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/test/bs_match_SUITE.erl | 33 +++++++++++++++++++++++---------- 1 file changed, 23 insertions(+), 10 deletions(-) (limited to 'lib/compiler/test/bs_match_SUITE.erl') diff --git a/lib/compiler/test/bs_match_SUITE.erl b/lib/compiler/test/bs_match_SUITE.erl index 6742571b86..89f851ac3b 100644 --- a/lib/compiler/test/bs_match_SUITE.erl +++ b/lib/compiler/test/bs_match_SUITE.erl @@ -887,28 +887,41 @@ matching_and_andalso(Config) when is_list(Config) -> {'EXIT',{function_clause,_}} = (catch matching_and_andalso_1(<<1,2,3>>, blurf)), {'EXIT',{function_clause,_}} = (catch matching_and_andalso_1(<<1,2,3>>, 19)), - {"abc",<<"xyz">>} = matching_and_andalso_2("abc", <<"-xyz">>), - {"abc",<<"">>} = matching_and_andalso_2("abc", <<($a-1)>>), - {"abc",<<"">>} = matching_and_andalso_2("abc", <<($z+1)>>), - {"abc",<<"">>} = matching_and_andalso_2("abc", <<($A-1)>>), - {"abc",<<"">>} = matching_and_andalso_2("abc", <<($Z+1)>>), - error = matching_and_andalso_2([], <<>>), - error = matching_and_andalso_2([], <<$A>>), - error = matching_and_andalso_2([], <<$Z>>), - error = matching_and_andalso_2([], <<$a>>), - error = matching_and_andalso_2([], <<$z>>), + {"abc",<<"xyz">>} = matching_and_andalso_23("abc", <<"-xyz">>), + {"abc",<<"">>} = matching_and_andalso_23("abc", <<($a-1)>>), + {"abc",<<"">>} = matching_and_andalso_23("abc", <<($z+1)>>), + {"abc",<<"">>} = matching_and_andalso_23("abc", <<($A-1)>>), + {"abc",<<"">>} = matching_and_andalso_23("abc", <<($Z+1)>>), + error = matching_and_andalso_23([], <<>>), + error = matching_and_andalso_23([], <<$A>>), + error = matching_and_andalso_23([], <<$Z>>), + error = matching_and_andalso_23([], <<$a>>), + error = matching_and_andalso_23([], <<$z>>), ok. matching_and_andalso_1(<>, K) when is_integer(K) andalso size(Bitmap) >= K andalso 0 < K -> ok. +matching_and_andalso_23(Datetime, Bin) -> + Res = matching_and_andalso_2(Datetime, Bin), + Res = matching_and_andalso_3(Datetime, Bin), + Res. + matching_and_andalso_2(Datetime, <>) when not ((H >= $a) andalso (H =< $z)) andalso not ((H >= $A) andalso (H =< $Z)) -> {Datetime,T}; matching_and_andalso_2(_, _) -> error. +%% Contrived example to ensure we cover the handling of 'call' instructions +%% in v3_codegen:bsm_rename_ctx/4. +matching_and_andalso_3(Datetime, <>) + when not ((abs(H) >= $a) andalso (abs(H) =< $z)) andalso + not ((abs(H) >= $A) andalso (abs(H) =< $Z)) -> + {Datetime,T}; +matching_and_andalso_3(_, _) -> error. + %% Thanks to Tomas Stejskal. otp_7188(Config) when is_list(Config) -> MP3 = <<84,65,71,68,117,154,105,232,107,121,0,0,0,0,0,0,0,0,0,0, -- cgit v1.2.3