[Mlir-commits] [mlir] [mlir][core|ptr] Add `PtrLikeTypeInterface` and casting ops to the `ptr` dialect (PR #137469)

[Mehdi Amini]

================
@@ -41,6 +41,54 @@ void PtrDialect::initialize() {
       >();
 }
 
+//===----------------------------------------------------------------------===//
+// FromPtrOp
+//===----------------------------------------------------------------------===//
+
+OpFoldResult FromPtrOp::fold(FoldAdaptor adaptor) {
+  // Fold the pattern:
+  // %ptr = ptr.to_ptr %v : type -> ptr
+  // (%mda = ptr.get_metadata %v : type)?
+  // %val = ptr.from_ptr %ptr (metadata %mda)? : ptr -> type
+  // To:
+  // %val -> %v
+  auto toPtr = dyn_cast_or_null<ToPtrOp>(getPtr().getDefiningOp());
+  // Cannot fold if it's not a `to_ptr` op or the initial and final types are
+  // different.
----------------
joker-eph wrote:

I don't follow your explanation, you have `...` in your chain which isn't handled by the folder as far as I can tell (I was expecting to see a traversal of the chain, but neither here or the ToPtrOp have it).

An example would be:

```
func.func @test_from_ptr_0(%mr: memref<f32, #ptr.generic_space>, %md: !ptr.ptr_metadata<memref<f32, #ptr.generic_space>>) -> memref<f32, #ptr.generic_space> {
   %ptr1 = ptr.to_ptr %mr : memref<f32, #ptr.generic_space> -> !ptr.ptr<#ptr.generic_space>
   %memrefWithOtherMd = ptr.from_ptr %ptr1 metadata %md : !ptr.ptr<#ptr.generic_space> -> memref<f32, #ptr.generic_space>

   %ptr = ptr.to_ptr %memrefWithOtherMd : memref<f32, #ptr.generic_space> -> !ptr.ptr<#ptr.generic_space>
   %mda = ptr.get_metadata %mr : memref<f32, #ptr.generic_space>
   %res = ptr.from_ptr %ptr metadata %mda : !ptr.ptr<#ptr.generic_space> -> memref<f32, #ptr.generic_space>
   return %res : memref<f32, #ptr.generic_space>
 }

```

https://github.com/llvm/llvm-project/pull/137469