[llvm-branch-commits] [llvm] [Dexter] Add !step node for testing stepping behaviour (PR #203844)

[Orlando Cazalet-Hyams via llvm-branch-commits]

================
@@ -156,3 +156,80 @@ def get_variable_metrics(
         "missing_values": ScalarMetric(num_missing_values, improves_asc=False),
     }
     return metrics
+
+
+def lcs_len(a: List[int], b: List[int]) -> int:
+    """Returns the length of the longest common subsequence between a and b."""
+    lcs_table: List[List[int]] = [
+        [0 for _ in range(len(b) + 1)] for _ in range(len(a) + 1)
+    ]
+    for a_idx in range(len(a)):
+        for b_idx in range(len(b)):
+            if a[a_idx] == b[b_idx]:
+                lcs_table[a_idx + 1][b_idx + 1] = 1 + lcs_table[a_idx][b_idx]
+            else:
+                lcs_table[a_idx + 1][b_idx + 1] = max(
+                    lcs_table[a_idx + 1][b_idx], lcs_table[a_idx][b_idx + 1]
+                )
+    return lcs_table[-1][-1]
+
+
+def get_step_metrics(
+    expect: Step, expected_lines: List[int], step_lines: List[int]
+) -> Dict[str, Metric]:
+    """Given an Expect node with its expected values and a list of all matches for that Expect in a debugger session,
+    returns the computed metrics for that Expect node."""
+
+    expected_line_set = set(expected_lines)
+    actual_line_set = set(step_lines)
+
+    total_line_steps = len(step_lines)
+    if expect.kind == "exactly" or expect.kind == "order":
+        num_matching_steps = lcs_len(expected_lines, step_lines)
+        # Inefficient, but not to the point that we care!
+        num_matching_steps_ignoring_order = lcs_len(
+            sorted(expected_lines), sorted(step_lines)
+        )
+
+        max_possible_correct_line_steps = len(expected_lines)
+        correct_line_steps = num_matching_steps
+        misordered_line_steps = num_matching_steps_ignoring_order - num_matching_steps
+        missing_lines = sum(1 for e in expected_line_set if e not in actual_line_set)
----------------
OCHyams wrote:

is `missing_lines = len(expected_line_set - actual_line_set)` clearer? I guess that's a bit wasteful constructing a throwaway set. Doesn't really matter either way so I'll leave it up to you

(there's another instance in the `else` branch)

https://github.com/llvm/llvm-project/pull/203844