Re: immediate strings #2

[Ken Raeburn <raeburn@raeburn.org>]

On Nov 29, 2011, at 03:44, Andreas Schwab wrote:
> Ken Raeburn <raeburn@raeburn.org> writes:
> 
>> Well, I think Stefan's technically right... the "as-if" rule lets the
>> compiler get away with a lot, if it can analyze enough of the program
>> to figure out that it wouldn't make a difference to the semantics
> 
> Only if the address is never taken, or sizeof is never applied.

If the compiler really wants to play some games in the name of space optimization, it could pack the type as densely as possible (rearrange or eliminate fields, limit integer or pointer fields to the number of bits that will actually get used, etc) for actual storage, and still print sizes and offsets consistent with the official alignment rules for the platform, if it can keep the two cases straight.  (Allocating the actually-used smaller size instead of the larger "normal" size would still be consistent as long as the difference isn't visible by certain criteria; I'm pretty sure process size under "ps" isn't one of those criteria.)  It'd be a lot of effort and probably not worthwhile, but not outside of the rules.

Ken