llvm/mlir/test/Dialect/Affine/loop-tiling-validity.mlir

// RUN: mlir-opt %s  -split-input-file -affine-loop-tile="tile-size=32" -verify-diagnostics | FileCheck %s

// -----

// There is no dependence violated in this case. No error should be raised.

// CHECK-DAG: [[$LB:#map[0-9]*]] = affine_map<(d0) -> (d0)>
// CHECK-DAG: [[$UB:#map[0-9]*]] = affine_map<(d0) -> (d0 + 32)>

// CHECK-LABEL: func @legal_loop()
func.func @legal_loop() {
  %0 = memref.alloc() : memref<64xf32>

  affine.for %i = 0 to 64 {
    %1 = affine.load %0[%i] : memref<64xf32>
    %2 = arith.addf %1, %1 : f32
    affine.store %2, %0[%i] : memref<64xf32>
  }

  return
}

// CHECK:   affine.for %{{.*}} = 0 to 64 step 32 {
// CHECK-NEXT:     affine.for %{{.*}} = [[$LB]](%{{.*}}) to [[$UB]](%{{.*}}) {

// -----

// There are dependences along the diagonal of the 2d iteration space,
// specifically, they are of direction (+, -).
// The default tiling method (hyper-rect) will violate tiling legality.
// We expect a remark that points that issue out to be emitted.

func.func @illegal_loop_with_diag_dependence() {
  %A = memref.alloc() : memref<64x64xf32>

  affine.for %i = 0 to 64 {
    // expected-remark@above {{tiling nest is invalid due to dependences}}
    affine.for %j = 0 to 64 {
      %0 = affine.load %A[%j, %i] : memref<64x64xf32>
      %1 = affine.load %A[%i, %j - 1] : memref<64x64xf32>
      %2 = arith.addf %0, %1 : f32
      affine.store %2, %A[%i, %j] : memref<64x64xf32>
    }
  }

  return
}