Could it be related to something like this perhaps?

Just for curiosity I tried

Code
objdump -d C:\mingw64-w32\libexec\gcc\i686-w64-mingw32\4.6.3\cc1.exe > \Tmp\cc1-exe-objdump.txt
... and I found a lot of CMOVxx instructions that are likely to be missing in old processors (see here).

A mind is like a parachute. It doesn't work unless it's open. [Frank Zappa]