[clang] [CIR] Add VTableAddrPointOp (PR #148730)

[Henrich Lauko via cfe-commits]

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@@ -1669,6 +1669,51 @@ def GetGlobalOp : CIR_Op<"get_global",
   }];
 }
 
+//===----------------------------------------------------------------------===//
+// VTableAddrPointOp
+//===----------------------------------------------------------------------===//
+
+def VTableAddrPointOp : CIR_Op<"vtable.address_point",
+    [Pure, DeclareOpInterfaceMethods<SymbolUserOpInterface>]> {
+  let summary = "Get the vtable (global variable) address point";
+  let description = [{
+    The `vtable.address_point` operation retrieves the effective address
+    (address point) of a C++ virtual table. An object internal `__vptr`
+    gets initializated on top of the value returned by this operation.
+
+    `address_point.index` (vtable index) provides the appropriate vtable within
+    the vtable group (as specified by Itanium ABI), and `address_point.offset`
+    (address point index) the actual address point within that vtable.
+
+    The return type is always a `!cir.ptr<!cir.ptr<() -> i32>>`.
+
+    Example:
+    ```mlir
+    cir.global linkonce_odr @_ZTV1B = ...
+    ...
+    %3 = cir.vtable.address_point(@_ZTV1B, address_point = <index = 0,
+                                  offset = 2>) : !cir.ptr<!cir.ptr<() -> i32>>
+    ```
+  }];
+
+  let arguments = (ins OptionalAttr<FlatSymbolRefAttr>:$name,
+                       Optional<CIR_AnyType>:$sym_addr,
----------------
xlauko wrote:

I believe this should not be CIR_AnyType; should it be CIR_PtrTo<CIR_AnyFuncType> instead? However, neither the description nor the example clarifies what is expected for sym_addr. It would be helpful to include that in the documentation as well.

https://github.com/llvm/llvm-project/pull/148730