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: http://gcc.gnu.org/viewcvs/trunk/gcc/tree-ssa-structalias.c?r1=159098&r2=159097&pathrev=159098 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. Allan