[Bug c++/15795] No way to teach operator new anything about alignment requirements

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2004-06-08 15:55 -------
The glibc people have decided that they will not change malloc to provide the   
alignment requirements one would need for the case in this PR (see   
http://sources.redhat.com/bugzilla/show_bug.cgi?id=206):   
---------------------------   
MALLOC_ALIGNMENT in glibc is really not going to change, it is a quality of   
implementation, sure, by making it bigger the quality implementation would drop   
a lot for most of the programs out there.   
SSE types are certainly out of the scope of the C standard.  GCC allows to create   
objects with arbitrary alignment, not just __m128, but you can use say:   
__attribute__((aligned (256))).  With the same argumentation, you could request   
that all malloc memory is 256 bytes aligned (or 4K or whatever you choose).   
If you want to make C++ new working on these types, the compiler will simply   
need to do its part and call some (non-standard) new operator with additional   
alignment argument, which would in turn call posix_memalign, perhaps guarded with   
some compiler option which will otherwise result in a compile time error if new   
is used on types with too big alignment requirement.   
--------------------------------   
 
In other words, the ball is back in our field. Anyone got ideas as to what to do? 
How do other compilers do this? (I just verified that icc 8.0 also segfaults on 
the small testcase in comment #11, but maybe some compiler is more clever 
there...) 
 
W. 

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at redhat dot com
             Status|RESOLVED                    |UNCONFIRMED
         Resolution|WONTFIX                     |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15795