changes in sbcl-2.1.1 relative to sbcl-2.1.0:
* platform support:
** restore non-threaded NetBSD builds;
** adjust how the finalizer thread is started; (lp#1906571, lp#1907872)
** fix the encoding of PEXTR on x86-64;
* minor incompatible change: emit warnings for list iteration forms when the
object being iterated over is known not to be a list. (lp#1908819,
reported by Michael Fiano)
* bug fix: detect 2 or 1 as an invalid number of arguments passed to
optimized slot writing or reading effective method respectively.
(lp#1909659, reported by Michal Herda)
* bug fix: division by zero errors were in some cases not being signalled.
(lp#1910098, reported by il71)
* bug fix: erroneous coercions in the type system could lose precision.
(lp#1910294)
* bug fix: literal (read-time evaluated) NaNs in source code no longer cause
compiler crashes. (lp#1909881, reported by Michal Herda)
* bug fix: detect more erroneous syntax in method bodies. (lp#1912362,
reported by Paul M. Rodriguez)
* optimization: the compiler's understanding of EXPT is improved, reducing
the introduction of COMPLEX types. (lp#1908830, reported by Michael Fiano)
* optimization: the compiler is better at computing numeric contagion when
(COMPLEX FLOAT) types are involved.
* micro-optimizations:
** moving from slightly-bigger-than-fixnum ranges is more efficient on x86-64;
** encode character comparisons with smaller operands on x86-64;
** truncating (and related operations) on floats can be inlined in more
cases on 64-bit platforms;
** rounding can use specialized instructions on ARM64 and on x86-64 when
SSE4 is available;