Eliminating static roots from gcj

Tue Mar 14 18:40:00 GMT 2006

Andrew Haley wrote:
> Hans,
>> I have a problem before merging this code to the trunk.
>> Accesses to String and Class constants is now slower than before.
> Previously, such an access was simply
>> _CD_<class>[N]
>> where _CD_<class> was an array in the initialized data section. With
> PIC, this simply generated a PC+offset fetch instruction:
>> movq 8+_CD_q(%rip), %rax
>> Now that we aren't scanning the data sections of objects, we have to
> do something like
>> class$->constants.data[i]
>
Why is this? For a shared object, the relative position of different 
parts of the object are not going to be moving around, are they?
I could see a possiblilty of problems with dynamically generated Class 
objects (from the interpreter).
.
.
.
> Clearly, ceasing to scan shared objects conservatively is a big
> advance for gcj, but I'd prefer it not to be accompanied by
> regressions in code quality.
>I agree with that. I just need a little help understanding the issue.
Thanks,
David Daney