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authorBjörn Gustavsson <[email protected]>2016-09-15 16:33:57 +0200
committerBjörn Gustavsson <[email protected]>2016-11-18 11:58:34 +0100
commit348b5e6bee2f83d10642558d511cc904f5015ab3 (patch)
tree796175b689cfcf463fa854b2f306cfdf5f5d46bf /lib/compiler/test/bs_match_SUITE.erl
parentcb4b1276acae0406344a24d4597c0d33a1d72ac7 (diff)
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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 $
Diffstat (limited to 'lib/compiler/test/bs_match_SUITE.erl')
-rw-r--r--lib/compiler/test/bs_match_SUITE.erl33
1 files changed, 23 insertions, 10 deletions
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(<<Bitmap/binary>>, 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, <<H,T/binary>>)
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, <<H,T/binary>>)
+ 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,