representation of struct field offsets

[Chris Lattner]

On Sep 28, 2006, at 1:58 PM, Mark Mitchell wrote:

> Chris Lattner wrote:
>
>> An alternative design, which would save a field, is just to keep  
>> the offset of a field, in bits, from the start of the structure.
>
> Yes, that would also work.  But, in many cases, you need the byte  
> offset, so there's a time/space tradeoff.

Yup, that's true.

> Also, because of GCC's internal representation of integers, you  
> have to be careful that you have enough bits; for example, you need  
> 72 bits to represent things in a 64-bit address space.

Actually, just 67, right?  Does GCC support structures whose size is  
greater than 2^61 ?

-Chris