Description:

The current GCC version in Arch (4.6.0 20110513 prerelease) has issues with OpenMP that lead to "internal compiler error", when compiling my open-source renderer (http://users.softlab.ece.ntua.gr/~ttsiod/renderer.html).

This didn't happen with older releases of GCC.
I reported the bug upstream, here:

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49223

The GCC version is...

bash$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/i686-pc-linux-gnu/4.6.0/lto-wrapper
Target: i686-pc-linux-gnu
Configured with: /build/src/gcc-4.6-20110513/configure --prefix=/usr --libdir=/usr/lib --libexecdir=/usr/lib --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=https://bugs.archlinux.org/ --enable-languages=c,c++,ada,fortran,go,lto,objc,obj-c++ --enable-shared --enable-threads=posix --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-clocale=gnu --enable-gnu-unique-object --enable-linker-build-id --with-ppl --enable-cloog-backend=isl --enable-lto --enable-gold --enable-ld=default --enable-plugin --with-plugin-ld=ld.gold --disable-multilib --disable-libstdcxx-pch --enable-checking=release
Thread model: posix
gcc version 4.6.0 20110513 (prerelease) (GCC)

The platform is...

bash$ uname -a
Linux home 2.6.38-ARCH #1 SMP PREEMPT Fri May 13 07:54:18 UTC 2011 i686 Intel(R) Celeron(R) CPU E3400 @ 2.60GHz GenuineIntel GNU/Linux

Steps to reproduce:
From the link mentioned above (the upstream GCC bugreport) download the preprocessed input file, and try to compile it, with and without -fopenmp:

bash$ g++ -c -fopenmp -O3 -g -Wall -Wextra -fomit-frame-pointer
-ffast-math -funsafe-math-optimizations -mtune=native -msse -mrecip
-mfpmath=sse -msse2 -mssse3 renderer-Rasterizers.i

You'll get the internal compiler error. Without openmp, it works:

bash$ g++ -c -O3 -g -Wall -Wextra -fomit-frame-pointer -ffast-math
-funsafe-math-optimizations -mtune=native -msse -mrecip -mfpmath=sse -msse2
-mssse3 renderer-Rasterizers.i

I'll update this bug report if/when the upstream GCC bugreport has any activity.