[Mlir-commits] [mlir] [WIP][mlir][sparse] Setting up sparse_tensor.iterator-related Ops. (PR #85958)

[Ingo Müller]

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@@ -0,0 +1,152 @@
+//===--------- SparseSpaceCollapse.cpp - Collapse Sparse Space 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "mlir/Dialect/Func/IR/FuncOps.h"
+#include "mlir/IR/IRMapping.h"
+#include "mlir/Transforms/Passes.h"
+
+#include "mlir/Dialect/SparseTensor/IR/SparseTensor.h"
+#include "mlir/Dialect/SparseTensor/Transforms/Passes.h"
+
+namespace mlir {
+
+#define GEN_PASS_DEF_SPARSESPACECOLLAPSE
+#include "mlir/Dialect/SparseTensor/Transforms/Passes.h.inc"
+
+namespace sparse_tensor {
+
+bool isCollapsableIterations(LoopLikeOpInterface parent,
+                             LoopLikeOpInterface node) {
+  auto pIterArgs = parent.getRegionIterArgs();
+  auto nInitArgs = node.getInits();
+  if (pIterArgs.size() != nInitArgs.size())
+    return false;
+
+  auto pYields = parent.getYieldedValues();
+  auto nResult = node.getLoopResults().value();
+
+  bool yieldEq =
+      llvm::all_of(llvm::zip_equal(pYields, nResult), [](auto zipped) {
+        return std::get<0>(zipped) == std::get<1>(zipped);
+      });
+
+  // Parent iter_args should be passed directly to the node's init_args.
+  bool iterArgEq =
+      llvm::all_of(llvm::zip_equal(pIterArgs, nInitArgs), [](auto zipped) {
+        return std::get<0>(zipped) == std::get<1>(zipped);
+      });
+
+  return yieldEq && iterArgEq;
+}
+
+bool legalToCollapse(ExtractIterSpaceOp parent, ExtractIterSpaceOp node) {
+  auto pItOp = llvm::dyn_cast<IterateOp>(parent->getParentOp());
+  auto nItOp = llvm::dyn_cast<IterateOp>(node->getParentOp());
+
+  // Can only collapse spaces extracted from the same tensor.
+  if (parent.getTensor() != node.getTensor() || !parent->hasOneUse())
+    return false;
+
+  // Can only collapse consecutive simple iteration on one tensor (i.e., no
+  // coiteration).
+  if (!nItOp || nItOp.getIterSpace() != parent.getResult() ||
+      nItOp->getBlock() != parent->getBlock())
+    return false;
+
+  if (pItOp && !isCollapsableIterations(pItOp, nItOp))
+    return false;
+
+  // TODO: Make sure all other operations in the same basic block as `node` can
+  // be collapsed and sink into the collapsed iteration (through Interfaces
+  // defined in TD files).
+  return true;
+}
+
+void collapseSparseSpace(ArrayRef<ExtractIterSpaceOp> toCollapse) {
+  if (toCollapse.size() < 2)
+    return;
+
+  ExtractIterSpaceOp root = toCollapse.front();
+  ExtractIterSpaceOp leaf = toCollapse.back();
+  Location loc = root.getLoc();
+
+  if (!leaf->hasOneUse())
+    return;
+  assert(root->hasOneUse());
+
+  // Insert collapsed operation at the same scope as root operation.
+  OpBuilder builder(toCollapse.front());
+
+  // Construct the collapsed iteration space.
+  auto collapsedSpace = builder.create<ExtractIterSpaceOp>(
+      loc, root.getTensor(), root.getParentIter(), root.getLoLvl(),
+      leaf.getHiLvl());
----------------
ingomueller-net wrote:

Am I right that the collapsed space is inferred here? I.e., is this the answer to the question I have been asking several times? XD We know that the collapsed space is `compressed(nonunique),singleton` because we know which vector we iterate over and take the information from there?

https://github.com/llvm/llvm-project/pull/85958