CFI for saved argument registers

[Andreas Krebbel]

On 5/16/22 16:39, Andreas Schwab wrote:
> On Mai 16 2022, Andreas Krebbel via Gcc wrote:
> 
>> The only way I see right now is adding a new reg note to invalidate
>> the save information in the reg_save array in dwarf2cfi.
>>
>> Would this be acceptable? Is there perhaps an easier way to achieve that?
> 
> Doesn't it work to use .cfi_remember_state/.cfi_restore_state?
> 
This might work but I think also for that I would have to implement means to trigger it explicitely
with an RTX somehow.

Also I rather would avoid emitting special CFI for that purpose. I think the CFI I currently have
(with more .cfi_offset's than .cfi_restore's) is valid. I only have to convince the validation step
in dwarf2cfi to accept this. Therefore the idea was to introduce a new regnote to say that at a
certain point it is intentional that there is no .cfi_restore for a register. The action in
dwarf2cfi should only be to remove the reg from reg_save and be done with it.

Bye,

Andreas