Loop Inversion is a compiler optimization technique where a while Loop is replaced by an if block containing a do..while loop.
How does loop inversion improve performance?
Let me explain with an example.int i = 0;
int a[] = new int[10];
while (i 10) {
a[i] = 0;
i++;
}
Post loop inversion optimization, above code will be transformed like below.
int i = 0;
int a[] = new int[10];
if (i 10) {
do {
a[i] = 0;
i++;
} while (i 10);
}
How this transformation improve performance?
When the value of i is 10, the processor need not execute a goto instruction to come out of the loop (which is required in the first case). This improves performance. By nature, any jump in the code causes a pipeline stall, which is a detriment to performance.
Reference
https://en.wikipedia.org/wiki/Pipeline_stallYou may like
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