GAP Message (Diagnostic ID 30526)

Message

To parallelize the loop at line %d, annotate the routine %s with %s.

Advice

If the loop contains a call to a function, the compiler cannot parallelize the loop without more information about the function being called.

However, if the function being called in the loop is a const function or a concurrency-safe function, then the call does not inhibit parallelization of the loop.

Example

Consider the following:

#define N 10000 
double A[N], B[N]; 
int bar(int); 
void foo(){
  int i;
  for (i=0;i<N;i++){
    A[i] = B[i] * bar(i);
  } 
}

In this case, the compiler does not parallelize the loop because it is not safe to do so without further information about routine bar, which is being called.

#define N 10000 
double A[N], B[N]; 
__declspec(const) int bar(int); 
void foo(){
  int i;
  for (i=0;i<N;i++){
    A[i] = B[i] * bar(i);
  } 
}

#define N 10000 
double A[N], B[N]; 
__declspec(concurrency_safe(profitable)) int bar(int); 
void foo(){
  int i;
  for (i=0;i<N;i++){
    A[i] = B[i] * bar(i);
  } 
}

Example

Consider the following:

Verify

Confirm the routine satisfies the semantics of this annotation. A weaker annotation able to achieve a similar effect is __declspec(concurrency_safe(profitable).