Performance optimization

[t2ym]

Performance optimization

Targets

• [x] forEach to for loop in _preprocess() - slight insignificant performance gain
• [x] cache espree.parse() results in _preprocess() - 30%~40% reduction of load time
• [x] compact code generation option - 20%~25% reduction of load time
• [x] Use function scope local variables instead of redundant block scope ones in _preprocess()
• [x] Eliminate extra string replacements in _espreeParse()
• [x] Eliminate redundant references to .body[0] in _preprocess()
• [x] Eliminate unnecessary JSON parsing of .start/.end/.raw in _espreeParse()
• [x] Eliminate intermediate JSON strings in _espreeParse()
• [x] Eliminate unnecessary AST traversal into tokens and comments in non-compact mode
• [x] Cache contexts for faster context generation (Issue #125) - ~20% reduction of hook time
• [x] Replace delete obj.prop with obj.prop = undefined (delete is 100 times slower than undefined assignment)
• [x] Replace native Object.assign() with custom objectAssign() function with simple for in loop (native Object.assign() is 100 times slower than for in assignment loop)
• [x] Skip unnecessary location operations when _sourceMap is not configured
• [x] Eliminate unnecessary delete operations of harmless ast.__scope__
• [x] Replace switch statements with constant object references
• [x] "with" statement scope check without Object.getPrototypeOf()
• [x] Replace o[p].apply(o,a) with o[p](...a) in hook callback
• [x] Use Map object when it is faster in hook callback
• [x] Avoid indexing in the target string in hook callback
• [x] Avoid empty for looping for globalAssignments
• [x] Use switch statement instead of argsMap object
• [x] Use a raw Regex instead of URL object for script[.]m?js checking
• [x] Use Map object instead of Object for Fix #180
• [x] Eliminate some deoptimization points in _analyzeScope
• [ ] More...

[t2ym]

Use Map object when it is faster in hook callback in 0.0.162

Benchmarks with hookBenchmark('__hook__acl')

Chrome version	hookacl	. (op/s)	= (op/s)	() (op/s)	f (op/s)
61.0.3163.100	0.0.159	1,824,817	2,110,595	954,380	5,824,111
63.0.3239.0	0.0.159	642,756	644,870	315,547	11,494,252
61.0.3163.100	0.0.160	2,236,636	2,283,626	1,034,768	6,172,839
63.0.3239.100	0.0.160	2,123,593	2,382,086	1,034,447	10,695,187
62.0.3202.75	0.0.161	2,718,868	2,503,755	1,198,753	11,185,682
64.0.3251.0	0.0.161	2,534,211	2,478,929	1,251,094	10,615,711
62.0.3202.75	0.0.162	3,657,644	3,463,803	1,327,140	11,123,470
64.0.3251.0	0.0.162	3,374,957	3,328,894	1,426,940	11,261,261
62.0.3202.75	0.0.163	3,707,823	3,828,483	1,536,570	11,876,484
64.0.3251.0	0.0.163	3,173,595	3,423,485	1,636,661	11,976,047
62.0.3202.75	0.0.164	3,780,718	3,599,712	1,534,448	11,682,242
64.0.3251.0	0.0.164	3,585,514	3,462,603	1,488,095	11,467,889
62.0.3202.75	0.0.166	3,590,664	3,692,762	2,135,383	11,402,508
64.0.3251.0	0.0.166	3,457,814	3,542,330	2,298,850	11,454,753
62.0.3202.75	0.0.167	3,724,394	3,838,771	2,030,044	12,019,230
62.0.3202.75	0.0.168	3,620,564	3,425,830	1,962,708	11,001,100
62.0.3202.75	0.0.170	3,536,067	3,579,098	1,860,119	10,193,679
64.0.3256.0	0.0.170	3,980,891	3,947,887	2,370,229	10,905,125
64.0.3260.0	0.0.170	3,885,003	3,897,116	2,408,477	12,787,723
64.0.3260.0	0.0.171	4,086,636	3,595,828	2,397,506	12,360,939

Note

• Chrome Canary 64.0.3254.0 crashes on 0.0.167 demo

[t2ym]

Benchmarks with hookBenchmark()

Chrome	version	hook	. (op/s)	= (op/s)	() (op/s)	f (op/s)
80.0.3987.87	0.4.0-a.8	acl	1,645,278	1,638,269	1,173,020	3,874,467
80.0.3987.87	0.4.0-a.*	min	11,782,726	11,113,580	6,385,288	8,086,689
80.0.3987.87	0.4.0-a.*	acl	1,173,158	1,198,897	858,737	4,006,410
80.0.3987.87	0.4.0-a.*		633,874	642,797	519,912	2,023,062

Note

• 0.4.0-alpha.* is undergoing changes