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CPUs offer feature flags that can be queried to learn about the availability of a particular extension. If a compiler wants to generate code that uses an extens
by Slartie 4y ago
CPUs offer feature flags that can be queried to learn about the availability of a particular extension. If a compiler wants to generate code that uses an extension if available, but falls back to an explicit (but slower) implementation if that's not the case, it can simply generate a branch instruction in front of the opcodes using the extension which checks for the feature flag first, branching into the fallback implementation if the extension isn't available.
- IshKebab 4y agoThat's true, though in practice - at least in C, C++, Rust, Go etc. - the compiler won't do that automatically. You need to write code to do it yourself (which very few people do for obvious reasons).