feat(aten::slice): Patching slice for new optional params

Signed-off-by: Naren Dasan <naren@narendasan.com>
Signed-off-by: Naren Dasan <narens@nvidia.com>

Author: narendasan

core/conversion/converters/impl/select.cpp

@@ -197,19 +197,30 @@ auto select_registrations TRTORCH_UNUSED =
                return true;
              }})
         .pattern(
-            {"aten::slice.Tensor(Tensor(a) self, int dim=0, int start=0, int end=9223372036854775807, int step=1) -> Tensor(a)",
+            {"aten::slice.Tensor(Tensor(a) self, int dim=0, int? start=None, int? end=None, int step=1) -> Tensor(a)",
              [](ConversionCtx* ctx, const torch::jit::Node* n, args& args) -> bool {
                auto in = args[0].ITensor();
                auto axis = args[1].unwrapToInt();
                auto maxDim = static_cast<int64_t>(in->getDimensions().d[axis]);
+               auto startIdx = 0;
+               auto startIdxIVal = args[2].IValue();
+               if (!startIdxIVal->isNone()) {
+                 startIdx = startIdxIVal->toInt();
+               }
                // Handle case when given tensor index is negative
-               auto startIdx = args[2].unwrapToInt();
                auto start = (startIdx < 0) ? (maxDim + startIdx) : startIdx;
                // Bound the end index to input tensor dimensions at specified axis
-               auto endIdx = std::min(args[3].unwrapToInt(), maxDim);
+               auto endIdx = maxDim;
+               auto endIdxIVal = args[3].IValue();
+               if (!endIdxIVal->isNone()) {
+                 endIdx = std::min(endIdxIVal->toInt(), maxDim);
+               }
                auto end = (endIdx < 0) ? (maxDim + endIdx) : endIdx;
                auto step = args[4].unwrapToInt();
 
+               LOG_DEBUG("Start idx: " << start);
+               LOG_DEBUG("End idx: " << end);
+
                // indices to be accessed need to be an at::Tensor
                at::Tensor indices = torch::arange(start, end, step).to(torch::kI32);
                auto weights = Weights(ctx, indices);

tests/core/conversion/converters/test_select.cpp

@@ -170,15 +170,15 @@ TEST(Converters, ATenEmbeddingConvertsCorrectly) {
 TEST(Converters, ATenSliceConvertsCorrectly) {
   const auto graph = R"IR(
         graph(%x.1 : Tensor):
-              %2 : int = prim::Constant[value=9223372036854775807]()
+              %2 : None = prim::Constant()
               %3 : int = prim::Constant[value=2]()
               %4 : int = prim::Constant[value=4]()
               %5 : int = prim::Constant[value=1]()
               %6 : int = prim::Constant[value=0]()
               %7 : Tensor = aten::select(%x.1, %6, %6)
               %8 : Tensor = aten::select(%7, %6, %5)
               %9 : Tensor = aten::slice(%8, %6, %5, %4, %3)
-              %10 : Tensor = aten::slice(%9, %5, %6, %2, %5)
+              %10 : Tensor = aten::slice(%9, %5, %2, %2, %5)
               return (%10))IR";
 
   auto g = std::make_shared<torch::jit::Graph>();