,res=gb_trees:empty()}, case check_liveness_at(R, Lbl, St0) of {killed,_} -> true; - {used,_} -> false + {_,_} -> false end. %% is_not_used(Register, [Instruction], State) -> true|false @@ -86,43 +115,38 @@ is_killed_at(R, Lbl, D) when is_integer(Lbl) -> %% The state is used to allow us to determine the usage state %% across branches. +-spec is_not_used(beam_asm:reg(), [instruction()], code_index()) -> boolean(). + is_not_used(R, Is, D) -> - St = #live{bl=fun check_used_block/3,lbl=D,res=gb_trees:empty()}, + St = #live{lbl=D,res=gb_trees:empty()}, case check_liveness(R, Is, St) of - {killed,_} -> true; - {used,_} -> false - end. - -%% is_not_used(Register, [Instruction], State) -> true|false -%% Determine whether a register is never used in the instruction sequence -%% (it could still be referenced by an allocate instruction, meaning that -%% it MUST be initialized, but that its value does not matter). -%% The state is used to allow us to determine the usage state -%% across branches. - -is_not_used_at(R, Lbl, D) -> - St = #live{bl=fun check_used_block/3,lbl=D,res=gb_trees:empty()}, - case check_liveness_at(R, Lbl, St) of - {killed,_} -> true; - {used,_} -> false + {used,_} -> false; + {_,_} -> true end. %% index_labels(FunctionIs) -> State %% Index the instruction sequence so that we can quickly %% look up the instruction following a specific label. +-spec index_labels([instruction()]) -> code_index(). + index_labels(Is) -> index_labels_1(Is, []). %% empty_label_index() -> State %% Create an empty label index. +-spec empty_label_index() -> code_index(). + empty_label_index() -> gb_trees:empty(). %% index_label(Label, [Instruction], State) -> State %% Add an index for a label. +-spec index_label(beam_asm:label(), [instruction()], code_index()) -> + code_index(). + index_label(Lbl, Is0, Acc) -> Is = drop_labels(Is0), gb_trees:enter(Lbl, Is, Acc). @@ -131,12 +155,16 @@ index_label(Lbl, Is0, Acc) -> %% code_at(Label, State) -> [I]. %% Retrieve the code at the given label. +-spec code_at(beam_asm:label(), code_index()) -> [instruction()]. + code_at(L, Ll) -> gb_trees:get(L, Ll). %% bif_to_test(Bif, [Op], Fail) -> {test,Test,Fail,[Op]} %% Convert a BIF to a test. Fail if not possible. +-spec bif_to_test(atom(), list(), fail()) -> test(). + bif_to_test(is_atom, [_]=Ops, Fail) -> {test,is_atom,Fail,Ops}; bif_to_test(is_boolean, [_]=Ops, Fail) -> {test,is_boolean,Fail,Ops}; bif_to_test(is_binary, [_]=Ops, Fail) -> {test,is_binary,Fail,Ops}; @@ -169,6 +197,9 @@ bif_to_test(is_record, [_,_,_]=Ops, Fail) -> {test,is_record,Fail,Ops}. %% Return 'true' if the test instruction does not modify any %% registers and/or bit syntax matching state. %% + +-spec is_pure_test(test()) -> boolean(). + is_pure_test({test,is_eq,_,[_,_]}) -> true; is_pure_test({test,is_ne,_,[_,_]}) -> true; is_pure_test({test,is_eq_exact,_,[_,_]}) -> true; @@ -191,7 +222,9 @@ is_pure_test({test,Op,_,Ops}) -> %% whose destination is a register that will not be used. %% Also insert {'%live',Live,Regs} annotations at the beginning %% and end of each block. -%% + +-spec live_opt([instruction()]) -> [instruction()]. + live_opt(Is0) -> {[{label,Fail}|_]=Bef,[Fi|Is]} = splitwith(fun({func_info,_,_,_}) -> false; @@ -204,7 +237,9 @@ live_opt(Is0) -> %% delete_live_annos([Instruction]) -> [Instruction]. %% Delete all live annotations. -%% + +-spec delete_live_annos([instruction()]) -> [instruction()]. + delete_live_annos([{block,Bl0}|Is]) -> case delete_live_annos(Bl0) of [] -> delete_live_annos(Is); @@ -219,6 +254,8 @@ delete_live_annos([]) -> []. %% combine_heap_needs(HeapNeed1, HeapNeed2) -> HeapNeed %% Combine the heap need for two allocation instructions. +-spec combine_heap_needs(term(), term()) -> term(). + combine_heap_needs({alloc,Alloc1}, {alloc,Alloc2}) -> {alloc,combine_alloc_lists(Alloc1, Alloc2)}; combine_heap_needs({alloc,Alloc}, Words) when is_integer(Words) -> @@ -231,6 +268,8 @@ combine_heap_needs(H1, H2) when is_integer(H1), is_integer(H2) -> %% split_even/1 %% [1,2,3,4,5,6] -> {[1,3,5],[2,4,6]} +-spec split_even(list()) -> {list(),list()}. + split_even(Rs) -> split_even(Rs, [], []). @@ -240,15 +279,19 @@ split_even(Rs) -> split_even(Rs, [], []). %% check_liveness(Reg, [Instruction], #live{}) -> -%% {killed | used, #live{}} +%% {killed | not_used | used, #live{}} %% Find out whether Reg is used or killed in instruction sequence. -%% 'killed' means that Reg is assigned a new value or killed by an -%% allocation instruction. 'used' means that Reg is used in some way. +%% +%% killed - Reg is assigned or killed by an allocation instruction. +%% not_used - the value of Reg is not used, but Reg must not be garbage +%% used - Reg is used -check_liveness(R, [{block,Blk}|Is], #live{bl=BlockCheck}=St0) -> - case BlockCheck(R, Blk, St0) of - {transparent,St} -> check_liveness(R, Is, St); - {Other,_}=Res when is_atom(Other) -> Res +check_liveness(R, [{block,Blk}|Is], St0) -> + case check_liveness_block(R, Blk, St0) of + {transparent,St1} -> + check_liveness(R, Is, St1); + {Other,_}=Res when is_atom(Other) -> + Res end; check_liveness(R, [{label,_}|Is], St) -> check_liveness(R, Is, St); @@ -258,8 +301,12 @@ check_liveness(R, [{test,_,{f,Fail},As}|Is], St0) -> {used,St0}; false -> case check_liveness_at(R, Fail, St0) of - {killed,St} -> check_liveness(R, Is, St); - {_,_}=Other -> Other + {killed,St1} -> + check_liveness(R, Is, St1); + {not_used,St1} -> + not_used(check_liveness(R, Is, St1)); + {used,_}=Used -> + Used end end; check_liveness(R, [{test,Op,Fail,Live,Ss,Dst}|Is], St) -> @@ -329,7 +376,7 @@ check_liveness(R, [{call,Live,_}|Is], St) -> case R of {x,X} when X < Live -> {used,St}; {x,_} -> {killed,St}; - {y,_} -> check_liveness(R, Is, St) + {y,_} -> not_used(check_liveness(R, Is, St)) end; check_liveness(R, [{call_ext,Live,_}=I|Is], St) -> case R of @@ -340,7 +387,7 @@ check_liveness(R, [{call_ext,Live,_}=I|Is], St) -> {y,_} -> case beam_jump:is_exit_instruction(I) of false -> - check_liveness(R, Is, St); + not_used(check_liveness(R, Is, St)); true -> %% We must make sure we don't check beyond this %% instruction or we will fall through into random @@ -352,43 +399,20 @@ check_liveness(R, [{call_fun,Live}|Is], St) -> case R of {x,X} when X =< Live -> {used,St}; {x,_} -> {killed,St}; - {y,_} -> check_liveness(R, Is, St) + {y,_} -> not_used(check_liveness(R, Is, St)) end; check_liveness(R, [{apply,Args}|Is], St) -> case R of {x,X} when X < Args+2 -> {used,St}; {x,_} -> {killed,St}; - {y,_} -> check_liveness(R, Is, St) - end; -check_liveness(R, [{bif,Op,{f,Fail},Ss,D}|Is], St0) -> - case check_liveness_fail(R, Op, Ss, Fail, St0) of - {killed,St} = Killed -> - case member(R, Ss) of - true -> {used,St}; - false when R =:= D -> Killed; - false -> check_liveness(R, Is, St) - end; - Other -> - Other - end; -check_liveness(R, [{gc_bif,Op,{f,Fail},Live,Ss,D}|Is], St0) -> - case R of - {x,X} when X >= Live -> - {killed,St0}; - {x,_} -> - {used,St0}; - _ -> - case check_liveness_fail(R, Op, Ss, Fail, St0) of - {killed,St}=Killed -> - case member(R, Ss) of - true -> {used,St}; - false when R =:= D -> Killed; - false -> check_liveness(R, Is, St) - end; - Other -> - Other - end - end; + {y,_} -> not_used(check_liveness(R, Is, St)) + end; +check_liveness(R, [{bif,Op,Fail,Ss,D}|Is], St) -> + Set = {set,[D],Ss,{bif,Op,Fail}}, + check_liveness(R, [{block,[Set]}|Is], St); +check_liveness(R, [{gc_bif,Op,{f,Fail},Live,Ss,D}|Is], St) -> + Set = {set,[D],Ss,{alloc,Live,{gc_bif,Op,Fail}}}, + check_liveness(R, [{block,[Set]}|Is], St); check_liveness(R, [{bs_put,{f,0},_,Ss}|Is], St) -> case member(R, Ss) of true -> {used,St}; @@ -414,7 +438,7 @@ check_liveness(R, [{make_fun2,_,_,_,NumFree}|Is], St) -> case R of {x,X} when X < NumFree -> {used,St}; {x,_} -> {killed,St}; - _ -> check_liveness(R, Is, St) + {y,_} -> not_used(check_liveness(R, Is, St)) end; check_liveness({x,_}=R, [{'catch',_,_}|Is], St) -> %% All x registers will be killed if an exception occurs. @@ -483,18 +507,9 @@ check_liveness(R, [{get_map_elements,{f,Fail},S,{list,L}}|Is], St0) -> Other end end; -check_liveness(R, [{put_map,{f,_},_,Src,_D,Live,{list,_}}|_], St0) -> - case R of - Src -> - {used,St0}; - {x,X} when X < Live -> - {used,St0}; - {x,_} -> - {killed,St0}; - {y,_} -> - %% Conservatively mark it as used. - {used,St0} - end; +check_liveness(R, [{put_map,F,Op,S,D,Live,{list,Puts}}|Is], St) -> + Set = {set,[D],[S|Puts],{alloc,Live,{put_map,Op,F}}}, + check_liveness(R, [{block,[Set]}||Is], St); check_liveness(R, [{test_heap,N,Live}|Is], St) -> I = {block,[{set,[],[],{alloc,Live,{nozero,nostack,N,[]}}}]}, check_liveness(R, [I|Is], St); @@ -507,16 +522,24 @@ check_liveness(R, [{get_list,S,D1,D2}|Is], St) -> check_liveness(_R, Is, St) when is_list(Is) -> %% Not implemented. Conservatively assume that the register is used. {used,St}. - -check_liveness_everywhere(R, [{f,Lbl}|T], St0) -> - case check_liveness_at(R, Lbl, St0) of - {killed,St} -> check_liveness_everywhere(R, T, St); - {_,_}=Other -> Other + +check_liveness_everywhere(R, Lbls, St0) -> + check_liveness_everywhere_1(R, Lbls, killed, St0). + +check_liveness_everywhere_1(R, [{f,Lbl}|T], Res0, St0) -> + {Res1,St} = check_liveness_at(R, Lbl, St0), + Res = case Res1 of + killed -> Res0; + _ -> Res1 + end, + case Res of + used -> {used,St}; + _ -> check_liveness_everywhere_1(R, T, Res, St) end; -check_liveness_everywhere(R, [_|T], St) -> - check_liveness_everywhere(R, T, St); -check_liveness_everywhere(_, [], St) -> - {killed,St}. +check_liveness_everywhere_1(R, [_|T], Res, St) -> + check_liveness_everywhere_1(R, T, Res, St); +check_liveness_everywhere_1(_, [], Res, St) -> + {Res,St}. check_liveness_at(R, Lbl, #live{lbl=Ll,res=ResMemorized}=St0) -> case gb_trees:lookup(Lbl, ResMemorized) of @@ -530,56 +553,20 @@ check_liveness_at(R, Lbl, #live{lbl=Ll,res=ResMemorized}=St0) -> {Res,St#live{res=gb_trees:insert(Lbl, Res, St#live.res)}} end. +not_used({killed,St}) -> {not_used,St}; +not_used({_,_}=Res) -> Res. + check_liveness_ret(R, R, St) -> {used,St}; check_liveness_ret(_, _, St) -> {killed,St}. -check_liveness_fail(_, _, _, 0, St) -> - {killed,St}; -check_liveness_fail(R, Op, Args, Fail, St) -> - Arity = length(Args), - case erl_internal:comp_op(Op, Arity) orelse - erl_internal:new_type_test(Op, Arity) of - true -> {killed,St}; - false -> check_liveness_at(R, Fail, St) - end. - -%% check_killed_block(Reg, [Instruction], State) -> killed | transparent | used -%% Finds out how Reg is used in the instruction sequence inside a block. -%% Returns one of: -%% killed - Reg is assigned a new value or killed by an allocation instruction -%% transparent - Reg is neither used nor killed -%% used - Reg is used or referenced by an allocation instruction. -%% -%% (Unknown instructions will cause an exception.) - -check_killed_block_fun() -> - fun(R, Is, St) -> {check_killed_block(R, Is),St} end. - -check_killed_block({x,X}, [{set,_,_,{alloc,Live,_}}|_]) -> - if - X >= Live -> killed; - true -> used - end; -check_killed_block(R, [{set,Ds,Ss,_Op}|Is]) -> - case member(R, Ss) of - true -> used; - false -> - case member(R, Ds) of - true -> killed; - false -> check_killed_block(R, Is) - end - end; -check_killed_block(R, [{'%live',_,Regs}|Is]) -> - case R of - {x,X} when (Regs bsr X) band 1 =:= 0 -> killed; - _ -> check_killed_block(R, Is) - end; -check_killed_block(_, []) -> transparent. - -%% check_used_block(Reg, [Instruction], State) -> killed | transparent | used +%% check_liveness_block(Reg, [Instruction], State) -> +%% {killed | not_used | used | transparent,State'} %% Finds out how Reg is used in the instruction sequence inside a block. %% Returns one of: -%% killed - Reg is assigned a new value or killed by an allocation instruction +%% killed - Reg is assigned a new value or killed by an +%% allocation instruction +%% not_used - The value is not used, but the register is referenced +%% e.g. by an allocation instruction %% transparent - Reg is neither used nor killed %% used - Reg is explicitly used by an instruction %% @@ -587,45 +574,64 @@ check_killed_block(_, []) -> transparent. %% %% (Unknown instructions will cause an exception.) -check_used_block({x,X}=R, [{set,Ds,Ss,{alloc,Live,Op}}|Is], St) -> +check_liveness_block({x,X}=R, [{set,Ds,Ss,{alloc,Live,Op}}|Is], St0) -> if - X >= Live -> {killed,St}; - true -> check_used_block_1(R, Ss, Ds, Op, Is, St) + X >= Live -> + {killed,St0}; + true -> + case check_liveness_block_1(R, Ss, Ds, Op, Is, St0) of + {killed,St} -> {not_used,St}; + {transparent,St} -> {not_used,St}; + {_,_}=Res -> Res + end end; -check_used_block(R, [{set,Ds,Ss,Op}|Is], St) -> - check_used_block_1(R, Ss, Ds, Op, Is, St); -check_used_block(_, [], St) -> {transparent,St}. +check_liveness_block({y,_}=R, [{set,Ds,Ss,{alloc,_Live,Op}}|Is], St) -> + check_liveness_block_1(R, Ss, Ds, Op, Is, St); +check_liveness_block(R, [{set,Ds,Ss,Op}|Is], St) -> + check_liveness_block_1(R, Ss, Ds, Op, Is, St); +check_liveness_block(_, [], St) -> {transparent,St}. -check_used_block_1(R, Ss, Ds, Op, Is, St0) -> +check_liveness_block_1(R, Ss, Ds, Op, Is, St0) -> case member(R, Ss) of true -> {used,St0}; false -> - case is_reg_used_at(R, Op, St0) of - {true,St} -> - {used,St}; - {false,St} -> + case check_liveness_block_2(R, Op, Ss, St0) of + {killed,St} -> case member(R, Ds) of true -> {killed,St}; - false -> check_used_block(R, Is, St) - end + false -> check_liveness_block(R, Is, St) + end; + {not_used,St} -> + not_used(case member(R, Ds) of + true -> {killed,St}; + false -> check_liveness_block(R, Is, St) + end); + {used,St} -> + {used,St} end end. -is_reg_used_at(R, {gc_bif,_,{f,Lbl}}, St) -> - is_reg_used_at_1(R, Lbl, St); -is_reg_used_at(R, {bif,_,{f,Lbl}}, St) -> - is_reg_used_at_1(R, Lbl, St); -is_reg_used_at(_, _, St) -> - {false,St}. +check_liveness_block_2(R, {gc_bif,_Op,{f,Lbl}}, _Ss, St) -> + check_liveness_block_3(R, Lbl, St); +check_liveness_block_2(R, {bif,Op,{f,Lbl}}, Ss, St) -> + Arity = length(Ss), + case erl_internal:comp_op(Op, Arity) orelse + erl_internal:new_type_test(Op, Arity) of + true -> + {killed,St}; + false -> + check_liveness_block_3(R, Lbl, St) + end; +check_liveness_block_2(R, {put_map,_Op,{f,Lbl}}, _Ss, St) -> + check_liveness_block_3(R, Lbl, St); +check_liveness_block_2(_, _, _, St) -> + {killed,St}. -is_reg_used_at_1(_, 0, St) -> - {false,St}; -is_reg_used_at_1(R, Lbl, St0) -> - case check_liveness_at(R, Lbl, St0) of - {killed,St} -> {false,St}; - {used,St} -> {true,St} - end. +check_liveness_block_3(_, 0, St) -> + {killed,St}; +check_liveness_block_3(R, Lbl, St0) -> + check_liveness_at(R, Lbl, St0). index_labels_1([{label,Lbl}|Is0], Acc) -> Is = drop_labels(Is0), @@ -783,37 +789,48 @@ live_opt([{recv_mark,_}=I|Is], Regs, D, Acc) -> live_opt([], _, _, Acc) -> Acc. -live_opt_block([{set,Ds,Ss,Op}=I0|Is], Regs0, D, Acc) -> +live_opt_block([{set,Ds,Ss,Op0}|Is], Regs0, D, Acc) -> Regs1 = x_live(Ss, x_dead(Ds, Regs0)), - {I,Regs} = case Op of - {alloc,Live0,Alloc} -> - %% The life-time analysis used by the code generator - %% is sometimes too conservative, so it may be - %% possible to lower the number of live registers - %% based on the exact liveness information. - %% The main benefit is that more optimizations that - %% depend on liveness information (such as the - %% beam_bool and beam_dead passes) may be applied. - Live = live_regs(Regs1), - true = Live =< Live0, %Assertion. - I1 = {set,Ds,Ss,{alloc,Live,Alloc}}, - {I1,live_call(Live)}; - _ -> - {I0,Regs1} - end, + {Op, Regs} = live_opt_block_op(Op0, Regs1, D), + I = {set, Ds, Ss, Op}, + case Ds of - [{x,X}] -> - case (not is_live(X, Regs0)) andalso Op =:= move of - true -> - live_opt_block(Is, Regs0, D, Acc); - false -> - live_opt_block(Is, Regs, D, [I|Acc]) - end; - _ -> - live_opt_block(Is, Regs, D, [I|Acc]) - end; + [{x,X}] -> + case (not is_live(X, Regs0)) andalso Op =:= move of + true -> + live_opt_block(Is, Regs0, D, Acc); + false -> + live_opt_block(Is, Regs, D, [I|Acc]) + end; + _ -> + live_opt_block(Is, Regs, D, [I|Acc]) + end; +live_opt_block([{'%live',_,_}|Is], Regs, D, Acc) -> + live_opt_block(Is, Regs, D, Acc); live_opt_block([], Regs, _, Acc) -> {Acc,Regs}. +live_opt_block_op({alloc,Live0,AllocOp}, Regs0, D) -> + Regs = + case AllocOp of + {Kind, _N, Fail} when Kind =:= gc_bif; Kind =:= put_map -> + live_join_label(Fail, D, Regs0); + _ -> + Regs0 + end, + + %% The life-time analysis used by the code generator is sometimes too + %% conservative, so it may be possible to lower the number of live + %% registers based on the exact liveness information. The main benefit is + %% that more optimizations that depend on liveness information (such as the + %% beam_bool and beam_dead passes) may be applied. + Live = live_regs(Regs), + true = Live =< Live0, + {{alloc,Live,AllocOp}, live_call(Live)}; +live_opt_block_op({bif,_N,Fail} = Op, Regs, D) -> + {Op, live_join_label(Fail, D, Regs)}; +live_opt_block_op(Op, Regs, _D) -> + {Op, Regs}. + live_join_labels([{f,L}|T], D, Regs0) when L =/= 0 -> Regs = gb_trees:get(L, D) bor Regs0, live_join_labels(T, D, Regs); |