Isn't this an off-by-one error of sorts? I'm by no means an expert on Turbofan range analysis, but it seems that if TF realized that i is strictly less than the array length, then that would be enough to optimize away the overflow check on the increment?
On Wed, Feb 3, 2021 at 5:46 AM 'Suraj Sharma' via v8-dev < [email protected]> wrote: > Hello everyone, > > I was running a micro benchmark(attached at the bottom) and noticed > something interesting. > > There is a significant difference in performance between TypedArray and > regular JSArray when performing arithmetic in a loop, > > When timing the function foo() on release build of d8 on x64 machine we > get following result: > > JSArray: 616 ms > > TypedArray: 1261 ms > > I did some investigation and found that we always perform an overflow > check for loop variable i when using TypedArray irrespective of the value > of length. > > I have made some progress in addressing this issue, but need some help in > putting some pieces together. > > Here is the link > <https://docs.google.com/document/d/1tBwy698i0TUhQa5-uxEp3_5y9557bniMfyXjHCTn3OU/edit?usp=sharing>summarizing > my investigation. > > PTAL > > Thanks > > Suraj > > [image: foo.png] > > -- > -- > v8-dev mailing list > [email protected] > http://groups.google.com/group/v8-dev > --- > You received this message because you are subscribed to the Google Groups > "v8-dev" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/v8-dev/c2c96e24-ce44-4afb-9a98-ab2829c9cae2n%40googlegroups.com > <https://groups.google.com/d/msgid/v8-dev/c2c96e24-ce44-4afb-9a98-ab2829c9cae2n%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- -- v8-dev mailing list [email protected] http://groups.google.com/group/v8-dev --- You received this message because you are subscribed to the Google Groups "v8-dev" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/v8-dev/CAKSzg3QKPe-3CwFm%2BU626FX2JTaNrT1u6ZD%3DF1izQfnsYwgyaA%40mail.gmail.com.
