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author | Björn Gustavsson <[email protected]> | 2016-09-15 16:33:57 +0200 |
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committer | Björn Gustavsson <[email protected]> | 2016-11-18 11:58:34 +0100 |
commit | 348b5e6bee2f83d10642558d511cc904f5015ab3 (patch) | |
tree | 796175b689cfcf463fa854b2f306cfdf5f5d46bf /lib/compiler/test/core_SUITE.erl | |
parent | cb4b1276acae0406344a24d4597c0d33a1d72ac7 (diff) | |
download | otp-348b5e6bee2f83d10642558d511cc904f5015ab3.tar.gz otp-348b5e6bee2f83d10642558d511cc904f5015ab3.tar.bz2 otp-348b5e6bee2f83d10642558d511cc904f5015ab3.zip |
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/core_SUITE.erl')
-rw-r--r-- | lib/compiler/test/core_SUITE.erl | 20 |
1 files changed, 14 insertions, 6 deletions
diff --git a/lib/compiler/test/core_SUITE.erl b/lib/compiler/test/core_SUITE.erl index b768f49e2c..f8839da42f 100644 --- a/lib/compiler/test/core_SUITE.erl +++ b/lib/compiler/test/core_SUITE.erl @@ -26,8 +26,9 @@ seq_in_guard/1,make_effect_seq/1,eval_is_boolean/1, unsafe_case/1,nomatch_shadow/1,reversed_annos/1, map_core_test/1,eval_case/1,bad_boolean_guard/1, - bs_shadowed_size_var/1 - ]). + bs_shadowed_size_var/1, + cover_v3_kernel_1/1,cover_v3_kernel_2/1,cover_v3_kernel_3/1, + cover_v3_kernel_4/1,cover_v3_kernel_5/1]). -include_lib("common_test/include/ct.hrl"). @@ -53,8 +54,10 @@ groups() -> [dehydrated_itracer,nested_tries,seq_in_guard,make_effect_seq, eval_is_boolean,unsafe_case,nomatch_shadow,reversed_annos, map_core_test,eval_case,bad_boolean_guard, - bs_shadowed_size_var - ]}]. + bs_shadowed_size_var, + cover_v3_kernel_1,cover_v3_kernel_2,cover_v3_kernel_3, + cover_v3_kernel_4,cover_v3_kernel_5 + ]}]. init_per_suite(Config) -> @@ -64,10 +67,10 @@ end_per_suite(_Config) -> ok. init_per_group(_GroupName, Config) -> - Config. + Config. end_per_group(_GroupName, Config) -> - Config. + Config. ?comp(dehydrated_itracer). @@ -82,6 +85,11 @@ end_per_group(_GroupName, Config) -> ?comp(eval_case). ?comp(bad_boolean_guard). ?comp(bs_shadowed_size_var). +?comp(cover_v3_kernel_1). +?comp(cover_v3_kernel_2). +?comp(cover_v3_kernel_3). +?comp(cover_v3_kernel_4). +?comp(cover_v3_kernel_5). try_it(Mod, Conf) -> |