Patch forthcoming.
Created attachment 115473 [details] the patch
Comment on attachment 115473 [details] the patch r=me
It's performance-neutral. Benchmark report for SunSpider, V8, and Kraken on bigmac.local (MacPro5,1). VMs tested: "TipOfTree" at /Volumes/Data/pizlo/quinary/OpenSource/WebKitBuild/Release/jsc (r100522) "DFGWeak" at /Volumes/Data/pizlo/tertiary/OpenSource/WebKitBuild/Release/jsc (r100522) Collected 12 samples per benchmark/VM, with 4 VM invocations per benchmark. Emitted a call to gc() between sample measurements. 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 DFGWeak SunSpider: 3d-cube 7.4398+-0.0273 7.4265+-0.0310 3d-morph 8.3947+-0.0303 ? 8.4720+-0.1302 ? 3d-raytrace 7.8433+-0.1168 7.7104+-0.0512 might be 1.0172x faster access-binary-trees 1.6054+-0.0134 1.5999+-0.0096 access-fannkuch 7.6610+-0.1248 ^ 7.5207+-0.0105 ^ definitely 1.0187x faster access-nbody 4.1811+-0.0077 ? 4.1882+-0.0328 ? access-nsieve 3.1675+-0.0434 3.1550+-0.0475 bitops-3bit-bits-in-byte 1.2622+-0.0191 1.2533+-0.0158 bitops-bits-in-byte 4.9339+-0.0287 4.9009+-0.0143 bitops-bitwise-and 3.2972+-0.0169 ? 3.3324+-0.0443 ? might be 1.0107x slower bitops-nsieve-bits 5.6792+-0.0333 5.6682+-0.0405 controlflow-recursive 2.3004+-0.0291 ? 2.3032+-0.0241 ? crypto-aes 7.1191+-0.0418 7.1127+-0.0367 crypto-md5 2.5027+-0.0186 ? 2.5536+-0.0460 ? might be 1.0203x slower crypto-sha1 2.1973+-0.0230 2.1954+-0.0332 date-format-tofte 10.9261+-0.2857 10.7098+-0.0489 might be 1.0202x faster date-format-xparb 11.3367+-0.2987 11.1948+-0.3314 might be 1.0127x faster math-cordic 7.2301+-0.0726 ^ 7.1259+-0.0186 ^ definitely 1.0146x faster math-partial-sums 10.5693+-0.1449 10.5256+-0.0354 math-spectral-norm 2.6410+-0.0325 ^ 2.5981+-0.0080 ^ definitely 1.0165x faster regexp-dna 13.0281+-0.0726 13.0013+-0.0620 string-base64 3.9365+-0.0144 ? 3.9419+-0.0189 ? string-fasta 7.3809+-0.0333 ? 7.3940+-0.0269 ? string-tagcloud 13.2893+-0.1496 13.1009+-0.0725 might be 1.0144x faster string-unpack-code 22.2383+-0.0946 ? 22.3519+-0.2027 ? string-validate-input 5.6933+-0.1166 5.5768+-0.0504 might be 1.0209x faster <arithmetic> * 6.8406+-0.0350 6.8044+-0.0253 might be 1.0053x faster <geometric> 5.4390+-0.0263 5.4151+-0.0212 might be 1.0044x faster <harmonic> 4.2287+-0.0205 4.2161+-0.0221 might be 1.0030x faster TipOfTree DFGWeak V8: crypto 77.3485+-0.2738 ? 78.1872+-1.1799 ? might be 1.0108x slower deltablue 168.2160+-0.6230 ! 171.4753+-2.2625 ! definitely 1.0194x slower earley-boyer 106.4277+-2.1540 105.0603+-1.3109 might be 1.0130x faster raytrace 63.1313+-0.5673 ? 63.3722+-1.1857 ? regexp 126.4038+-0.5045 126.2782+-0.5559 richards 139.0056+-1.9669 ? 140.8099+-1.9653 ? might be 1.0130x slower splay 89.7563+-0.7820 ? 90.6418+-1.2659 ? <arithmetic> 110.0413+-0.6796 ? 110.8321+-0.4371 ? might be 1.0072x slower <geometric> * 104.6856+-0.6344 ? 105.3143+-0.5341 ? might be 1.0060x slower <harmonic> 99.4776+-0.5807 ? 100.0015+-0.6478 ? might be 1.0053x slower TipOfTree DFGWeak Kraken: ai-astar 819.2897+-10.1898 818.7022+-10.9279 audio-beat-detection 206.4602+-1.0583 204.8580+-0.6615 audio-dft 268.9449+-10.0384 262.9276+-2.6183 might be 1.0229x faster audio-fft 133.3716+-0.2218 133.2630+-0.2694 audio-oscillator 293.6317+-0.2900 ? 294.6799+-1.6204 ? imaging-darkroom 335.0992+-5.0936 333.3226+-4.6104 imaging-desaturate 240.9964+-0.0905 240.9428+-0.2223 imaging-gaussian-blur 620.8911+-0.2228 ? 621.7937+-2.1577 ? json-parse-financial 73.4866+-0.2516 ^ 72.5241+-0.2918 ^ definitely 1.0133x faster json-stringify-tinderbox 85.6875+-0.8347 ? 85.7868+-0.5077 ? stanford-crypto-aes 117.0081+-0.7022 116.6514+-0.6636 stanford-crypto-ccm 115.9199+-0.4262 115.5942+-1.0340 stanford-crypto-pbkdf2 232.3294+-0.4827 231.3283+-1.0463 stanford-crypto-sha256-iterative 93.3015+-0.1997 93.2156+-0.1988 <arithmetic> * 259.7442+-0.8163 258.9707+-0.9146 might be 1.0030x faster <geometric> 200.1064+-0.6275 199.3300+-0.3560 might be 1.0039x faster <harmonic> 161.0712+-0.5026 160.3877+-0.2369 might be 1.0043x faster TipOfTree DFGWeak All benchmarks: <arithmetic> 97.5439+-0.2197 97.4112+-0.2341 might be 1.0014x faster <geometric> 24.7285+-0.0957 24.6616+-0.0674 might be 1.0027x faster <harmonic> 7.4535+-0.0358 7.4318+-0.0383 might be 1.0029x faster TipOfTree DFGWeak Geomean of preferred means: <scaled-result> 57.0823+-0.1913 57.0386+-0.1300 might be 1.0008x faster
Landed in http://trac.webkit.org/changeset/100527