loop_count

Intel® C++ Compiler Classic Developer Guide and Reference

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ID 767249

Date 3/31/2023

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loop_count

Specifies the iterations for a for loop.

Syntax

#pragma loop_count(n)

#pragma loop_count=n

#pragma loop_count(n1[, n2]...)

#pragma loop_count=n1[, n2]...

#pragma loop_count min(n),max(n),avg(n)

#pragma loop_count min=n, max=n, avg=n

Arguments

`(n) or =n`	A non-negative integer value. The compiler will attempt to iterate the next loop the number of times specified in `n`; however, the number of iterations is not guaranteed.
`(n1[,n2]...) or = n1[,n2]...`	Non-negative integer values. The compiler will attempt to iterate the next loop the number of time specified by `n1` or `n2`, or some other unspecified number of times. This behavior allows the compiler some flexibility in attempting to unroll the loop. The number of iterations is not guaranteed.
`min(n), max(n), avg(n) or min=n, max=n, avg=n`	Non-negative integer values. Specify one or more in any order without duplication. The compiler insures the next loop iterates for the specified maximum, minimum, or average number (`n1`) of times. The specified number of iterations is guaranteed for min and max.

Description

The loop_count pragma specifies the minimum, maximum, or average number of iterations for a for loop. In addition, a list of commonly occurring values can be specified to help the compiler generate multiple versions and perform complete unrolling.

You can specify more than one pragma for a single loop; however, do not duplicate the pragma.

Examples

Use the loop_count pragma to iterate through the loop a minimum of three, a maximum of ten, and average of five times:

#include <stdio.h> 
int i; 
int mysum(int start, int end, int a) {
  int iret=0; 
  #pragma loop_count min(3), max(10), avg(5)
    for (i=start;i<=end;i++)
    iret += a;
    return iret; 
} 

int main() {
  int t;
  t = mysum(1, 10, 3);
  printf("t1=%d\r\n",t);
  t = mysum(2, 6, 2);
  printf("t2=%d\r\n",t);
  t = mysum(5, 12, 1);
  printf("t3=%d\r\n",t); 
}

Parent topic: Intel-Specific Pragma Reference

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Intel® C++ Compiler Classic Developer Guide and Reference

loop_count

Syntax

Arguments

Description

Examples