there's a lot I don't understand about optimizers, but is it unreasonable to expect a modern C++ compiler to turn foo() into an add instruction?pic.twitter.com/GrWFSFWZLK
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"std::vector<int> v {a, b}" seems to make a huge difference with gcc trunk. But still not a simple add. https://godbolt.org/z/DDrOCO
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In general, I don't think either Clang or GCC is capable of getting rid of malloc/free or new/delete outside of a special case for completely dead stores. They aren't capable of doing escape analysis and lowering it to a stack allocation / virtual registers so it won't go away.
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Last time I checked, the GCC dead store elimination also only works for malloc/free and only when the code is buggy and lacks an out-of-memory check. Clang is better at this, but it lacks a way to turn this into a dead store anyway. It can't work with malloc/new directly either.
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