dip1000 and preview in combine to cause extra safety errors

[forkit]

On Tuesday, 14 June 2022 at 02:35:22 UTC, rikki cattermole wrote:
> All heap memory allocations are expensive.
>
> I cannot emphasize this enough.
>
> Stack allocation costs one instruction, an add. That's it. Heap 
> allocation cannot compete.

ok. just in terms of 'allocation', for an int, for example:

https://d.godbolt.org/z/Y6E668hEn

it's a difference of 4 instructions (with stack having the lesser 
amount)

then the question I have is, how much faster does it take for 
*my* cpu to do those 6 instructions, vs those 10 instructions.

that seems difficult to accurately determine - as a constant ;-)

So I presume the assertion that stack 'allocation' is faster than 
heap 'allocation', is based purely on the basis that there are 'a 
few less' instructions involved in stack allocation.