[Mlir-commits] [mlir] [MLIR] Add a utility pass to linearize `memref` (PR #136797)

[Krzysztof Drewniak]

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@@ -0,0 +1,286 @@
+//===----- FlattenMemRefs.cpp - MemRef ops flattener pass  ----------------===//
+//
+// 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 file contains patterns for flattening an multi-rank memref-related
+// ops into 1-d memref ops.
+//
+//===----------------------------------------------------------------------===//
+
+#include "mlir/Dialect/Affine/IR/AffineOps.h"
+#include "mlir/Dialect/Arith/IR/Arith.h"
+#include "mlir/Dialect/MemRef/IR/MemRef.h"
+#include "mlir/Dialect/MemRef/Transforms/Passes.h"
+#include "mlir/Dialect/MemRef/Transforms/Transforms.h"
+#include "mlir/Dialect/MemRef/Utils/MemRefUtils.h"
+#include "mlir/Dialect/Utils/IndexingUtils.h"
+#include "mlir/Dialect/Utils/StaticValueUtils.h"
+#include "mlir/Dialect/Vector/IR/VectorOps.h"
+#include "mlir/IR/AffineExpr.h"
+#include "mlir/IR/Attributes.h"
+#include "mlir/IR/Builders.h"
+#include "mlir/IR/BuiltinTypes.h"
+#include "mlir/IR/OpDefinition.h"
+#include "mlir/IR/PatternMatch.h"
+#include "mlir/Pass/Pass.h"
+#include "mlir/Transforms/GreedyPatternRewriteDriver.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/TypeSwitch.h"
+
+#include <numeric>
+
+namespace mlir {
+namespace memref {
+#define GEN_PASS_DEF_FLATTENMEMREFSPASS
+#include "mlir/Dialect/MemRef/Transforms/Passes.h.inc"
+} // namespace memref
+} // namespace mlir
+
+using namespace mlir;
+
+static Value getValueFromOpFoldResult(OpBuilder &rewriter, Location loc,
+                                      OpFoldResult in) {
+  if (Attribute offsetAttr = dyn_cast<Attribute>(in)) {
+    return rewriter.create<arith::ConstantIndexOp>(
+        loc, cast<IntegerAttr>(offsetAttr).getInt());
+  }
+  return cast<Value>(in);
+}
+
+/// Returns a collapsed memref and the linearized index to access the element
+/// at the specified indices.
+static std::pair<Value, Value> getFlattenMemrefAndOffset(OpBuilder &rewriter,
+                                                         Location loc,
+                                                         Value source,
+                                                         ValueRange indices) {
+  int64_t sourceOffset;
+  SmallVector<int64_t, 4> sourceStrides;
+  auto sourceType = cast<MemRefType>(source.getType());
+  if (failed(sourceType.getStridesAndOffset(sourceStrides, sourceOffset))) {
+    assert(false);
+  }
+
+  memref::ExtractStridedMetadataOp stridedMetadata =
+      rewriter.create<memref::ExtractStridedMetadataOp>(loc, source);
+
+  auto typeBit = sourceType.getElementType().getIntOrFloatBitWidth();
+  OpFoldResult linearizedIndices;
+  memref::LinearizedMemRefInfo linearizedInfo;
+  std::tie(linearizedInfo, linearizedIndices) =
+      memref::getLinearizedMemRefOffsetAndSize(
+          rewriter, loc, typeBit, typeBit,
+          stridedMetadata.getConstifiedMixedOffset(),
+          stridedMetadata.getConstifiedMixedSizes(),
+          stridedMetadata.getConstifiedMixedStrides(),
+          getAsOpFoldResult(indices));
+
+  return std::make_pair(
+      rewriter.create<memref::ReinterpretCastOp>(
+          loc, source,
+          /* offset = */ linearizedInfo.linearizedOffset,
+          /* shapes = */
+          ArrayRef<OpFoldResult>{linearizedInfo.linearizedSize},
+          /* strides = */
+          ArrayRef<OpFoldResult>{rewriter.getIndexAttr(1)}),
+      getValueFromOpFoldResult(rewriter, loc, linearizedIndices));
+}
+
+static bool needFlattening(Value val) {
+  auto type = cast<MemRefType>(val.getType());
+  return type.getRank() > 1;
+}
+
+static bool checkLayout(Value val) {
+  auto type = cast<MemRefType>(val.getType());
+  return type.getLayout().isIdentity() ||
+         isa<StridedLayoutAttr>(type.getLayout());
+}
+
+namespace {
+static Value getTargetMemref(Operation *op) {
+  return llvm::TypeSwitch<Operation *, Value>(op)
+      .template Case<memref::LoadOp, memref::StoreOp, memref::AllocaOp,
+                     memref::AllocOp>([](auto op) { return op.getMemref(); })
+      .template Case<vector::LoadOp, vector::StoreOp, vector::MaskedLoadOp,
+                     vector::MaskedStoreOp, vector::TransferReadOp,
+                     vector::TransferWriteOp>(
+          [](auto op) { return op.getBase(); })
+      .Default([](auto) { return Value{}; });
+}
+
+template <typename T>
+static void castAllocResult(T oper, T newOper, Location loc,
+                            PatternRewriter &rewriter) {
+  memref::ExtractStridedMetadataOp stridedMetadata =
+      rewriter.create<memref::ExtractStridedMetadataOp>(loc, oper);
+  rewriter.replaceOpWithNewOp<memref::ReinterpretCastOp>(
+      oper, cast<MemRefType>(oper.getType()), newOper,
+      /*offset=*/rewriter.getIndexAttr(0),
+      stridedMetadata.getConstifiedMixedSizes(),
+      stridedMetadata.getConstifiedMixedStrides());
+}
+
+template <typename T>
+static void replaceOp(T op, PatternRewriter &rewriter, Value flatMemref,
+                      Value offset) {
+  Location loc = op->getLoc();
+  llvm::TypeSwitch<Operation *>(op.getOperation())
+      .template Case<memref::AllocOp>([&](auto oper) {
----------------
krzysz00 wrote:

Note for the future: is there a way to extend `bufferization::AllocationOpInterface` so we don't need to hardcode alloc/alloca?

https://github.com/llvm/llvm-project/pull/136797