[Mlir-commits] [mlir] [mlir][x86vector] Lower vector.contract to FMA or packed type dot-product (PR #168074)

[Adam Siemieniuk]

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@@ -0,0 +1,126 @@
+//===- VectorContractToFMA.cpp --------------------------------------------===//
+//
+// 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/Vector/IR/VectorOps.h"
+#include "mlir/Dialect/Vector/Utils/VectorUtils.h"
+#include "mlir/Dialect/X86Vector/Transforms.h"
+#include "mlir/Dialect/X86Vector/X86VectorDialect.h"
+
+#include "mlir/IR/BuiltinAttributes.h"
+#include "mlir/IR/Dominance.h"
+#include "mlir/IR/PatternMatch.h"
+
+#include "mlir/Pass/Pass.h"
+#include "mlir/Transforms/GreedyPatternRewriteDriver.h"
+
+using namespace mlir;
+using namespace mlir::vector;
+using namespace mlir::x86vector;
+
+// Implements outer product contraction as a sequence of broadcast and
+// FMA operations.
+//
+// For example - for F32 type:
+// ```
+//   vector.contract <1x1xf32>, <1x16xf32> into <1x16xf32>
+// ```
+// to
+// ```
+//   vector.broadcast %lhs to <16xf32>
+//   vector.fma vector<16xf32>
+// ```
+struct VectorContractToFMA : public OpRewritePattern<vector::ContractionOp> {
+  using OpRewritePattern<vector::ContractionOp>::OpRewritePattern;
+
+  LogicalResult matchAndRewrite(vector::ContractionOp contractOp,
+                                PatternRewriter &rewriter) const override {
+
+    if (contractOp.getKind() != vector::CombiningKind::ADD)
+      return rewriter.notifyMatchFailure(contractOp,
+                                         "Expects add combining kind");
+
+    VectorType lhsTy = contractOp.getLhsType();
+    if (!lhsTy.getElementType().isF32())
+      return rewriter.notifyMatchFailure(contractOp,
+                                         "Only F32 lowering is supported.");
+
+    ArrayRef<int64_t> lhsShape = lhsTy.getShape();
+    llvm::SmallVector<int64_t> dimsLhs;
+    llvm::copy_if(lhsShape, std::back_inserter(dimsLhs),
+                  [](int64_t dim) { return dim != 1; });
+
+    VectorType rhsTy = contractOp.getRhsType();
+    ArrayRef<int64_t> rhsShape = rhsTy.getShape();
+    llvm::SmallVector<int64_t> dimsRhs;
+    llvm::copy_if(rhsShape, std::back_inserter(dimsRhs),
+                  [](int64_t dim) { return dim != 1; });
+
+    if (dimsLhs.size() > 0 && dimsRhs.size() > 0)
+      return rewriter.notifyMatchFailure(
+          contractOp, "Excepts unit dimensions for either LHS or RHS shape.");
+
+    if (dimsLhs.size() != 1 && dimsRhs.size() != 1)
+      return rewriter.notifyMatchFailure(contractOp,
+                                         "Irregular LHS or RHS shape.");
+
+    VectorType accTy = dyn_cast<VectorType>(contractOp.getAccType());
+    if (!accTy)
+      return rewriter.notifyMatchFailure(contractOp, "Wrong accmulator type");
+
+    ArrayRef<int64_t> accShape = accTy.getShape();
+    llvm::SmallVector<int64_t> dimsAcc;
+    llvm::copy_if(accShape, std::back_inserter(dimsAcc),
+                  [](int64_t dim) { return dim != 1; });
+    if (dimsAcc.size() != 1)
+      return rewriter.notifyMatchFailure(contractOp, "Irregular ACC shape");
+
+    // Lowers vector.contract into a broadcast+FMA sequence.
+    auto loc = contractOp.getLoc();
+    auto castAcc = vector::ShapeCastOp::create(
+        rewriter, loc, VectorType::get(dimsAcc.front(), accTy.getElementType()),
+        contractOp.getAcc());
+
+    vector::FMAOp fma;
+
+    if (dimsRhs.size() > 0) {
----------------
adam-smnk wrote:

Also could use a comment to make it more obvious.

https://github.com/llvm/llvm-project/pull/168074