[CHERIoT] Preserve/propagate the cheriot subarch in more places.

Author: resistor

clang/lib/Driver/Driver.cpp

@@ -791,8 +791,9 @@ static llvm::Triple computeTargetTriple(const Driver &D,
           ArchName, /*EnableExperimentalExtensions=*/true);
       if (!llvm::errorToBool(ISAInfo.takeError())) {
         unsigned XLen = (*ISAInfo)->getXLen();
+        // CHERIOT: Preserve the subarch if it was set.
         if (XLen == 32)
-          Target.setArch(llvm::Triple::riscv32);
+          Target.setArch(llvm::Triple::riscv32, Target.getSubArch());
         else if (XLen == 64)
           Target.setArch(llvm::Triple::riscv64);
       }

llvm/lib/TargetParser/Triple.cpp

@@ -159,6 +159,15 @@ StringRef Triple::getArchName(ArchType Kind, SubArchType SubArch) {
       break;
     }
     break;
+  case Triple::riscv32: {
+    switch (SubArch) {
+    case Triple::RISCV32SubArch_cheriot_v1:
+      return "riscv32cheriotv1";
+    default:
+      break;
+    }
+    break;
+  }
   default:
     break;
   }