Issue: Assumed dependency present

The compiler assumed there is an anti-dependency (Write after read - WAR) or a true dependency (Read after write - RAW) in the loop. Improve performance by investigating the assumption and handling accordingly.

Recommendation: Confirm dependency is real

There is no confirmation that a real (proven) dependency is present in the loop. To confirm: Run a Dependencies analysis.

Recommendation: Resolve dependency

The Dependencies analysis shows there is a real (proven) dependency in the loop. To fix: Do one of the following:

If there is an anti-dependency, enable vectorization using the directive !$OMP SIMD SAFELEN(length) , where length is smaller than the distance between dependent iterations in anti-dependency. For example:
```
!$OMP SIMD SAFELEN(4)
  do i = 1, N-4, 4
     a(i+4) = b(i) * c
  enddo
```
If there is a reduction pattern dependency in the loop, enable vectorization using the directive !$OMP SIMD REDUCTION(operator:list). For example:
```
!$OMP SIMD REDUCTION(+:SUMX)
  do k = 1, size2
     sumx = sumx + x(k) * b(k)
  enddo
```
Rewrite the code to remove the dependency. Use programming techniques such as variable privatization.

Read More:

Getting Started with Intel Compiler Pragmas and Directives and Vectorization Resources for Intel® Advisor Users

Recommendation: Enable vectorization

The Dependencies analysis shows there is no real dependency in the loop for the given workload. Tell the compiler it is safe to vectorize using the restrict keyword or a directive:

Directive	Outcome
!DIR$ SIMD or !$OMP SIMD	Ignores all dependencies in the loop
!DIR$ IVDEP	Ignores only vector dependencies (which is safest)

Example:

!DIR$ OMP SIMD IVDEP
  do i = 1, N-4, 4
     a(i+4) = b(i) * c
  enddo

Read More:

w Getting Started with Intel Compiler Pragmas and Directives and Vectorization Resources for Intel® Advisor Users