PATCH: Updated version of x86_64-pc-mingw32 support of gcc.

Michael Matz matz@suse.de
Mon Mar 19 16:57:00 GMT 2007


Hi,

On Mon, 19 Mar 2007, Kai Tietz wrote:

> > explicitely restricted to a maximum of 2 GB.  So, the small code model 
> > is completely enough.
> 
> That is true just for executables. But shared objects (DLL's) can be 
> placed far behind this boundary.

Like on Linux.

> Reasoned by the RVA relocation, which is 64-bit, it is necessary for 
> sure. As rev. see the msvcrt.dll, where it's base loading address is 
> placed.

Hmm, I've forgotten most about PE, so you might be right.  But as you have 
PC relative addressing the difference between %rip and any data from the 
same module is never larger than 2GB --> small model is enough.  If you 
can encode addresses of module X directly in .text of module Y, only then 
you need the large model.  You generally really really want to avoid using 
it, e.g. by indirecting over a pointer holding that 64bit address, but 
placed in .data (or GOT in ELF), and loading from it, instead of encoding 
that 64bit address directly into .text.


Ciao,
Michael.



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