Fix a bug in getSCEVAtScope w.r.t. non-canonical loops

The issue is that if we have a loop with multiple predecessors outside the loop, the code was expecting to merge them and only return if equal, but instead returned the first one seen.

I have no idea if this actually tripped anywhere.  I noticed it by accident when reading the code and have no idea how to go about constructing a test case.

llvm-svn: 363112

llvm/lib/Analysis/ScalarEvolution.cpp

@@ -8126,10 +8126,10 @@ const SCEV *ScalarEvolution::computeSCEVAtScope(const SCEV *V, const Loop *L) {
                     break;
                   }
                 }
+              }
               if (!MultipleInitValues && InitValue)
                 return getSCEV(InitValue);
             }
-            }
             // Okay, we know how many times the containing loop executes.  If
             // this is a constant evolving PHI node, get the final value at
             // the specified iteration number.