Constant embedded for loop condition optimization in C++ with gcc
- by solinent
Will a compiler optimize tihs:
bool someCondition = someVeryTimeConsumingTask(/* ... */);
for (int i=0; i<HUGE_INNER_LOOP; ++i)
{
if (someCondition)
doCondition(i);
else
bacon(i);
}
into:
bool someCondition = someVeryTimeConsumingTask(/* ... */);
if (someCondition)
for (int i=0; i<HUGE_INNER_LOOP; ++i)
doCondition(i);
else
for (int i=0; i<HUGE_INNER_LOOP; ++i)
bacon(i);
someCondition is trivially constant within the for loop.
This may seem obvious and that I should do this myself, but if you have more than one condition then you are dealing with permuatations of for loops, so the code would get quite a bit longer. I am deciding on whether to do it (I am already optimizing) or whether it will be a waste of my time.
