I have done a bit of testing with regards to my optllvm failures in the testsuite. Some tests compile but segfault when they are run, others fail to compile, both with HEAD and 7.8.2, but those I tested all work with 7.6.3, although 7.6 gives the warning: You are using a new version of LLVM that hasn't been tested yet! We will try though... I suspect that the LLVM backend thinks I have a different version than I actually have, or maybe the LLVM tools think I have a different CPU than I have: dafis@schwartz:~/JNthPrime> llc --version LLVM (http://llvm.org/): LLVM version 3.2svn Optimized build. Default target: x86_64-unknown-linux-gnu Host CPU: corei7-avx Registered Targets: arm - ARM ppc32 - PowerPC 32 ppc64 - PowerPC 64 thumb - Thumb x86 - 32-bit X86: Pentium-Pro and above x86-64 - 64-bit X86: EM64T and AMD64 dafis@schwartz:~/JNthPrime> opt --version LLVM (http://llvm.org/): LLVM version 3.2svn Optimized build. Default target: x86_64-unknown-linux-gnu Host CPU: corei7-avx But my CPU is a Core i5, not i7. Can somebody confirm or deny that that may be the cause?