[llvm] [DirectX][NFC] Change specification of overload types and attribute in DXIL.td (PR #81184)

[S. Bharadwaj Yadavalli via llvm-commits]

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@@ -268,36 +296,45 @@ static void emitDXILIntrinsicMap(std::vector<DXILOperationDesc> &Ops,
 
 static std::string emitDXILOperationFnAttr(StringRef FnAttr) {
   return StringSwitch<std::string>(FnAttr)
-      .Case("rn", "Attribute::ReadNone")
-      .Case("ro", "Attribute::ReadOnly")
+      .Case("NoReadMemory", "Attribute::ReadNone")
+      .Case("ReadMemory", "Attribute::ReadOnly")
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bharadwajy wrote:

I changed the type of `Attribute` to `EnumAttr` type to get the benefit of appropriately constrained values that can be specified and validating at compile-time as opposed to using a `string`.

https://github.com/llvm/llvm-project/pull/81184