LLVM leaves that problem for users of the library. Users instantiate optimization passes and specify in what order to call them. For example, 'opt' has (http://llvm.org/cmds/opt.html):
-{passname}
opt provides the ability to run any of LLVM's optimization or analysis passes in any order. The -help option lists all the passes available. The order in which the options occur on the command line are the order in which they are executed (within pass constraints).
-std-compile-opts
This is short hand for a standard list of compile time optimization passes. This is typically used to optimize the output from the llvm-gcc front end. It might be useful for other front end compilers as well. To discover the full set of options available, use the following command:
I do not know whether compilers 'included' with LLVM (clang, llvm_gcc) have support for tweaking the order. If they do not, you can always let them write unoptimized IR, and pipe the output through opt.
