Function LLVMInitializeFunctionPassManager 

pub unsafe extern "C" fn LLVMInitializeFunctionPassManager(
    FPM: LLVMPassManagerRef,
) -> LLVMBool

Initializes all of the function passes scheduled in the function pass manager. Returns 1 if any of the passes modified the module, 0 otherwise. @see llvm::FunctionPassManager::doInitialization