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Day 1 of Advent of Compiler Optimisations!
Why do compilers love `xor eax, eax` for zeroing registers? It's brilliant: saves bytes compared to `mov eax, 0`, AND x86 CPUs recognise this "zeroing idiom" early in the pipeline—breaking register dependencies and removing it from execution entirely. Even better: writing to `eax` zeroes the top 32 bits of `rax` for free, handling 64-bit longs in one instruction.
Read more: https://xania.org/202512/01-xor-eax-eax
Watch: https://youtu.be/eLjZ48gqbyg
How exactly do you get code onto a computer? Like, the machine code? Surely you need a program to assemble it...but if you don't have a computer yet, how do you start the whole process!?
One offhand remark in the middle of this video stole 4 days of work from me :-)
See if you can guess which bit nerd-sniped me!
My #CppCon2025 talk is up: C++: Some Assembly Required
I talk a out the importance of assembly for C++, hopefully in a surprising and informative way. There will be embarrassing family photos along the way...
Check it out: https://youtu.be/zoYT7R94S3c