[X86] FindSingleBitChange - reduce scope of dyn_cast checks. NFC.

Author: RKSimon

llvm/lib/Target/X86/X86ISelLowering.cpp

@@ -30529,8 +30529,7 @@ enum BitTestKind : unsigned {
 static std::pair<Value *, BitTestKind> FindSingleBitChange(Value *V) {
   using namespace llvm::PatternMatch;
   BitTestKind BTK = UndefBit;
-  auto *C = dyn_cast<ConstantInt>(V);
-  if (C) {
+  if (auto *C = dyn_cast<ConstantInt>(V)) {
     // Check if V is a power of 2 or NOT power of 2.
     if (isPowerOf2_64(C->getZExtValue()))
       BTK = ConstantBit;
@@ -30540,8 +30539,7 @@ static std::pair<Value *, BitTestKind> FindSingleBitChange(Value *V) {
   }
 
   // Check if V is some power of 2 pattern known to be non-zero
-  auto *I = dyn_cast<Instruction>(V);
-  if (I) {
+  if (auto *I = dyn_cast<Instruction>(V)) {
     bool Not = false;
     // Check if we have a NOT
     Value *PeekI;