[Bug preprocessor/58379] default mmap based implementation (mmap_gt_pch_get_address/mmap_gt_pch_use_address) is useless

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58379

Andrew Pinski  changed:

   What|Removed |Added

   See Also||https://gcc.gnu.org/bugzill
   ||a/show_bug.cgi?id=71934

--- Comment #3 from Andrew Pinski  ---
I think this is getting fixed via PR 71934.

[Bug preprocessor/58379] default mmap based implementation (mmap_gt_pch_get_address/mmap_gt_pch_use_address) is useless

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58379

--- Comment #1 from Richard Biener rguenth at gcc dot gnu.org ---
Well, it doesn't _rely_ on it - it basically makes systems where that is the
case work out of the box (every system pre address-space-randomization area).

If you have a system that randomizes then you have to re-define the hook.

[Bug preprocessor/58379] default mmap based implementation (mmap_gt_pch_get_address/mmap_gt_pch_use_address) is useless

[martin at netbsd dot org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58379

--- Comment #2 from Martin Husemann martin at netbsd dot org ---
(In reply to Richard Biener from comment #1)
 If you have a system that randomizes then you have to re-define the hook.

Besides ASLR there are various things out of control of the compiler that do
result in varying mapping adresses (like malloc using mmap instead of brk), so
chances are low in any modern system.

I'm not opposed to create a hook for NetBSD, but I have a hard time seeing a
possible sensible implementation. Look at the #ifdef cascade in
config/host-openbsd.c for a disgusting example of code that should not be in a
compiler (IMHO).

How hard is making the externalized format address neutral?