[InstCombine] Simplify code. NFCI.

Author: d0k

llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp

@@ -2635,17 +2635,9 @@ Instruction *InstCombinerImpl::visitShuffleVectorInst(ShuffleVectorInst &SVI) {
   // If the result mask is equal to one of the original shuffle masks,
   // or is a splat, do the replacement.
   if (isSplat || newMask == LHSMask || newMask == RHSMask || newMask == Mask) {
-    SmallVector<Constant*, 16> Elts;
-    for (unsigned i = 0, e = newMask.size(); i != e; ++i) {
-      if (newMask[i] < 0) {
-        Elts.push_back(UndefValue::get(Int32Ty));
-      } else {
-        Elts.push_back(ConstantInt::get(Int32Ty, newMask[i]));
-      }
-    }
     if (!newRHS)
       newRHS = UndefValue::get(newLHS->getType());
-    return new ShuffleVectorInst(newLHS, newRHS, ConstantVector::get(Elts));
+    return new ShuffleVectorInst(newLHS, newRHS, newMask);
   }
 
   return MadeChange ? &SVI : nullptr;