Add support for function result attributes.

This allows dialect-specific attributes to be attached to func results. (or more specifically, FunctionLike ops).

For example:

```
func @f() -> (i32 {my_dialect.some_attr = 3})
```

This attaches my_dialect.some_attr with value 3 to the first result of func @f.

Another more complex example:

```
func @g() -> (i32, f32 {my_dialect.some_attr = "foo", other_dialect.some_other_attr = [1,2,3]}, i1)
```

Here, the second result has two attributes attached.

PiperOrigin-RevId: 275564165

2 files changed, 26 insertions, 0 deletions

diff --git a/mlir/test/lib/TestDialect/TestDialect.cpp b/mlir/test/lib/TestDialect/TestDialect.cpp
index ee8325fd13e..2e3d97b473f 100644
--- a/mlir/test/lib/TestDialect/TestDialect.cpp
+++ b/mlir/test/lib/TestDialect/TestDialect.cpp
@@ -114,6 +114,24 @@ TestDialect::TestDialect(MLIRContext *context)
   allowUnknownOperations();
 }
 
+LogicalResult TestDialect::verifyRegionArgAttribute(Operation *op,
+                                                    unsigned regionIndex,
+                                                    unsigned argIndex,
+                                                    NamedAttribute namedAttr) {
+  if (namedAttr.first == "test.invalid_attr")
+    return op->emitError() << "invalid to use 'test.invalid_attr'";
+  return success();
+}
+
+LogicalResult
+TestDialect::verifyRegionResultAttribute(Operation *op, unsigned regionIndex,
+                                         unsigned resultIndex,
+                                         NamedAttribute namedAttr) {
+  if (namedAttr.first == "test.invalid_attr")
+    return op->emitError() << "invalid to use 'test.invalid_attr'";
+  return success();
+}
+
 //===----------------------------------------------------------------------===//
 // Test IsolatedRegionOp - parse passthrough region arguments.
 //===----------------------------------------------------------------------===//
diff --git a/mlir/test/lib/TestDialect/TestDialect.h b/mlir/test/lib/TestDialect/TestDialect.h
index ffe2a1c50ec..ade0eb81c40 100644
--- a/mlir/test/lib/TestDialect/TestDialect.h
+++ b/mlir/test/lib/TestDialect/TestDialect.h
@@ -40,6 +40,14 @@ public:
 
   /// Get the canonical string name of the dialect.
   static StringRef getDialectName() { return "test"; }
+
+  LogicalResult verifyRegionArgAttribute(Operation *, unsigned regionIndex,
+                                         unsigned argIndex,
+                                         NamedAttribute) override;
+
+  LogicalResult verifyRegionResultAttribute(Operation *, unsigned regionIndex,
+                                            unsigned resultIndex,
+                                            NamedAttribute) override;
 };
 
 #define GET_OP_CLASSES