Unaligned access trade-offs for SFrame FRE layout

[Indu Bhagat]

On 9/12/25 1:17 PM, Sterling Augustine wrote:
> Agreed with the others that optimizing for size is preferred, but that 
> it would be very nice to know just how much performance we are talking 
> about.
> 
> I wonder if a partial solution would be enough to alleviate the concerns.
> 
> Some of the unaligned accesses can be fixed without a change to the 
> specification at all. An implementation could align just the first 
> sframe_row_entry for every function. That first entry is accessed every 
> time a function is unwound, so this idea reduces the number of unaligned 
> accesses by about one per frame.
> 

Yes, I too thought about that.  And correct, that should be easily doable.

> Not sure what the size penalty would be, but probably quite a bit less 
> than 22%.

Much less than 22%. I would expect it to be quite low. A few bytes per 
FDE essentially.