3.4 Options Reference

possible. It is employed in situations where the user knows either that the dependences do not matter or that they never occur in practice.

The interpretation of !DIR$ IVDEP directives depend upon the value of the -xivdep option. The following values for p are interpreted as follows:

-loop — ignore assumed loop-carried vector dependences

-loop_any — ignore all loop-carried vector dependences

-back — ignore assumed backward loop-carried vector dependences

-back_any — ignore all backward loop-carried vector dependences

-none — do not ignore any dependences (disables IVDEP directives)

These interpretations are provided for compatibility with other vendor's interpretations of the IVDEP directive.

The default when —xivdep is not specified, and when —xivdep is specified without an argument, are both —xivdep=loop, which implies that the !DIR$ IVDEP directives are enabled by default.

For more information, see “2.3.3 IVDEP Directive” on page 37 for details.

3.4.140 -xjobs{=n|auto}

Compile with multiple processes. If this flag is not specified, the default behavior is - xjobs=auto.

Specify the -xjobs option to set how many processes the compiler creates to complete its work. This option can reduce the build time on a multi-cpu machine. Currently, -xjobs works only with the -xipo option. When you specify -xjobs=n, the interprocedural optimizer uses n as the maximum number of code generator instances it can invoke to compile different files.

Generally, a safe value for n is 1.5 multiplied by the number of available processors. Using a value that is many times the number of available processors can degrade performance because of context switching overheads among spawned jobs. Also, using a very high number can exhaust the limits of system resources such as swap space.

When -xjobs=auto is specified, the compiler will automatically choose the appropriate number of parallel jobs.

134 Oracle Developer Studio 12.6: Fortran User's Guide • July 2017