llvm-svn: 20506

hopefully not breaking too many other things.

llvm-svn: 20505

llvm-svn: 20501

llvm-svn: 20497

llvm-svn: 20467

llvm-svn: 20466

power of two.  This emphatically includes the zeroeth power of two.

llvm-svn: 20429

  * Loop invariant code does not dominate the loop header, but rather
    the end of the loop preheader.

  * The base for a reduced GEP isn't a constant unless all of its
    operands (preceding the induction variable) are constant.

  * Allow induction variable elimination for the simple case after all.

Also made changes recommended by Chris for properly deleting
instructions.

llvm-svn: 20383

for reasons explained in the comments, I also deactivated this code as it needs
more thought.

llvm-svn: 20367

llvm-svn: 20360

llvm-svn: 20358

loops.  This optimization is not turned on by default yet, but may be run
with the opt tool's -loop-reduce flag.  There are many FIXMEs listed in the
code that will make it far more applicable to a wide range of code, but you
have to start somewhere :)

This limited version currently triggers on the following tests in the
MultiSource directory:
pcompress2: 7 times
cfrac: 5 times
anagram: 2 times
ks: 6 times
yacr2: 2 times

llvm-svn: 17134