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Loop Collapsing Some nested loops can be collapsed into a single-nested loop to reduce loop overhead and improve run-time performance. Example: In the code fragment below, the double-nested loop on i and j can be collapsed into a single-nested loop. int a[100][300]; for (i = 0; i < 300; i++) for (j = 0; j < 100; j++) a[j][i] = 0; Here is the code fragment after the loop has been collapsed. int a[100][300]; int *p = &a[0][0]; for (i = 0; i < 30000; i++) *p++ = 0; Notes: Loop collapsing can improve the opportunities for other optimizations, such as loop unrolling. Loop collapsing is not common in C compilers, but is supported in some C compilers that target the scientific market. © 1990-2012 Nullstone Corporation. All Rights Reserved.