[Mlir-commits] [mlir] [MLIR][LLVM] Support Recursive DITypes (PR #80251)

[Billy Zhu]

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@@ -319,4 +319,64 @@ def LLVM_PointerElementTypeInterface
   ];
 }
 
+//===----------------------------------------------------------------------===//
+// LLVM dialect attr interfaces.
+//===----------------------------------------------------------------------===//
+
+def LLVM_DIRecursiveTypeAttrInterface
+  : AttrInterface<"DIRecursiveTypeAttrInterface"> {
+  let description = [{
+    This attribute represents a DITypeAttr that is recursive. Only DITypeAttrs
+    that translate to LLVM DITypes that support mutation should implement this
+    interface.
+
+    There are two modes for conforming attributes:
+
+    1. "rec-decl":
+      - This attr is a recursive declaration identified by a recId.
+
+    2. "rec-self":
+      - This attr is considered a recursive self reference.
+      - This attr itself is a placeholder type that should be conceptually
+        replaced with the closest parent attr of the same type with the same
+        recId.
+
+    e.g. To represent a linked list struct:
+
+      #rec_self = di_composite_type<recId = 0>
+      #ptr = di_derived_type<baseType: #struct_self, ...>
+      #field = di_derived_type<name = "next", baseType: #ptr, ...>
+      #rec = di_composite_type<recId = 0, name = "Node", elements: #field, ...>
+      #var = di_local_variable<type = #rec, ...>
+
+    Note that a rec-self without an outer rec-decl with the same recId is
+    conceptually the same as an "unbound" variable. The context needs to provide
+    meaning to the rec-self.
+
+    This can be avoided by calling the `getUnfoldedBaseType()` method on a
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zyx-billy wrote:

oh thank you, yes I ended up deleting this since it wasn't used anywhere 🤦. I'll update this.

https://github.com/llvm/llvm-project/pull/80251