* Visual C++ now has very aggressive SSA-based optimization rules.
* One of these optimizations is the bit estimator, which tracks the state of each bit of local variables.
I'm not aware of LLVM/GCC or other compilers using a bit estimator. I found some hits in the CS literature but I'm not aware of any other compilers using it, and it seems like a pretty potent optimization!
tl;dr +generated a lot more CMOV's. While conditional moves are a cheap way to get performance on poorly branch predicted programs, speculatively inserting them is _NOT_ a good idea for general performance as it may hurt performance (because of serializing conditional path) and should only be considered with Profiling information.
