In C++, is empty() faster than comparing the size with zero?

Re:In C++, is empty() faster than comparing the size with zero? by spatulon on Thursday October 28, 2021 @04:12PM (#29031275)

Is the LLVM optimisation pass that does this hyper-specialised for this one particular trick, and, if so, is it valuable in practice?

Here's an example where (I think) the two functions are equivalent, so I'm a little disappointed it couldn't make the same optimisation on the second one. (At least it still optimised the tail call to a jump.)

https://godbolt.org/z/K9rMajsjK

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Re:In C++, is empty() faster than comparing the size with zero? by Someone on Thursday October 28, 2021 @05:14PM (#29032090)

No, it is very generic. See https://kristerw.blogspot.com/2019/04/how-llvm-optimizes-geo..., https://blog.matthieud.me/2020/exploring-clang-llvm-optimiza... (discussed at https://news.ycombinator.com/item?id=28207207)

(I remember reading a page with more examples, but cannot find it)

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