[Dexter] Allow Dexter watch commands to specify a range of acceptable FP values

This patch adds an optional argument to DexExpectWatchBase, float_range,
which defines a +- acceptance range for expected floating point values.
If passed, this assumes every expected value to be a floating point
value, and an exception will be thrown if this is not the case.

Differential Revision: https://reviews.llvm.org/D124511

cross-project-tests/debuginfo-tests/dexter/Commands.md

@@ -144,7 +144,7 @@ type checked against the list of `types`
 ---
 ## DexExpectWatchValue
     DexExpectWatchValue(expr, *values [,**from_line=1][,**to_line=Max]
-                        [,**on_line][,**require_in_order=True])
+                        [,**on_line][,**require_in_order=True][,**float_range])
 
     Args:
         expr (str): expression to evaluate.
@@ -159,6 +159,9 @@ type checked against the list of `types`
         on_line (int): Only evaluate the expression on this line. If provided,
             this overrides from_line and to_line.
         require_in_order (bool): If False the values can appear in any order.
+        float_range (float): If provided, `values` must be floats, and will
+            match an actual value if they are within `float_range` of each other.
+
 
 ### Description
 Expect the expression `expr` to evaluate to the list of `values`

cross-project-tests/debuginfo-tests/dexter/dex/command/ParseCommand.py

@@ -15,7 +15,7 @@ from copy import copy
 from pathlib import PurePath
 from collections import defaultdict, OrderedDict
 
-from dex.utils.Exceptions import CommandParseError
+from dex.utils.Exceptions import CommandParseError, NonFloatValueInCommand
 
 from dex.command.CommandBase import CommandBase
 from dex.command.commands.DexCommandLine import DexCommandLine
@@ -310,6 +310,10 @@ def _find_all_commands_in_file(path, file_lines, valid_commands, source_root_dir
                 err_point = copy(cmd_point)
                 err_point.char += len(command_name)
                 raise format_parse_err(str(e), path, file_lines, err_point)
+            except NonFloatValueInCommand as e:
+                err_point = copy(cmd_point)
+                err_point.char += len(command_name)
+                raise format_parse_err(str(e), path, file_lines, err_point)
             else:
                 if type(command) is DexLabel:
                     add_line_label(labels, command, path, cmd_point.get_lineno())

cross-project-tests/debuginfo-tests/dexter/dex/command/commands/DexExpectWatchBase.py

@@ -18,6 +18,7 @@ from pathlib import PurePath
 
 from dex.command.CommandBase import CommandBase, StepExpectInfo
 from dex.command.StepValueInfo import StepValueInfo
+from dex.utils.Exceptions import NonFloatValueInCommand
 
 class AddressExpression(object):
     def __init__(self, name, offset=0):
@@ -56,6 +57,13 @@ class DexExpectWatchBase(CommandBase):
             self._from_line = kwargs.pop('from_line', 1)
             self._to_line = kwargs.pop('to_line', 999999)
         self._require_in_order = kwargs.pop('require_in_order', True)
+        self.float_range = kwargs.pop('float_range', None)
+        if self.float_range is not None:
+            for value in self.values:
+                try:
+                    float(value)
+                except ValueError:
+                    raise NonFloatValueInCommand(f'Non-float value \'{value}\' when float_range arg provided')
         if kwargs:
             raise TypeError('unexpected named args: {}'.format(
                 ', '.join(kwargs)))
@@ -135,6 +143,33 @@ class DexExpectWatchBase(CommandBase):
         """Return a field from watch that this ExpectWatch command is checking.
         """
 
+    def _match_expected_floating_point(self, value):
+        """Checks to see whether value is a float that falls within the
+        acceptance range of one of this command's expected float values, and
+        returns the expected value if so; otherwise returns the original
+        value."""
+        try:
+            value_as_float = float(value)
+        except ValueError:
+            return value
+
+        possible_values = self.values
+        for expected in possible_values:
+          try:
+              expected_as_float = float(expected)
+              difference = abs(value_as_float - expected_as_float)
+              if difference <= self.float_range:
+                  return expected
+          except ValueError:
+              pass
+        return value
+
+    def _maybe_fix_float(self, value):
+        if self.float_range is not None:
+            return self._match_expected_floating_point(value)
+        else:
+            return value
+
     def _handle_watch(self, step_info):
         self.times_encountered += 1
 
@@ -150,23 +185,25 @@ class DexExpectWatchBase(CommandBase):
             self.irretrievable_watches.append(step_info)
             return
 
+        expected_value = self._maybe_fix_float(step_info.expected_value)
+
         # Check to see if this value matches with a resolved address.
         matching_address = None
         for v in self.values:
             if (isinstance(v, AddressExpression) and
                     v.name in self.address_resolutions and
-                    self.resolve_value(v) == step_info.expected_value):
+                    self.resolve_value(v) == expected_value):
                 matching_address = v
                 break
 
         # If this is not an expected value, either a direct value or an address,
         # then this is an unexpected watch.
-        if step_info.expected_value not in self.values and matching_address is None:
+        if expected_value not in self.values and matching_address is None:
             self.unexpected_watches.append(step_info)
             return
 
         self.expected_watches.append(step_info)
-        value_to_remove = matching_address if matching_address is not None else step_info.expected_value
+        value_to_remove = matching_address if matching_address is not None else expected_value
         try:
             self._missing_values.remove(value_to_remove)
         except KeyError:
@@ -177,7 +214,7 @@ class DexExpectWatchBase(CommandBase):
         or not.
         """
         differences = []
-        actual_values = [w.expected_value for w in actual_watches]
+        actual_values = [self._maybe_fix_float(w.expected_value) for w in actual_watches]
         value_differences = list(difflib.Differ().compare(actual_values,
                                                           expected_values))
 
@@ -229,14 +266,16 @@ class DexExpectWatchBase(CommandBase):
             # A list of all watches where the value has changed.
             value_change_watches = []
             prev_value = None
+            all_expected_values = []
             for watch in self.expected_watches:
-                if watch.expected_value != prev_value:
+                expected_value = self._maybe_fix_float(watch.expected_value)
+                all_expected_values.append(expected_value)
+                if expected_value != prev_value:
                     value_change_watches.append(watch)
-                    prev_value = watch.expected_value
+                    prev_value = expected_value
 
             resolved_values = [self.resolve_value(v) for v in self.values]
             self.misordered_watches = self._check_watch_order(
                 value_change_watches, [
-                    v for v in resolved_values if v in
-                    [w.expected_value for w in self.expected_watches]
+                    v for v in resolved_values if v in all_expected_values
                 ])

cross-project-tests/debuginfo-tests/dexter/dex/utils/Exceptions.py

@@ -54,6 +54,14 @@ class CommandParseError(Dexception):
         self.caret = None
 
 
+class NonFloatValueInCommand(CommandParseError):
+    """If a command has the float_range arg but at least one of its expected
+    values cannot be converted to a float."""
+
+    def __init__(self, *args, **kwargs):
+        super(NonFloatValueInCommand, self).__init__(*args, **kwargs)
+        self.value = None
+
 class ToolArgumentError(Dexception):
     """If a tool argument is invalid."""
     pass

cross-project-tests/debuginfo-tests/dexter/feature_tests/commands/penalty/float_range_out_range.cpp

@@ -0,0 +1,16 @@
+// Purpose:
+//      Check that a \DexExpectWatchValue float_range that is not large enough
+//      detects unexpected watch values.
+//
+// UNSUPPORTED: system-darwin
+//
+// RUN: not %dexter_regression_test -- %s | FileCheck %s
+// CHECK: float_range_out_range.cpp:
+
+int main() {
+  float a = 1.0f;
+  a = a - 0.5f;
+  return a;  //DexLabel('check')
+}
+
+// DexExpectWatchValue('a', '1.00000', from_line=ref('check1'), to_line=ref('check2'), float_range=0.4)

cross-project-tests/debuginfo-tests/dexter/feature_tests/commands/penalty/float_range_zero_nonmatch.cpp

@@ -0,0 +1,15 @@
+// Purpose:
+//      Check that \DexExpectWatchValue float_range=0.0 matches only exact
+//      values.
+//
+// UNSUPPORTED: system-darwin
+//
+// RUN: not %dexter_regression_test -- %s | FileCheck %s
+// CHECK: float_range_zero_nonmatch.cpp:
+
+int main() {
+  float a = 1.0f;
+  return a; //DexLabel('check')
+}
+
+// DexExpectWatchValue('a', '1.0000001', on_line=ref('check'), float_range=0.0)

cross-project-tests/debuginfo-tests/dexter/feature_tests/commands/perfect/float_range_watch/float_range_multiple.cpp

@@ -0,0 +1,18 @@
+// Purpose:
+//      Check that \DexExpectWatchValue float_range=0.5 considers a range
+//      difference of 0.49999 to be an expected watch value for multple values.
+//
+// UNSUPPORTED: system-darwin
+//
+// RUN: %dexter_regression_test -- %s | FileCheck %s
+// CHECK: float_range_multiple.cpp:
+
+int main() {
+  float a = 1.0f;
+  float b = 100.f;
+  a = a + 0.4999f;
+  a = a + b; // DexLabel('check1')
+  return a;  //DexLabel('check2')
+}
+
+// DexExpectWatchValue('a', '1.0', '100.0', from_line=ref('check1'), to_line=ref('check2'), float_range=0.5)

cross-project-tests/debuginfo-tests/dexter/feature_tests/commands/perfect/float_range_watch/float_range_no_arg.cpp

@@ -0,0 +1,16 @@
+// Purpose:
+//      Check that omitted float_range from \DexExpectWatchValue turns off
+//      the floating point range evalution and defaults back to
+//      pre-float evalution.
+//
+// UNSUPPORTED: system-darwin
+//
+// RUN: %dexter_regression_test -- %s | FileCheck %s
+// CHECK: float_range_no_arg.cpp:
+
+int main() {
+  float a = 1.0f;
+  return a;  //DexLabel('check')
+}
+
+// DexExpectWatchValue('a', '1.00000', on_line=ref('check'))

cross-project-tests/debuginfo-tests/dexter/feature_tests/commands/perfect/float_range_watch/float_range_small.cpp

@@ -0,0 +1,16 @@
+// Purpose:
+//      Check that \DexExpectWatchValue float_range=0.5 considers a range
+//      difference of 0.49999 to be an expected watch value.
+//
+// UNSUPPORTED: system-darwin
+//
+// RUN: %dexter_regression_test -- %s | FileCheck %s
+// CHECK: float_range_small.cpp:
+
+int main() {
+  float a = 1.0f;
+  a = a - 0.49999f;
+  return a; //DexLabel('check')
+}
+
+// DexExpectWatchValue('a', '1.0', on_line=ref('check'), float_range=0.5)

cross-project-tests/debuginfo-tests/dexter/feature_tests/commands/perfect/float_range_watch/float_range_zero_match.cpp

@@ -0,0 +1,14 @@
+// Purpose:
+//      Check that \DexExpectWatchValue float_range=0.0 matches exact values.
+//
+// UNSUPPORTED: system-darwin
+//
+// RUN: %dexter_regression_test -- %s | FileCheck %s
+// CHECK: float_range_zero_match.cpp:
+
+int main() {
+  float a = 1.0f;
+  return a; //DexLabel('check')
+}
+
+// DexExpectWatchValue('a', '1.0000000', on_line=ref('check'), float_range=0.0)