Address comments.

Author: Leon Clark

llvm/lib/Transforms/Vectorize/VectorCombine.cpp

@@ -3520,10 +3520,10 @@ bool VectorCombine::foldInterleaveIntrinsics(Instruction &I) {
   return true;
 }
 
-// Attempt to narrow a phi of shufflevector instructions where the two incoming
-// values have the same operands but different masks. If the two shuffle masks
-// are offsets of one another we can use one branch to rotate the incoming
-// vector and perform one larger shuffle after the phi.
+/// Attempt to narrow a phi of shufflevector instructions where the two incoming
+/// values have the same operands but different masks. If the two shuffle masks
+/// are offsets of one another we can use one branch to rotate the incoming
+/// vector and perform one larger shuffle after the phi.
 bool VectorCombine::shrinkPhiOfShuffles(Instruction &I) {
   auto *Phi = dyn_cast<PHINode>(&I);
   if (!Phi || Phi->getNumIncomingValues() != 2u)
@@ -3566,8 +3566,7 @@ bool VectorCombine::shrinkPhiOfShuffles(Instruction &I) {
   // Ensure all elements of the new mask are equal. If the difference between
   // the incoming mask elements is the same, the two must be constant offsets
   // of one another.
-  if (NewMask.empty() ||
-      !std::equal(NewMask.begin() + 1u, NewMask.end(), NewMask.begin()))
+  if (NewMask.empty() || !all_equal(NewMask))
     return false;
 
   // Create new mask using difference of the two incoming masks.
@@ -3591,8 +3590,7 @@ bool VectorCombine::shrinkPhiOfShuffles(Instruction &I) {
     return false;
 
   // Create new shuffles and narrowed phi.
-  auto Builder = IRBuilder(&I);
-  Builder.SetInsertPoint(Shuf);
+  auto Builder = IRBuilder(Shuf);
   Builder.SetCurrentDebugLocation(Shuf->getDebugLoc());
   auto *PoisonVal = PoisonValue::get(InputVT);
   auto *NewShuf0 = Builder.CreateShuffleVector(Op, PoisonVal, NewMask);