s390: larl for Simode on 64-bit

[Jeff Law]

On 07/08/2015 02:33 PM, DJ Delorie wrote:
> Is there any reason that LARL can't be used to load a 32-bit symbolic
> value, in 64-bit mode?  On TPF (64-bit) the app has the option of
> being loaded in the first 4Gb so that all symbols are also valid
> 32-bit addresses, for backward compatibility.  (and if not, the linker
> would complain)
It would seem that we'd want the compiler to know when the app is going 
to be loaded into that first 4G so that it can use the more efficient 
addressing modes.
Jeff