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

[Fabian Mora]

================
@@ -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.
+  if (!toPtr || toPtr.getPtr().getType() != getType())
+    return nullptr;
+  Value md = getMetadata();
+  if (!md)
+    return toPtr.getPtr();
----------------
fabianmcg wrote:

The verifier of `from_ptr` will check whether `PtrLikeType` expects non-trivial metadata, and if it does, it always asks for it. The only way to not provide the metadata is if `trivial_metadata` is set, which tells the compiler it's safe to assume that all info is statically encoded in the type.

Therefore in this case, it is known from the verifier that the op can be folded.

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