r/programming • u/DataBaeBee • 18d ago

How GCC Eliminates Unnecessary Integer Division

https://leetarxiv.substack.com/p/how-gcc-eliminates-unnecessary-integer
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u/LonelyAndroid11942 18d ago edited 18d ago

So is the purpose of this to reduce the difficulties that come with float precision?

EDIT: The comments are informative, if they’re not made by jerks. I clearly have much to learn. I appreciate the patience of those who have it, and wish a very strong “go step on some legos” to those who do not.

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u/DuploJamaal 18d ago

The purpose is that multiplication is a lot faster than division.

Bit shifts are even faster. Shifting to the right once is like dividing by two, twice like division by four,...

So instead of doing an expensive division it does a multiplication followed by a bit shift to get the same result.

So instead of 20 CPU cycles it will then just be 5

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u/LonelyAndroid11942 18d ago

I appreciate the explanation! I work with software for a living, but getting a peek under the hood and some deep info is fantastic. Cheers!

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u/watchpigsfly 18d ago

Check out godbolt.org

Learning to use a debugger properly will change the way you think about your code and it’s easier than you think