You know the ARM-based M1 chips that are used in modern mac computers. On those macs, some number of software are ran through the layer called Rosetta (Discord, Steam), some natively, directly through M1 (Slack, IntelliJ) and some actually doesn't work in either way (Virtual Box). Huge list holding the status can be found here.

Apps that can be ran only with Rosetta are not yet M1 optimized, their developers have to optimize it, it takes some time to do so. But what does it mean to optimize it? What the process looks like? I'm quite sure that they don't rewrite the whole application code to another language (like Swift), because Jetbrains was able to M1 optimize their apps quite quickly. On the other hand, Discord is not yet optimized, same for Unity game engine (it's in beta though).

CodePudding user response：

At bottom, it just means that the compiler's backend was configured to emit ARM64 instructions for the program instead of (or in-addition to) x86-64 instructions.

This means that certain x86-64 specific functionality instruction can no longer be used, unless equivalent ARM instructions are used instead.

This usually isn't much of a problem though, because most macOS software is typically written at a higher level of abstraction, using system-provided frameworks.

For example, using CoreImage to manipulate images abstracts you from the details of the CPU and GPU. In such cases, Apple does the heavy lifting of porting over their frameworks. All you have to do as an application developer is to check a box that says "target ARM64".