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 using namespace mlir::affine;
  21
  22 #define DEBUG_TYPE "test-affine-parametric-tile"
  23
  24 namespace {
  25 struct TestAffineLoopParametricTiling
  26     : public PassWrapper<TestAffineLoopParametricTiling,
  27                          OperationPass<func::FuncOp>> {
  28   MLIR_DEFINE_EXPLICIT_INTERNAL_INLINE_TYPE_ID(TestAffineLoopParametricTiling)
  29
  30   StringRef getArgument() const final { return "test-affine-parametric-tile"; }
  31   StringRef getDescription() const final {
  32     return "Tile affine loops using SSA values as tile sizes";
  33   }
  34   void runOnOperation() override;
  35 };
  36 } // namespace
  37
  38 /// Checks if the function enclosing the loop nest has any arguments passed to
  39 /// it, which can be used as tiling parameters. Assumes that atleast 'n'
  40 /// arguments are passed, where 'n' is the number of loops in the loop nest.
  41 static LogicalResult checkIfTilingParametersExist(ArrayRef<AffineForOp> band) {
  42   assert(!band.empty() && "no loops in input band");
  43   AffineForOp topLoop = band[0];
  44
  45   if (func::FuncOp funcOp = dyn_cast<func::FuncOp>(topLoop->getParentOp()))
  46     if (funcOp.getNumArguments() < band.size())
  47       return topLoop->emitError(
  48           "too few tile sizes provided in the argument list of the function "
  49           "which contains the current band");
  50   return success();
  51 }
  52
  53 /// Captures tiling parameters, which are expected to be passed as arguments
  54 /// to the function enclosing the loop nest. Also checks if the required
  55 /// parameters are of index type. This approach is temporary for testing
  56 /// purposes.
  57 static LogicalResult
  58 getTilingParameters(ArrayRef<AffineForOp> band,
  59                     SmallVectorImpl<Value> &tilingParameters) {
  60   AffineForOp topLoop = band[0];
  61   Region *funcOpRegion = topLoop->getParentRegion();
  62   unsigned nestDepth = band.size();
  63
  64   for (BlockArgument blockArgument :
  65        funcOpRegion->getArguments().take_front(nestDepth)) {
  66     if (blockArgument.getArgNumber() < nestDepth) {
  67       if (!blockArgument.getType().isIndex())
  68         return topLoop->emitError(
  69             "expected tiling parameters to be of index type");
  70       tilingParameters.push_back(blockArgument);
  71     }
  72   }
  73   return success();
  74 }
  75
  76 void TestAffineLoopParametricTiling::runOnOperation() {
  77   // Bands of loops to tile.
  78   std::vector<SmallVector<AffineForOp, 6>> bands;
  79   getTileableBands(getOperation(), &bands);
  80
  81   // Tile each band.
  82   for (MutableArrayRef<AffineForOp> band : bands) {
  83     // Capture the tiling parameters from the arguments to the function
  84     // enclosing this loop nest.
  85     SmallVector<AffineForOp, 6> tiledNest;
  86     SmallVector<Value, 6> tilingParameters;
  87     // Check if tiling parameters are present.
  88     if (checkIfTilingParametersExist(band).failed())
  89       return;
  90
  91     // Get function arguments as tiling parameters.
  92     if (getTilingParameters(band, tilingParameters).failed())
  93       return;
  94
  95     (void)tilePerfectlyNestedParametric(band, tilingParameters, &tiledNest);
  96   }
  97 }
  98
  99 namespace mlir {
 100 namespace test {
 101 void registerTestAffineLoopParametricTilingPass() {
 102   PassRegistration<TestAffineLoopParametricTiling>();
 103 }
 104 } // namespace test
 105 } // namespace mlir