Archive — AoCO2025

December 2025

Multiplying with a constant
Compilers know all the tricks for avoiding doing actual multiplies.
You can't fool the optimiser
Pattern recognition can see through obfuscated code to find the right instruction
Addressing the adding situation
We learn why adding on x86 isn't as obvious as you might think
Why xor eax, eax?
Why do compilers love xor-ing registers so much?

November 2025

Introducing the Advent of Compiler Optimisations 2025
Announcing AoCO 2025 - daily December posts about compiler optimisations

About Matt Godbolt

Matt Godbolt is a C++ developer living in Chicago. He works for Hudson River Trading on super fun but secret things. He is one half of the Two's Complement podcast. Follow him on Mastodon or Bluesky.

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