[llvm] [CodeGen, CHERI] Add capability types to MVT. (PR #156616)

[Alexander Richardson via llvm-commits]

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@@ -228,6 +228,9 @@ namespace llvm {
       return isSimple() ? V.is2048BitVector() : isExtended2048BitVector();
     }
 
+    /// Return true if this is a capability type.
+    bool isCapability() const { return isSimple() ? V.isCapability() : false; }
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arichardson wrote:

How about a compromise: keep using c64/c128 and change `bool isCapability()` to `bool isCheriCapability()`?

https://github.com/llvm/llvm-project/pull/156616