[Dexter] Collate penalties of the same type into a single line for each

Currently in Dexter, every step at which a DexExpectWatchValue/Type does
not have the correct value is printed on a separate line. This patch
reduces the size of the text output by instead printing each incorrect
result (i.e. each incorrect value seen, 'Variable optimized out', and so
on) on its own line, alongside a list of the steps at which that result
was seen. This makes for much less spam in the output when watches are
missing or wrong for many steps.

Differential Revision: https://reviews.llvm.org/D120716

cross-project-tests/debuginfo-tests/dexter/dex/heuristic/Heuristic.py

@@ -98,6 +98,32 @@ def add_heuristic_tool_arguments(parser):
         metavar='<int>')
 
 
+class PenaltyLineRanges:
+    def __init__(self, first_step, penalty):
+        self.ranges = [(first_step, first_step)]
+        self.penalty = penalty
+
+    def add_step(self, next_step, penalty):
+        last_range = self.ranges[-1]
+        last_step = last_range[1]
+        if (next_step == last_step + 1):
+            self.ranges[-1] = (last_range[0], next_step)
+        else:
+            self.ranges.append((next_step, next_step))
+        self.penalty += penalty
+
+    def __str__(self):
+        range_to_str = lambda r: str(r[0]) if r[0] == r[1] else f'{r[0]}-{r[1]}'
+        if self.ranges[0][0] == self.ranges[-1][1]:
+            text = f'step {self.ranges[0][0]}'
+        else:
+            step_list = ', '.join([range_to_str(r) for r in self.ranges])
+            text = f'steps [{step_list}]'
+        if self.penalty:
+            text += ' <r>[-{}]</>'.format(self.penalty)
+        return text
+
+
 class Heuristic(object):
     def __init__(self, context, steps):
         self.context = context
@@ -456,11 +482,23 @@ class Heuristic(object):
             for category in sorted(pen_cmd.pen_dict):
                 lines.append('    <r>{}</>:\n'.format(category))
 
+                step_value_results = {}
+                for result, penalty in pen_cmd.pen_dict[category]:
+                    if not isinstance(result, StepValueInfo):
+                        continue
+                    if result.expected_value not in step_value_results:
+                        step_value_results[result.expected_value] = PenaltyLineRanges(result.step_index, penalty)
+                    else:
+                        step_value_results[result.expected_value].add_step(result.step_index, penalty)
+
+                for value, penalty_line_range in step_value_results.items():
+                    text = f'({value}): {penalty_line_range}'
+                    total_penalty += penalty_line_range.penalty
+                    lines.append('      {}\n'.format(text))
+
                 for result, penalty in pen_cmd.pen_dict[category]:
                     if isinstance(result, StepValueInfo):
-                        text = 'step {}'.format(result.step_index)
+                        continue
-                        if result.expected_value:
-                            text += ' ({})'.format(result.expected_value)
                     else:
                         text = str(result)
                     if penalty:

cross-project-tests/debuginfo-tests/dexter/feature_tests/subtools/test/address_printing.cpp

@@ -30,8 +30,8 @@
 // CHECK-NEXT: address 'x_2' (0x[[X2_VAL]])
 // CHECK-NEXT: address 'y' (0x[[Y_VAL]])
 // CHECK: misordered result:
-// CHECK-NEXT: step 4 (0x[[Y_VAL]])
+// CHECK-NEXT: (0x[[Y_VAL]]): step 4
-// CHECK-NEXT: step 5 (0x[[X2_VAL]])
+// CHECK-NEXT: (0x[[X2_VAL]]): step 5
 
 int main() {
     int *x = new int(5);