ix86_data_alignment: bad defaults?

[DJ Delorie]

> Yes, BIGGEST_ALIGNMENT is supposed to be the biggest alignment the
> compiler will ever use.

Will ever use, or can ever use?  Based on the code, it looks like "can
ever use" - i.e. it's an edict to the compiler to not exceed that
value, thus varasm warns when you exceed it.

> So if ix86_data_alignment wants to return 256 for some variable,
> then it seems to me that BIGGEST_ALIGNMENT should be 256.

What if the object format doesn't allow recording alignments that
high?  For example, DJGPP's coff format can only record alignments up
to 2**4 (16) bytes, but 256 bits is 2**5 (32) bytes.