diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 1c9ee5d..b498a12 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -6808,9 +6808,9 @@
 }
 
 // Replace target shuffle mask elements with known undef/zero sentinels.
-static void resolveTargetShuffleAndZeroables(SmallVectorImpl<int> &Mask,
-                                             const APInt &KnownUndef,
-                                             const APInt &KnownZero) {
+static void resolveTargetShuffleFromZeroables(SmallVectorImpl<int> &Mask,
+                                              const APInt &KnownUndef,
+                                              const APInt &KnownZero) {
   unsigned NumElts = Mask.size();
   assert(KnownUndef.getBitWidth() == NumElts &&
          KnownZero.getBitWidth() == NumElts && "Shuffle mask size mismatch");
@@ -6823,6 +6823,22 @@
   }
 }
 
+// Extract target shuffle mask sentinel elements to known undef/zero bitmasks.
+static void resolveZeroablesFromTargetShuffle(const SmallVectorImpl<int> &Mask,
+                                              APInt &KnownUndef,
+                                              APInt &KnownZero) {
+  unsigned NumElts = Mask.size();
+  KnownUndef = KnownZero = APInt::getNullValue(NumElts);
+
+  for (unsigned i = 0; i != NumElts; ++i) {
+    int M = Mask[i];
+    if (SM_SentinelUndef == M)
+      KnownUndef.setBit(i);
+    if (SM_SentinelZero == M)
+      KnownZero.setBit(i);
+  }
+}
+
 // Forward declaration (for getFauxShuffleMask recursive check).
 // TODO: Use DemandedElts variant.
 static bool getTargetShuffleInputs(SDValue Op, SmallVectorImpl<SDValue> &Inputs,
@@ -7273,19 +7289,12 @@
 
   if (getTargetShuffleAndZeroables(Op, Mask, Inputs, KnownUndef, KnownZero)) {
     if (ResolveKnownElts)
-      resolveTargetShuffleAndZeroables(Mask, KnownUndef, KnownZero);
+      resolveTargetShuffleFromZeroables(Mask, KnownUndef, KnownZero);
     return true;
   }
   if (getFauxShuffleMask(Op, DemandedElts, Mask, Inputs, DAG, Depth,
                          ResolveKnownElts)) {
-    KnownUndef = KnownZero = APInt::getNullValue(Mask.size());
-    for (int i = 0, e = Mask.size(); i != e; ++i) {
-      int M = Mask[i];
-      if (SM_SentinelUndef == M)
-        KnownUndef.setBit(i);
-      if (SM_SentinelZero == M)
-        KnownZero.setBit(i);
-    }
+    resolveZeroablesFromTargetShuffle(Mask, KnownUndef, KnownZero);
     return true;
   }
   return false;
@@ -33047,7 +33056,7 @@
                               OpZero, DAG, Depth, false))
     return SDValue();
 
-  resolveTargetShuffleAndZeroables(OpMask, OpUndef, OpZero);
+  resolveTargetShuffleFromZeroables(OpMask, OpUndef, OpZero);
 
   // Add the inputs to the Ops list, avoiding duplicates.
   SmallVector<SDValue, 16> Ops(SrcOps.begin(), SrcOps.end());