[TypePromotion] Remove an unreachable 'return false'. NFC

The if and the else above this both return so this is unreachable.
Delete it and remove the else after return.

Author: topperc

llvm/lib/CodeGen/TypePromotion.cpp

@@ -359,22 +359,21 @@ bool TypePromotionImpl::isSafeWrap(Instruction *I) {
   if (!OverflowConst.isNonPositive())
     return false;
 
+  SafeWrap.insert(I);
+
   // Using C1 = OverflowConst and C2 = ICmpConst, we can either prove that:
   //   zext(x) + sext(C1) <u zext(C2)  if C1 < 0 and C1 >s C2
   //   zext(x) + sext(C1) <u sext(C2)  if C1 < 0 and C1 <=s C2
   if (OverflowConst.sgt(ICmpConst)) {
     LLVM_DEBUG(dbgs() << "IR Promotion: Allowing safe overflow for sext "
                       << "const of " << *I << "\n");
-    SafeWrap.insert(I);
-    return true;
-  } else {
-    LLVM_DEBUG(dbgs() << "IR Promotion: Allowing safe overflow for sext "
-                      << "const of " << *I << " and " << *CI << "\n");
-    SafeWrap.insert(I);
-    SafeWrap.insert(CI);
     return true;
   }
-  return false;
+
+  LLVM_DEBUG(dbgs() << "IR Promotion: Allowing safe overflow for sext "
+                    << "const of " << *I << " and " << *CI << "\n");
+  SafeWrap.insert(CI);
+  return true;
 }
 
 bool TypePromotionImpl::shouldPromote(Value *V) {