llvm-svn: 22560

target data to decide which loop induction variables to strength reduce
and how to do so.  This work is mostly by Chris Lattner, with tweaks by
me to get it working on some of MultiSource.

llvm-svn: 22558

llvm-svn: 21427

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