Example: Atomic Directive

• optimization of mutual exclusion for certain cases:

  • the directives applies to the statement immediately following it
  • the statement must not be a structured block:
    • x = x op expr
    • x = intrinsic(x,expr)
    • x binop = expr;
    • x++; x--; ++x; --x
  • All references to storage x must be of the same type
  • enables fast implementation on some hardware, others will use the critical section construct

!$OMP ATOMIC

Y(INDEX(I)) = Y(INDEX(I)) + Z

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