Constant Folding

Q1: What is Constant Folding?

Answer:

Constant Folding is an optimization technique in which the compiler calculates those expressions which gives a constant answer. This technique is very useful as it reduces the execution time and also helps in efficient memory management.

Q2: Suppose we have been given a code snippet?

Answer:

int main(){
int a=1*4-9;
int b=a-1;
cout<<b;
}

Q3: In which lines of code would the compiler use the constant folding to reduce the overall execution time.

Answer:

In line 2 and line 3 the compiler will use the Constant Folding Technique. In line 2 the expression of a produces a constant result. So the compiler will compute the expression and directly substitute the value of a in line 3. The value is -5 in this case.

As we all know humans understand only programming languages like C, C++, Python, Java, etc. whereas a computer can only understand bytecodes or machine languages. So compiler acts as a converter. Its aim is to convert the high-level language to machine-level language. However, during conversion, some optimization processes are followed to make the code more efficient thereby increasing the execution speed as well. One such optimization technique is Constant Folding.