strict-aliasing and typedefs

[Fergus Henderson]

On 14-May-2003, Brad Lucier <lucier@math.purdue.edu> wrote:
> I've read the documentation and done a google and gcc search, but
> I still have this question.
> 
> If I have the typedefs and variables
> 
> typedef int stackslot;
> typedef int heapslot;
> 
> stackslot *sp;
> heapslot *hp;
> 
> then can sp and hp point to the same location in memory with
> ISO C's aliasing rules?

Yes.

> I'm wondering if a Scheme->C compiler
> can use typedefs and ISO C's aliasing rules to tell gcc that certain
> memory locations cannot alias each other.

I don't think so.

You might be able to do it using single-member structs instead of typedefs;
but doing that might inhibit some of GCC's other optimizations.

-- 
Fergus Henderson <fjh@cs.mu.oz.au>  |  "I have always known that the pursuit
The University of Melbourne         |  of excellence is a lethal habit"
WWW: <http://www.cs.mu.oz.au/~fjh>  |     -- the last words of T. S. Garp.