diff options
Diffstat (limited to 'lib/compiler/src')
| -rw-r--r-- | lib/compiler/src/beam_block.erl | 98 | ||||
| -rw-r--r-- | lib/compiler/src/beam_dead.erl | 7 | ||||
| -rw-r--r-- | lib/compiler/src/compile.erl | 20 |
3 files changed, 78 insertions, 47 deletions
diff --git a/lib/compiler/src/beam_block.erl b/lib/compiler/src/beam_block.erl index 85d332c56e..ec41925beb 100644 --- a/lib/compiler/src/beam_block.erl +++ b/lib/compiler/src/beam_block.erl @@ -159,14 +159,43 @@ find_fixpoint(OptFun, Is0) -> end. %% move_allocates(Is0) -> Is -%% Move allocate instructions upwards in the instruction stream, in the -%% hope of getting more possibilities for optimizing away moves later. +%% Move allocate instructions upwards in the instruction stream +%% (within the same block), in the hope of getting more possibilities +%% for optimizing away moves later. %% -%% NOTE: Moving allocation instructions is only safe because it is done -%% immediately after code generation so that we KNOW that if {x,X} is -%% initialized, all x registers with lower numbers are also initialized. -%% That assumption may not be true after other optimizations, such as -%% the beam_utils:live_opt/1 optimization. +%% For example, we can transform the following instructions: +%% +%% get_tuple_element x(1) Element => x(2) +%% allocate_zero StackSize 3 %% x(0), x(1), x(2) are live +%% +%% to the following instructions: +%% +%% allocate_zero StackSize 2 %% x(0) and x(1) are live +%% get_tuple_element x(1) Element => x(2) +%% +%% NOTE: Since the beam_reorder pass has been run, it is no longer +%% safe to assume that if x(N) is initialized, then all lower-numbered +%% x registers are also initialized. +%% +%% For example, in general it is not safe to transform the following +%% instructions: +%% +%% get_tuple_element x(0) Element => x(1) +%% allocate_zero StackSize 3 %x(0), x(1), x(2) are live +%% +%% to the following instructions: +%% +%% allocate_zero StackSize 3 +%% get_tuple_element x(0) Element => x(1) +%% +%% The transformation is safe if and only if x(1) has been +%% initialized previously. Unfortunately, beam_reorder may have moved +%% a get_tuple_element instruction so that x(1) is not always +%% initialized when this code is reached. To find whether or not x(1) +%% is initialized, we would need to analyze all code preceding these +%% two instructions (across branches). Since we currently don't have +%% any practical mechanism for doing that, we will have to +%% conservatively assume that the transformation is unsafe. move_allocates([{block,Bl0}|Is]) -> Bl = move_allocates_1(reverse(Bl0), []), @@ -175,27 +204,19 @@ move_allocates([I|Is]) -> [I|move_allocates(Is)]; move_allocates([]) -> []. -move_allocates_1([{set,[],[],{alloc,_,_}=Alloc}|Is0], Acc0) -> - {Is,Acc} = move_allocates_2(Alloc, Is0, Acc0), - move_allocates_1(Is, Acc); +move_allocates_1([I|Is], [{set,[],[],{alloc,Live0,Info}}|Acc]=Acc0) -> + case {alloc_may_pass(I),alloc_live_regs(I, Live0)} of + {false,_} -> + move_allocates_1(Is, [I|Acc0]); + {true,not_possible} -> + move_allocates_1(Is, [I|Acc0]); + {true,Live} when is_integer(Live) -> + A = {set,[],[],{alloc,Live,Info}}, + move_allocates_1(Is, [A,I|Acc]) + end; move_allocates_1([I|Is], Acc) -> move_allocates_1(Is, [I|Acc]); -move_allocates_1([], Is) -> Is. - -move_allocates_2({alloc,Live,Info}, [{set,[],[],{alloc,Live0,Info0}}|Is], Acc) -> - Live = Live0, % Assertion. - Alloc = {alloc,Live,combine_alloc(Info0, Info)}, - move_allocates_2(Alloc, Is, Acc); -move_allocates_2({alloc,Live,Info}=Alloc0, [I|Is]=Is0, Acc) -> - case alloc_may_pass(I) of - false -> - {Is0,[{set,[],[],Alloc0}|Acc]}; - true -> - Alloc = {alloc,alloc_live_regs(I, Live),Info}, - move_allocates_2(Alloc, Is, [I|Acc]) - end; -move_allocates_2(Alloc, [], Acc) -> - {[],[{set,[],[],Alloc}|Acc]}. +move_allocates_1([], Acc) -> Acc. alloc_may_pass({set,_,_,{alloc,_,_}}) -> false; alloc_may_pass({set,_,_,{set_tuple_element,_}}) -> false; @@ -204,9 +225,6 @@ alloc_may_pass({set,_,_,put_list}) -> false; alloc_may_pass({set,_,_,put}) -> false; alloc_may_pass({set,_,_,_}) -> true. -combine_alloc({_,Ns,Nh1,Init}, {_,nostack,Nh2,[]}) -> - {zero,Ns,beam_utils:combine_heap_needs(Nh1, Nh2),Init}. - %% opt([Instruction]) -> [Instruction] %% Optimize the instruction stream inside a basic block. @@ -393,10 +411,19 @@ eliminate_use_of_from_reg([I]=Is, From, _To, Acc) -> %% opt_alloc(Instructions) -> Instructions' %% Optimises all allocate instructions. +opt_alloc([{set,[],[],{alloc,Live0,Info0}}, + {set,[],[],{alloc,Live,Info}}|Is]) -> + Live = Live0, %Assertion. + Alloc = combine_alloc(Info0, Info), + I = {set,[],[],{alloc,Live,Alloc}}, + opt_alloc([I|Is]); opt_alloc([{set,[],[],{alloc,R,{_,Ns,Nh,[]}}}|Is]) -> [{set,[],[],opt_alloc(Is, Ns, Nh, R)}|Is]; opt_alloc([I|Is]) -> [I|opt_alloc(Is)]; opt_alloc([]) -> []. + +combine_alloc({_,Ns,Nh1,Init}, {_,nostack,Nh2,[]}) -> + {zero,Ns,beam_utils:combine_heap_needs(Nh1, Nh2),Init}. %% opt_alloc(Instructions, FrameSize, HeapNeed, LivingRegs) -> [Instr] %% Generates the optimal sequence of instructions for @@ -445,13 +472,14 @@ count_ones(Bits, Acc) -> alloc_live_regs({set,Ds,Ss,_}, Regs0) -> Rset = x_live(Ss, x_dead(Ds, (1 bsl Regs0)-1)), - live_regs(Rset). + live_regs(0, Rset). -live_regs(Regs) -> - live_regs_1(0, Regs). - -live_regs_1(N, 0) -> N; -live_regs_1(N, Regs) -> live_regs_1(N+1, Regs bsr 1). +live_regs(N, 0) -> + N; +live_regs(N, Regs) when Regs band 1 =:= 1 -> + live_regs(N+1, Regs bsr 1); +live_regs(_, _) -> + not_possible. x_dead([{x,N}|Rs], Regs) -> x_dead(Rs, Regs band (bnot (1 bsl N))); x_dead([_|Rs], Regs) -> x_dead(Rs, Regs); diff --git a/lib/compiler/src/beam_dead.erl b/lib/compiler/src/beam_dead.erl index b01f58f683..6f6d742293 100644 --- a/lib/compiler/src/beam_dead.erl +++ b/lib/compiler/src/beam_dead.erl @@ -272,17 +272,14 @@ backward([{jump,{f,To}}=J|[{bif,Op,_,Ops,Reg}|Is]=Is0], D, Acc) -> catch throw:not_possible -> backward(Is0, D, [J|Acc]) end; -backward([{test,bs_start_match2,F,Live,[R,_]=Args,Ctxt}|Is], D, +backward([{test,bs_start_match2,F,_,[R,_],Ctxt}=I|Is], D, [{test,bs_match_string,F,[Ctxt,Bs]}, {test,bs_test_tail2,F,[Ctxt,0]}|Acc0]=Acc) -> - {f,To0} = F, - To = shortcut_bs_start_match(To0, R, D), case beam_utils:is_killed(Ctxt, Acc0, D) of true -> - Eq = {test,is_eq_exact,{f,To},[R,{literal,Bs}]}, + Eq = {test,is_eq_exact,F,[R,{literal,Bs}]}, backward(Is, D, [Eq|Acc0]); false -> - I = {test,bs_start_match2,{f,To},Live,Args,Ctxt}, backward(Is, D, [I|Acc]) end; backward([{test,bs_start_match2,{f,To0},Live,[Src|_]=Info,Dst}|Is], D, Acc) -> diff --git a/lib/compiler/src/compile.erl b/lib/compiler/src/compile.erl index 82ff8a95f3..e951a25e04 100644 --- a/lib/compiler/src/compile.erl +++ b/lib/compiler/src/compile.erl @@ -43,6 +43,10 @@ -type abstract_code() :: [erl_parse:abstract_form()]. +%% Internal representations used for 'from_asm' and 'from_beam' compilation can +%% also be valid, but have no relevant types defined. +-type forms() :: abstract_code() | cerl:c_module(). + -type option() :: atom() | {atom(), term()} | {'d', atom(), term()}. -type err_info() :: {erl_anno:line() | 'none', @@ -88,7 +92,7 @@ file(File, Opt) -> forms(Forms) -> forms(Forms, ?DEFAULT_OPTIONS). --spec forms(abstract_code(), [option()] | option()) -> comp_ret(). +-spec forms(forms(), [option()] | option()) -> comp_ret(). forms(Forms, Opts) when is_list(Opts) -> do_compile({forms,Forms}, [binary|Opts++env_default_opts()]); @@ -116,7 +120,7 @@ noenv_file(File, Opts) when is_list(Opts) -> noenv_file(File, Opt) -> noenv_file(File, [Opt|?DEFAULT_OPTIONS]). --spec noenv_forms(abstract_code(), [option()] | option()) -> comp_ret(). +-spec noenv_forms(forms(), [option()] | option()) -> comp_ret(). noenv_forms(Forms, Opts) when is_list(Opts) -> do_compile({forms,Forms}, [binary|Opts]); @@ -236,6 +240,8 @@ format_error({epp,E}) -> epp:format_error(E); format_error(write_error) -> "error writing file"; +format_error({write_error, Error}) -> + io_lib:format("error writing file: ~ts", [file:format_error(Error)]); format_error({rename,From,To,Error}) -> io_lib:format("failed to rename ~ts to ~ts: ~ts", [From,To,file:format_error(Error)]); @@ -1206,7 +1212,7 @@ makedep_output(#compile{code=Code,options=Opts,ofile=Ofile}=St) -> end, {ok,St} catch - exit:_ -> + error:_ -> %% Couldn't write to output Makefile. Err = {St#compile.ifile,[{none,?MODULE,write_error}]}, {error,St#compile{errors=St#compile.errors++[Err]}} @@ -1479,8 +1485,8 @@ save_binary_1(St) -> end, {error,St#compile{errors=St#compile.errors ++ Es}} end; - {error,_Error} -> - Es = [{Tfile,[{none,compile,write_error}]}], + {error,Error} -> + Es = [{Tfile,[{none,compile,{write_error,Error}}]}], {error,St#compile{errors=St#compile.errors ++ Es}} end. @@ -1628,8 +1634,8 @@ listing(LFun, Ext, St) -> LFun(Lf, Code), ok = file:close(Lf), {ok,St}; - {error,_Error} -> - Es = [{Lfile,[{none,compile,write_error}]}], + {error,Error} -> + Es = [{Lfile,[{none,compile,{write_error,Error}}]}], {error,St#compile{errors=St#compile.errors ++ Es}} end. |