4.5.1 -aggressive, -ag, (-noaggressive), -nag

The -aggressive switch must take one of two forms as follows:

• The first form, -aggressive=a , tells KAP to pad COMMON blocks to avoid cache line collisions. This form of optimization is safe when the following conditions are satisfied:

  • All COMMON blocks are visible to KAP as it processes the source file. You must use KAP on all of your files so that all COMMON blocks are visible to KAP.

  • If the same COMMON block has two different layouts, the different layouts do not pass data between them; they are fully independent.

  • There are no bounds violations. This means that no adjustable arrays are being referenced outside their declared bounds.

  Most Fortran programs satisfy these conditions, so enabling this form of optimization can yield significant performance gains.

• The second form, -aggressive=ab , in addition to padding COMMON blocks, adjusts the leading dimensions of arrays away from a power of 2, if the arrays are not used as actual arguments to any user procedure calls. Use -aggressive=ab only if the -aggressive=a requirements hold, and if the performance of the program will not be affected by changing the leading dimensions of arrays.

• The third form, -aggressive=c , permits KAP to inline routines that contain static SAVE or DATA variables by promoting the static variables to members of a COMMON that is introduced into the program.

  If the original program has DATA statements on some of the static variables, these DATA statements will now be to elements of a COMMON.

To explicitly disable this transformation, specify -noaggressive . See also the -natural , -cacheline , -cachesize , and -setassociativity command-line switches.

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