7.3.1 Induction Variable Recognition

Induction variables are integer or floating point variables that are incremented or decremented the same amount for each for -loop iteration. Recognizing their relationship to the loop control variables often lifts data dependence restrictions and permits further optimization, as shown in the following example:

for ( i=0; i<n; i++ ) {
    a[j] = b[k];
    j++;
    k+=2;
    }

Becomes:

_Kii2 = k;
    _Kii1 = j;
      for ( i = 0; i<n; i++ ) {
      a[_Kii1+i] = b[_Kii2+i*2];
   }


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Command-Line Qualifiers

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