[InstCombine] reduce duplicated code; NFC

llvm-svn: 370399

Author: rotateright

llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp

@@ -2391,26 +2391,29 @@ Instruction *InstCombiner::visitBitCast(BitCastInst &CI) {
     }
   }
 
-  if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(Src)) {
+  if (auto *Shuf = dyn_cast<ShuffleVectorInst>(Src)) {
     // Okay, we have (bitcast (shuffle ..)).  Check to see if this is
     // a bitcast to a vector with the same # elts.
-    if (SVI->hasOneUse() && DestTy->isVectorTy() &&
-        DestTy->getVectorNumElements() == SVI->getType()->getNumElements() &&
-        SVI->getType()->getNumElements() ==
-        SVI->getOperand(0)->getType()->getVectorNumElements()) {
+    Value *ShufOp0 = Shuf->getOperand(0);
+    Value *ShufOp1 = Shuf->getOperand(1);
+    unsigned NumShufElts = Shuf->getType()->getVectorNumElements();
+    unsigned NumSrcVecElts = ShufOp0->getType()->getVectorNumElements();
+    if (Shuf->hasOneUse() && DestTy->isVectorTy() &&
+        DestTy->getVectorNumElements() == NumShufElts &&
+        NumShufElts == NumSrcVecElts) {
       BitCastInst *Tmp;
       // If either of the operands is a cast from CI.getType(), then
       // evaluating the shuffle in the casted destination's type will allow
       // us to eliminate at least one cast.
-      if (((Tmp = dyn_cast<BitCastInst>(SVI->getOperand(0))) &&
+      if (((Tmp = dyn_cast<BitCastInst>(ShufOp0)) &&
            Tmp->getOperand(0)->getType() == DestTy) ||
-          ((Tmp = dyn_cast<BitCastInst>(SVI->getOperand(1))) &&
+          ((Tmp = dyn_cast<BitCastInst>(ShufOp1)) &&
            Tmp->getOperand(0)->getType() == DestTy)) {
-        Value *LHS = Builder.CreateBitCast(SVI->getOperand(0), DestTy);
-        Value *RHS = Builder.CreateBitCast(SVI->getOperand(1), DestTy);
+        Value *LHS = Builder.CreateBitCast(ShufOp0, DestTy);
+        Value *RHS = Builder.CreateBitCast(ShufOp1, DestTy);
         // Return a new shuffle vector.  Use the same element ID's, as we
         // know the vector types match #elts.
-        return new ShuffleVectorInst(LHS, RHS, SVI->getOperand(2));
+        return new ShuffleVectorInst(LHS, RHS, Shuf->getOperand(2));
       }
     }
   }