[arch-dev-public] [toolchain] gcc 4.5 breakage

Allan McRae allan at archlinux.org
Thu May 6 07:33:34 EDT 2010

On 06/05/10 17:45, Thomas Bächler wrote:
> Am 06.05.2010 09:44, schrieb Thomas Bächler:
>> Am 05.05.2010 02:46, schrieb Allan McRae:
>>> Interesting...  Does fixing the aliasing fix this one too? I see no
>>> upstream bug reports that seem related so you should follow it up there.
>>>   I will pull in a new gcc-4.5 snapshot next week when I do the
>>> glibc-2.12 toolchain rebuild so hopefully that may contain a fix that I
>>> am missing...
>> There is no fix in the latest 4.5 branch (or trunk) yet.
>> http://gcc.gnu.org/PR43987 has more details.
>> Basically, the problem is caused by -ftree-fta, which is on by default
>> with -O1 and higher (and also -Os, which I use for busybox). The bug can
>> be worked around with -fno-tree-fta until a fix becomes available.
> Writing is difficult - it's -free-pta and -fno-tree-pta, of course.

Don't worry...  the gcc guy who fixed the bug got it wrong too!  :)

There is a patch on gcc trunk now:

I expect glibc-2.12 to be released in the next few days, so I will hold 
off until the next gcc-4.5 snapshot is released in the hope that this 
fix gets backported by then.  If not, it looks a simple backport, so I 
will adjust the patch.


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