In a single-pass run, you must generate code to keep the previous value in case the line actually was foo = ++a; or foo = a++; so that foo gets the pre-inc or post-inc value.

The small part that creates the code for the small "a++" part of the line will then produce a dead store of the pre-inc value, and no 2nd pass will remove it.

++godobject will simply increment that value.

godobject++ will make a copy of that object, returning it to you along with allocating another 50MB pool, purely to increment the value.

only if a is a very simple thing. plenty of "advanced" containers actually do things ; in the "a++" case they have to save the previous state to return a copy, in the "++a" case they don't. If your iterator for instance contains a std::vector<int> to maintain some internal state for a multidimensional dynamic matrix, then in one case you'll get a simple increment, in the other a whole dynamic allocation / free which may be optimized out by the compiler in release mode and definitely won't in debug mode