Multiple corrections to the 64-bit istructions specfication.


The 64-bit version of this instruction should produce a 64-bit signed integer result, rather than truncating to a 32-bit unsigned number.


The 64-bit version of this instruction should use a 64-bit signed integer as input, rather than reading only the low 32 bits. This does mean that 64-bit code wanting to convert a real 32-bit integer to single-precision must sign-extend beforehand, but that is also the case for more fundamental instructions like l.sfeq, and so should not be a burden.


These should be class I mandatory for ORBIS64, not relegated to class III optional.

In particular, there are no comparison instructions that ignore the high 32-bits, and one cannot simply use l.andi to discard the high 32 bits, so l.extw* will be used often prior to comparisons.