Secrets of F90 compiler optimization

How to specify levels . . .

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Tom Parker
by Tom Parker


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There are three main types of F90 compiler optimization on SCD Cray computers: vector, scalar, and autotasking (task). You can specify the desired level (0-3) of each type with the f90 -O option -- either individually, by using specific levels, or all three types at once, by using a general level.

This article summarizes the valid -O options you can specify.


  1. Specific optimization levels

  2. General optimization levels

  3. Valid combinations of specific levels

  4. All possible combinations and their results

  5. Optimization characteristics

  6. Optimization levels vs. debugging levels

  7. Examples


Reference information

For more information on optimization options, see Section 2.2.19 of the CF90 Commands and Directives Reference Manual, SR-3901 3.0.

This is available in hardcopy, or online at:

www.cdoc.ucar.edu/cgi/nph-dynaweb/library/all/3901_3.0/2959#X

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