diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/compiler/src/beam_trim.erl | 83 |
1 files changed, 75 insertions, 8 deletions
diff --git a/lib/compiler/src/beam_trim.erl b/lib/compiler/src/beam_trim.erl index 13cbedf3c0..0f1144e87f 100644 --- a/lib/compiler/src/beam_trim.erl +++ b/lib/compiler/src/beam_trim.erl @@ -21,12 +21,11 @@ -module(beam_trim). -export([module/2]). --import(lists, [reverse/1,reverse/2,splitwith/2,sort/1]). +-import(lists, [member/2,reverse/1,reverse/2,splitwith/2,sort/1]). -record(st, - {safe :: cerl_sets:set(beam_asm:label()), %Safe labels. - lbl :: beam_utils:code_index() %Code at each label. - }). + {safe :: cerl_sets:set(beam_asm:label()) %Safe labels. + }). -spec module(beam_utils:module_code(), [compile:option()]) -> {'ok',beam_utils:module_code()}. @@ -37,7 +36,7 @@ module({Mod,Exp,Attr,Fs0,Lc}, _Opts) -> function({function,Name,Arity,CLabel,Is0}) -> try - St = #st{safe=safe_labels(Is0, []),lbl=beam_utils:index_labels(Is0)}, + St = #st{safe=safe_labels(Is0, [])}, Is = trim(Is0, St, []), {function,Name,Arity,CLabel,Is} catch @@ -236,9 +235,9 @@ safe_labels([], Acc) -> cerl_sets:from_list(Acc). %% [{kill,Reg} | {live,Reg} | {dead,Reg}] %% Figure out the layout of the stack frame. -frame_layout(Is, Kills, #st{safe=Safe,lbl=D}) -> +frame_layout(Is, Kills, #st{safe=Safe}) -> N = frame_size(Is, Safe), - IsKilled = fun(R) -> beam_utils:is_not_used(R, Is, D) end, + IsKilled = fun(R) -> is_not_used(R, Is) end, {N,frame_layout_1(Kills, 0, N, IsKilled, [])}. frame_layout_1([{kill,{y,Y}}=I|Ks], Y, N, IsKilled, Acc) -> @@ -290,7 +289,8 @@ frame_size([{make_fun2,_,_,_,_}|Is], Safe) -> frame_size(Is, Safe); frame_size([{get_map_elements,{f,L},_,_}|Is], Safe) -> frame_size_branch(L, Is, Safe); -frame_size([{deallocate,N}|_], _) -> N; +frame_size([{deallocate,N}|_], _) -> + N; frame_size([{line,_}|Is], Safe) -> frame_size(Is, Safe); frame_size(_, _) -> throw(not_possible). @@ -302,3 +302,70 @@ frame_size_branch(L, Is, Safe) -> false -> throw(not_possible); true -> frame_size(Is, Safe) end. + +%% is_not_used(Y, [Instruction]) -> true|false. +%% Test whether the value of Y is unused in the instruction sequence. +%% Return true if the value of Y is not used, and false if it is used. +%% +%% This function handles the same instructions as frame_size/2. It +%% assumes that any labels in the instructions are safe labels. + +is_not_used(Y, [{apply,_}|Is]) -> + is_not_used(Y, Is); +is_not_used(Y, [{bif,_,{f,_},Ss,Dst}|Is]) -> + is_not_used_ss_dst(Y, Ss, Dst, Is); +is_not_used(Y, [{block,Bl}|Is]) -> + case is_not_used_block(Y, Bl) of + used -> false; + killed -> true; + transparent -> is_not_used(Y, Is) + end; +is_not_used(Y, [{bs_init,_,_,_,Ss,Dst}|Is]) -> + is_not_used_ss_dst(Y, Ss, Dst, Is); +is_not_used(Y, [{bs_put,{f,_},_,Ss}|Is]) -> + not member(Y, Ss) andalso is_not_used(Y, Is); +is_not_used(Y, [{call,_,_}|Is]) -> + is_not_used(Y, Is); +is_not_used(Y, [{call_ext,_,_}=I|Is]) -> + beam_jump:is_exit_instruction(I) orelse is_not_used(Y, Is); +is_not_used(Y, [{call_fun,_}|Is]) -> + is_not_used(Y, Is); +is_not_used(_Y, [{deallocate,_}|_]) -> + true; +is_not_used(Y, [{gc_bif,_,{f,_},_Live,Ss,Dst}|Is]) -> + is_not_used_ss_dst(Y, Ss, Dst, Is); +is_not_used(Y, [{get_map_elements,{f,_},S,{list,List}}|Is]) -> + {Ss,Ds} = beam_utils:split_even(List), + case member(Y, [S|Ss]) of + true -> + false; + false -> + member(Y, Ds) orelse is_not_used(Y, Is) + end; +is_not_used(Y, [{kill,Yreg}|Is]) -> + Y =:= Yreg orelse is_not_used(Y, Is); +is_not_used(Y, [{line,_}|Is]) -> + is_not_used(Y, Is); +is_not_used(Y, [{make_fun2,_,_,_,_}|Is]) -> + is_not_used(Y, Is); +is_not_used(Y, [{test,_,_,Ss}|Is]) -> + not member(Y, Ss) andalso is_not_used(Y, Is); +is_not_used(Y, [{test,_Op,{f,_},_Live,Ss,Dst}|Is]) -> + is_not_used_ss_dst(Y, Ss, Dst, Is). + +is_not_used_block(Y, [{set,Ds,Ss,_}|Is]) -> + case member(Y, Ss) of + true -> + used; + false -> + case member(Y, Ds) of + true -> + killed; + false -> + is_not_used_block(Y, Is) + end + end; +is_not_used_block(_Y, []) -> transparent. + +is_not_used_ss_dst(Y, Ss, Dst, Is) -> + not member(Y, Ss) andalso (Y =:= Dst orelse is_not_used(Y, Is)). |