Unswitching
A loop containing a loop-invariant IF statement can be transformed into an IF statement containing two loops.
Example:
In the example below, the IF expression is loop-invariant, and can be hoisted out of the loop.
for (i = 0; i < N; i++)
if (x)
a[i] = 0;
else
b[i] = 0;
After unswitching, the IF expression is only executed once, thus improving run-time performance.
if (x)
for (i = 0; i < N; i++)
a[i] = 0;
else
for (i = 0; i < N; i++)
b[i] = 0;