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### 7.9 Stale Extensions

SBCL has inherited from CMUCL various hooks to allow the user to tweak and monitor the garbage collection process. These are somewhat stale code, and their interface might need to be cleaned up. If you have urgent need of them, look at the code in `src/code/gc.lisp` and bring it up on the developers' mailing list.

SBCL has various hooks inherited from CMUCL, like `sb-ext:float-denormalized-p`, to allow a program to take advantage of IEEE floating point arithmetic properties which aren't conveniently or efficiently expressible using the ANSI standard. These look good, and their interface looks good, but IEEE support is slightly broken due to a stupid decision to remove some support for infinities (because it wasn't in the ANSI spec and it didn't occur to me that it was in the IEEE spec). If you need this stuff, take a look at the code and bring it up on the developers' mailing list.