On domingo, 29 de julho de 2012 08.13.20, [email protected] wrote: > - actually for loading time, the bottleneck is the R_ARM_ABS32 relocation, > which is reduced around 97% now ! > > Finally the overall loading time is reduced from ~10-20s to ~1s...
Wow! Any chance you can blog about this somewhere? If you don't, I will based
on your data.
> But I still have some question about the R_ARM_ABS32 relocation.
>
> It seems if the function is virtual (with "default" visibility), then it
> will be added into .rel.dyn as the R_ARM_ABS32 type, for example: 007b0124
> 0011a802 R_ARM_ABS32 00311e4b
> _ZN20QEventDispatcherUNIX13processEventsE6QFlagsIN10QEventLoop17ProcessEven
> tsFlagEE
>
> Could someone help with below:
> 1. why the virtual function with "default" visibility needs relocation even
> if it's implemented inside ?
That's what "default" means: the symbol can be interposed by another, from a
different library. It is possible that another library implements a different
version of this function.
If it weren't like that, if it resolved to the local library, it would be
behaviour of "protected" visibility. That is:
> 2. when changed to "protected" visibility, I
> guess it's optimized to add a GOT.PLT entry as a R_ARM_RELATIVE relocation,
> is that true ?
The virtual table gets a relative relocation, true. Virtual calls don't need
PLT entries since they're always indirect. The PLT for a virtual function only
shows up if that function is called non-virtually: that is, from the
constructor, when the full class name was specified or when the compiler could
prove what class the object is.
--
Thiago Macieira - thiago.macieira (AT) intel.com
Software Architect - Intel Open Source Technology Center
Intel Sweden AB - Registration Number: 556189-6027
Knarrarnäsgatan 15, 164 40 Kista, Stockholm, Sweden
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