Generalize IVUsers to track arbitrary expressions rather than expressions
explicitly split into stride-and-offset pairs. Also, add the
ability to track multiple post-increment loops on the same expression.

This refines the concept of "normalizing" SCEV expressions used for
to post-increment uses, and introduces a dedicated utility routine for
normalizing and denormalizing expressions.

This fixes the expansion of expressions which are post-increment users
of more than one loop at a time. More broadly, this takes LSR another
step closer to being able to reason about more than one loop at a time.

llvm-svn: 100699
diff --git a/llvm/test/Transforms/LoopStrengthReduce/quadradic-exit-value.ll b/llvm/test/Transforms/LoopStrengthReduce/quadradic-exit-value.ll
index 8959c17..59f14fc 100644
--- a/llvm/test/Transforms/LoopStrengthReduce/quadradic-exit-value.ll
+++ b/llvm/test/Transforms/LoopStrengthReduce/quadradic-exit-value.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -analyze -iv-users | grep {\{1,+,3,+,2\}<%loop> (post-inc)}
+; RUN: opt < %s -analyze -iv-users | grep {\{1,+,3,+,2\}<%loop> (post-inc with loop %loop)}
 
 ; The value of %r is dependent on a polynomial iteration expression.