[TableGen] Validate the shift amount for !srl, !shl, and !sra operators.

The C operator has undefined behavior for out of bounds shifts
so we should check this.

Author: topperc

llvm/lib/TableGen/Record.cpp

@@ -1537,7 +1537,13 @@ const Init *BinOpInit::Fold(const Record *CurRec) const {
     if (LHSi && RHSi) {
       int64_t LHSv = LHSi->getValue(), RHSv = RHSi->getValue();
       int64_t Result;
-      switch (getOpcode()) {
+
+      unsigned Opc = getOpcode();
+      if ((Opc == SHL || Opc == SRA || Opc == SRL) && (RHSv < 0 || RHSv >= 64))
+        PrintFatalError(CurRec->getLoc(),
+                        "Illegal operation: out of bounds shift");
+
+      switch (Opc) {
       default: llvm_unreachable("Bad opcode!");
       case ADD: Result = LHSv + RHSv; break;
       case SUB: Result = LHSv - RHSv; break;
@@ -1556,7 +1562,7 @@ const Init *BinOpInit::Fold(const Record *CurRec) const {
       case OR:  Result = LHSv | RHSv; break;
       case XOR: Result = LHSv ^ RHSv; break;
       case SHL: Result = (uint64_t)LHSv << (uint64_t)RHSv; break;
-      case SRA: Result = LHSv >> RHSv; break;
+      case SRA: Result = LHSv >> (uint64_t)RHSv; break;
       case SRL: Result = (uint64_t)LHSv >> (uint64_t)RHSv; break;
       }
       return IntInit::get(getRecordKeeper(), Result);