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Value Range Optimization
While the value of a variable may not be known or may vary, the possible range of values may be known, and can be used to perform optimizations. Example:In the code fragment below, the value of i is known to be in the range 1 to 99 inclusive. The IF expression is known to evaluate to true, and the IF test can be eliminated. for (i = 1; i < 100; i++) { if (i) g (); } In the code fragment below, the IF expression has been eliminated. for (i = 1; i < 100; i++) { g (); } Notes:Value range optimization is not commonly supported in production C compilers. © 1990-2012 Nullstone Corporation. All Rights Reserved. |