On 06/15/2016 07:14 PM, Alan Modra wrote:
On Wed, Jun 15, 2016 at 04:03:04PM -0600, Jeff Law wrote:
FWIW I don't think ownership of the argument slots has ever been
definitively addressed by any ABI and it's been an open question in my mind
for 20+ years -- though I've largely leaned towards callee ownership on my
own thinking. In an ideal world we'd push to get this clarified at the ABI
level.
The PowerPC64 ABI specifies that the stack parameter save area is not
preserved over calls. There's a good reason for this: An ABI that
specifies stack argument slots as preserved over calls cannot allow
sibling calls.
I didn't know it was specified there. Excellent. Good to see someone
doing the right thing with getting that nailed down.
I did read your message about sibling call support implying callee
ownership of the slots -- and I agree with that conclusion.
jeff
