[Stream] Do not specialize encodings that is either unrecognized or a…

…lready serialized (#20054)

A recognized encoding indicates an attribute that implements
SerializableEncodingAttrInterface. If an encoding does not implement the
interface, it is an unknown/unrecognized encoding.

The revision makes the SpecializeEncoding pass more robust. It filters
all the ops that need the specialization. I.e., it filters out the ops
that do not have any recognized encoding. For DispatchTensorOp, it also
checks if the corresponding executables/functions match the assumptions
or not. In the pass, the specializable cases must match:

- The corresponding executable is a stream.executable op.
- The function arguments, where the types are !stream.binding_type, are
only used by stream.binding.subspan ops. Furthermore, the result type of
subspan ops have to implement IREE::Encoding::EncodingTypeInterface.

If one of the requirements does not meet, the op won't be updated. If
the encoding is unrecognized, the pass does nothing. If the encoding is
recognized and it is already serialized, the pass updates the bindings
with the serialized encodings.

To test unrecognized encoding, the revision introduces
`UnknownEncodingAttr` and uses it for testing.

---------

Signed-off-by: hanhanW <hanhan0912@gmail.com>

compiler/src/iree/compiler/Dialect/Encoding/IR/EncodingAttrs.td

@@ -210,6 +210,17 @@ def TestingEncodingAttr :
   let genVerifyDecl = 0;
 }
 
+def UnknownEncodingAttr : IREEEncoding_Attr<"UnknownEncoding"> {
+  let mnemonic = "unknown_encoding";
+  let summary = "A pure encoding attribute for testing purpose";
+
+  let description = [{
+    An attribute for testing purpose. It is intended to be attached on
+    RankedTensorType as an encoding.
+  }];
+  let genVerifyDecl = 0;
+}
+
 def UnspecializedEncodingAttr :
     IREEEncoding_Attr<"UnspecializedEncoding", [
       DeclareAttrInterfaceMethods<IREEEncoding_EncodingLayoutResolverAttrInterface, [

compiler/src/iree/compiler/Dialect/Encoding/IR/EncodingDialect.cpp

@@ -36,7 +36,8 @@ struct EncodingOpAsmInterface : public OpAsmDialectInterface {
   /// `.` or end with a numeric digit([0-9]+). Returns success if an alias was
   /// provided, failure otherwise.
   AliasResult getAlias(Attribute attr, raw_ostream &os) const override {
-    if (llvm::isa<EncodingAttr, TestingEncodingAttr>(attr)) {
+    if (llvm::isa<EncodingAttr, TestingEncodingAttr, UnknownEncodingAttr>(
+            attr)) {
       os << "encoding";
       return AliasResult::OverridableAlias;
     }