Re-run of loop pass

[Jeffrey A Law]

  In message < 13871.53637.686739.360606@ongaonga.elec.canterbury.ac.nz >you writ
e:
  > Michael Hayes writes:
  >  > I've done some experimentation with this code snippet.  With
  >  > -funroll-loops or BCT optimisation the generated code is _attrocious_
  >  > since the constant iteration count cannot be determined.  The patch at
  >  > the end seems to fix this problem...
  > 
  > I've come up with a better patch that tries to determine what the
  > expressions for the loop initial and final values are if they are not
  > constant.  If the initial and final expressions are the sum of an
  > equivalent base register and some constants, then the initial and
  > final values are replaced with the constants.  The number of loop
  > iterations is now simply calculable and thus the loop unroll and loop
  > BCT optimisations are happy.
Does this latest version subsume your earlier unroll.c changes?

[ Still catching up after being away for a few days... ]

jeff