The cDEC$ IVDEP directive allows you to help control certain optimizations related to dependence analysis in a DO loop. Place the cDEC$ IVDEP directive before the DO loop you want to help control the optimizations for. Not all DO loops should use this directive.
The cDEC$ IVDEP directive tells the optimizer to begin dependence analysis by assuming all dependences occur in the same forward direction as their appearance in the normal scalar execution order. This contrasts with normal compiler behavior, which is for the dependence analysis to make no initial assumptions about the direction of a dependence.
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