aboutsummaryrefslogtreecommitdiffstats
path: root/lib/compiler/test/bs_match_SUITE.erl
diff options
context:
space:
mode:
authorBjörn Gustavsson <[email protected]>2012-08-16 14:36:55 +0200
committerBjörn Gustavsson <[email protected]>2012-10-09 15:24:38 +0200
commitb68297d347a9a041854410a77861982b1d0861d2 (patch)
treec9f6c9ef206f0bfcc7215ac3bd1e4e7265382391 /lib/compiler/test/bs_match_SUITE.erl
parentb76588fb5a4057dce8c26307e497370a33217a44 (diff)
downloadotp-b68297d347a9a041854410a77861982b1d0861d2.tar.gz
otp-b68297d347a9a041854410a77861982b1d0861d2.tar.bz2
otp-b68297d347a9a041854410a77861982b1d0861d2.zip
Improve binary matching of literals
The bs_match_string instruction is used to speed up matching of binary literals. For example, given this source code: foo1(<<1,2,3>>) -> ok. The matching part of the code will look like: {test,bs_start_match2,{f,1},1,[{x,0},0],{x,0}}. {test,bs_match_string,{f,3},[{x,0},24,{string,[1,2,3]}]}. {test,bs_test_tail2,{f,3},[{x,0},0]}. Nice. However, if we do a simple change to the source code: foo2(<<1,2,3>>) -> ok; foo2(<<>>) -> error. the resulting matching code will look like (sligthly simplified): {test,bs_start_match2,{f,4},1,[{x,0},0],{x,0}}. {test,bs_get_integer2,{f,7},1,[{x,0},{integer,8},1,Flags],{x,1}}. {test,is_eq_exact,{f,8},[{x,1},{integer,1}]}. {test,bs_match_string,{f,6},[{x,0},16,{string,[2,3]}]}. {test,bs_test_tail2,{f,6},[{x,0},0]}. {move,{atom,ok},{x,0}}. return. {label,6}. {bs_restore2,{x,0},{atom,start}}. {label,7}. {test,bs_test_tail2,{f,8},[{x,0},0]}. That is, matching of the first byte is not combined into the bs_match_string instruction that follows. Fix this problem by allowing a bs_match_string instruction to be used if all clauses will match either the same integer literal or the empty binary.
Diffstat (limited to 'lib/compiler/test/bs_match_SUITE.erl')
0 files changed, 0 insertions, 0 deletions