I can't remember having seen such problems with x86_64. Works fine AFAICT

More info: bots running on the server can't move either. Players can shoot (and kill) but only in the direction they started. Players can turn around in the game, but it isn't reflected on the server.

Any hints ?

have you tried turning off strict aliasing (as I suppose you use the patch you posted)?

I was building from clean trunk. Both "release" and "debug" (-O0 does not enable strict aliasing), I also tried adding -fwrapv and -fsigned-char.
Other thing I tried was once to force and other time to disable idppc macro.
In all the cases effect is the same.

I've got the solution.
Thanks Ludwig ! You probably can't imagine how much help you've been.

Citing your comment from Bug 3805: "Just grep for union". So I did, and I found this flower:

static ID_INLINE float _vmf(intptr_t x)
{
        union { 
                intptr_t l;
                float f;
        } t;
        t.l = x;
        return t.f;
}

Which is wrong, because union of two different size variables is very hard to predict. I don't know why it works on x86_64, but there's no chance it's going to work on ppc64. All the interesting data is in lower bytes of 'l', while the float starts at the beginning of the union.

Code using int-float union works well on both x86_64 and ppc64, it looks like this:

static ID_INLINE float _vmf( intptr_t x )
{
        union { 
                int l;
                float f;
        } t;
        t.l = (int) x;
        return t.f;
}

I'll integrate the change into Bug 3805 patch.

OK, I have tested full "release" build, with version 4 of patch in bug 3805, and with JIT compiler. It works now.

fixed, thanks!