Need help with project
| TheToaster wrote: |
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| You could also use an enum here right? |
Yes I could, but the constexpr's that I used are compile time constants too. Both methods guarantee that they are compile time constants, and I think that's the most important thing.
However, in the constexpr version, the compiler is not prohibited from creating an actual variable from it. While a variable declared “constexpr” can only be initialized with a compile-time constant expression, to my understanding the compiler is not prohibited from creating a real variable from it and converting expressions like “if(c == 5)" into runtime comparisons at the lowest optimization levels.
See the following: https://godbolt.org/z/Qqfeiq
If you look at this compiler output from four C++ compilers at zero optimization level, you notice all of them create a physical local stack variable for the "constexpr int" also. https://godbolt.org/z/Ap7TCs
This is at the lowest optimization level of course, but higher optimization levels don’t guarantee the removal of redundant local variables.
This is just something interesting I found out about the other day and wanted to see what you thought about it.
See the following: https://godbolt.org/z/Qqfeiq
If you look at this compiler output from four C++ compilers at zero optimization level, you notice all of them create a physical local stack variable for the "constexpr int" also. https://godbolt.org/z/Ap7TCs
This is at the lowest optimization level of course, but higher optimization levels don’t guarantee the removal of redundant local variables.
This is just something interesting I found out about the other day and wanted to see what you thought about it.
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