LLVM sets certain default configure options to make sure our developers don't break things for constrained platforms. These settings are not optimal for most desktop systems, and we hope that packagers (i.e., Redhat, Debian, MacPorts, etc.) will tweak them. This document lists settings we suggest you tweak.

RTTI

LLVM disables RTTI by default. Add REQUIRES_RTTI=1 to your environment while running make to re-enable it. This will allow users to build with RTTI enabled and inherit from LLVM classes.

Exceptions

LLVM disables exceptions by default. Add REQUIRES_EH=1 to your environment while running make to re-enable them. This will allow users to link LLVM and exception-using code. It also re-enables RTTI.

Configure with --enable-shared to build libLLVM-major.minor.(so|dylib) and link the tools against it. This saves lots of binary size at the cost of some startup time.