[Mlir-commits] [mlir] [MLIR][XeGPU] Add unroll patterns for XeGPU (1/N) (PR #137010)

[Charitha Saumya]

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@@ -0,0 +1,480 @@
+//===- XeGPUUnroll.cpp - patterns to do unrolling ---------------*- 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "mlir/Dialect/XeGPU/Transforms/Passes.h"
+
+#include "mlir/Dialect/Utils/IndexingUtils.h"
+#include "mlir/Dialect/XeGPU/IR/XeGPU.h"
+#include "mlir/Dialect/XeGPU/Transforms/Transforms.h"
+#include "mlir/Transforms/GreedyPatternRewriteDriver.h"
+#include "llvm/Support/Debug.h"
+#include <numeric>
+
+namespace mlir {
+namespace xegpu {
+#define GEN_PASS_DEF_XEGPUUNROLL
+#include "mlir/Dialect/XeGPU/Transforms/Passes.h.inc"
+} // namespace xegpu
+} // namespace mlir
+
+#define DEBUG_TYPE "xegpu-unroll"
+#define DBGS() (llvm::dbgs() << "[" DEBUG_TYPE "]: ")
+#define LDBG(X) LLVM_DEBUG(DBGS() << X << "\n")
+
+using namespace mlir;
+
+namespace {
+
+template <typename SourceOp>
+struct UnrollPattern : public OpRewritePattern<SourceOp> {
+  UnrollPattern(MLIRContext *context, const xegpu::UnrollOptions &options,
+                PatternBenefit benefit = 1)
+      : OpRewritePattern<SourceOp>(context, benefit), options(options) {}
+
+protected:
+  std::optional<SmallVector<int64_t>> getTargetShape(Operation *op) const {
+    LDBG("");
+    LDBG("Get unroll shape for: " << *op);
+    assert(options.nativeShape &&
+           "expects the native shape for native shape call back function.");
+    auto nativeShape = options.nativeShape(op);
+    return nativeShape;
+  }
+
+  std::optional<SmallVector<int64_t>>
+  computeGrids(llvm::ArrayRef<int64_t> shape,
+               llvm::ArrayRef<int64_t> subShape) const {
+    // if the shape == subshape, we don't need to unroll.
+    if (shape == subShape) {
+      LDBG("shape == subshape, no unroll");
+      return std::nullopt;
+    }
+    return computeShapeRatio(shape, subShape);
+  }
+
+  // copy the layout attribte and drops the inst_data field.
+  xegpu::LayoutAttr getLaneLayoutAttr(Attribute attr) const {
+    auto layout = dyn_cast_if_present<xegpu::LayoutAttr>(attr);
+    if (!layout || layout.getLaneLayout() == nullptr)
+      return xegpu::LayoutAttr();
+    return layout.dropInstData();
+  };
+
+  SmallVector<Type> convertType(ShapedType type,
+                                ArrayRef<int64_t> blockSize) const {
+    auto elemTy = type.getElementType();
+    Type newTy;
+    // TensorDescType needs to drop the inst_data field in the layout attribute
+    if (auto tdescTy = dyn_cast<xegpu::TensorDescType>(type)) {
+      auto ctx = tdescTy.getContext();
+      auto encoding = tdescTy.getEncoding();
+      auto layout = tdescTy.getLayout();
+      newTy = xegpu::TensorDescType::get(ctx, blockSize, elemTy, encoding,
+                                         getLaneLayoutAttr(layout));
+    } else {
+      newTy = type.clone(blockSize, elemTy);
+    }
+
+    auto ratio = computeShapeRatio(type.getShape(), blockSize);
+    assert(ratio && "Expecting the ratio to be valid.");
+    return llvm::SmallVector<Type>(computeProduct(*ratio), newTy);
+  }
+
+  // emulate the the unpack behavior using insert_strided_slice for VectorType
+  // values and unrealized_conversion_cast for TileType values.
+  Value unpack(ValueRange srcs, Type destTy, llvm::ArrayRef<int64_t> blockSize,
+               Location loc, PatternRewriter &rewriter) const {
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charithaintc wrote:

can you clarify why this is called `unpack`? seems like it is packing the sources into a larger vector.

https://github.com/llvm/llvm-project/pull/137010