[llvm] [TableGen] Add `!instances` operator to get defined records (PR #129680)

[Artem Belevich via llvm-commits]

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@@ -0,0 +1,60 @@
+// RUN: llvm-tblgen %s | FileCheck %s
+// RUN: not llvm-tblgen -DERROR1 %s 2>&1 | FileCheck --check-prefix=ERROR1 %s
+// RUN: not llvm-tblgen -DERROR2 %s 2>&1 | FileCheck --check-prefix=ERROR2 %s
+// RUN: not llvm-tblgen -DERROR3 %s 2>&1 | FileCheck --check-prefix=ERROR3 %s
+// XFAIL: vg_leak
+
+class A;
+def a0 : A;
+def a1 : A;
+
+class B : A;
+def b0 : B;
+def b1 : B;
+
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Artem-B wrote:

If I use `!instances<>` inside of a class, does it take effect at the point where it's parsed, or at the point where the class record is instantiated?

```
class X {
   list<A> instances = !instances<A>();
}

def ax: A;
def x: X; 
```

Is such use allowed at all? If so, will `x.instances` include `ax`?

We do not seem to have any test cases for use of `!instances` inside class/multiclass. We want to check use cases in the body and in the default arguments.


https://github.com/llvm/llvm-project/pull/129680