-qarch

The -qarch argument specifies the type of processor on which the executable code will be run, and produces an executable program that contains machine instructions specific to that processor. This allows the compiler to take advantage of processor-specific instructions that can improve performance at the cost of producing an executable program that will run on only one type of processor. The default for this argument is -qarch=com, which will produce a program that is runnable on any POWER or POWERPC processor.

The recommended value for this argument is

      -qarch=auto

The -qarch=auto option tells the compiler to produce a program with machine instructions specific to the processor on which it is compiled.