[llvm] r282367 - [SCEV] Document a gotcha; NFC

[Sanjoy Das via llvm-commits]

Author: sanjoy
Date: Sun Sep 25 18:12:06 2016
New Revision: 282367

URL: http://llvm.org/viewvc/llvm-project?rev=282367&view=rev
Log:
[SCEV] Document a gotcha; NFC

We should re-consider the design decision that led to this gotcah, but
for now just document it.

Modified:
    llvm/trunk/include/llvm/Analysis/ScalarEvolution.h

Modified: llvm/trunk/include/llvm/Analysis/ScalarEvolution.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/ScalarEvolution.h?rev=282367&r1=282366&r2=282367&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Analysis/ScalarEvolution.h (original)
+++ llvm/trunk/include/llvm/Analysis/ScalarEvolution.h Sun Sep 25 18:12:06 2016
@@ -368,6 +368,9 @@ public:
 /// This class represents a composition of other SCEV predicates, and is the
 /// class that most clients will interact with.  This is equivalent to a
 /// logical "AND" of all the predicates in the union.
+///
+/// NB! Unlike other SCEVPredicate sub-classes this class does not live in the
+/// ScalarEvolution::Preds folding set.  This is why the \c add function is sound.
 class SCEVUnionPredicate final : public SCEVPredicate {
 private:
   typedef DenseMap<const SCEV *, SmallVector<const SCEVPredicate *, 4>>