limit checks in FFT

[Stephen Weeks]

> I  talked  to  Suresh  about  this, but he also can't explain it: why did his
> inliner, which decreased the number of trampolines in FFT from 20,975,390  to
> 904, increase the number of limit checks from 7,888,027 to 13,127,749?

Here is a possibility.  I did not look at the code, but remember that
limit checks are inserted at:
  * function entry
  * continuation/handler entry
  * loop header
  * array allocation

So, if you have the following code:

  if ...
    then ... no allocation ...
  else f(x)

where
  * the body of f does allocation, and hence a limit check
  * the then branch is dynamically the common branch

Then, inlining f will increase the dynamic number of limit checks
because the limit check will be moved in front of the if.