Re: Still crashes due to aliasing violation (Re: [RFC, PATCH] Split pool_allocator and create a new object_allocator)

[Richard Biener <richard.guenther@gmail.com>]

On July 17, 2015 6:54:32 PM GMT+02:00, Ulrich Weigand <uweigand@de.ibm.com> wrote:
>Richard Biener wrote:
>> On July 17, 2015 3:50:19 PM GMT+02:00, "Martin Liška"
><mliska@suse.cz> wrote:
>> >Question is why aliasing oracle still wrongly aliases these
>pointers?
>> >Another option (suggested by Martin Jambor) would be to place
>> >::allocate implementation
>> >to alloc-pool.c file.
>> 
>> Note that all compilers up to 4.4 have aliasing issues with placement
>new.
>> A fix is to move the placement new out-of-line.
>
>Yes, that's what I just noticed as well.  In fact, my particular
>problem
>already disappears with 4.3, presumably due to the fix for PR 29286.
>
>So do we now consider host compilers < 4.3 (4?) unsupported for
>building
>mainline GCC, or should we try to work around the issue (e.g. by moving
>the allocator out-of-line or using some other aliasing barrier)?

Why is this an issue for stage1 which runs w/o optimization?  For cross compiling we already suggest using known good compilers.

>Bye,
>Ulrich