limit check insertion

[Henry Cejtin]

The  code  size increase is really amazing.  Ah, it must be because the limit
check includes the GC loop.  I.e., checking once per block wouldn't (I  would
claim)  make the code much bigger as long as the code to actually call the GC
was shared.  I.e., you have to pass
    how many bytes you need
    something indicating your frame layout
and then you have to go to C code.  That C code can do the looping.  I  don't
think that it does currently.

If  it  does,  then the conclusion must be that the average size of our basic
blocks is very small.