[Bug middle-end/43987] [4.5 regression] type-punning causes broken binaries unless -O0 is used

[thomas at archlinux dot org]

------- Comment #3 from thomas at archlinux dot org  2010-05-04 23:06 -------
What is -fwrapv supposed to do? I don't see any changes in behaviour or
compiler output.


As I said, I don't know exactly what to put into a test case (I didn't write
any of the code that breaks), but I can try my best to find one.


I first encountered this problem in gap (http://www.gap-system.org), and it was
fixed by this patch:
http://www.math.leidenuniv.nl/~wpalenst/sage/gap_gcc45_strict_aliasing.patch
(look at the sysinfo.c part, that was what caused the problems apparently).

I now encountered it again in busybox's 'sed' applet. I will try to take that
code apart until I find out what's going wrong and hopefully produce a test
case.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43987