[rfc] Frame based register cache / frame->unwind

[Kevin Buettner]

On Apr 14,  4:58pm, Andrew Cagney wrote:

> I'm not too worried about the apparent 2% overhead per frame create 
> though.  With the patch applied, the code ends up maintaining both this 
> new cache and the old ->saved_regs table.  Rewriting a target to just 
> use the ->unwind_cache, should, I think, claw back the 2% and then some 
> - less need to go out to the target.

I'm puzzled.  Assuming you don't have dwarf2cfi or the like, how do you
avoid maintaining the old ->saved_regs table?

Hmm...  I see that the unwind cache has an ``addr'' field.  Does that
mean that that the prologue analysis function calls
frame_supply_unwound_register() to set this field?

What is the ``optimized'' flag (in the frame cache) used for?

Kevin