Now you can run "`ldc test.d -c -mem2reg -simplifycfg`" if you feel the urge.
The -O<N> options are still supported, and are inserted in the passes list in
the position where they appear on the command line.
(so -simplifycfg -O1 -instcombine does the "right thing")
One small change: -inline is renamed to -enable-inlining due to a naming
conflict with the option to add the -inline pass. -inline now inserts the
inlining pass in the position specified, not in the middle of -O<N>.
(ldmd has been updated to translate -inline to -enable-inlining)
The switch allows the optimizer and inliner to run on all modules at once and opens the door for template instantiation improvements that should lower compile time and executable size.