================
@@ -496,6 +496,46 @@ def CIR_GlobalViewAttr : CIR_Attr<"GlobalView",
"global_view", [
}];
}
+//===----------------------------------------------------------------------===//
+// VTableAttr
+//===----------------------------------------------------------------------===//
+
+def VTableAttr : CIR_Attr<"VTable", "vtable", [TypedAttrInterface]> {
+ let summary = "Represents a C++ vtable";
+ let description = [{
+ Wraps a #cir.const_record containing vtable data.
----------------
andykaylor wrote:
This can potentially wrap a record containing multiple vtable arrays. In the
simple case, we create an anonymous record that has a single array element,
which looks like this:
```
cir.global linkonce_odr @_ZTV6Mother =
#cir.vtable<{
#cir.const_array<[
#cir.ptr<null> : !cir.ptr<!u8i>,
#cir.global_view<@_ZTI6Mother> : !cir.ptr<!u8i>,
#cir.global_view<@_ZN6Mother9MotherFooEv> : !cir.ptr<!u8i>,
#cir.global_view<@_ZN6Mother10MotherFoo2Ev> : !cir.ptr<!u8i>
]> : !cir.array<!cir.ptr<!u8i> x 4>
}> : !rec_anon_struct2 {alignment = 8 : i64 }
```
But in cases involving multiple inheritence, there can be multiple vtables
within the record, like this:
```
cir.global linkonce_odr @_ZTV5Child =
#cir.vtable<{
#cir.const_array<[
#cir.ptr<null> : !cir.ptr<!u8i>,
#cir.global_view<@_ZTI5Child> : !cir.ptr<!u8i>,
#cir.global_view<@_ZN5Child9MotherFooEv> : !cir.ptr<!u8i>,
#cir.global_view<@_ZN6Mother10MotherFoo2Ev> : !cir.ptr<!u8i>
]> : !cir.array<!cir.ptr<!u8i> x 4>,
#cir.const_array<[
#cir.ptr<-8 : i64> : !cir.ptr<!u8i>,
#cir.global_view<@_ZTI5Child> : !cir.ptr<!u8i>,
#cir.global_view<@_ZN6Father9FatherFooEv> : !cir.ptr<!u8i>
]> : !cir.array<!cir.ptr<!u8i> x 3>
}> : !rec_anon_struct4 {alignment = 8 : i64}
```
The `index` attribute in the `address_point` selects which of the wrapped
vtables is being referenced:
` %6 = cir.vtable.address_point(@_ZTV5Child, address_point = <index = 1,
offset = 2>) : !cir.vptr
https://github.com/llvm/llvm-project/pull/154415
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