PCH and exec-shield...

[Ian Lance Taylor]

Mike Stump <mrs@apple.com> writes:

> On Tuesday, March 16, 2004, at 03:50 PM, Zack Weinberg wrote:
> > To ask a tangential question, if (as presently implemented) PCH has to
> > reload data structures at the original address, why is there a problem
> > with hashing pointers?
> 
> We swizzle on PCH write.  PCH write can be amortized across multiple
> uses better, also, during writing, memory is hot.  During load, we
> could have to bring in (from disk/network) and COW it.

On PCH write, gcc swizzles pointers and also copies the hash tables to
the PCH address.  It seems to me that gcc could rehash the pointer
values while copying the hash tables.

So I still don't understand why we can't hash on pointer values.

Ian