Initial attempt at floating point debugging

[vatral]

This is a bit of a hack to try to get to the bottom of all the NaN issues.

It adds a new parameter, which allows to enable floating point exceptions. There's a hack to disable this around QML because when enabled, there's an apparently limitless amount of divides by zero coming from the QML for AvatarInputsBar.qml for some reason.

With this patch, and running interface --floatExcept divbyzero here's what I get:

Thread 81 "Thread (pooled)" hit Breakpoint 5, fpe_handler (signum=8) at /home/vadim/git/overte/overte/interface/src/main.cpp:59
59	   ++fpe_counter;
(gdb) bt
#0  fpe_handler (signum=8) at /home/vadim/git/overte/overte/interface/src/main.cpp:59
#1  0x00007fffcce210b0 in <signal handler called> () at /lib64/libc.so.6
#2  _mm256_div_ps(float __vector(8), float __vector(8)) (__A=..., __B=...) at /usr/lib/gcc/x86_64-redhat-linux/16/include/avxintrin.h:227
#3  packBlendshapeOffsets_AVX2 (unpacked=unpacked@entry=0x7ffe602c9948, packed=packed@entry=0x7ffe60034aa8, size=size@entry=559)
    at /home/vadim/git/overte/overte/libraries/shared/src/avx2/BlendshapePacking_avx2.cpp:65
#4  0x00007ffff5cb9c10 in packBlendshapeOffsets (unpacked=unpacked@entry=0x7ffe602c9948, packed=0x7ffe60034aa8, size=559)
    at /home/vadim/git/overte/overte/libraries/render-utils/src/Model.cpp:1888
#5  0x00007ffff5cbac92 in Blender::run (this=0x31a37c60) at /home/vadim/git/overte/overte/libraries/render-utils/src/Model.cpp:1991
#6  0x00007ffff5e5dccb in QThreadPoolThread::run (this=0x27b594c0) at thread/qthreadpool.cpp:100
#7  0x00007ffff5e5aaaa in operator() (__closure=<optimized out>) at thread/qthread_unix.cpp:350
#8  (anonymous namespace)::terminate_on_exception<QThreadPrivate::start(void*)::<lambda()> > (t=<optimized out>) at thread/qthread_unix.cpp:287
#9  QThreadPrivate::start (arg=0x27b594c0) at thread/qthread_unix.cpp:310
#10 0x00007fffcce79d19 in start_thread (arg=<optimized out>) at pthread_create.c:454
#11 0x00007fffccefd64c in __GI___clone3 () at ../sysdeps/unix/sysv/linux/x86_64/clone3.S:78
(gdb) frame 4
#4  0x00007ffff5cb9c10 in packBlendshapeOffsets (unpacked=unpacked@entry=0x7ffe602c9948, packed=0x7ffe60034aa8, size=559)
    at /home/vadim/git/overte/overte/libraries/render-utils/src/Model.cpp:1888
1888	       packBlendshapeOffsets_AVX2((float(*)[9])unpacked, (uint32_t(*)[4])packed, size);
(gdb) print unpacked
$6 = (BlendshapeOffsetUnpacked *) 0x7ffe602c9948
(gdb) print *unpacked
$7 = {positionOffsetX = 0, positionOffsetY = 0, positionOffsetZ = 0, normalOffsetX = 0, normalOffsetY = 0, normalOffsetZ = 0, tangentOffsetX = 0, tangentOffsetY = 0, 
  tangentOffsetZ = 0}
(gdb) frame 3
#3  packBlendshapeOffsets_AVX2 (unpacked=unpacked@entry=0x7ffe602c9948, packed=packed@entry=0x7ffe60034aa8, size=size@entry=559)
    at /home/vadim/git/overte/overte/libraries/shared/src/avx2/BlendshapePacking_avx2.cpp:65
65	       __m256 rcp = _mm256_div_ps(_mm256_set1_ps(1.0f), len);
(gdb) print len
$8 = {0, 0, 0, 0, 0, 0, 0, 0}
(gdb)  

@ada-tv -- Does this help any?

[ada-tv]

The Windows build is failing. I don't think fedisableexcept has an equivalent on Windows, so the OffscreenSurface changes might need to be ifdef'd.

libraries\qml\src\qml\OffscreenSurface.cpp(468,5): error C3861: 'fedisableexcept': identifier not found