mlir/test/lib/Dialect/Affine/TestAffineLoopParametricTiling.cpp

   1 //= TestAffineLoopParametricTiling.cpp -- Parametric Affine loop tiling pass =//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file implements a test pass to test parametric tiling of perfectly
  10 // nested affine for loops.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "mlir/Dialect/Affine/IR/AffineOps.h"
  15 #include "mlir/Dialect/Affine/LoopUtils.h"
  16 #include "mlir/Dialect/Affine/Passes.h"
  17 #include "mlir/Dialect/Func/IR/FuncOps.h"
  18
  19 using namespace mlir;
  20
  21 #define DEBUG_TYPE "test-affine-parametric-tile"
  22
  23 namespace {
  24 struct TestAffineLoopParametricTiling
  25     : public PassWrapper<TestAffineLoopParametricTiling,
  26                          OperationPass<func::FuncOp>> {
  27   MLIR_DEFINE_EXPLICIT_INTERNAL_INLINE_TYPE_ID(TestAffineLoopParametricTiling)
  28
  29   StringRef getArgument() const final { return "test-affine-parametric-tile"; }
  30   StringRef getDescription() const final {
  31     return "Tile affine loops using SSA values as tile sizes";
  32   }
  33   void runOnOperation() override;
  34 };
  35 } // namespace
  36
  37 /// Checks if the function enclosing the loop nest has any arguments passed to
  38 /// it, which can be used as tiling parameters. Assumes that atleast 'n'
  39 /// arguments are passed, where 'n' is the number of loops in the loop nest.
  40 static void checkIfTilingParametersExist(ArrayRef<AffineForOp> band) {
  41   assert(!band.empty() && "no loops in input band");
  42   AffineForOp topLoop = band[0];
  43
  44   if (func::FuncOp funcOp = dyn_cast<func::FuncOp>(topLoop->getParentOp()))
  45     assert(funcOp.getNumArguments() >= band.size() && "Too few tile sizes");
  46 }
  47
  48 /// Captures tiling parameters, which are expected to be passed as arguments
  49 /// to the function enclosing the loop nest. Also checks if the required
  50 /// parameters are of index type. This approach is temporary for testing
  51 /// purposes.
  52 static void getTilingParameters(ArrayRef<AffineForOp> band,
  53                                 SmallVectorImpl<Value> &tilingParameters) {
  54   AffineForOp topLoop = band[0];
  55   Region *funcOpRegion = topLoop->getParentRegion();
  56   unsigned nestDepth = band.size();
  57
  58   for (BlockArgument blockArgument :
  59        funcOpRegion->getArguments().take_front(nestDepth)) {
  60     if (blockArgument.getArgNumber() < nestDepth) {
  61       assert(blockArgument.getType().isIndex() &&
  62              "expected tiling parameters to be of index type.");
  63       tilingParameters.push_back(blockArgument);
  64     }
  65   }
  66 }
  67
  68 void TestAffineLoopParametricTiling::runOnOperation() {
  69   // Bands of loops to tile.
  70   std::vector<SmallVector<AffineForOp, 6>> bands;
  71   getTileableBands(getOperation(), &bands);
  72
  73   // Tile each band.
  74   for (MutableArrayRef<AffineForOp> band : bands) {
  75     // Capture the tiling parameters from the arguments to the function
  76     // enclosing this loop nest.
  77     SmallVector<AffineForOp, 6> tiledNest;
  78     SmallVector<Value, 6> tilingParameters;
  79     // Check if tiling parameters are present.
  80     checkIfTilingParametersExist(band);
  81
  82     // Get function arguments as tiling parameters.
  83     getTilingParameters(band, tilingParameters);
  84
  85     (void)tilePerfectlyNestedParametric(band, tilingParameters, &tiledNest);
  86   }
  87 }
  88
  89 namespace mlir {
  90 namespace test {
  91 void registerTestAffineLoopParametricTilingPass() {
  92   PassRegistration<TestAffineLoopParametricTiling>();
  93 }
  94 } // namespace test
  95 } // namespace mlir