[llvm] r329051 - [SCEV] Fix PR36974.

[Serguei Katkov via llvm-commits]

Author: skatkov
Date: Tue Apr  3 00:29:00 2018
New Revision: 329051

URL: http://llvm.org/viewvc/llvm-project?rev=329051&view=rev
Log:
[SCEV] Fix PR36974.

The patch changes the usage of dominate to properlyDominate
to satisfy the condition !(a < a) while using std::max.

It is actually NFC due to set data structure is used to keep
the Loops and no two identical loops can be in collection.
So in reality there is no difference between usage of
dominate and properlyDominate in this particular case.
However it might be changed so it is better to fix it.

Modified:
    llvm/trunk/lib/Analysis/ScalarEvolution.cpp

Modified: llvm/trunk/lib/Analysis/ScalarEvolution.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolution.cpp?rev=329051&r1=329050&r2=329051&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/ScalarEvolution.cpp (original)
+++ llvm/trunk/lib/Analysis/ScalarEvolution.cpp Tue Apr  3 00:29:00 2018
@@ -8668,11 +8668,12 @@ bool ScalarEvolution::isKnownViaInductio
               DT.dominates(L2->getHeader(), L1->getHeader())) &&
              "Domination relationship is not a linear order");
 #endif
-  
-  const Loop *MDL = *std::max_element(LoopsUsed.begin(), LoopsUsed.end(),
-                                        [&](const Loop *L1, const Loop *L2) {
-                         return DT.dominates(L1->getHeader(), L2->getHeader());
-                       });
+
+  const Loop *MDL =
+      *std::max_element(LoopsUsed.begin(), LoopsUsed.end(),
+                        [&](const Loop *L1, const Loop *L2) {
+         return DT.properlyDominates(L1->getHeader(), L2->getHeader());
+       });
 
   // Get init and post increment value for LHS.
   auto SplitLHS = SplitIntoInitAndPostInc(MDL, LHS);