[mlir] Extend the promise interface mechanism

This patch pairs a promised interface with the object (Op/Attr/Type/Dialect) requesting the promise, ie:
```
declarePromisedInterface<MyAttr, MyInterface>();
```
Allowing to make fine grained promises. It also adds a mechanism to query if `Op/Attr/Type` has an specific promise returning true if the promise is there or if an implementation has been added. Finally it adds a couple of `Attr|TypeConstraints` that can be used in ODS to query if the promise or an implementation is there.

This patch tries to solve 2 issues:
1. Different entities cannot use the same promise.
```
declarePromisedInterface<MyInterface>();
// Resolves a promise.
MyAttr1::attachInterface<MyInterface>(ctx);
// Doesn't resolves a promise, as the previous attachment removed the promise.
MyAttr2::attachInterface<MyInterface>(ctx);
```
2. Is not possible to query if a promise has been declared.

Reviewed By: mehdi_amini

Differential Revision: https://reviews.llvm.org/D158464

1 files changed, 26 insertions, 0 deletions

diff --git a/mlir/unittests/IR/InterfaceAttachmentTest.cpp b/mlir/unittests/IR/InterfaceAttachmentTest.cpp
index fe85516..2e1309a 100644
--- a/mlir/unittests/IR/InterfaceAttachmentTest.cpp
+++ b/mlir/unittests/IR/InterfaceAttachmentTest.cpp
@@ -417,4 +417,30 @@ TEST(InterfaceAttachment, OperationDelayedContextAppend) {
   EXPECT_FALSE(isa<TestExternalOpInterface>(opI.getOperation()));
 }
 
+TEST(InterfaceAttachmentTest, PromisedInterfaces) {
+  // Attribute interfaces use the exact same mechanism as types, so just check
+  // that the promise mechanism works for attributes.
+  MLIRContext context;
+  auto testDialect = context.getOrLoadDialect<test::TestDialect>();
+  auto attr = test::SimpleAAttr::get(&context);
+
+  // `SimpleAAttr` doesn't implement nor promises the
+  // `TestExternalAttrInterface` interface.
+  EXPECT_FALSE(isa<TestExternalAttrInterface>(attr));
+  EXPECT_FALSE(
+      attr.hasPromiseOrImplementsInterface<TestExternalAttrInterface>());
+
+  // Add a promise `TestExternalAttrInterface`.
+  testDialect->declarePromisedInterface<test::SimpleAAttr,
+                                        TestExternalAttrInterface>();
+  EXPECT_TRUE(
+      attr.hasPromiseOrImplementsInterface<TestExternalAttrInterface>());
+
+  // Attach the interface.
+  test::SimpleAAttr::attachInterface<TestExternalAttrInterface>(context);
+  EXPECT_TRUE(isa<TestExternalAttrInterface>(attr));
+  EXPECT_TRUE(
+      attr.hasPromiseOrImplementsInterface<TestExternalAttrInterface>());
+}
+
 } // namespace