add handling of out-of-range indices to Slice (#3689)

Summary:

Seeing some ops in graph like:
```aten edge dialect
new_k[-self.left_context :, :, :],
        slice_66: "f32[10, 1, 256]" = torch.ops.aten.slice.Tensor(cat_8, 0, -10, 9223372036854775807);  cat_8 = None
```
Negative indices and 9223372036854775807 are valid inputs to `start` and `end` params on slice op, but runtime checks in Slice.cpp don't accept them.
(9223372036854775807 is the max value of signed int_64; it maps to the index not being provided.)

Adding code to compute the real values to the range [0, size(dim))

Differential Revision: D57597106

Author: nathanaelsee

backends/vulkan/runtime/graph/ops/impl/Slice.cpp

@@ -57,8 +57,27 @@ void add_slice_tensor_out_node(
   int64_t start = opt_start.value_or(0);
   int64_t end = opt_end.value_or(in_sizes[dim]);
 
-  VK_CHECK_COND((0 <= start) && (start < in_sizes[dim]));
-  VK_CHECK_COND((0 <= end) && (end <= in_sizes[dim]));
+  // if start or end is < 0, calculate real index
+  start = start < 0 ? start + in_sizes[dim] : start;
+  end = end < 0 ? end + in_sizes[dim] : end;
+
+  // if end is LONG_MAX, we are slicing to the end of the dim
+  if (end == LONG_MAX) {
+    end = in_sizes[dim];
+  }
+
+  VK_CHECK_COND(
+      (0 <= start) && (start < in_sizes[dim]),
+      "start must be in range of [0, self.size(dim)), but current start's value is ",
+      start,
+      " and self.size(dim) = ",
+      in_sizes[dim]);
+  VK_CHECK_COND(
+      (0 <= end) && (end <= in_sizes[dim]),
+      "end must be in range of [0, self.size(dim)), but current end's value is ",
+      end,
+      " and self.size(dim) = ",
+      in_sizes[dim]);
 
   if (dim_index == kChannel4D) {
     // slice by channel

backends/vulkan/test/op_tests/cases.py

@@ -382,6 +382,23 @@ def get_slice_inputs():
         Test(self=[13, 1, 10], dim=0, start=1, step=20),
     ]
 
+    # Slice by negative/unspecified indices
+    LONG_MAX = 9223372036854775807  # represents arr[:]
+    test_cases += [
+        Test(self=[8, 9], dim=0, start=-2, step=1),
+        Test(self=[8, 9], dim=0, start=-2, step=2),
+        Test(self=[8, 9], dim=0, end=-2, step=1),
+        Test(self=[8, 9], dim=0, end=-2, step=2),
+        Test(self=[8, 9], dim=0, end=LONG_MAX, step=1),
+        Test(self=[8, 9], dim=0, end=LONG_MAX, step=2),
+        Test(self=[8, 9], dim=1, start=-2, step=1),
+        Test(self=[8, 9], dim=1, start=-2, step=2),
+        Test(self=[8, 9], dim=1, end=-2, step=1),
+        Test(self=[8, 9], dim=1, end=-2, step=2),
+        Test(self=[8, 9], dim=1, end=LONG_MAX, step=1),
+        Test(self=[8, 9], dim=1, end=LONG_MAX, step=2),
+    ]
+
     test_suite = VkTestSuite([tuple(tc) for tc in test_cases])
 
     test_suite.dtypes = ["at::kFloat"]