changes in sbcl-2.2.2 relative to sbcl-2.2.1:
* platform support:
** all architectures now share the coverage mark instrumentation
implementation, meaning that performance now equals what had been
implemented only on x86 architectures.
** fixed a performance regression on x86-64 from changes in AVX2 register
handling. (lp#1960081, reported by Michael Kappert)
** fixed a garbage collection bug on ppc64 manifesting in occasional
corruption on threaded programs. (lp#1959338, lp#1952973)
** micro-optimizations in type tests for (SIGNED-BYTE 64).
* enhancement: improved handling of source locations for some classes
of compile time and runtime errors.
* enhancement: better source locations for structure accessors.
* bug fix: SB-COVER now always instruments top level forms correctly.
* bug fix: muffling conditions now works correctly on higher debug settings.
* bug fix: local muffling declarations now scope correctly with respect to
undefined variable warnings.
* optimization: calls to STRING= can now return NIL more quickly on strings
of unequal length.