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Conditionals

if (plural-exp)
   ... 
else 
   ... 
  1. Save value of mask register (MR).
  2. Evaluate plural expression on each active PE.
  3. Set MR to result of evaluation
    Active processor set = set of processors where MR is set.
  4. Execute then branch on active processor set.
  5. Revert MR.
  6. Execute else branch on active processor set.
  7. Restore saved value of MR.
Both branches are evaluated sequentially!
T(if) = T(exp)+T(then)+T(else)

Author: Wolfgang Schreiner
Last modification: November 15, 1996