GCC 4.5 doesn't compile a certain quicksort implementation correctly when optimizing with -O1 or higher

[Hans-Kristian Arntzen]

I have a reproducible test case which shows that GCC 4.5 (20091112) 
doesn't compile a certain quicksort implementation correctly. It runs 
fine, but the sorting is plain wrong when trying to optimize with -O1 or 
higher. I have made a reproducible test case. There might be something 
wrong with the quicksort implementation itself, but it compiles and runs 
fine when not optimizing anything with GCC 4.5. It also runs, and 
executes correctly on 4.3 and 4.4 with all optimizations applied.

The code in question is here:
http://pastebin.com/m270ad2a5

Output when compiling with
    gcc-4.5 -o qsort qsort.c -O

    http://pastebin.com/m44c8f6f2

Output with
    gcc-4.5 -o qsort qsort.c

    http://pastebin.com/m6ee486a0

Output with
    gcc-4.4 -o qsort qsort.c $CRAZYSTUFF_HERE

    http://pastebin.com/m78d55249