[mlir][tblgen] Emit deprecation warning if `kEmitRawAttributes` is used

[zero9178]

Summary

As discussed in https://reviews.llvm.org/D140886, emitting a warning if the old API is used may be beneficial to encourage migration to the new fold API.
This reuse the existing Deprecated infrastructure within TableGen, and simply marks the def for kEmitRawAttributesFolder causing a use of it in a record (even if set within a base class) to emit a warning.

Error message as printed in the terminal:

Included from C:/llvm-project/mlir/python/mlir/dialects/TensorOps.td:13:
Included from C:/llvm-project/mlir/include\mlir/Dialect/Tensor/IR/TensorOps.td:12:
C:/llvm-project/mlir/include\mlir/Dialect/Tensor/IR/TensorBase.td:14:5: warning: Using deprecated def `kEmitRawAttributesFolder`
def Tensor_Dialect : Dialect {
    ^
note: 'useFoldAPI' of 'kEmitRawAttributesFolder' (default) has been deprecated and is pending removal. Please switch to 'kEmitFoldAdaptorFolder'. See https://discourse.llvm.org/t/psa-new-improved-fold-method-signature-has-landed-please-update-your-downstream-projects/67618

Depends on https://reviews.llvm.org/D141530 (to not emit warnings in tree)

If accepted I'd probably not land this for a week or two (since the new fold has only just landed) to give people more time before emitting warnings.

[mehdi_amini]

You have a typo in the title: warining -> warning

mlir/tools/mlir-tblgen/OpDefinitionsGen.cpp

2343 ↗

(On Diff #488592)

Can you print the dialect name as well here?

[zero9178]

Address review comments:

• Include dialect name in the warning message. This uses the name of the dialect, as is used as prefix in IR, not the name of the TableGen record.

[jpienaar]

Could we reuse/extend https://github.com/llvm/llvm-project/blob/b1e92f8def98c5e34fdb3b4c18ac16d65fb613a2/mlir/lib/Tools/mlir-tblgen/MlirTblgenMain.cpp#L65 to do this?

[zero9178]

Make use of the existing Deprecation infrastructure in TableGen

Compared to the previous manual approach this differs in the following ways:

• It always warns on usage, regardless of if there are any Ops in the Dialect nor any fold methods in any Ops within the Dialect. I have already found some test dialects in tree that I missed migrating thanks to this. One could also consider this a con however, as it'll warn even if a dialect does not have any fold methods.'
• It warns more often, since any TableGen invocation including a dialect with the old fold value will now emit a warning not just when generating Op defs and decls for a specific dialect.
• Dialect name is sadly no longer printed in the warning message.

One of the only things I had to adapt in the existing infrastructure is that I tentatively removed the check whether the def is in the Main source file. This is problematic because Dialects are often not required in the main source file being processed by mlir-tblgen (usually that is the Op file), which would therefore not emit a warning.
@jpienaar do you happen to know whether there was a concrete case where with this check removed, it'd otherwise emit too many warnings or was the check motivated elseway?

Now depends on https://reviews.llvm.org/D141794, otherwise a warning will be emitted for every Op within a dialect, not just once for a dialect.

New error message:

Included from C:/llvm-project/mlir/python/mlir/dialects/TensorOps.td:13:
Included from C:/llvm-project/mlir/include\mlir/Dialect/Tensor/IR/TensorOps.td:12:
C:/llvm-project/mlir/include\mlir/Dialect/Tensor/IR/TensorBase.td:14:5: warning: Using deprecated def `kEmitRawAttributesFolder`
def Tensor_Dialect : Dialect {
    ^
note: 'useFoldAPI' of 'kEmitRawAttributesFolder' (default) has been deprecated and is pending removal. Please switch to 'kEmitFoldAdaptorFolder'. See https://discourse.llvm.org/t/psa-new-improved-fold-method-signature-has-landed-please-update-your-downstream-projects/67618

I'd also like to note that I don't have a strong preference for either the previous manual approch or this one, although I think this one is kind of neat given its mostly TableGen code changes :-)

[jpienaar]

I like this one more too (we get towards having a better functioning deprecation mechanism). Normally I err on keeping .td files unchanged where possible. But don't think you have option either way and this has same user facing impact.

mlir/include/mlir/IR/DialectBase.td

16

We may need new diagram of which include is more abstract than which :-) (this base is higher than that base). Not due to you or blocker here.

mlir/lib/Tools/mlir-tblgen/MlirTblgenMain.cpp

109

I think your removal of traversing anonymous classes helped reduce need for this guard.

mlir/include/mlir/IR/DialectBase.td

 //===-- DialectBase.td - Base Dialect definition file ------*- tablegen -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 // This file contains the base set of constructs for defining Dialect classes.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef DIALECTBASE_TD
 #define DIALECTBASE_TD
 
+// Helper for marking deprecated classes or defs. To mark a def as deprecated,
+// mix in the `Deprecate` class with a reason.
+class Deprecated<string reason> {
+  string odsDeprecated = reason;
+}
+
 //===----------------------------------------------------------------------===//
 // Dialect definitions
 //===----------------------------------------------------------------------===//
 
+class EmitFolderBase;
 // Generate 'fold' method with 'ArrayRef<Attribute>' parameter.
 // New code should prefer using 'kEmitFoldAdaptorFolder' and
 // consider 'kEmitRawAttributesFolder' deprecated and to be
 // removed in the future.
-defvar kEmitRawAttributesFolder = 0;
+def kEmitRawAttributesFolder : EmitFolderBase, Deprecated<
+  "'useFoldAPI' of 'kEmitRawAttributesFolder' (default) has been deprecated "
+  # "and is pending removal. Please switch to 'kEmitFoldAdaptorFolder'. See "
+  # "https://discourse.llvm.org/t/psa-new-improved-fold-method-signature-has-landed-please-update-your-downstream-projects/67618"
+> {}
 // Generate 'fold' method with 'FoldAdaptor' parameter.
-defvar kEmitFoldAdaptorFolder = 1;
+def kEmitFoldAdaptorFolder : EmitFolderBase {}
 
 class Dialect {
   // The name of the dialect.
   string name = ?;
 
   // Short summary of the dialect.
   string summary = ?;
 
class Dialect {
 
   // If this dialect overrides the hook for canonicalization patterns.
   bit hasCanonicalizer = 0;
 
   // If this dialect can be extended at runtime with new operations or types.
   bit isExtensible = 0;
 
   // Fold API to use for operations in this dialect.
-  int useFoldAPI = kEmitRawAttributesFolder;
+  EmitFolderBase useFoldAPI = kEmitRawAttributesFolder;
 }
 
 #endif // DIALECTBASE_TD

mlir/include/mlir/IR/OpBase.td

 //
 // StrConcat<["a", "b", "c"]>.result
 //
 // to get the string "abc"
 class StrFunc<string r> {
   string result = r;
 }
 
-// Helper for marking deprecated classes or defs. To mark a def as deprecated,
-// mix in the `Deprecate` class with a reason.
-class Deprecated<string reason> {
-  string odsDeprecated = reason;
-}
-
 //===----------------------------------------------------------------------===//
 // Predicate definitions
 //===----------------------------------------------------------------------===//
 
 // Base class for logical predicates.
 //
 // Predicates are used to compose constraints (see next section for details).
 // There are two categories of predicates:

mlir/lib/TableGen/Dialect.cpp

 //===- Dialect.cpp - Dialect wrapper class --------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 // Dialect wrapper to simplify using TableGen Record defining a MLIR dialect.
 //
 //===----------------------------------------------------------------------===//
 
 #include "mlir/TableGen/Dialect.h"
+#include "llvm/ADT/StringSwitch.h"
 #include "llvm/TableGen/Error.h"
 #include "llvm/TableGen/Record.h"
 
 using namespace mlir;
 using namespace mlir::tblgen;
 Dialect::Dialect(const llvm::Record *def) : def(def) {
   if (def == nullptr)
     return;
bool Dialect::useDefaultTypePrinterParser() const {
   return def->getValueAsBit("useDefaultTypePrinterParser");
 }
 
 bool Dialect::isExtensible() const {
   return def->getValueAsBit("isExtensible");
 }
 
 Dialect::FolderAPI Dialect::getFolderAPI() const {
-  int64_t value = def->getValueAsInt("useFoldAPI");
-  if (value < static_cast<int64_t>(FolderAPI::RawAttributes) ||
-      value > static_cast<int64_t>(FolderAPI::FolderAdaptor))
+  llvm::Record *value = def->getValueAsDef("useFoldAPI");
+  auto converted =
+      llvm::StringSwitch<std::optional<Dialect::FolderAPI>>(value->getName())
+          .Case("kEmitRawAttributesFolder", FolderAPI::RawAttributes)
+          .Case("kEmitFoldAdaptorFolder", FolderAPI::FolderAdaptor)
+          .Default(std::nullopt);
+
+  if (!converted)
     llvm::PrintFatalError(def->getLoc(),
                           "Invalid value for dialect field `useFoldAPI`");
 
-  return static_cast<FolderAPI>(value);
+  return *converted;
 }
 
 bool Dialect::operator==(const Dialect &other) const {
   return def == other.def;
 }
 
 bool Dialect::operator<(const Dialect &other) const {
   return getName() < other.getName();
 }

mlir/lib/Tools/mlir-tblgen/MlirTblgenMain.cpp

if (!r || !r->getValue())
       continue;
 
     llvm::DenseMap<Init *, bool> hasUse;
     if (auto *si = dyn_cast<StringInit>(r->getValue())) {
       for (auto &jt : records.getDefs()) {
         // Skip anonymous defs.
         if (jt.second->isAnonymous())
           continue;
-        // Skip all outside main file to avoid flagging redundantly.
-        unsigned buf =
-            SrcMgr.FindBufferContainingLoc(jt.second->getLoc().front());
-        if (buf != SrcMgr.getMainFileID())
-          continue;
 
         if (findUse(*jt.second, it.second->getDefInit(), hasUse)) {
           PrintWarning(jt.second->getLoc(),
                        "Using deprecated def `" + it.first + "`");
           PrintNote(si->getAsUnquotedString());
           deprecatedDefsFounds = true;
         }
       }

mlir/test/mlir-tblgen/has-fold-invalid-values.td

 // RUN: not mlir-tblgen -gen-op-decls -I %S/../../include %s 2>&1 | FileCheck %s
 
 include "mlir/IR/OpBase.td"
 
+def Bad : EmitFolderBase;
+
 def Test_Dialect : Dialect {
   let name = "test";
   let cppNamespace = "NS";
-  let useFoldAPI = 3;
+  let useFoldAPI = Bad;
 }
 
 def InvalidValue_Op : Op<Test_Dialect, "invalid_op"> {
   let hasFolder = 1;
 }
 
 // CHECK: Invalid value for dialect field `useFoldAPI`