From 5e963a24415eb88d512eb74c8addf87051f7969a Mon Sep 17 00:00:00 2001
From: Sanne Wouda <Sanne.Wouda@arm.com>
Date: Fri, 19 Feb 2021 16:59:33 +0000
Subject: [PATCH] Rehome an orphaned comment [NFC]

As seen in 35827164c4, the "shuffle x, x, mask" comment has drifted away
from the implementation of the pattern. Put it back.
---
 llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp b/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
index 06f22cd..d7474e3 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
@@ -2287,7 +2287,6 @@ Instruction *InstCombinerImpl::visitShuffleVectorInst(ShuffleVectorInst &SVI) {
   if (isa<ScalableVectorType>(LHS->getType()))
     return nullptr;
 
-  // shuffle x, x, mask --> shuffle x, undef, mask'
   unsigned VWidth = cast<FixedVectorType>(SVI.getType())->getNumElements();
   unsigned LHSWidth = cast<FixedVectorType>(LHS->getType())->getNumElements();
   ArrayRef<int> Mask = SVI.getShuffleMask();
@@ -2323,6 +2322,7 @@ Instruction *InstCombinerImpl::visitShuffleVectorInst(ShuffleVectorInst &SVI) {
     }
   }
 
+  // shuffle x, x, mask --> shuffle x, undef, mask'
   if (LHS == RHS) {
     assert(!isa<UndefValue>(RHS) && "Shuffle with 2 undef ops not simplified?");
     // Remap any references to RHS to use LHS.
-- 
2.7.4