AMD 250 manual Avoid, 134

Software Optimization Guide for AMD64 Processors 25112 Rev. 3.06 September 2005

Avoid

long fac(long a)
{
if (a == 0) {
return (1);
} else {
myp(a);	// Can cause returns to be mispredicted

return (a * fac(a - 1));

}

}

void myp(long a)

{

printf("myp "); return;

}

Because the function fac, in the following example, is end-recursive, it can be converted to iterative code. A recursive function is classified as end-recursive when the function call to itself is at the end of the code. The following listing shows the rewritten code:

Preferred

long fac1(long a)

{

long t = 1; while (a > 0) {

myp(a); t *= a; a--;

}

return (t);

}

134 Branch Optimizations Chapter 6