Re: [avr-llvm-devel] Load / Store

[John M. <ato...@gm...>]

On Thu, Nov 4, 2010 at 7:09 PM, Weddington, Eric
<Eri...@at...>wrote:

>  >
> > Eric,
> >
> > I think transparently placing, for example, const qualified
> > objects in flash will only take creating an LLVM
> > transformation Pass. Which means the extra work has already
> > been done by the LLVM Pass Framework. Now if we have to do
> > work in the front end then I can see your point.
> >
> > --John
>
> Oh, I'm sorry, I didn't fully grasp what we're talking about here.
>
> It really is not appropriate to automatically put const qualified objects
> in flash. The keyword 'const' has a specific meaning (read-only value) which
> does not necessarily mean that it should be put into a specific memory
> space, even if it is a read-only value. We will need to have an additional
> memory space qualifier on the object to put it in a different address space.
> That way it is the least surprise to users who are used to using GCC and IAR
> (and other compilers).
>
> Eric
>

I don't see why it would be inappropriate from the standpoint of a High
Level Language or even C.  A linker frees the user from needing to manually
place objects and it seems to me having the compiler place const qualified
objects in specific areas is no different. I agree that we will still need
to support memory space qualifiers.