Re: malloc attributes and realloc

[Gabriel Dos Reis <gdr at integrable-solutions dot net>]

Russ Allbery <rra@stanford.edu> writes:

| Kaveh R Ghazi <ghazi@caip.rutgers.edu> writes:
| 
| > Hum, that is surprising.  If we can't rely on pointer ordering, then
| > libiberty/alloca.c wouldn't work since it uses exactly this ordering to
| > detect the stack growth direction and also to detect when storage can be
| > freed.
| 
| Right.  I'm fairly sure that it's not possible to write a portable alloca
| implementation without compiler extensions (although that particular
| extension is ubiquitous).  It's the kind of facility that is best
| implemented internal to the compiler, in the program that already
| thoroughly understands the architecture of the target host.

And I will point out that libstdc++ depends on that pointer ordering
behaving "correctly" in its implementation of std::less<T*>.

-- Gaby