On Mon, Apr 27, 2009 at 7:02 PM, Ryan M. Lefever <lefever at crhc.illinois.edu> wrote: > I assume that when -O3 (or O2 or O1) is passed to llvm-gcc, then it > utilizes opt. No, llvm-gcc links in the optimization passes and runs them directly. See http://llvm.org/viewvc/llvm-project/llvm-gcc-4.2/trunk/gcc/llvm-backend.cpp?revision=70258&view=markup . -Eli