TableGen: Avoid undefined behaviour by doing this shift in int64

Found by ubsan. This was taking a bool and left shifting by 32 - the
result is 64 bit, so we should really do the math in a type it fits
in.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237345 91177308-0d34-0410-b5e6-96231b3b80d8

lib/TableGen/Record.cpp

@@ -230,7 +230,7 @@ Init *IntRecTy::convertValue(BitsInit *BI) {
   int64_t Result = 0;
   for (unsigned i = 0, e = BI->getNumBits(); i != e; ++i)
     if (BitInit *Bit = dyn_cast<BitInit>(BI->getBit(i)))
-      Result |= Bit->getValue() << i;
+      Result |= static_cast<int64_t>(Bit->getValue()) << i;
     else
       return nullptr;
   return IntInit::get(Result);