I'm finding it's quite easy to write .cmm files with subtle errors that cause ghc to emit code that wasn't what I wanted! For example, I wrote a comparison between two arguments of different integer sizes and the code generator picked the wrong size. After tracking down the bug, I tried -dcmm-lint and it caught my error right away.

It makes sense not to have -dcmm-lint enabled by default for Cmm produced from Stg, but I've seen here on the GHC wiki that -dcmm-lint is advised for hand-written .cmm files. But integer-gmp, and probably many other packages, don't build .cmm files with -dcmm-lint. Is there a reason we can't/shouldn't just make it the default?