gcc-2.7 creates faster code than pgcc-1.1.1

[Jeffrey A Law]

  In message < 9903050403.AA36338@marc.watson.ibm.com >you write:
  > 	GCC is missing a general feature of value propagation which would
  > help with a lot of optimizations like this.  Hopefully this infrastructure
  > will be added or contributed someday.
Most of the papers I've read have indicated only trivial gains from value
range propagation.  I've also had discussions with folks that have implemented
this opt in a commercial compiler -- it's so minor of a win that they didn't
consider it worth the effort.

It's best use appears to be for optimizing array bounds checking in languages
that require such checks.


jeff