Fix slice size calculation (#189)

Also, reenable parfor tests on CI

Author: Hardcode84

azure-pipelines.yml

@@ -126,6 +126,7 @@ jobs:
       export OCL_ICD_FILENAMES=libintelocl.so
       export SYCL_DEVICE_FILTER=opencl:cpu
       export NUMBA_DISABLE_PERFORMANCE_WARNINGS=1
+      export DPCOMP_ENABLE_PARFOR_TESTS=1
       pytest -n1 -vv --capture=tee-sys -rXF
     displayName: 'Tests'
 

numba_dpcomp/numba_dpcomp/mlir/tests/test_numpy.py

@@ -1140,6 +1140,19 @@ def py_func(a, i, j, k):
     assert_equal(py_func(arr, 1, 2, 3), jit_func(arr, 1, 2, 3))
 
 
+@pytest.mark.parametrize("count", [0, 1, 5, 7, 8, 16, 17, 32])
+def test_slice3(count):
+    def py_func(A):
+        B = A[::3]
+        for i in range(len(B)):
+            B[i] = i
+        return B
+
+    arr = np.zeros(count)
+    jit_func = njit(py_func)
+    assert_equal(py_func(arr.copy()[::2]), jit_func(arr.copy()[::2]))
+
+
 def test_multidim_slice():
     def py_func(a, b):
         return a[1, b, :]

numba_dpcomp/numba_dpcomp/mlir_compiler/lib/pipelines/plier_to_linalg.cpp

@@ -627,6 +627,7 @@ computeIndices(mlir::OpBuilder &builder, mlir::Location loc, mlir::Value value,
   };
 
   auto zero = builder.create<mlir::arith::ConstantIndexOp>(loc, 0);
+  auto one = builder.create<mlir::arith::ConstantIndexOp>(loc, 1);
 
   auto foldConst = [&](mlir::Value val) -> mlir::OpFoldResult {
     if (auto intVal = mlir::getConstantIntValue(val))
@@ -678,6 +679,13 @@ computeIndices(mlir::OpBuilder &builder, mlir::Location loc, mlir::Value value,
       auto end = handleNegativeVal(getItemOrConst(1));
       auto stride = getItemOrConst(2);
       auto size = builder.createOrFold<mlir::arith::SubIOp>(loc, end, offset);
+
+      auto constStride = mlir::getConstantIntValue(stride);
+      if (!constStride || *constStride > 1 || *constStride < -1) {
+        size = builder.createOrFold<mlir::arith::SubIOp>(loc, size, one);
+        size = builder.createOrFold<mlir::arith::AddIOp>(loc, size, stride);
+        size = builder.createOrFold<mlir::arith::DivUIOp>(loc, size, stride);
+      }
       return {foldConst(offset), foldConst(size), stride, true};
     } else if (auto literal = valType.dyn_cast<plier::LiteralType>()) {
       auto offset = foldConst(handleNegativeVal(literal.getValue()));