Nugget: Little compiler optimisation

Published on 03 August 2011 • Estimated reading time: 1 minutes

Found this little C# compiler optimisation which is really cool. Here is the start code:

int y = 0;
int x = 10;

if (x * 0 == 0)
{
    y = 123;
}

Console.WriteLine(y);

If you know a bit of math, anything multiplied by 0 always equals 0 (line 4). So the compiler optimises that out, and then because x is never used, it’s also optimised out, and you end up with:

int y = 0;

if (0 == 0)
{
    y = 123;
}

Console.WriteLine(y);

So very smart! 😊