Bug 69233

Summary: DFG misses some obvious opportunities for common subexpression elimination
Product: WebKit Reporter: Filip Pizlo <fpizlo>
Component: JavaScriptCoreAssignee: Nobody <webkit-unassigned>
Status: RESOLVED FIXED    
Severity: Normal    
Priority: P2    
Version: 528+ (Nightly build)   
Hardware: All   
OS: All   
Attachments:
Description Flags
the patch oliver: review+

Filip Pizlo
Reported 2011-10-02 18:32:47 PDT
DFG CSE has some small issues: - It assumes that GetArrayLength is pure, even though it's not quite, since PutByVal can change the array length. - It assumes that a PutByVal changes structures, even though it doesn't. - It assumes that a PutByVal can affect property storage, even though it can't. - It assumes that a PutByOffset and PutStructure can affect array values, even though they can't.
Attachments
the patch (5.65 KB, patch)
2011-10-02 18:35 PDT, Filip Pizlo 		oliver: review+
DetailsFormatted DiffDiff
View All Add attachment proposed patch, testcase, etc.
Filip Pizlo
Comment 1 2011-10-02 18:35:05 PDT
Created attachment 109433 [details] the patch
Filip Pizlo
Comment 2 2011-10-02 18:37:28 PDT
Benchmark report for SunSpider, V8, and Kraken. VMs tested: "TipOfTree" at /Volumes/Data/pizlo/quinary/OpenSource/WebKitBuild/Release/jsc "BetterCSE" at /Volumes/Data/pizlo/septenary/OpenSource/WebKitBuild/Release/jsc Collected 30 samples per benchmark/VM, with 10 VM invocations per benchmark. Used 1 benchmark iteration per VM invocation for warm-up. Used the jsc-specific preciseTime() function to get microsecond-level timing. Reporting benchmark execution times with 95% confidence intervals in milliseconds. TipOfTree BetterCSE SunSpider: 3d-cube 7.5046+-0.1042 ? 7.5562+-0.1585 ? 3d-morph 7.5106+-0.0913 7.4168+-0.0906 might be 1.0127x faster 3d-raytrace 8.2949+-0.1256 8.2606+-0.1456 access-binary-trees 1.8232+-0.0648 1.8117+-0.0522 access-fannkuch 6.5405+-0.0993 6.4741+-0.0940 might be 1.0103x faster access-nbody 3.6042+-0.0701 3.5328+-0.0550 might be 1.0202x faster access-nsieve 2.6308+-0.0429 2.6169+-0.0398 bitops-3bit-bits-in-byte 1.7234+-0.0258 ? 1.7439+-0.0363 ? might be 1.0119x slower bitops-bits-in-byte 2.7558+-0.0494 ? 2.7863+-0.0448 ? might be 1.0110x slower bitops-bitwise-and 3.2326+-0.0454 ? 3.2411+-0.0434 ? bitops-nsieve-bits 5.3901+-0.0673 ? 5.4930+-0.0939 ? might be 1.0191x slower controlflow-recursive 2.0976+-0.0347 2.0861+-0.0318 crypto-aes 6.8874+-0.1255 ^ 6.6021+-0.1546 ^ definitely 1.0432x faster crypto-md5 2.8488+-0.0452 2.8352+-0.0489 crypto-sha1 2.5384+-0.0562 2.5211+-0.0491 date-format-tofte 10.1327+-0.1970 ? 10.1969+-0.1884 ? date-format-xparb 9.6255+-0.2156 9.3088+-0.1642 might be 1.0340x faster math-cordic 6.5242+-0.1773 6.2920+-0.0602 might be 1.0369x faster math-partial-sums 7.5976+-0.0878 7.5502+-0.0724 math-spectral-norm 2.9130+-0.0600 2.8608+-0.0540 might be 1.0182x faster regexp-dna 10.9628+-0.0961 10.9094+-0.1177 string-base64 5.5743+-0.0751 ? 5.6800+-0.1060 ? might be 1.0190x slower string-fasta 6.7034+-0.0966 6.6029+-0.0968 might be 1.0152x faster string-tagcloud 11.9118+-0.2269 11.8688+-0.2448 string-unpack-code 21.3631+-0.2577 21.2992+-0.2574 string-validate-input 6.3661+-0.1176 ? 6.3754+-0.1222 ? <arithmetic> * 6.3484+-0.0209 ^ 6.3047+-0.0168 ^ definitely 1.0069x faster <geometric> 5.2011+-0.0154 5.1695+-0.0167 <harmonic> 4.2598+-0.0216 4.2421+-0.0240 TipOfTree BetterCSE V8: crypto 72.4069+-0.4387 71.9852+-0.2791 deltablue 226.0043+-1.0641 225.5008+-1.1243 earley-boyer 87.9457+-0.3612 87.6738+-0.2001 raytrace 60.5582+-0.2882 ! 61.3586+-0.2842 ! definitely 1.0132x slower regexp 103.1425+-0.2652 ? 103.6629+-0.3114 ? richards 186.0587+-0.4058 ! 187.2996+-0.3897 ! definitely 1.0067x slower splay 90.7291+-0.3171 ? 90.9486+-0.2721 ? <arithmetic> 118.1208+-0.1917 ? 118.3471+-0.2055 ? <geometric> * 106.1333+-0.1626 ? 106.3785+-0.1427 ? <harmonic> 96.9275+-0.1764 ? 97.2004+-0.1431 ? TipOfTree BetterCSE Kraken: ai-astar 488.2833+-1.0508 ? 489.7596+-2.1248 ? audio-beat-detection 190.2345+-0.4833 189.9833+-0.7610 audio-dft 280.0364+-1.9020 279.1998+-1.6599 audio-fft 128.5120+-0.6387 ^ 125.7692+-0.3395 ^ definitely 1.0218x faster audio-oscillator 256.4819+-1.1002 ? 256.5966+-1.4991 ? imaging-darkroom 418.9083+-0.5420 ? 420.0696+-1.0855 ? imaging-desaturate 224.1991+-0.4250 224.1621+-0.6741 imaging-gaussian-blur 582.6255+-1.0266 ^ 580.6442+-0.8892 ^ definitely 1.0034x faster json-parse-financial 48.7130+-0.2418 ^ 48.0643+-0.1532 ^ definitely 1.0135x faster json-stringify-tinderbox 67.5046+-0.1666 ! 67.9862+-0.3144 ! definitely 1.0071x slower stanford-crypto-aes 130.5309+-1.0694 130.2505+-0.9259 stanford-crypto-ccm 101.3395+-0.3694 ? 101.8324+-0.6299 ? stanford-crypto-pbkdf2 194.0272+-1.1882 ? 195.6992+-1.0436 ? stanford-crypto-sha256-iterative 76.6602+-0.4262 76.3504+-0.2175 <arithmetic> * 227.7183+-0.3129 227.5977+-0.2831 <geometric> 177.2977+-0.2818 177.0157+-0.2768 <harmonic> 136.9826+-0.2585 136.5452+-0.2483 TipOfTree BetterCSE All benchmarks: <arithmetic> 88.9353+-0.1095 88.9089+-0.0849 <geometric> 23.3176+-0.0433 23.2360+-0.0452 <harmonic> 7.4864+-0.0371 7.4560+-0.0411 TipOfTree BetterCSE Geomean of preferred means: <scaled-result> 53.5343+-0.0684 53.4431+-0.0510
Filip Pizlo
Comment 3 2011-10-02 19:12:32 PDT
Landed in r96482.
Note You need to log in before you can comment on or make changes to this bug.