[mlir][bufferization] Define a pipeline for buffer deallocation (#66352)

Since ownership based buffer deallocation requires a few passes to be run in a somewhat fixed sequence, it makes sense to have a pipeline for convenience (and to reduce the number of transform ops to represent default deallocation).

mlir/include/mlir/Dialect/Bufferization/Pipelines/Passes.h

@@ -0,0 +1,50 @@
+//===- Passes.h - Bufferization pipeline entry points -----------*- C++ -*-===//
+//
+// 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 header file defines prototypes of all bufferization pipelines.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef MLIR_DIALECT_BUFFERIZATION_PIPELINES_PASSES_H
+#define MLIR_DIALECT_BUFFERIZATION_PIPELINES_PASSES_H
+
+#include "mlir/Pass/PassOptions.h"
+
+namespace mlir {
+namespace bufferization {
+
+/// Options for the buffer deallocation pipeline.
+struct BufferDeallocationPipelineOptions
+    : public PassPipelineOptions<BufferDeallocationPipelineOptions> {
+  PassOptions::Option<bool> privateFunctionDynamicOwnership{
+      *this, "private-function-dynamic-ownership",
+      llvm::cl::desc(
+          "Allows to add additional arguments to private functions to "
+          "dynamically pass ownership of memrefs to callees. This can enable "
+          "earlier deallocations."),
+      llvm::cl::init(false)};
+};
+
+//===----------------------------------------------------------------------===//
+// Building and Registering.
+//===----------------------------------------------------------------------===//
+
+/// Adds the buffer deallocation pipeline to the `OpPassManager`. This
+/// is the standard pipeline for deallocating the MemRefs introduced by the
+/// One-Shot bufferization pass.
+void buildBufferDeallocationPipeline(
+    OpPassManager &pm, const BufferDeallocationPipelineOptions &options);
+
+/// Registers all pipelines for the `bufferization` dialect. Currently,
+/// this includes only the "buffer-deallocation-pipeline".
+void registerBufferizationPipelines();
+
+} // namespace bufferization
+} // namespace mlir
+
+#endif // MLIR_DIALECT_BUFFERIZATION_PIPELINES_PASSES_H

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

@@ -30,7 +30,8 @@ std::unique_ptr<Pass> createBufferDeallocationPass();
 
 /// Creates an instance of the OwnershipBasedBufferDeallocation pass to free all
 /// allocated buffers.
-std::unique_ptr<Pass> createOwnershipBasedBufferDeallocationPass();
+std::unique_ptr<Pass> createOwnershipBasedBufferDeallocationPass(
+    bool privateFuncDynamicOwnership = false);
 
 /// Creates a pass that optimizes `bufferization.dealloc` operations. For
 /// example, it reduces the number of alias checks needed at runtime using

mlir/include/mlir/InitAllPasses.h

@@ -20,6 +20,7 @@
 #include "mlir/Dialect/Arith/Transforms/Passes.h"
 #include "mlir/Dialect/ArmSME/Transforms/Passes.h"
 #include "mlir/Dialect/Async/Passes.h"
+#include "mlir/Dialect/Bufferization/Pipelines/Passes.h"
 #include "mlir/Dialect/Bufferization/Transforms/Passes.h"
 #include "mlir/Dialect/Func/Transforms/Passes.h"
 #include "mlir/Dialect/GPU/Transforms/Passes.h"
@@ -81,6 +82,7 @@ inline void registerAllPasses() {
   arm_sme::registerArmSMEPasses();
 
   // Dialect pipelines
+  bufferization::registerBufferizationPipelines();
   sparse_tensor::registerSparseTensorPipelines();
 }
 

mlir/lib/Dialect/Bufferization/CMakeLists.txt

@@ -1,3 +1,4 @@
 add_subdirectory(IR)
+add_subdirectory(Pipelines)
 add_subdirectory(TransformOps)
 add_subdirectory(Transforms)

mlir/lib/Dialect/Bufferization/Pipelines/BufferizationPipelines.cpp

@@ -0,0 +1,46 @@
+//===- BufferizationPipelines.cpp - Pipelines for bufferization -----------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "mlir/Dialect/Bufferization/Pipelines/Passes.h"
+
+#include "mlir/Dialect/Bufferization/Transforms/Passes.h"
+#include "mlir/Dialect/Func/IR/FuncOps.h"
+#include "mlir/Dialect/MemRef/Transforms/Passes.h"
+#include "mlir/Pass/PassManager.h"
+#include "mlir/Transforms/Passes.h"
+
+//===----------------------------------------------------------------------===//
+// Pipeline implementation.
+//===----------------------------------------------------------------------===//
+
+void mlir::bufferization::buildBufferDeallocationPipeline(
+    OpPassManager &pm, const BufferDeallocationPipelineOptions &options) {
+  pm.addNestedPass<func::FuncOp>(
+      memref::createExpandReallocPass(/*emitDeallocs=*/false));
+  pm.addNestedPass<func::FuncOp>(createCanonicalizerPass());
+  pm.addNestedPass<func::FuncOp>(createOwnershipBasedBufferDeallocationPass(
+      options.privateFunctionDynamicOwnership.getValue()));
+  pm.addNestedPass<func::FuncOp>(createCanonicalizerPass());
+  pm.addNestedPass<func::FuncOp>(createBufferDeallocationSimplificationPass());
+  pm.addPass(createLowerDeallocationsPass());
+  pm.addNestedPass<func::FuncOp>(createCSEPass());
+  pm.addNestedPass<func::FuncOp>(createCanonicalizerPass());
+}
+
+//===----------------------------------------------------------------------===//
+// Pipeline registration.
+//===----------------------------------------------------------------------===//
+
+void mlir::bufferization::registerBufferizationPipelines() {
+  PassPipelineRegistration<BufferDeallocationPipelineOptions>(
+      "buffer-deallocation-pipeline",
+      "The default pipeline for automatically inserting deallocation "
+      "operations after one-shot bufferization. Deallocation operations "
+      "(except `memref.realloc`) may not be present already.",
+      buildBufferDeallocationPipeline);
+}

mlir/lib/Dialect/Bufferization/Pipelines/CMakeLists.txt

@@ -0,0 +1,13 @@
+add_mlir_dialect_library(MLIRBufferizationPipelines
+  BufferizationPipelines.cpp
+
+  ADDITIONAL_HEADER_DIRS
+  ${MLIR_MAIN_INCLUDE_DIR}/mlir/Dialect/Bufferization
+
+  LINK_LIBS PUBLIC
+  MLIRBufferizationTransforms
+  MLIRMemRefTransforms
+  MLIRFuncDialect
+  MLIRPass
+  MLIRTransforms
+)

mlir/lib/Dialect/Bufferization/Transforms/OwnershipBasedBufferDeallocation.cpp

@@ -994,6 +994,11 @@ namespace {
 struct OwnershipBasedBufferDeallocationPass
     : public bufferization::impl::OwnershipBasedBufferDeallocationBase<
           OwnershipBasedBufferDeallocationPass> {
+  OwnershipBasedBufferDeallocationPass() = default;
+  OwnershipBasedBufferDeallocationPass(bool privateFuncDynamicOwnership)
+      : OwnershipBasedBufferDeallocationPass() {
+    this->privateFuncDynamicOwnership.setValue(privateFuncDynamicOwnership);
+  }
   void runOnOperation() override {
     func::FuncOp func = getOperation();
     if (func.isExternal())
@@ -1025,6 +1030,8 @@ LogicalResult bufferization::deallocateBuffersOwnershipBased(
 //===----------------------------------------------------------------------===//
 
 std::unique_ptr<Pass>
-mlir::bufferization::createOwnershipBasedBufferDeallocationPass() {
-  return std::make_unique<OwnershipBasedBufferDeallocationPass>();
+mlir::bufferization::createOwnershipBasedBufferDeallocationPass(
+    bool privateFuncDynamicOwnership) {
+  return std::make_unique<OwnershipBasedBufferDeallocationPass>(
+      privateFuncDynamicOwnership);
 }

mlir/test/Dialect/Bufferization/Transforms/OwnershipBasedBufferDeallocation/dealloc-branchop-interface.mlir

@@ -2,6 +2,8 @@
 // RUN:  -buffer-deallocation-simplification -split-input-file %s | FileCheck %s
 // RUN: mlir-opt -verify-diagnostics -ownership-based-buffer-deallocation=private-function-dynamic-ownership=true -split-input-file %s > /dev/null
 
+// RUN: mlir-opt %s -buffer-deallocation-pipeline --split-input-file > /dev/null
+
 // Test Case:
 //    bb0
 //   /   \

mlir/test/Dialect/Bufferization/Transforms/OwnershipBasedBufferDeallocation/dealloc-callop-interface.mlir

@@ -3,6 +3,9 @@
 // RUN: mlir-opt -verify-diagnostics -ownership-based-buffer-deallocation=private-function-dynamic-ownership=true \
 // RUN:   --buffer-deallocation-simplification -split-input-file %s | FileCheck %s --check-prefix=CHECK-DYNAMIC
 
+// RUN: mlir-opt %s -buffer-deallocation-pipeline --split-input-file > /dev/null
+// RUN: mlir-opt %s -buffer-deallocation-pipeline=private-function-dynamic-ownership --split-input-file > /dev/null
+
 func.func private @f(%arg0: memref<f64>) -> memref<f64> {
   return %arg0 : memref<f64>
 }

mlir/test/Dialect/Bufferization/Transforms/OwnershipBasedBufferDeallocation/dealloc-existing-deallocs.mlir

@@ -1,6 +1,8 @@
 // RUN: mlir-opt -verify-diagnostics -expand-realloc=emit-deallocs=false -ownership-based-buffer-deallocation \
 // RUN:  --buffer-deallocation-simplification -split-input-file %s | FileCheck %s
 
+// RUN: mlir-opt %s -buffer-deallocation-pipeline --split-input-file > /dev/null
+
 func.func @auto_dealloc() {
   %c10 = arith.constant 10 : index
   %c100 = arith.constant 100 : index

mlir/test/Dialect/Bufferization/Transforms/OwnershipBasedBufferDeallocation/dealloc-function-boundaries.mlir

@@ -3,6 +3,9 @@
 // RUN: mlir-opt --allow-unregistered-dialect -verify-diagnostics -ownership-based-buffer-deallocation=private-function-dynamic-ownership=true \
 // RUN:  --buffer-deallocation-simplification -split-input-file %s | FileCheck %s --check-prefix=CHECK-DYNAMIC
 
+// RUN: mlir-opt %s -buffer-deallocation-pipeline --split-input-file > /dev/null
+// RUN: mlir-opt %s -buffer-deallocation-pipeline=private-function-dynamic-ownership --split-input-file > /dev/null
+
 // Test Case: Existing AllocOp with no users.
 // BufferDeallocation expected behavior: It should insert a DeallocOp right
 // before ReturnOp.

mlir/test/Dialect/Bufferization/Transforms/OwnershipBasedBufferDeallocation/dealloc-memoryeffect-interface.mlir

@@ -2,6 +2,8 @@
 // RUN:   --buffer-deallocation-simplification -split-input-file %s | FileCheck %s
 // RUN: mlir-opt -verify-diagnostics -ownership-based-buffer-deallocation=private-function-dynamic-ownership=true -split-input-file %s > /dev/null
 
+// RUN: mlir-opt %s -buffer-deallocation-pipeline --split-input-file > /dev/null
+
 // Test Case: Dead operations in a single block.
 // BufferDeallocation expected behavior: It only inserts the two missing
 // DeallocOps after the last BufferBasedOp.

mlir/test/Dialect/Bufferization/Transforms/OwnershipBasedBufferDeallocation/dealloc-region-branchop-interface.mlir

@@ -2,6 +2,8 @@
 // RUN:  --buffer-deallocation-simplification -split-input-file %s | FileCheck %s
 // RUN: mlir-opt -allow-unregistered-dialect -verify-diagnostics -ownership-based-buffer-deallocation=private-function-dynamic-ownership=true -split-input-file %s > /dev/null
 
+// RUN: mlir-opt %s -buffer-deallocation-pipeline --split-input-file --verify-diagnostics > /dev/null
+
 // Test Case: Nested regions - This test defines a BufferBasedOp inside the
 // region of a RegionBufferBasedOp.
 // BufferDeallocation expected behavior: The AllocOp for the BufferBasedOp

mlir/test/Dialect/Bufferization/Transforms/OwnershipBasedBufferDeallocation/dealloc-subviews.mlir

@@ -2,6 +2,8 @@
 // RUN:   --buffer-deallocation-simplification -split-input-file %s | FileCheck %s
 // RUN: mlir-opt -verify-diagnostics -ownership-based-buffer-deallocation=private-function-dynamic-ownership=true -split-input-file %s > /dev/null
 
+// RUN: mlir-opt %s -buffer-deallocation-pipeline --split-input-file > /dev/null
+
 // CHECK-LABEL: func @subview
 func.func @subview(%arg0 : index, %arg1 : index, %arg2 : memref<?x?xf32>) {
   %0 = memref.alloc() : memref<64x4xf32, strided<[4, 1], offset: 0>>

utils/bazel/llvm-project-overlay/mlir/BUILD.bazel

@@ -8249,6 +8249,7 @@ cc_library(
         ":AsyncToLLVM",
         ":AsyncTransforms",
         ":BufferizationDialect",
+        ":BufferizationPipelines",
         ":BufferizationTransformOps",
         ":BufferizationTransforms",
         ":CastInterfaces",
@@ -12214,6 +12215,21 @@ cc_library(
     ],
 )
 
+cc_library(
+    name = "BufferizationPipelines",
+    srcs = glob(["lib/Dialect/Bufferization/Pipelines/*.cpp"]),
+    hdrs = ["include/mlir/Dialect/Bufferization/Pipelines/Passes.h"],
+    includes = ["include"],
+    deps = [
+        ":BufferizationToMemRef",
+        ":BufferizationTransforms",
+        ":FuncDialect",
+        ":MemRefTransforms",
+        ":Pass",
+        ":Transforms",
+    ],
+)
+
 td_library(
     name = "DLTIDialectTdFiles",
     srcs = [