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@fabianmcg fabianmcg commented Jul 22, 2025

This patch adds the getPropertyFromAttr and setPropertyFromAttr methods to various places. These methods are similar to getPropertiesFromAttr and setPropertiesFromAttr, in that they get or set a property to or from an attr, but they set or get props based on a name.

The reasoning behind adding these methods is that getPropertiesFromAttr and setPropertiesFromAttr are meant for getting and setting collections of props, which is not always desirable specially in language bindings like the python bindings, and can be wasteful.

Also, while it would be possible to use setPropertiesFromAttr to set a single prop, the method introduces additional logic to set default values if the value is not present, which is not something desirable once the op has been created. Further, getPropertiesFromAttr always converts all properties, which might be a wasteful process for large props.

This is also the first step in fixing #150009 .

@llvmbot llvmbot added mlir:core MLIR Core Infrastructure mlir labels Jul 22, 2025
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llvmbot commented Jul 22, 2025

@llvm/pr-subscribers-mlir

@llvm/pr-subscribers-mlir-core

Author: Fabian Mora (fabianmcg)

Changes

This patch adds the getPropertyFromAttr and setPropertyFromAttr methods to various places. These methods are similar to getPropertiesFromAttr and setPropertiesFromAttr, in that set a property from an attr, but they set or get props based on a name.

The reasoning behind adding these methods is that getPropertiesFromAttr and setPropertiesFromAttr are meant for getting and setting collections of props, which is not always desirable specially in language bindings like the python bindings, and can be wasteful.

Also, while it would be possible to use setPropertiesFromAttr to set a single prop, the method introduces additional logic to set default values if the value is not present, which is not something desirable once the op has been created. Further, getPropertiesFromAttr always converts all properties, which might be a wasteful process for large props.

This is also the first step in fixing #150009 .


Patch is 24.80 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/150060.diff

8 Files Affected:

  • (modified) mlir/include/mlir/IR/ExtensibleDialect.h (+11)
  • (modified) mlir/include/mlir/IR/OpDefinition.h (+21)
  • (modified) mlir/include/mlir/IR/Operation.h (+17)
  • (modified) mlir/include/mlir/IR/OperationSupport.h (+45)
  • (modified) mlir/lib/IR/MLIRContext.cpp (+14)
  • (modified) mlir/lib/IR/Operation.cpp (+15)
  • (modified) mlir/tools/mlir-tblgen/OpDefinitionsGen.cpp (+97-24)
  • (modified) mlir/unittests/IR/OpPropertiesTest.cpp (+94)
diff --git a/mlir/include/mlir/IR/ExtensibleDialect.h b/mlir/include/mlir/IR/ExtensibleDialect.h
index 955faaad9408b..204b3f59db1a5 100644
--- a/mlir/include/mlir/IR/ExtensibleDialect.h
+++ b/mlir/include/mlir/IR/ExtensibleDialect.h
@@ -493,6 +493,17 @@ class DynamicOpDefinition : public OperationName::Impl {
     return failure();
   }
   Attribute getPropertiesAsAttr(Operation *op) final { return {}; }
+
+  LogicalResult
+  setPropertyFromAttr(OperationName opName, OpaqueProperties properties,
+                      StringRef name, Attribute attr,
+                      function_ref<InFlightDiagnostic()> emitError) final {
+    emitError() << "extensible Dialects don't support properties";
+    return failure();
+  }
+  FailureOr<Attribute> getPropertyAsAttr(Operation *op, StringRef name) final {
+    return {};
+  }
   void copyProperties(OpaqueProperties lhs, OpaqueProperties rhs) final {}
   bool compareProperties(OpaqueProperties, OpaqueProperties) final { return false; }
   llvm::hash_code hashProperties(OpaqueProperties prop) final { return {}; }
diff --git a/mlir/include/mlir/IR/OpDefinition.h b/mlir/include/mlir/IR/OpDefinition.h
index 883ece32967e4..2e610ec21000c 100644
--- a/mlir/include/mlir/IR/OpDefinition.h
+++ b/mlir/include/mlir/IR/OpDefinition.h
@@ -1758,6 +1758,17 @@ class Op : public OpState, public Traits<ConcreteType>... {
                         function_ref<InFlightDiagnostic()> emitError) {
     return setPropertiesFromAttribute(prop, attr, emitError);
   }
+  /// Convert the provided attribute to a property and assigned it to the
+  /// corresponding property. This default implementation forwards to a free
+  /// function `setPropertiesFromAttribute` that can be looked up with ADL in
+  /// the namespace where the properties are defined. It can also be overridden
+  /// in the derived ConcreteOp.
+  template <typename PropertiesTy>
+  static LogicalResult
+  setPropertyFromAttr(PropertiesTy &prop, StringRef name, Attribute attr,
+                      function_ref<InFlightDiagnostic()> emitError) {
+    return setPropertyFromAttribute(prop, name, attr, emitError);
+  }
   /// Convert the provided properties to an attribute. This default
   /// implementation forwards to a free function `getPropertiesAsAttribute` that
   /// can be looked up with ADL in the namespace where the properties are
@@ -1767,6 +1778,16 @@ class Op : public OpState, public Traits<ConcreteType>... {
                                        const PropertiesTy &prop) {
     return getPropertiesAsAttribute(ctx, prop);
   }
+  /// Convert the provided named property to an attribute. This default
+  /// implementation forwards to a free function `getPropertiesAsAttribute` that
+  /// can be looked up with ADL in the namespace where the properties are
+  /// defined. It can also be overridden in the derived ConcreteOp.
+  template <typename PropertiesTy>
+  static FailureOr<Attribute> getPropertyAsAttr(MLIRContext *ctx,
+                                                const PropertiesTy &prop,
+                                                StringRef name) {
+    return getPropertyAsAttribute(ctx, prop, name);
+  }
   /// Hash the provided properties. This default implementation forwards to a
   /// free function `computeHash` that can be looked up with ADL in the
   /// namespace where the properties are defined. It can also be overridden in
diff --git a/mlir/include/mlir/IR/Operation.h b/mlir/include/mlir/IR/Operation.h
index fa8a4873572ce..42ab61c055bc3 100644
--- a/mlir/include/mlir/IR/Operation.h
+++ b/mlir/include/mlir/IR/Operation.h
@@ -920,6 +920,12 @@ class alignas(8) Operation final
   /// operation. Returns an empty attribute if no properties are present.
   Attribute getPropertiesAsAttribute();
 
+  /// Return a named property converted to an attribute.
+  /// This is expensive, and mostly useful when dealing with unregistered
+  /// operations or in language bindings. Returns failure if there's no property
+  /// under such name.
+  FailureOr<Attribute> getPropertyAsAttribute(StringRef name);
+
   /// Set the properties from the provided attribute.
   /// This is an expensive operation that can fail if the attribute is not
   /// matching the expectations of the properties for this operation. This is
@@ -930,6 +936,17 @@ class alignas(8) Operation final
   setPropertiesFromAttribute(Attribute attr,
                              function_ref<InFlightDiagnostic()> emitError);
 
+  /// Set a named property from the provided attribute.
+  /// This is an expensive operation that can fail if the attribute is not
+  /// matching the expectations of the properties for this operation. This is
+  /// mostly useful for unregistered operations, used when parsing the
+  /// generic format, or in language bindings. An optional diagnostic emitter
+  /// can be passed in for richer errors, if none is passed then behavior is
+  /// undefined in error case.
+  LogicalResult
+  setPropertyFromAttribute(StringRef name, Attribute attr,
+                           function_ref<InFlightDiagnostic()> emitError);
+
   /// Copy properties from an existing other properties object. The two objects
   /// must be the same type.
   void copyProperties(OpaqueProperties rhs);
diff --git a/mlir/include/mlir/IR/OperationSupport.h b/mlir/include/mlir/IR/OperationSupport.h
index 1ff7c56ddca38..7aadcca8f1232 100644
--- a/mlir/include/mlir/IR/OperationSupport.h
+++ b/mlir/include/mlir/IR/OperationSupport.h
@@ -139,6 +139,12 @@ class OperationName {
     setPropertiesFromAttr(OperationName, OpaqueProperties, Attribute,
                           function_ref<InFlightDiagnostic()> emitError) = 0;
     virtual Attribute getPropertiesAsAttr(Operation *) = 0;
+    virtual LogicalResult
+    setPropertyFromAttr(OperationName, OpaqueProperties, StringRef name,
+                        Attribute,
+                        function_ref<InFlightDiagnostic()> emitError) = 0;
+    virtual FailureOr<Attribute> getPropertyAsAttr(Operation *,
+                                                   StringRef name) = 0;
     virtual void copyProperties(OpaqueProperties, OpaqueProperties) = 0;
     virtual bool compareProperties(OpaqueProperties, OpaqueProperties) = 0;
     virtual llvm::hash_code hashProperties(OpaqueProperties) = 0;
@@ -220,6 +226,11 @@ class OperationName {
     setPropertiesFromAttr(OperationName, OpaqueProperties, Attribute,
                           function_ref<InFlightDiagnostic()> emitError) final;
     Attribute getPropertiesAsAttr(Operation *) final;
+    LogicalResult
+    setPropertyFromAttr(OperationName, OpaqueProperties, StringRef name,
+                        Attribute,
+                        function_ref<InFlightDiagnostic()> emitError) final;
+    FailureOr<Attribute> getPropertyAsAttr(Operation *, StringRef name) final;
     void copyProperties(OpaqueProperties, OpaqueProperties) final;
     bool compareProperties(OpaqueProperties, OpaqueProperties) final;
     llvm::hash_code hashProperties(OpaqueProperties) final;
@@ -441,6 +452,20 @@ class OperationName {
                                             emitError);
   }
 
+  /// Return an op property converted to an Attribute.
+  FailureOr<Attribute> getOpPropertyAsAttribute(Operation *op,
+                                                StringRef name) const {
+    return getImpl()->getPropertyAsAttr(op, name);
+  }
+
+  /// Define an op property from the provided Attribute.
+  LogicalResult setOpPropertyFromAttribute(
+      OperationName opName, OpaqueProperties properties, StringRef name,
+      Attribute attr, function_ref<InFlightDiagnostic()> emitError) const {
+    return getImpl()->setPropertyFromAttr(opName, properties, name, attr,
+                                          emitError);
+  }
+
   void copyOpProperties(OpaqueProperties lhs, OpaqueProperties rhs) const {
     return getImpl()->copyProperties(lhs, rhs);
   }
@@ -650,6 +675,26 @@ class RegisteredOperationName : public OperationName {
       }
       return {};
     }
+    LogicalResult
+    setPropertyFromAttr(OperationName opName, OpaqueProperties properties,
+                        StringRef name, Attribute attr,
+                        function_ref<InFlightDiagnostic()> emitError) final {
+      if constexpr (hasProperties) {
+        auto p = properties.as<Properties *>();
+        return ConcreteOp::setPropertyFromAttr(*p, name, attr, emitError);
+      }
+      emitError() << "this operation does not support properties";
+      return failure();
+    }
+    FailureOr<Attribute> getPropertyAsAttr(Operation *op,
+                                           StringRef name) final {
+      if constexpr (hasProperties) {
+        auto concreteOp = cast<ConcreteOp>(op);
+        return ConcreteOp::getPropertyAsAttr(concreteOp->getContext(),
+                                             concreteOp.getProperties(), name);
+      }
+      return failure();
+    }
     bool compareProperties(OpaqueProperties lhs, OpaqueProperties rhs) final {
       if constexpr (hasProperties) {
         return *lhs.as<Properties *>() == *rhs.as<Properties *>();
diff --git a/mlir/lib/IR/MLIRContext.cpp b/mlir/lib/IR/MLIRContext.cpp
index 06ec1c85fb4d5..7b49a945c549b 100644
--- a/mlir/lib/IR/MLIRContext.cpp
+++ b/mlir/lib/IR/MLIRContext.cpp
@@ -901,6 +901,20 @@ Attribute
 OperationName::UnregisteredOpModel::getPropertiesAsAttr(Operation *op) {
   return *op->getPropertiesStorage().as<Attribute *>();
 }
+LogicalResult OperationName::UnregisteredOpModel::setPropertyFromAttr(
+    OperationName opName, OpaqueProperties properties, StringRef name,
+    Attribute attr, function_ref<InFlightDiagnostic()> emitError) {
+  assert(false &&
+         "`setPropertyFromAttr` doesn't work with unregistered operations.");
+  return failure();
+}
+FailureOr<Attribute>
+OperationName::UnregisteredOpModel::getPropertyAsAttr(Operation *op,
+                                                      StringRef name) {
+  assert(false &&
+         "`getPropertyAsAttr` doesn't work with unregistered operations.");
+  return failure();
+}
 void OperationName::UnregisteredOpModel::copyProperties(OpaqueProperties lhs,
                                                         OpaqueProperties rhs) {
   *lhs.as<Attribute *>() = *rhs.as<Attribute *>();
diff --git a/mlir/lib/IR/Operation.cpp b/mlir/lib/IR/Operation.cpp
index 8bcfa465e4a22..edd2efedf5a45 100644
--- a/mlir/lib/IR/Operation.cpp
+++ b/mlir/lib/IR/Operation.cpp
@@ -351,6 +351,12 @@ Attribute Operation::getPropertiesAsAttribute() {
     return *getPropertiesStorage().as<Attribute *>();
   return info->getOpPropertiesAsAttribute(this);
 }
+FailureOr<Attribute> Operation::getPropertyAsAttribute(StringRef name) {
+  std::optional<RegisteredOperationName> info = getRegisteredInfo();
+  assert(info &&
+         "`getPropertyAsAttribute` only works for registered operations.");
+  return info->getOpPropertyAsAttribute(this, name);
+}
 LogicalResult Operation::setPropertiesFromAttribute(
     Attribute attr, function_ref<InFlightDiagnostic()> emitError) {
   std::optional<RegisteredOperationName> info = getRegisteredInfo();
@@ -361,6 +367,15 @@ LogicalResult Operation::setPropertiesFromAttribute(
   return info->setOpPropertiesFromAttribute(
       this->getName(), this->getPropertiesStorage(), attr, emitError);
 }
+LogicalResult Operation::setPropertyFromAttribute(
+    StringRef name, Attribute attr,
+    function_ref<InFlightDiagnostic()> emitError) {
+  std::optional<RegisteredOperationName> info = getRegisteredInfo();
+  assert(info &&
+         "`setPropertyFromAttribute` only works for registered operations.");
+  return info->setOpPropertyFromAttribute(
+      this->getName(), this->getPropertiesStorage(), name, attr, emitError);
+}
 
 void Operation::copyProperties(OpaqueProperties rhs) {
   name.copyOpProperties(getPropertiesStorage(), rhs);
diff --git a/mlir/tools/mlir-tblgen/OpDefinitionsGen.cpp b/mlir/tools/mlir-tblgen/OpDefinitionsGen.cpp
index f35cfa6826388..31834554cdd43 100644
--- a/mlir/tools/mlir-tblgen/OpDefinitionsGen.cpp
+++ b/mlir/tools/mlir-tblgen/OpDefinitionsGen.cpp
@@ -1411,7 +1411,7 @@ void OpEmitter::genPropertiesSupport() {
     attrOrProperties.push_back(&emitHelper.getOperandSegmentsSize().value());
   if (emitHelper.getResultSegmentsSize())
     attrOrProperties.push_back(&emitHelper.getResultSegmentsSize().value());
-  auto &setPropMethod =
+  auto &setPropsMethod =
       opClass
           .addStaticMethod(
               "::llvm::LogicalResult", "setPropertiesFromAttr",
@@ -1421,12 +1421,31 @@ void OpEmitter::genPropertiesSupport() {
                   "::llvm::function_ref<::mlir::InFlightDiagnostic()>",
                   "emitError"))
           ->body();
-  auto &getPropMethod =
+  auto &getPropsMethod =
       opClass
           .addStaticMethod("::mlir::Attribute", "getPropertiesAsAttr",
                            MethodParameter("::mlir::MLIRContext *", "ctx"),
                            MethodParameter("const Properties &", "prop"))
           ->body();
+  auto &setPropMethod =
+      opClass
+          .addStaticMethod(
+              "::llvm::LogicalResult", "setPropertyFromAttr",
+              MethodParameter("Properties &", "prop"),
+              MethodParameter("llvm::StringRef", "name"),
+              MethodParameter("::mlir::Attribute", "attr"),
+              MethodParameter(
+                  "::llvm::function_ref<::mlir::InFlightDiagnostic()>",
+                  "emitError"))
+          ->body();
+  auto &getPropMethod =
+      opClass
+          .addStaticMethod("llvm::FailureOr<::mlir::Attribute>",
+                           "getPropertyAsAttr",
+                           MethodParameter("::mlir::MLIRContext *", "ctx"),
+                           MethodParameter("const Properties &", "prop"),
+                           MethodParameter("llvm::StringRef", "name"))
+          ->body();
   auto &hashMethod =
       opClass
           .addStaticMethod("llvm::hash_code", "computePropertiesHash",
@@ -1468,7 +1487,7 @@ void OpEmitter::genPropertiesSupport() {
 
   // Convert the property to the attribute form.
 
-  setPropMethod << R"decl(
+  setPropsMethod << R"decl(
   ::mlir::DictionaryAttr dict = ::llvm::dyn_cast<::mlir::DictionaryAttr>(attr);
   if (!dict) {
     emitError() << "expected DictionaryAttr to set properties";
@@ -1480,9 +1499,9 @@ void OpEmitter::genPropertiesSupport() {
                ::llvm::function_ref<::mlir::InFlightDiagnostic()> emitError) -> ::mlir::LogicalResult {{
         {0}
       };
-      {1};
+      {1}
 )decl";
-  const char *attrGetNoDefaultFmt = R"decl(;
+  const char *attrGetNoDefaultFmt = R"decl(
       if (attr && ::mlir::failed(setFromAttr(prop.{0}, attr, emitError)))
         return ::mlir::failure();
 )decl";
@@ -1515,22 +1534,33 @@ void OpEmitter::genPropertiesSupport() {
       }
 
       fctx.withBuilder(odsBuilder);
-      setPropMethod << "{\n"
+      setPropsMethod << "{\n"
+                     << formatv(
+                            propFromAttrFmt,
+                            tgfmt(prop.getConvertFromAttributeCall(),
+                                  &fctx.addSubst("_attr", propertyAttr)
+                                       .addSubst("_storage", propertyStorage)
+                                       .addSubst("_diag", propertyDiag)),
+                            getAttr);
+      if (prop.hasStorageTypeValueOverride()) {
+        setPropsMethod << formatv(attrGetDefaultFmt, name,
+                                  prop.getStorageTypeValueOverride());
+      } else if (prop.hasDefaultValue()) {
+        setPropsMethod << formatv(attrGetDefaultFmt, name,
+                                  tgfmt(prop.getDefaultValue(), &fctx));
+      } else {
+        setPropsMethod << formatv(attrGetNoDefaultFmt, name);
+      }
+      setPropsMethod << "  }\n";
+      setPropMethod << formatv("  if (name == \"{0}\") {{", name)
                     << formatv(propFromAttrFmt,
                                tgfmt(prop.getConvertFromAttributeCall(),
                                      &fctx.addSubst("_attr", propertyAttr)
                                           .addSubst("_storage", propertyStorage)
                                           .addSubst("_diag", propertyDiag)),
-                               getAttr);
-      if (prop.hasStorageTypeValueOverride()) {
-        setPropMethod << formatv(attrGetDefaultFmt, name,
-                                 prop.getStorageTypeValueOverride());
-      } else if (prop.hasDefaultValue()) {
-        setPropMethod << formatv(attrGetDefaultFmt, name,
-                                 tgfmt(prop.getDefaultValue(), &fctx));
-      } else {
-        setPropMethod << formatv(attrGetNoDefaultFmt, name);
-      }
+                               "");
+      setPropMethod << formatv(attrGetNoDefaultFmt, name);
+      setPropMethod << "    return ::mlir::success();\n";
       setPropMethod << "  }\n";
     } else {
       const auto *namedAttr =
@@ -1548,7 +1578,7 @@ void OpEmitter::genPropertiesSupport() {
         os << "   if (!attr) attr = dict.get(\"result_segment_sizes\");";
       }
 
-      setPropMethod << formatv(R"decl(
+      setPropsMethod << formatv(R"decl(
   {{
     auto &propStorage = prop.{0};
     {1}
@@ -1563,16 +1593,38 @@ void OpEmitter::genPropertiesSupport() {
     }
   }
 )decl",
-                               name, getAttr);
+                                name, getAttr);
+      setPropMethod << formatv(R"decl(
+  {{
+    auto &propStorage = prop.{0};
+    if (attr == nullptr) {{
+      propStorage = nullptr;
+      return ::mlir::success();
+    }
+    auto convertedAttr = ::llvm::dyn_cast<std::remove_reference_t<decltype(propStorage)>>(attr);
+    if (convertedAttr) {{
+      propStorage = convertedAttr;
+      return ::mlir::success();
+    } else {{
+      emitError() << "Invalid attribute `{0}` in property conversion: " << attr;
+      return ::mlir::failure();
     }
   }
-  setPropMethod << "  return ::mlir::success();\n";
+)decl",
+                               name);
+    }
+  }
+  setPropsMethod << "  return ::mlir::success();\n";
+  setPropMethod << "  return emitError() << \"`\" << name << \"` is not an op "
+                   "property\";\n";
 
   // Convert the attribute form to the property.
 
-  getPropMethod << "    ::mlir::SmallVector<::mlir::NamedAttribute> attrs;\n"
-                << "    ::mlir::Builder odsBuilder{ctx};\n";
-  const char *propToAttrFmt = R"decl(
+  getPropsMethod << "    ::mlir::SmallVector<::mlir::NamedAttribute> attrs;\n"
+                 << "    ::mlir::Builder odsBuilder{ctx};\n";
+  getPropMethod << "    ::mlir::Builder odsBuilder{ctx};\n"
+                << "    (void)odsBuilder;\n";
+  const char *propsToAttrFmt = R"decl(
     {
       const auto &propStorage = prop.{0};
       auto attr = [&]() -> ::mlir::Attribute {{
@@ -1580,6 +1632,15 @@ void OpEmitter::genPropertiesSupport() {
       }();
       attrs.push_back(odsBuilder.getNamedAttr("{0}", attr));
     }
+)decl";
+  const char *propToAttrFmt = R"decl(
+    if (name == "{0}") {
+      const auto &propStorage = prop.{0};
+      auto attr = [&]() -> ::mlir::Attribute {{
+        {1}
+      }();
+      return attr;
+    }
 )decl";
   for (const auto &attrOrProp : attrOrProperties) {
     if (const auto *namedProperty =
@@ -1587,6 +1648,11 @@ void OpEmitter::genPropertiesSupport() {
       StringRef name = namedProperty->name;
       auto &prop = namedProperty->prop;
       FmtContext fctx;
+      getPropsMethod << formatv(
+          propsToAttrFmt, name,
+          tgfmt(prop.getConvertToAttributeCall(),
+                &fctx.addSubst("_ctxt", "ctx")
+                     .addSubst("_storage", propertyStorage)));
       getPropMethod << formatv(
           propToAttrFmt, name,
           tgfmt(prop.getConvertToAttributeCall(),
@@ -1597,21 +1663,28 @@ void OpEmitter::genPropertiesSupport() {
     const auto *namedAttr =
         llvm::dyn_cast_if_present<const AttributeMetadata *>(attrOrProp);
     StringRef name = namedAttr->attrName;
-    getPropMethod << formatv(R"decl(
+    getPropsMethod << formatv(R"decl(
     {{
       const auto &propStorage = prop.{0};
       if (propStorage)
         attrs.push_back(odsBuilder.getNamedAttr("{0}",
                                        propStorage));
     }
+)decl",
+                              name);
+    getPropMethod << formatv(R"decl(
+    if (name == "{0}") {...
[truncated]

@fabianmcg fabianmcg force-pushed the users/fabian/pr-get-set-property branch from c912836 to dd612d6 Compare July 22, 2025 17:32
@joker-eph
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The reasoning behind adding these methods is that getPropertiesFromAttr and setPropertiesFromAttr are meant for getting and setting collections of props

It's not really that: these only exists because of the generic format printing/parsing actually, as well as default bytecode emission (if I remember correctly). They aren't meant to be used otherwise.

which is not always desirable specially in language bindings like the python bindings, and can be wasteful.

But I wouldn't want to have to go through attributes to manipulate properties, that defeats the whole point of properties!
We need instead a more direct way of setting them here and exposing them to binding code.

@fabianmcg
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fabianmcg commented Jul 23, 2025

They aren't meant to be used otherwise.

Unfortunately they are also used by the C-API to create ops, see https://github.com/llvm/llvm-project/blob/main/mlir/lib/CAPI/IR/IR.cpp#L615 and https://github.com/llvm/llvm-project/blob/main/mlir/lib/IR/Operation.cpp#L41 , which is also the main mechanism to create ops in python.

But it's true those funcs are almost never used in the codebase and are there for very specific uses.

But I wouldn't want to have to go through attributes to manipulate properties, that defeats the whole point of properties!
We need instead a more direct way of setting them here and exposing them to binding code.

I agree on the first point, any of these calls shouldn't be used in C++ code.

But properties are an inherently C++ construct, thus interacting with them outside C++ is not trivial. Therefore, something like a tablegen solution for auto generating the bindings like in the C or python case is not longer possible, as users at the very least would have to provide code to teach the bindings how to interact with non-trivial props. Further, we would likely have to generate some binding code for each Op concrete class.

While, we could accept this is an acceptable tradeoff, we need to realize it's a significant departure from the current model of the C and python bindings, where all custom ops interact opaquely with the Operation class and there are almost no Op specific functions (ie, we don't generate binding code for each MyOp : public Op<... C++ class, we interact with MlirOperation).

One way to not alter the current model, is to treat properties as attributes outside C++, which IMO is an acceptable tradeoff, because if one really wants to enjoy properties or MLIR to the fullest, then use C++, otherwise pay that price.

I'm open to suggestions, because there might be another path that I'm missing.

@joker-eph
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But properties are an inherently C++ construct,

But... Attributes are just as much C++ construct though, what's special about properties?

@fabianmcg
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But... Attributes are just as much C++ construct though

True, and to get good attribute support we currently have to add custom classes https://github.com/llvm/llvm-project/blob/main/mlir/lib/Bindings/Python/DialectGPU.cpp#L47 .

However, even in the absence of those custom bindings it's possible to create attributes in python or C by parsing a string. Something, that's not possible with properties as they there's no generic parsePropertyFromString.

what's special about properties?

To answer more explicitly, in my view props are a C++ storage detail of the IR element Operation, whereas an attribute is an IR element itself. As such, prop storage doesn't have a well defined meaning outside C++, unlike an Attr, Op or Type that do have a meaning. We could change that, but I don't see a large benefit, and see many potential challenges.

@joker-eph
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However, even in the absence of those custom bindings it's possible to create attributes in python or C by parsing a string. Something, that's not possible with properties as they there's no generic parsePropertyFromString.

So: properties don't have a mnemnonic and registration for their parsing logic, but in general they can be parsed/printed if you know the class you want to parse/print I think.
Look at the let parser and let printer in the property class in ODS.

To answer more explicitly, in my view props are a C++ storage detail of the IR element Operation, whereas an attribute is an IR element itself. As such, prop storage doesn't have a well defined meaning outside C++, unlike an Attr, Op or Type that do have a meaning.

What is the meaning of an Attribute?
That is for example what difference to you make between EnumProp and EnumAttr?

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fabianmcg commented Jul 24, 2025

So: properties don't have a mnemnonic and registration for their parsing logic, but in general they can be parsed/printed if you know the class you want to parse/print I think.
Look at the let parser and let printer in the property class in ODS.

Yes, they can be parsed in the context of an op, but there's still no method to do it outside an op.

To use a similar example, yes, we can parse attrtype parameters with a FieldParser, but there's no generic parameter parsing logic because it doesn't make sense, they are meant to be parsed inside attrs or types, not as a standalone units.

What is the meaning of an Attribute?
That is for example what difference to you make between EnumProp and EnumAttr?

Attrs are a mechanism to specify constant information, the specific semantics are defined by the attr itself [1], and they have a well defined syntax inside the IR.

Now, wrt the second question. An EnumAttr has semantics and syntax outside an operation. I'd argue that a EnumProp currently only gains meaning inside an operation [2]. Further, I'd argue that a valuable comparison is that a Prop is like a attr/type parameter for operations, so an impl detail to information of an op. We can change this, but AFAICT this is the status quo.

[1] https://mlir.llvm.org/docs/LangRef/#attributes
[2] https://mlir.llvm.org/docs/LangRef/#properties

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