The results from this test does not seem right: http://jsperf.com/math-floor-divide-2-vs-bit-shift/3 The tests are basically: i >> 1, Math.floor(i/2), & Math.floor(i*.5)
Results in Ops/sec UserAgent: Bit shift | .floor /2 | .floor *.5 || # Tests Chrome 24: 4,688,830 | 4,683,492 | 2,435,539 || 4 PM/FF19: 5,392,935 | 2,165,562 | 2,500,029 || 2 The Firefox results are what I expect; bit shifting is wicked-fast (since it is a fast, simple opcode). Math.floor(i/2) in Firefox is a bit faster than what I expected, but still much slower than >>. Multiply is naturally faster than the divide opcode. In this test Chrome is fast with the bit shift, almost as fast with Math.floor(i/2), BUT much slower than Math.floor(i*.5). Something seems wrong here. I can see that Chrome/v8 has a super-fast Math.floor() http://rocha.la/JavaScript-bitwise-operators-in-practice However, it should be fast with the second .floor also, since *.5 is a faster form of /2. Thoughts please? & is this best posted here or on Chromium? -- -- v8-users mailing list [email protected] http://groups.google.com/group/v8-users --- You received this message because you are subscribed to the Google Groups "v8-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/groups/opt_out.
