Compiling libjvm.so as PIC

[Andrew Haley]

Matthias Klose wrote:
> Andrew Haley schrieb:
>> Omair Majid wrote:

>>> I just finished running the tests with SELinux disabled. The performance
>>> difference between a PIC jvm and a non-PIC jvm was about 0.9%, with the
>>> PIC jvm being actually faster. So any performance loss is negligible.

>> Thanks.  I suspect that the problem this non-PIC compile was supposed to fix
>> may be a bit of ancient history based on an old version of gcc.  It's not
>> entirely surprising that PIC might be faster, since fixing up the non-PIC
>> relocations takes extra time.
> 
> I don't share this point. The python interpreter, statically built with
> gcc-4.2.x is about 10% faster than the version built with -fPIC.

> When built with
> gcc-4.3.x it runs the pybench in pic/non-pic with the same speed as the
> gcc-4.2.x build with pic. So with gcc-4.3.x it doesn't make a difference, while
> it did with gcc-4.2.x. However I didn't explicitely check jvm builds. How were
> the performance checks done?

With SPEC JVM.
I doubt very much that it makes any difference with gcc-4.2.x either,
but we've already spent of ton of time on this and the case is proved
for 4.3.x.
We could conditionalize this on gcc-4.3.x, I suppose,

Andrew.