On Fri, 9 Mar 2012, Dave Martin wrote:
Register variables feel like a red herring though. We're only using those because we can't do the needful thing and actually desscribe these constraints in the asm constraints (which would seem to be the right place). We specifically don't care where those values are except at the boundaries of the asm block itself.
Absolutely.
Is there a reason why ARM gcc doesn't provide the ability to specify such exact-register constraints, or is this more for historical reasons? It is possible?
I don't know how much things have changed since I last looked at the gcc code, but implementing this seemed to be pretty trivial at the time. The problem would be to determine a good letter scheme to map to actual registers.
Nicolas