Function LLVMGetAggregateElement 

pub unsafe extern "C" fn LLVMGetAggregateElement(
    C: LLVMValueRef,
    Idx: c_uint,
) -> LLVMValueRef

Get element of a constant aggregate (struct, array or vector) at the specified index. Returns null if the index is out of range, or it’s not possible to determine the element (e.g., because the constant is a constant expression.)

@see llvm::Constant::getAggregateElement()