[MLIR][OpenMP] Remove the ReductionClauseInterface, NFC (#130978)

This patch removes the `ReductionClauseInterface` and all definitions of
its associated `getAllReductionVars` method.

The method mandated by this interface is not used anywhere and the
conflicts its definition produces when multiple reduction clauses are
present in an operation result in a more convoluted operation
definition, so it seems better to remove it and only add something like
this if there's a clear advantage to it.

Author: skatrak

mlir/include/mlir/Dialect/OpenMP/OpenMPClauses.td

@@ -606,7 +606,7 @@ class OpenMP_InReductionClauseSkip<
   > : OpenMP_Clause<traits, arguments, assemblyFormat, description,
                     extraClassDeclaration> {
   let traits = [
-    BlockArgOpenMPOpInterface, ReductionClauseInterface
+    BlockArgOpenMPOpInterface
   ];
 
   let arguments = (ins
@@ -615,14 +615,6 @@ class OpenMP_InReductionClauseSkip<
     OptionalAttr<SymbolRefArrayAttr>:$in_reduction_syms
   );
 
-  let extraClassDeclaration = [{
-    /// Returns the reduction variables.
-    SmallVector<Value> getAllReductionVars() {
-      return SmallVector<Value>(getInReductionVars().begin(),
-                                getInReductionVars().end());
-    }
-  }];
-
   // Description varies depending on the operation. Assembly format not defined
   // because this clause must be processed together with the first region of the
   // operation, as it defines entry block arguments.
@@ -1156,7 +1148,7 @@ class OpenMP_ReductionClauseSkip<
   > : OpenMP_Clause<traits, arguments, assemblyFormat, description,
                     extraClassDeclaration> {
   let traits = [
-    BlockArgOpenMPOpInterface, ReductionClauseInterface
+    BlockArgOpenMPOpInterface
   ];
 
   let arguments = (ins
@@ -1287,7 +1279,7 @@ class OpenMP_TaskReductionClauseSkip<
   > : OpenMP_Clause<traits, arguments, assemblyFormat, description,
                     extraClassDeclaration> {
   let traits = [
-    BlockArgOpenMPOpInterface, ReductionClauseInterface
+    BlockArgOpenMPOpInterface
   ];
 
   let arguments = (ins
@@ -1296,14 +1288,6 @@ class OpenMP_TaskReductionClauseSkip<
     OptionalAttr<SymbolRefArrayAttr>:$task_reduction_syms
   );
 
-  let extraClassDeclaration = [{
-    /// Returns the reduction variables.
-    SmallVector<Value> getAllReductionVars() {
-      return SmallVector<Value>(getTaskReductionVars().begin(),
-                                getTaskReductionVars().end());
-    }
-  }];
-
   let description = [{
     The `task_reduction` clause specifies a reduction among tasks. For each list
     item, the number of copies is unspecified. Any copies associated with the

mlir/include/mlir/Dialect/OpenMP/OpenMPOps.td

@@ -751,11 +751,9 @@ def TaskloopOp : OpenMP_Op<"taskloop", traits = [
     RecursiveMemoryEffects, SingleBlock
   ], clauses = [
     OpenMP_AllocateClause, OpenMP_FinalClause, OpenMP_GrainsizeClause,
-    OpenMP_IfClause, OpenMP_InReductionClauseSkip<extraClassDeclaration = true>,
-    OpenMP_MergeableClause, OpenMP_NogroupClause, OpenMP_NumTasksClause,
-    OpenMP_PriorityClause, OpenMP_PrivateClause,
-    OpenMP_ReductionClauseSkip<extraClassDeclaration = true>,
-    OpenMP_UntiedClause
+    OpenMP_IfClause, OpenMP_InReductionClause, OpenMP_MergeableClause,
+    OpenMP_NogroupClause, OpenMP_NumTasksClause, OpenMP_PriorityClause,
+    OpenMP_PrivateClause, OpenMP_ReductionClause, OpenMP_UntiedClause
   ], singleRegion = true> {
   let summary = "taskloop construct";
   let description = [{
@@ -821,9 +819,6 @@ def TaskloopOp : OpenMP_Op<"taskloop", traits = [
   }];
 
   let extraClassDeclaration = [{
-    /// Returns the reduction variables
-    SmallVector<Value> getAllReductionVars();
-
     void getEffects(SmallVectorImpl<MemoryEffects::EffectInstance> &effects);
   }] # clausesExtraClassDeclaration;
 

mlir/include/mlir/Dialect/OpenMP/OpenMPOpsInterfaces.td

@@ -216,22 +216,6 @@ def MapClauseOwningOpInterface : OpInterface<"MapClauseOwningOpInterface"> {
   ];
 }
 
-def ReductionClauseInterface : OpInterface<"ReductionClauseInterface"> {
-  let description = [{
-    OpenMP operations that support reduction clause have this interface.
-  }];
-
-  let cppNamespace = "::mlir::omp";
-
-  let methods = [
-    InterfaceMethod<
-      "Get reduction vars", "::mlir::SmallVector<::mlir::Value>",
-      "getAllReductionVars", (ins), [{}], [{
-        return $_op.getReductionVars();
-      }]>,
-  ];
-}
-
 def LoopWrapperInterface : OpInterface<"LoopWrapperInterface"> {
   let description = [{
     OpenMP operations that wrap a single loop nest. They must only contain a

mlir/lib/Dialect/OpenMP/IR/OpenMPDialect.cpp

@@ -2726,14 +2726,6 @@ void TaskloopOp::build(OpBuilder &builder, OperationState &state,
                     makeArrayAttr(ctx, clauses.reductionSyms), clauses.untied);
 }
 
-SmallVector<Value> TaskloopOp::getAllReductionVars() {
-  SmallVector<Value> allReductionNvars(getInReductionVars().begin(),
-                                       getInReductionVars().end());
-  allReductionNvars.insert(allReductionNvars.end(), getReductionVars().begin(),
-                           getReductionVars().end());
-  return allReductionNvars;
-}
-
 LogicalResult TaskloopOp::verify() {
   if (getAllocateVars().size() != getAllocatorVars().size())
     return emitError(