From 348b5e6bee2f83d10642558d511cc904f5015ab3 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= Date: Thu, 15 Sep 2016 16:33:57 +0200 Subject: v3_kernel: Generate optimized code for guards The compiler produces poor code for complex guard expressions with andalso/orelse. Here is an example from the filename module: -define(IS_DRIVELETTER(Letter),(((Letter >= $A) andalso (Letter =< $Z)) orelse ((Letter >= $a) andalso (Letter =< $z)))). skip_prefix(Name, false) -> Name; skip_prefix([L, DrvSep|Name], DrvSep) when ?IS_DRIVELETTER(L) -> Name; skip_prefix(Name, _) -> Name. beam_bool fails to simplify the code for the guard, leaving several 'bif' instructions: {function, skip_prefix, 2, 49}. {label,48}. {line,[{location,"filename.erl",187}]}. {func_info,{atom,filename},{atom,skip_prefix},2}. {label,49}. {test,is_ne_exact,{f,52},[{x,1},{atom,false}]}. {test,is_nonempty_list,{f,52},[{x,0}]}. {get_list,{x,0},{x,2},{x,3}}. {test,is_nonempty_list,{f,52},[{x,3}]}. {get_list,{x,3},{x,4},{x,5}}. {bif,'=:=',{f,52},[{x,1},{x,4}],{x,6}}. {test,is_ge,{f,50},[{x,2},{integer,65}]}. {bif,'=<',{f,52},[{x,2},{integer,90}],{x,7}}. {test,is_eq_exact,{f,51},[{x,7},{atom,false}]}. {test,is_ge,{f,50},[{x,2},{integer,97}]}. {bif,'=<',{f,52},[{x,2},{integer,122}],{x,7}}. {jump,{f,51}}. {label,50}. {move,{atom,false},{x,7}}. {label,51}. {bif,'=:=',{f,52},[{x,7},{atom,true}],{x,7}}. {test,is_eq_exact,{f,52},[{x,6},{atom,true}]}. {test,is_eq_exact,{f,52},[{x,7},{atom,true}]}. {move,{x,5},{x,0}}. return. {label,52}. return. We can add optimizations of guard tests to v3_kernel to achive a better result: {function, skip_prefix, 2, 49}. {label,48}. {line,[{location,"filename.erl",187}]}. {func_info,{atom,filename},{atom,skip_prefix},2}. {label,49}. {test,is_ne_exact,{f,51},[{x,1},{atom,false}]}. {test,is_nonempty_list,{f,51},[{x,0}]}. {get_list,{x,0},{x,2},{x,3}}. {test,is_nonempty_list,{f,51},[{x,3}]}. {get_list,{x,3},{x,4},{x,5}}. {test,is_eq_exact,{f,51},[{x,1},{x,4}]}. {test,is_ge,{f,51},[{x,2},{integer,65}]}. {test,is_lt,{f,50},[{integer,90},{x,2}]}. {test,is_ge,{f,51},[{x,2},{integer,97}]}. {test,is_ge,{f,51},[{integer,122},{x,2}]}. {label,50}. {move,{x,5},{x,0}}. return. {label,51}. return. Looking at the STDLIB application, there were 112 lines of BIF calls in guards that beam_bool failed to convert to test instructions. This commit eliminates all those BIF calls. Here is how I counted the instructions: $ PATH=$ERL_TOP/bin:$PATH erlc -I ../include -I ../../kernel/include -S *.erl $ grep "bif,'[=<>]" *.S | grep -v f,0 dets.S: {bif,'=:=',{f,547},[{x,4},{atom,read_write}],{x,4}}. dets.S: {bif,'=:=',{f,547},[{x,5},{atom,saved}],{x,5}}. dets.S: {bif,'=:=',{f,589},[{x,5},{atom,read}],{x,5}}. . . . $ grep "bif,'[=<>]" *.S | grep -v f,0 | wc 112 224 6765 $ --- lib/compiler/src/v3_codegen.erl | 20 +++++++++++++++++--- 1 file changed, 17 insertions(+), 3 deletions(-) (limited to 'lib/compiler/src/v3_codegen.erl') diff --git a/lib/compiler/src/v3_codegen.erl b/lib/compiler/src/v3_codegen.erl index c2e0c2bd1a..3627cdb7cd 100644 --- a/lib/compiler/src/v3_codegen.erl +++ b/lib/compiler/src/v3_codegen.erl @@ -363,7 +363,7 @@ bsm_rename_ctx(#l{ke={match,Ms0,Rs}}=L, Old, New, InProt) -> bsm_rename_ctx(#l{ke={guard_match,Ms0,Rs}}=L, Old, New, InProt) -> Ms = bsm_rename_ctx(Ms0, Old, New, InProt), L#l{ke={guard_match,Ms,Rs}}; -bsm_rename_ctx(#l{ke={test,_,_}}=L, _, _, _) -> L; +bsm_rename_ctx(#l{ke={test,_,_,_}}=L, _, _, _) -> L; bsm_rename_ctx(#l{ke={bif,_,_,_}}=L, _, _, _) -> L; bsm_rename_ctx(#l{ke={gc_bif,_,_,_}}=L, _, _, _) -> L; bsm_rename_ctx(#l{ke={set,_,_}}=L, _, _, _) -> L; @@ -1051,8 +1051,15 @@ guard_cg(#l{ke={protected,Ts,Rs},i=I,vdb=Pdb}, Fail, _Vdb, Bef, St) -> protected_cg(Ts, Rs, Fail, I, Pdb, Bef, St); guard_cg(#l{ke={block,Ts},i=I,vdb=Bdb}, Fail, _Vdb, Bef, St) -> guard_cg_list(Ts, Fail, I, Bdb, Bef, St); -guard_cg(#l{ke={test,Test,As},i=I,vdb=_Tdb}, Fail, Vdb, Bef, St) -> - test_cg(Test, As, Fail, I, Vdb, Bef, St); +guard_cg(#l{ke={test,Test,As,Inverted},i=I,vdb=_Tdb}, Fail, Vdb, Bef, St0) -> + case Inverted of + false -> + test_cg(Test, As, Fail, I, Vdb, Bef, St0); + true -> + {Psucc,St1} = new_label(St0), + {Is,Aft,St2} = test_cg(Test, As, Psucc, I, Vdb, Bef, St1), + {Is++[{jump,{f,Fail}},{label,Psucc}],Aft,St2} + end; guard_cg(G, _Fail, Vdb, Bef, St) -> %%ok = io:fwrite("cg ~w: ~p~n", [?LINE,{G,Fail,Vdb,Bef}]), {Gis,Aft,St1} = cg(G, Vdb, Bef, St), @@ -1103,6 +1110,13 @@ test_cg(is_map, [A], Fail, I, Vdb, Bef, St) -> Arg = cg_reg_arg_prefer_y(A, Bef), Aft = clear_dead(Bef, I, Vdb), {[{test,is_map,{f,Fail},[Arg]}],Aft,St}; +test_cg(is_boolean, [{atom,Val}], Fail, I, Vdb, Bef, St) -> + Aft = clear_dead(Bef, I, Vdb), + Is = case is_boolean(Val) of + true -> []; + false -> [{jump,{f,Fail}}] + end, + {Is,Aft,St}; test_cg(Test, As, Fail, I, Vdb, Bef, St) -> Args = cg_reg_args(As, Bef), Aft = clear_dead(Bef, I, Vdb), -- cgit v1.2.3