[ruby-core:71931] [Ruby trunk - Feature #11786] [Open] [PATCH] micro-optimize case dispatch even harder

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Issue #11786 has been reported by Eric Wong. ---------------------------------------- Feature #11786: [PATCH] micro-optimize case dispatch even harder https://bugs.ruby-lang.org/issues/11786 * Author: Eric Wong * Status: Open * Priority: Normal * Assignee: ---------------------------------------- I noticed these optimizations while working on r52931. By using a bare hash table, we avoid the overhead of rb_hash_* functions as well as the cost of translating FIX2INT for jump labels. This also reduces GC overhead, as the iseq mark array no longer carries redundant objects nor the Hash object. Summary speedup: loop_whileloop2 1.000 vm2_case* 1.225 vm2_case_lit* 1.000 vm2_case_small* 1.162 Passes all tests and specs, so probably safe to commit soon... Full results: 2015-12-08 03:26:19 +0000 target 0: a (ruby 2.3.0dev (2015-12-08 trunk 52932) [x86_64-linux]) at "/home/ew/rrrr/b/ruby" target 1: b (ruby 2.3.0dev (2015-12-08 master 52932) [x86_64-linux] last_commit=micro-optimize case dispatch even harder) at "/home/ew/ruby/b/ruby" ----------------------------------------------------------- loop_whileloop2 i = 0 while i< 6_000_000 # benchmark loop 2 i += 1 end a 0.10256672604009509 a 0.10279557690955698 a 0.10286601004190743 a 0.10278227413073182 a 0.10278794192709029 b 0.10288732498884201 b 0.10327051300555468 b 0.1026718900538981 b 0.10263488302007318 b 0.10256404406391084 ----------------------------------------------------------- vm2_case i = 0 while i<6_000_000 # while loop 2 case :foo when :bar raise when :baz raise when :boo raise when :foo i += 1 end end a 0.18099936190992594 a 0.1836838680319488 a 0.1825075231026858 a 0.18087006197310984 a 0.18375545786693692 b 0.16652655508369207 b 0.16673082998022437 b 0.16754083498381078 b 0.16704767406918108 b 0.16648077592253685 ----------------------------------------------------------- vm2_case_lit i = 0 @ret = [ "foo", true, false, :sym, 6, nil, 0.1, 0xffffffffffffffff ] def foo(i) @ret[i % @ret.size] end while i<6_000_000 # while loop 2 case foo(i) when "foo" then :foo when true then true when false then false when :sym then :sym when 6 then :fix when nil then nil when 0.1 then :float when 0xffffffffffffffff then :big end i += 1 end a 0.670805990928784 a 0.6559841448906809 a 0.6560367799829692 a 0.655022048857063 a 0.671947613125667 b 0.659776204964146 b 0.6549702121410519 b 0.6788892599288374 b 0.6793588208965957 b 0.6878500080201775 ----------------------------------------------------------- vm2_case_small i = 0 while i<6_000_000 # while loop 2 case :foo when :foo i += 1 else raise end end a 0.1667630800511688 a 0.16669297800399363 a 0.1665362489875406 a 0.16644068900495768 a 0.16646360605955124 b 0.15790433110669255 b 0.15774213010445237 b 0.15753646893426776 b 0.15781028987839818 b 0.15771835204213858 Elapsed time: 11.069307098 (sec) ----------------------------------------------------------- benchmark results: minimum results in each 5 measurements. Execution time (sec) name a b loop_whileloop2 0.103 0.103 vm2_case* 0.078 0.064 vm2_case_lit* 0.552 0.552 vm2_case_small* 0.064 0.055 ---Files-------------------------------- 0001-micro-optimize-case-dispatch-even-harder.patch (9.34 KB) -- https://bugs.ruby-lang.org/