ValueTracking, InstSimplify: fix nits

Author: artagnon

llvm/include/llvm/Analysis/ValueTracking.h

@@ -791,8 +791,7 @@ bool onlyUsedByLifetimeMarkers(const Value *V);
 /// droppable instructions.
 bool onlyUsedByLifetimeMarkersOrDroppableInsts(const Value *V);
 
-/// Return true if the instruction doesn't potentially cross vector lanes. This
-/// is useful to make GVN-replacements for vector types.
+/// Return true if the instruction doesn't potentially cross vector lanes.
 bool isNotCrossLaneOperation(const Instruction *I);
 
 /// Return true if the instruction does not have any effects besides

llvm/lib/Analysis/InstructionSimplify.cpp

@@ -4343,9 +4343,9 @@ static Value *simplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp,
   if (isa<PHINode>(I))
     return nullptr;
 
+  // For vector types, the simplification must hold per-lane, so forbid
+  // potentially cross-lane operations like shufflevector.
   if (Op->getType()->isVectorTy() && !isNotCrossLaneOperation(I))
-    // For vector types, the simplification must hold per-lane, so forbid
-    // potentially cross-lane operations like shufflevector.
     return nullptr;
 
   // Don't fold away llvm.is.constant checks based on assumptions.