"it's that other design decisions can be much faster, such as those mentioned in the B3 JIT link above." The B3 JIT link describes things that LLVM plans on do

"it's that other design decisions can be much faster, such as those mentioned in the B3 JIT link above." The B3 JIT link describes things that LLVM plans on doing in the next year, precisely for these reasons, so ... Had they emailed the list, ever, they would have known this. It's not like these were design decisions that someone said "we should never change these", they were design decisions that were good at the time, but like anything else, need to grow and change over time. If you give up and rewrite an entire jit/compiler every time it might require rearchitecting, that may be fun but it doesn't make a lot of progress. You will spend years to get to a no-regressions vs old compiler state (unless your old compiler was truly bad)