[rmcclellan]

While I agree that this is totally possible, are there any shipping, non-buggy optimizers that do this? Sometimes C/C++ seems purposely designed to make the compiler/optimizer's job difficult.

[cygx]

I didn't test it with qsort() specifically (my use case was merge-sorting a linked list), but both gcc and clang are able to perform such optimizations.

I would be surprised if other high-performance compilers were unable to do so.