[MLIR] Add bufferization state class to OneShotBufferization pass (#138143)

This PR is a follow-up on #138125, and adds a bufferization state class providing information about the IR. The information currently consists of a cached list of symbol tables, which aims to solve the quadratic scaling of the bufferization task with respect to the number of symbols. The PR breaks API compatibility: the `bufferize` method of the `BufferizableOpInterface` has been enriched with a reference to a `BufferizationState` object.

The bufferization state must be kept in a valid state by the interface implementations. For example, if an operation with the `Symbol` trait is inserted or replaced, its parent `SymbolTable` must be updated accordingly (see, for example, the bufferization of `arith::ConstantOp`, where the symbol table of the module gets the new global symbol inserted). Similarly, the invalidation of a symbol table must be performed if an operation with the `SymbolTable` trait is removed (this can be performed using the `invalidateSymbolTable` method, introduced in #138014).

Author: mscuttari

mlir/include/mlir/Dialect/Bufferization/IR/BufferizableOpInterface.h

@@ -578,6 +578,20 @@ class AnalysisState {
       insideMutuallyExclusiveRegionsCache;
 };
 
+/// BufferizationState provides information about the state of the IR during the
+/// bufferization process.
+class BufferizationState {
+public:
+  /// Get a reference to the collection of cached symbol tables.
+  SymbolTableCollection &getSymbolTables();
+
+private:
+  /// The cached symbol tables.
+  /// The user is expected to update / invalidate the cached symbol tables if
+  /// the bufferized operation has the Symbol or SymbolTable traits.
+  SymbolTableCollection symbolTables;
+};
+
 /// Create an AllocTensorOp for the given shaped value (memref or tensor).
 /// If `copy` is set, the shaped value is copied. Otherwise, a tensor with
 /// undefined contents is allocated.

mlir/include/mlir/Dialect/Bufferization/IR/BufferizableOpInterface.td

@@ -426,7 +426,8 @@ def BufferizableOpInterface : OpInterface<"BufferizableOpInterface"> {
         /*retType=*/"::llvm::LogicalResult",
         /*methodName=*/"bufferize",
         /*args=*/(ins "::mlir::RewriterBase &":$rewriter,
-                      "const ::mlir::bufferization::BufferizationOptions &":$options),
+                      "const ::mlir::bufferization::BufferizationOptions &":$options,
+                      "::mlir::bufferization::BufferizationState &":$state),
         /*methodBody=*/"",
         /*defaultImplementation=*/[{
           llvm_unreachable("bufferize not implemented");

mlir/include/mlir/Dialect/Bufferization/IR/BufferizationOps.td

@@ -93,7 +93,8 @@ def Bufferization_AllocTensorOp : Bufferization_Op<"alloc_tensor",
 
   let extraClassDeclaration = [{
     LogicalResult bufferize(RewriterBase &rewriter,
-                            const BufferizationOptions &options);
+                            const BufferizationOptions &options,
+                            BufferizationState &state);
 
     bool resultBufferizesToMemoryWrite(OpResult opResult,
                                        const AnalysisState &state);
@@ -282,7 +283,8 @@ def Bufferization_MaterializeInDestinationOp
 
   let extraClassDeclaration = [{
     LogicalResult bufferize(RewriterBase &rewriter,
-                            const BufferizationOptions &options);
+                            const BufferizationOptions &options,
+                            BufferizationState &state);
 
     bool bufferizesToMemoryRead(OpOperand &opOperand,
                                 const AnalysisState &state);
@@ -375,7 +377,8 @@ def Bufferization_DeallocTensorOp : Bufferization_Op<"dealloc_tensor",
     }
 
     LogicalResult bufferize(RewriterBase &rewriter,
-                            const BufferizationOptions &options);
+                            const BufferizationOptions &options,
+                            BufferizationState &state);
   }];
 }
 
@@ -458,7 +461,8 @@ def Bufferization_ToTensorOp : Bufferization_Op<"to_tensor", [
     //===------------------------------------------------------------------===//
 
     LogicalResult bufferize(RewriterBase &rewriter,
-                            const BufferizationOptions &options) const {
+                            const BufferizationOptions &options,
+                            BufferizationState &state) const {
       // to_tensor/to_buffer pairs fold away after bufferization.
       return success();
     }
@@ -550,7 +554,8 @@ def Bufferization_ToBufferOp : Bufferization_Op<"to_buffer", [
     }
 
     LogicalResult bufferize(RewriterBase &rewriter,
-                            const BufferizationOptions &options);
+                            const BufferizationOptions &options,
+                            BufferizationState &state);
   }];
 
   let assemblyFormat = [{

mlir/include/mlir/Dialect/Bufferization/Transforms/BufferUtils.h

@@ -29,6 +29,7 @@ class GlobalOp;
 } // namespace memref
 
 namespace bufferization {
+class BufferizationState;
 
 /// A simple analysis that detects allocation operations.
 class BufferPlacementAllocs {
@@ -122,9 +123,14 @@ class BufferPlacementTransformationBase {
 // Globals are created lazily at the top of the enclosing ModuleOp with pretty
 // names. Duplicates are avoided.
 FailureOr<memref::GlobalOp> getGlobalFor(arith::ConstantOp constantOp,
+                                         SymbolTableCollection &symbolTables,
                                          uint64_t alignment,
                                          Attribute memorySpace = {});
 
+void removeSymbol(Operation *op, BufferizationState &state);
+
+void insertSymbol(Operation *op, BufferizationState &state);
+
 } // namespace bufferization
 } // namespace mlir
 

mlir/include/mlir/Dialect/Bufferization/Transforms/Bufferize.h

@@ -45,6 +45,7 @@ struct BufferizationStatistics {
 /// additional buffer copies or set "options.copyBeforeWrite = true". The
 /// general bufferization entry point is `runOneShotBufferize`.
 LogicalResult bufferizeOp(Operation *op, const BufferizationOptions &options,
+                          BufferizationState &bufferizationState,
                           BufferizationStatistics *statistics = nullptr);
 
 /// Bufferize the signature of `block` and its callers (i.e., ops that have the

mlir/include/mlir/Dialect/Bufferization/Transforms/OneShotAnalysis.h

@@ -270,6 +270,7 @@ LogicalResult analyzeOp(Operation *op, OneShotAnalysisState &state,
 /// Run One-Shot Bufferize on the given op: Analysis + Bufferization
 LogicalResult
 runOneShotBufferize(Operation *op, const OneShotBufferizationOptions &options,
+                    BufferizationState &state,
                     BufferizationStatistics *statistics = nullptr);
 
 } // namespace bufferization

mlir/include/mlir/Dialect/Bufferization/Transforms/OneShotModuleBufferize.h

@@ -20,6 +20,7 @@ namespace bufferization {
 struct BufferizationStatistics;
 class OneShotAnalysisState;
 struct OneShotBufferizationOptions;
+class BufferizationState;
 
 /// Analyze `moduleOp` and its nested ops. Bufferization decisions are stored in
 /// `state`.
@@ -38,6 +39,7 @@ analyzeModuleOp(ModuleOp moduleOp, OneShotAnalysisState &state,
 ///   will be inserted only to these FuncOps.
 llvm::LogicalResult
 bufferizeModuleOp(ModuleOp moduleOp, const OneShotBufferizationOptions &options,
+                  BufferizationState &state,
                   BufferizationStatistics *statistics = nullptr);
 
 /// Remove bufferization attributes on every FuncOp arguments in the ModuleOp.
@@ -50,7 +52,7 @@ void removeBufferizationAttributesInModule(ModuleOp moduleOp);
 llvm::LogicalResult runOneShotModuleBufferize(
     ModuleOp moduleOp,
     const bufferization::OneShotBufferizationOptions &options,
-    BufferizationStatistics *statistics = nullptr);
+    BufferizationState &state, BufferizationStatistics *statistics = nullptr);
 
 } // namespace bufferization
 } // namespace mlir

mlir/include/mlir/Dialect/Linalg/Transforms/Transforms.h

@@ -30,6 +30,7 @@ namespace mlir {
 namespace bufferization {
 class AllocTensorOp;
 class OneShotAnalysisState;
+class BufferizationState;
 } // namespace bufferization
 
 namespace linalg {

mlir/lib/Dialect/Arith/Transforms/BufferizableOpInterfaceImpl.cpp

@@ -24,7 +24,8 @@ struct ConstantOpInterface
     : public BufferizableOpInterface::ExternalModel<ConstantOpInterface,
                                                     arith::ConstantOp> {
   LogicalResult bufferize(Operation *op, RewriterBase &rewriter,
-                          const BufferizationOptions &options) const {
+                          const BufferizationOptions &options,
+                          BufferizationState &state) const {
     auto constantOp = cast<arith::ConstantOp>(op);
     auto type = dyn_cast<RankedTensorType>(constantOp.getType());
 
@@ -46,7 +47,8 @@ struct ConstantOpInterface
     // Create global memory segment and replace tensor with memref pointing to
     // that memory segment.
     FailureOr<memref::GlobalOp> globalOp =
-        getGlobalFor(constantOp, options.bufferAlignment, memorySpace);
+        getGlobalFor(constantOp, state.getSymbolTables(),
+                     options.bufferAlignment, memorySpace);
     if (failed(globalOp))
       return failure();
     memref::GlobalOp globalMemref = *globalOp;
@@ -83,7 +85,8 @@ struct IndexCastOpInterface
   }
 
   LogicalResult bufferize(Operation *op, RewriterBase &rewriter,
-                          const BufferizationOptions &options) const {
+                          const BufferizationOptions &options,
+                          BufferizationState &state) const {
     auto castOp = cast<arith::IndexCastOp>(op);
     auto resultTensorType = cast<TensorType>(castOp.getType());
 
@@ -131,7 +134,8 @@ struct SelectOpInterface
   }
 
   LogicalResult bufferize(Operation *op, RewriterBase &rewriter,
-                          const BufferizationOptions &options) const {
+                          const BufferizationOptions &options,
+                          BufferizationState &state) const {
     auto selectOp = cast<arith::SelectOp>(op);
     Location loc = selectOp.getLoc();
 

mlir/lib/Dialect/Bufferization/IR/BufferizableOpInterface.cpp

@@ -125,6 +125,10 @@ void AnalysisState::resetCache() {
   insideMutuallyExclusiveRegionsCache.clear();
 }
 
+SymbolTableCollection &BufferizationState::getSymbolTables() {
+  return symbolTables;
+}
+
 Region *bufferization::getNextEnclosingRepetitiveRegion(
     Region *region, const BufferizationOptions &options) {
   assert(isRepetitiveRegion(region, options) && "expected repetitive region");