On 6/8/2021 9:06 AM, H.J. Lu wrote:
On Tue, Jun 8, 2021 at 7:56 AM Jakub Jelinek via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
On Tue, Jun 08, 2021 at 08:47:26AM -0600, Jeff Law wrote:
Why is the machinery involving STACK_SLOT_ALIGNMENT and
spill_slot_alignment() (for spilling) or get_stack_local_alignment() (for
backing stack slots) not working for you? If everything is setup
correctly the input alignment to try_fit_stack_local ought to be correct
already.
We don't need the MEM as a whole aligned, just the offset in the address
calculation due to how we encode those instructions. If I've read that code
correctly, it would arrange for a dynamic realignment of the stack so that
it could then align the slot. None of that is necessary for us and we'd like
to avoid forcing the dynamic stack realignment. Or did I misread the code?
I think dynamic stack realignment is done only on x86, no other backend has
I believe that all pieces of infrastructure to realign the stack are
in place. You
just need to properly align the stack in the backend.
As I've stated, we don't need the stack aligned to these higher
boundaries. Nor do we need the slot as a whole aligned. That's
ultimately just wasteful since we don't need them. We just want to get
an aligned offset.
Jeff
