abort()
cons->list:cons
new option to disable letref optimization
two new var flags: REG & FREEREF
new node flag: TAIL to indicate if a node is in tail position
find-tail: set NFLAG_TAIL for each node (i.e., discover tail position)
find-free-refs: set VFLAG_FREEREF for each variable
minor: (print-string (format ...)) => (printf ...)
insn:close holds <nfree> (for gc)
get-register-variables: collect list of regvars from lenv
c-function: note any free regs
c-varset: index/reg were reversed (!!!)
safe-for-letreg: use new VFLAG-FREEREF rather than VFLAG-ESCAPES
new -n noletreg option
call find-tail
call find-free-refs
insn:close holds <nfree> (for gc)
emit-close: pass <nfree> to check_heap() call
emit-move: annotate reg varref/varset
prof-dump: print header for table
t_vm: fix the expected output
pull in the fixed vm from irken/vm/vm.scm so we can test it
default to 'cc' rather than clang
pre-compiled compiler