- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
* stack optimization:
  k StackVariable opaque struct
    - name string
    - frameSetIndex int
    - frameIndex int
  k convert StackFrame from map of name to *TypeGatedMlrvalVariable to array of *TypeGatedMlrvalVariable
  k convert StackFrameSet from list of StackFrame to array of StackFrame
    - comments about S/SF indef large b/c recursion; SF/SFS known statically
  o Define/Set/Get need to modify the indices:
    ? add comments for retain in CST node?
    - within Stack: map from name to idxpair
    - within Set/Get (re-use): fastcall to indexer if non-trivial
  o mods to use the indices when set

  o profile mand.mlr
    - c  3.2s
    - go pre-alloccate 45s

Why 5MB goal with GOGC=100????

GOGC=100000 GODEBUG=gctrace=1 mlr -n put -q -f u/mand.mlr 1> /dev/null

* u/mand.mlr silent option

https://blog.twitch.tv/en/2019/04/10/go-memory-ballast-how-i-learnt-to-stop-worrying-and-love-the-heap-26c2462549a2/
  	ballast := make([]byte, 10<<30)

https://dave.cheney.net/2014/07/11/visualising-the-go-garbage-collector
  go get -u -v github.com/davecheney/gcvis
  gcvis mlr -n put -q  -s iheight=500 -s iwidth=500 -f u/mand.mlr > /dev/null

* duffcopy/madvise (w/ GOGC=off), & heavy GC (w/ GOGC != off), are both indicators of the same thing: lots of allocation and lots of copying

https://github.com/golang/go/issues/23044
  "It has often been noted that programs which make a lot of allocations while
  maintaining a small live heap end up doing excessive garbage collections."
  yyyuuuuuuuuup
--> maybe plan out the CST w/ mlrvals for all slots pre-allocated, and point to them -- ?
--> and/or: Evaluate return *types.Mlrval ?
  o or instead of Evaluate(state*State) -> Mlrval, do Evaluate(state *State, poutput *Mlrval)
  o and not type BinaryFunc func(*Mlrval, *Mlrval) Mlrval but type BinaryFunc func(out *Mlrval, in1 *Mlrval, in2 *Mlrval)
  o idea: don't generate ANY garbage w/ this:
    zt = zr*zr - zi*zi + cr;
    zi = 2*zr*zi + ci;
    zr = zt;
  o leaf evaluables:
    - literals & local vars etc just point to storage

i https://hub.packtpub.com/implementing-memory-management-with-golang-garbage-collector/

i mlr --cpuprofile cpu.pprof -n put -q  -s iheight=100 -s iwidth=100 -f u/mand.mlr > /dev/null

? SetGCPercent
? SetMaxHeap

mlr --cpuprofile cpu.pprof -n put -q  -s iheight=500 -s iwidth=500 -f u/mand.mlr > /dev/null
go tool pprof mlr cpu.pprof
top10

go tool pprof --pdf mlr cpu.pprof > mlr-call-graph.pdf
mv mlr-call-graph.pdf ~/Desktop

runtime.duffcopy
  https://stackoverflow.com/questions/45786687/runtime-duffcopy-is-called-a-lot
runtime.madvise

GOGC=off
GODEBUG=gctrace=1

export PATH=${PATH}:~/git/brendangregg/FlameGraph/
go-torch cpu.pprof
mv torch.svg ~/Desktop/

i mlr --cpuprofile cpu.pprof -n put -q  -s iheight=500 -s iwidth=500 -f u/mand.mlr > /dev/null

i https://hub.packtpub.com/implementing-memory-management-with-golang-garbage-collector/

i https://golang.org/pkg/runtime/

! flame-graph readme; & profile-readme out of mlr.go & into separate .md file
i mlr --cpuprofile cpu.pprof -n put -q  -s iheight=100 -s iwidth=100 -f u/mand.mlr > /dev/null
i GODEBUG=gctrace=1 mlr -n put -q  -s iheight=500 -s iwidth=500 -f u/mand.mlr > /dev/null| head -n 100
  gc 1 @0.129s 1%: 0.012+3.9+0.002 ms clock, 0.048+3.7/3.7/7.5+0.010 ms cpu, 10240->10240->0 MB, 10241 MB goal, 4 P
  gc 2 @0.140s 2%: 0.009+2.1+0.002 ms clock, 0.038+2.0/2.0/4.0+0.011 ms cpu, 4->4->0         MB, 5     MB goal, 4 P
  gc 3 @0.149s 2%: 0.032+2.1+0.021 ms clock, 0.12+2.0/2.0/4.0+0.087  ms cpu, 4->4->0         MB, 5     MB goal, 4 P
  gc 4 @0.157s 3%: 0.035+2.1+0.014 ms clock, 0.14+2.0/1.9/4.1+0.059  ms cpu, 4->4->0         MB, 5     MB goal, 4 P
  gc 5 @0.166s 3%: 0.034+2.2+0.024 ms clock, 0.13+2.0/1.9/4.0+0.098  ms cpu, 4->4->0         MB, 5     MB goal, 4 P

mem.Alloc: 176104
mem.TotalAlloc: 176104
mem.HeapAlloc: 176104
mem.NumGC: 0

mem.Alloc: 1179440
mem.TotalAlloc: 16,529,643,664
mem.HeapAlloc: 1179440
mem.NumGC: 4254