Hackers' Pub

Syntax	Description	Examples
`"` keyword `"`	Finds the string within quotes, including spaces. Case-insensitive. (Escape quotes inside with `\"`)	`"Hackers' Pub"`
`from:` handle	Finds content written by the specified user.	`from:hongminhee` `from:hongminhee@hollo.social`
`lang:` ISO 639-1	Finds content written in the specified language.	`lang:en`
`#` tag	Finds content with the specified tag. Case-insensitive.	`#HackersPub`
condition condition	Finds content that satisfies both conditions on either side of the space (logical AND).	`"Hackers' Pub" lang:en`
condition `OR` condition	Finds content that satisfies at least one of the conditions on either side of the OR operator (logical OR).	`#HackersPub OR "Hackers' Pub" lang:en`
`(` condition `)`	Combines the operators within the parentheses first.	`(#HackersPub OR "Hackers' Pub" OR "Hackers Pub") lang:en`

matt godbolt @mattgodbolt@hachyderm.io

12/4/2025, 12:08:41 PM

Public

Day 4 of Advent of Compiler Optimisations!

Multiply by 2, 3, 4, 16, 25—which ones use the actual multiply instruction? Spoiler: fewer than you think! The compiler has a bag of tricks for avoiding multiplication, using shifts, adds, and that versatile LEA instruction. But when you outsmart it with your own shift-and-add... it un-optimises you right back!

#AoCO2025

Multiplying with a constant — Matt Godbolt’s blog

Compilers know all the tricks for avoiding doing actual multiplies.

xania.org

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