[RISCV] Add additional checking to tablgen RISCVVEmitter requested in D95016.

This errors, but doesn't give source location. We'd need to pass
the Record through several layers to get to the location.

Reviewed By: jrtc27

Differential Revision: https://reviews.llvm.org/D98379

Author: topperc

clang/utils/TableGen/RISCVVEmitter.cpp

@@ -19,6 +19,7 @@
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringSet.h"
 #include "llvm/ADT/Twine.h"
+#include "llvm/TableGen/Error.h"
 #include "llvm/TableGen/Record.h"
 #include <numeric>
 
@@ -536,7 +537,7 @@ void RVVType::applyBasicType() {
     ScalarType = ScalarTypeKind::Float;
     break;
   default:
-    llvm_unreachable("Unhandled type code!");
+    PrintFatalError("Unhandled type code!");
   }
   assert(ElementBitwidth != 0 && "Bad element bitwidth!");
 }
@@ -587,17 +588,23 @@ void RVVType::applyModifier(StringRef Transformer) {
     Scale = 0;
     break;
   default:
-    llvm_unreachable("Illegal primitive type transformers!");
+    PrintFatalError("Illegal primitive type transformers!");
   }
   Transformer = Transformer.drop_back();
 
   // Compute type transformers
   for (char I : Transformer) {
     switch (I) {
     case 'P':
+      if (IsConstant)
+        PrintFatalError("'P' transformer cannot be used after 'C'");
+      if (IsPointer)
+        PrintFatalError("'P' transformer cannot be used twice");
       IsPointer = true;
       break;
     case 'C':
+      if (IsConstant)
+        PrintFatalError("'C' transformer cannot be used twice");
       IsConstant = true;
       break;
     case 'K':
@@ -614,11 +621,11 @@ void RVVType::applyModifier(StringRef Transformer) {
       break;
     case 'S':
       LMUL = LMULType(0);
-      // Update ElementBitwidth need ot update Scale too.
+      // Update ElementBitwidth need to update Scale too.
       Scale = LMUL.getScale(ElementBitwidth);
       break;
     default:
-      llvm_unreachable("Illegal non-primitive type transformer!");
+      PrintFatalError("Illegal non-primitive type transformer!");
     }
   }
 }