Hello Arun, Crankshaft is now enabled by default on ARM processors supporting VFPv3. v8 does not use NEON (it is not worth using, at least currently), but I believe no processors with this configuration (NEON without VFPv3) exist anyway. So if the CPU feature detection work correctly, v8 should assume that you have VFPv3 if it detects NEON, and thus use use Crankshaft.
If I remember correctly there has been some issues with incorrect feature detection. A simple run of the v8 benchmarks with the latest bleeding_edge and the frequency of your CPU should be enough to determine if crankshaft is enabled. I hope this helps. Regards, Alexandre On Sat, Apr 2, 2011 at 7:40 AM, Arun M <[email protected]> wrote: > > > Hi > > Is Crankshaft optimizing compiler enabled for ARMv7-A + NEON devices > which does not have VFPv3 FPU? > > Thanks & Regards > Arun > > > On Mar 9, 6:02 pm, Søren Gjesse <[email protected]> wrote: > > For ARM crankshaft is now the default. This change is in the repository > > starting from V8 version 3.2. To use the previous optimizing compiler > > --nocrankshaft will have to be used. When crankshaft for ARM has been > fully > > stabilized the previous optimizing compiler will be removed from the > > repository and running with --nocrankshaft will no longer be possible. > There > > is no specific date to when this will happen but most likely it will be > > within a month or two. The removal of the previous optimizing compiler > will > > happen for all supported platforms simultaneously, > > > > The previous optimizing compiler can of cause still be found in previous > > versions of V8. > > > > Regards, > > Søren > > > > > > > > > > > > > > > > On Tue, Mar 8, 2011 at 20:05, Hugo Vincent <[email protected]> > wrote: > > > How much slower is full-compiler than nocrankshaft on ARM926ej-s - > > > anyone have any benchmarks? I'm hesitant to invest time in using V8 > > > for my project if it's going to get substantially slower soon. Is > > > there any estimated time frame for when nocrankshaft will be > > > deprecated? > > > > > Thanks, > > > Hugo > > > > > On Feb 23, 9:14 pm, Søren Gjesse <[email protected]> wrote: > > > > Just a follow-up note regarding the new optimizing compiler > (crankshaft). > > > > This will be enabled by default for ARM quite soon, and the existing > > > > optimizing compiler will be removed at some point. For non ARMv7+VFP > > > devices > > > > this means that the base JIT (non-optimizing/full-compiler) will be > used. > > > To > > > > measure the different compilers on a ARMv7+VFP device use following > > > options: > > > > > > --nocrankshaft (current optimizing JIT - the current default) > > > > --crankshaft (new optimizing JIT - the soon to be default) > > > > --always-full-compiler (base/non-optimizing compiler) > > > > > > Going forward using --crankshaft on a non ARMv7+VFP device will have > no > > > > effect and execution will fallback to --always-full-compiler. > > > > > > Regards, > > > > Søren > > > > > > On Wed, Feb 23, 2011 at 18:33, Rodolph Perfetta > > > > <[email protected]>wrote: > > > > > > > V8 can run on ARMv4 devices (non T though). > > > > > > > There is no interpreter in V8 so you will be using the JIT every > time, > > > > > perfromance should be good (keep in mind CPU like 926-ej-s do not > have > > > L2 > > > > > cache and this is going to have a visible impact). There is a new > JIT > > > > > infrastructure being developed (crankshaft) which features an > > > optimising JIT > > > > > and this will only be for ARMv7+VFP devices. > > > > > > > HTH, > > > > > Rodolph. > > > > > > > On 23 February 2011 17:12, Hugo Vincent <[email protected]> > > > wrote: > > > > > > >> Hi, > > > > > > >> I can't find in the documentation which ARM architecture types V8 > > > > >> supports. Does it support older ARM9 devices (I'm specifically > > > > >> interested in an ARMv5te architecture, ARM926ej-s device) or only > > > > >> newer ARMv7 (Cortex-A8 etc)? I can see that it is (supposed to) > build > > > > >> on ARMv5te, but do all the JIT features work or is it running in a > > > > >> byte code interpreter fallback or something? Can I expect good > > > > >> performance? > > > > > > >> Thanks, > > > > >> Hugo > > > > > > >> -- > > > > >> v8-users mailing list > > > > >> [email protected] > > > > >>http://groups.google.com/group/v8-users > > > > > > > -- > > > > > v8-users mailing list > > > > > [email protected] > > > > >http://groups.google.com/group/v8-users > > > > > -- > > > v8-users mailing list > > > [email protected] > > >http://groups.google.com/group/v8-users > > -- > v8-users mailing list > [email protected] > http://groups.google.com/group/v8-users > -- v8-users mailing list [email protected] http://groups.google.com/group/v8-users
