Checking for Inefficient Unaligned Data

During compilation, the Visual Fortran compiler naturally aligns as much data as possible. Exceptions that can result in unaligned data are described in Causes of Unaligned Data and Ensuring Natural Alignment.

Because unaligned data can slow run-time performance, it is worthwhile to:

• Double-check data declarations within common block, derived-type data, or record structures to ensure all data items are naturally aligned (see the data declaration rules in Ordering Data Declarations to Avoid Unaligned Data). Using modules to contain data declarations can ensure consistent alignment and use of such data.
• Avoid the EQUIVALENCE statement or use it in a manner that cannot cause unaligned data or data spanning natural boundaries.
• Ensure that passed arguments from outside the program unit are naturally aligned.
• Check that the size of array elements containing at least one derived-type data or record structure cause array elements to start on aligned boundaries (see Causes of Unaligned Data and Ensuring Natural Alignment).

During compilation, warning messages are issued for any data items that are known to be unaligned (unless you specify the /warn:noalignments option).