6 files changed, 35 insertions, 31 deletions
diff --git a/mlir/include/mlir/IR/Operation.h b/mlir/include/mlir/IR/Operation.h
index 781dbcd..4183845 100644
--- a/mlir/include/mlir/IR/Operation.h
+++ b/mlir/include/mlir/IR/Operation.h
@@ -407,13 +407,6 @@ public:
     return false;
   }
 
-  /// Returns whether the operation has side-effects.
-  bool hasNoSideEffect() {
-    if (auto *absOp = getAbstractOperation())
-      return absOp->hasProperty(OperationProperty::NoSideEffect);
-    return false;
-  }
-
   /// Represents the status of whether an operation is a terminator. We
   /// represent an 'unknown' status because we want to support unregistered
   /// terminators.
diff --git a/mlir/include/mlir/IR/OperationSupport.h b/mlir/include/mlir/IR/OperationSupport.h
index 2d4a968..8928886 100644
--- a/mlir/include/mlir/IR/OperationSupport.h
+++ b/mlir/include/mlir/IR/OperationSupport.h
@@ -68,19 +68,15 @@ enum class OperationProperty {
   /// results.
   Commutative = 0x1,
 
-  /// This bit is set for operations that have no side effects: that means that
-  /// they do not read or write memory, or access any hidden state.
-  NoSideEffect = 0x2,
-
   /// This bit is set for an operation if it is a terminator: that means
   /// an operation at the end of a block.
-  Terminator = 0x4,
+  Terminator = 0x2,
 
   /// This bit is set for operations that are completely isolated from above.
   /// This is used for operations whose regions are explicit capture only, i.e.
   /// they are never allowed to implicitly reference values defined above the
   /// parent operation.
-  IsolatedFromAbove = 0x8,
+  IsolatedFromAbove = 0x4,
 };
 
 /// This is a "type erased" representation of a registered operation.  This
diff --git a/mlir/include/mlir/Interfaces/SideEffects.h b/mlir/include/mlir/Interfaces/SideEffects.h
index 96714da..e0fd175 100644
--- a/mlir/include/mlir/Interfaces/SideEffects.h
+++ b/mlir/include/mlir/Interfaces/SideEffects.h
@@ -163,15 +163,6 @@ private:
 //===----------------------------------------------------------------------===//
 
 namespace OpTrait {
-/// This trait indicates that an operation never has side effects.
-template <typename ConcreteType>
-class HasNoSideEffect : public TraitBase<ConcreteType, HasNoSideEffect> {
-public:
-  static AbstractOperation::OperationProperties getTraitProperties() {
-    return static_cast<AbstractOperation::OperationProperties>(
-        OperationProperty::NoSideEffect);
-  }
-};
 /// This trait indicates that the side effects of an operation includes the
 /// effects of operations nested within its regions. If the operation has no
 /// derived effects interfaces, the operation itself can be assumed to have no
@@ -221,10 +212,24 @@ struct Write : public Effect::Base<Write> {};
 
 //===----------------------------------------------------------------------===//
 // SideEffect Interfaces
+//===----------------------------------------------------------------------===//
 
 /// Include the definitions of the side effect interfaces.
 #include "mlir/Interfaces/SideEffectInterfaces.h.inc"
 
+//===----------------------------------------------------------------------===//
+// SideEffect Utilities
+//===----------------------------------------------------------------------===//
+
+/// Return true if the given operation is unused, and has no side effects on
+/// memory that prevent erasing.
+bool isOpTriviallyDead(Operation *op);
+
+/// Return true if the given operation would be dead if unused, and has no side
+/// effects on memory that would prevent erasing. This is equivalent to checking
+/// `isOpTriviallyDead` if `op` was unused.
+bool wouldOpBeTriviallyDead(Operation *op);
+
 } // end namespace mlir
 
 #endif // MLIR_INTERFACES_SIDEEFFECTS_H
diff --git a/mlir/include/mlir/Interfaces/SideEffects.td b/mlir/include/mlir/Interfaces/SideEffects.td
index ebf3da6..8bb4072 100644
--- a/mlir/include/mlir/Interfaces/SideEffects.td
+++ b/mlir/include/mlir/Interfaces/SideEffects.td
@@ -98,6 +98,13 @@ class EffectOpInterfaceBase<string name, string baseEffect>
       getEffects(effects);
       return effects.empty();
     }
+
+    /// Returns if the given operation has no effects for this interface.
+    static bool hasNoEffect(Operation *op) {
+      if (auto interface = dyn_cast<}] # name # [{>(op))
+        return interface.hasNoEffect();
+      return op->hasTrait<OpTrait::HasRecursiveSideEffects>();
+    }
   }];
 
   // The base effect name of this interface.
@@ -108,11 +115,8 @@ class EffectOpInterfaceBase<string name, string baseEffect>
 // effect interfaces to define their effects.
 class SideEffect<EffectOpInterfaceBase interface, string effectName,
                  string resourceName> : OpVariableDecorator {
-  /// The parent interface that the effect belongs to.
-  string interfaceTrait = interface.trait;
-
   /// The name of the base effects class.
-  string baseEffect = interface.baseEffectName;
+  string baseEffectName = interface.baseEffectName;
 
   /// The derived effect that is being applied.
   string effect = effectName;
@@ -128,6 +132,9 @@ class SideEffectsTraitBase<EffectOpInterfaceBase parentInterface,
   /// The name of the interface trait to use.
   let trait = parentInterface.trait;
 
+  /// The name of the base effects class.
+  string baseEffectName = parentInterface.baseEffectName;
+
   /// The derived effects being applied.
   list<SideEffect> effects = staticEffects;
 }
@@ -193,7 +200,7 @@ def MemWrite : MemWrite<"">;
 //===----------------------------------------------------------------------===//
 
 // Op has no side effect.
-def NoSideEffect : NativeOpTrait<"HasNoSideEffect">;
+def NoSideEffect : MemoryEffects<[]>;
 // Op has recursively computed side effects.
 def RecursiveSideEffects : NativeOpTrait<"HasRecursiveSideEffects">;
 
diff --git a/mlir/include/mlir/TableGen/SideEffects.h b/mlir/include/mlir/TableGen/SideEffects.h
index c93502c..eb2a068 100644
--- a/mlir/include/mlir/TableGen/SideEffects.h
+++ b/mlir/include/mlir/TableGen/SideEffects.h
@@ -27,10 +27,7 @@ public:
   StringRef getName() const;
 
   // Return the name of the base C++ effect.
-  StringRef getBaseName() const;
-
-  // Return the name of the parent interface trait.
-  StringRef getInterfaceTrait() const;
+  StringRef getBaseEffectName() const;
 
   // Return the name of the resource class.
   StringRef getResource() const;
@@ -46,6 +43,9 @@ public:
   // Return the effects that are attached to the side effect interface.
   Operator::var_decorator_range getEffects() const;
 
+  // Return the name of the base C++ effect.
+  StringRef getBaseEffectName() const;
+
   static bool classof(const OpTrait *t);
 };
 
diff --git a/mlir/include/mlir/Transforms/FoldUtils.h b/mlir/include/mlir/Transforms/FoldUtils.h
index 56a78b1..83ce3bf 100644
--- a/mlir/include/mlir/Transforms/FoldUtils.h
+++ b/mlir/include/mlir/Transforms/FoldUtils.h
@@ -106,6 +106,9 @@ public:
     return op;
   }
 
+  /// Clear out any constants cached inside of the folder.
+  void clear();
+
 private:
   /// This map keeps track of uniqued constants by dialect, attribute, and type.
   /// A constant operation materializes an attribute with a type. Dialects may