i1 vectors (Re: [PATCH] Fix PR15267)

[Duncan Sands]

Hi,

> I think that at this point the representation of i1 vectors is clear. i1s are bit packed in memory. When AVX512 masks are saved to memory they are copied as-is. When an AVX mask are saved to memory they need to be packed. At the moment we have a bug in the code that packs i1s into memory. But this can be fixed. With the exception of the load/store bug everything else already works.

I agree that bit-packed is the right approach.  But last time I looked plenty of 
bits of the IR thought that 8xi1 would be stored in 8 bytes, one bit per byte. 
There needs to be a thorough audit.

Ciao, Duncan.