perf jevents: Parse metrics during conversion

Currently the 'MetricExpr' json value is passed from the json
file to the pmu-events.c. This change introduces an expression
tree that is parsed into. The parsing is done largely by using
operator overloading and python's 'eval' function. Two advantages
in doing this are:

1) Broken metrics fail at compile time rather than relying on
   `perf test` to detect. `perf test` remains relevant for checking
   event encoding and actual metric use.

2) The conversion to a string from the tree can minimize the metric's
   string size, for example, preferring 1e6 over 1000000, avoiding
   multiplication by 1 and removing unnecessary whitespace. On x86
   this reduces the string size by 2,930bytes (0.07%).

In future changes it would be possible to programmatically
generate the json expressions (a single line of text and so a
pain to write manually) for an architecture using the expression
tree. This could avoid copy-pasting metrics for all architecture
variants.

v4. Doesn't simplify "0*SLOTS" to 0, as the pattern is used to fix
    Intel metrics with topdown events.
v3. Avoids generic types on standard types like set that aren't
    supported until Python 3.9, fixing an issue with Python 3.6
    reported-by John Garry. v3 also fixes minor pylint issues and adds
    a call to Simplify on the read expression tree.
v2. Improvements to type information.

Committer notes:

Added one-line fixer from Ian, see first Link: tag below.

Signed-off-by: Ian Rogers <irogers@google.com>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc: Thomas Richter <tmricht@linux.ibm.com>
Link: https://lore.kernel.org/r/CAP-5=fWa=zNK_ecpWGoGggHCQx7z-oW0eGMQf19Maywg0QK=4g@mail.gmail.com
Link: https://lore.kernel.org/r/20221207055908.1385448-1-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Ian Rogers 2022-12-06 21:59:08 -08:00 коммит произвёл Arnaldo Carvalho de Melo
Родитель b897613510
Коммит 40769665b6
4 изменённых файлов: 669 добавлений и 4 удалений

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@ -21,7 +21,7 @@ $(OUTPUT)pmu-events/pmu-events.c: pmu-events/empty-pmu-events.c
$(call rule_mkdir)
$(Q)$(call echo-cmd,gen)cp $< $@
else
$(OUTPUT)pmu-events/pmu-events.c: $(JSON) $(JSON_TEST) $(JEVENTS_PY)
$(OUTPUT)pmu-events/pmu-events.c: $(JSON) $(JSON_TEST) $(JEVENTS_PY) pmu-events/metric.py
$(call rule_mkdir)
$(Q)$(call echo-cmd,gen)$(PYTHON) $(JEVENTS_PY) $(JEVENTS_ARCH) pmu-events/arch $@
endif

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@ -4,6 +4,7 @@
import argparse
import csv
import json
import metric
import os
import sys
from typing import (Callable, Dict, Optional, Sequence, Set, Tuple)
@ -268,9 +269,10 @@ class JsonEvent:
self.metric_name = jd.get('MetricName')
self.metric_group = jd.get('MetricGroup')
self.metric_constraint = jd.get('MetricConstraint')
self.metric_expr = jd.get('MetricExpr')
if self.metric_expr:
self.metric_expr = self.metric_expr.replace('\\', '\\\\')
self.metric_expr = None
if 'MetricExpr' in jd:
self.metric_expr = metric.ParsePerfJson(jd['MetricExpr']).Simplify()
arch_std = jd.get('ArchStdEvent')
if precise and self.desc and '(Precise Event)' not in self.desc:
extra_desc += ' (Must be precise)' if precise == '2' else (' (Precise '
@ -322,6 +324,10 @@ class JsonEvent:
s = ''
for attr in _json_event_attributes:
x = getattr(self, attr)
if x and attr == 'metric_expr':
# Convert parsed metric expressions into a string. Slashes
# must be doubled in the file.
x = x.ToPerfJson().replace('\\', '\\\\')
s += f'{x}\\000' if x else '\\000'
return s

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@ -0,0 +1,502 @@
# SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
"""Parse or generate representations of perf metrics."""
import ast
import decimal
import json
import re
from typing import Dict, List, Optional, Set, Union
class Expression:
"""Abstract base class of elements in a metric expression."""
def ToPerfJson(self) -> str:
"""Returns a perf json file encoded representation."""
raise NotImplementedError()
def ToPython(self) -> str:
"""Returns a python expr parseable representation."""
raise NotImplementedError()
def Simplify(self):
"""Returns a simplified version of self."""
raise NotImplementedError()
def Equals(self, other) -> bool:
"""Returns true when two expressions are the same."""
raise NotImplementedError()
def __str__(self) -> str:
return self.ToPerfJson()
def __or__(self, other: Union[int, float, 'Expression']) -> 'Operator':
return Operator('|', self, other)
def __ror__(self, other: Union[int, float, 'Expression']) -> 'Operator':
return Operator('|', other, self)
def __xor__(self, other: Union[int, float, 'Expression']) -> 'Operator':
return Operator('^', self, other)
def __and__(self, other: Union[int, float, 'Expression']) -> 'Operator':
return Operator('&', self, other)
def __lt__(self, other: Union[int, float, 'Expression']) -> 'Operator':
return Operator('<', self, other)
def __gt__(self, other: Union[int, float, 'Expression']) -> 'Operator':
return Operator('>', self, other)
def __add__(self, other: Union[int, float, 'Expression']) -> 'Operator':
return Operator('+', self, other)
def __radd__(self, other: Union[int, float, 'Expression']) -> 'Operator':
return Operator('+', other, self)
def __sub__(self, other: Union[int, float, 'Expression']) -> 'Operator':
return Operator('-', self, other)
def __rsub__(self, other: Union[int, float, 'Expression']) -> 'Operator':
return Operator('-', other, self)
def __mul__(self, other: Union[int, float, 'Expression']) -> 'Operator':
return Operator('*', self, other)
def __rmul__(self, other: Union[int, float, 'Expression']) -> 'Operator':
return Operator('*', other, self)
def __truediv__(self, other: Union[int, float, 'Expression']) -> 'Operator':
return Operator('/', self, other)
def __rtruediv__(self, other: Union[int, float, 'Expression']) -> 'Operator':
return Operator('/', other, self)
def __mod__(self, other: Union[int, float, 'Expression']) -> 'Operator':
return Operator('%', self, other)
def _Constify(val: Union[bool, int, float, Expression]) -> Expression:
"""Used to ensure that the nodes in the expression tree are all Expression."""
if isinstance(val, bool):
return Constant(1 if val else 0)
if isinstance(val, (int, float)):
return Constant(val)
return val
# Simple lookup for operator precedence, used to avoid unnecessary
# brackets. Precedence matches that of python and the simple expression parser.
_PRECEDENCE = {
'|': 0,
'^': 1,
'&': 2,
'<': 3,
'>': 3,
'+': 4,
'-': 4,
'*': 5,
'/': 5,
'%': 5,
}
class Operator(Expression):
"""Represents a binary operator in the parse tree."""
def __init__(self, operator: str, lhs: Union[int, float, Expression],
rhs: Union[int, float, Expression]):
self.operator = operator
self.lhs = _Constify(lhs)
self.rhs = _Constify(rhs)
def Bracket(self,
other: Expression,
other_str: str,
rhs: bool = False) -> str:
"""If necessary brackets the given other value.
If ``other`` is an operator then a bracket is necessary when
this/self operator has higher precedence. Consider: '(a + b) * c',
``other_str`` will be 'a + b'. A bracket is necessary as without
the bracket 'a + b * c' will evaluate 'b * c' first. However, '(a
* b) + c' doesn't need a bracket as 'a * b' will always be
evaluated first. For 'a / (b * c)' (ie the same precedence level
operations) then we add the bracket to best match the original
input, but not for '(a / b) * c' where the bracket is unnecessary.
Args:
other (Expression): is a lhs or rhs operator
other_str (str): ``other`` in the appropriate string form
rhs (bool): is ``other`` on the RHS
Returns:
str: possibly bracketed other_str
"""
if isinstance(other, Operator):
if _PRECEDENCE.get(self.operator, -1) > _PRECEDENCE.get(
other.operator, -1):
return f'({other_str})'
if rhs and _PRECEDENCE.get(self.operator, -1) == _PRECEDENCE.get(
other.operator, -1):
return f'({other_str})'
return other_str
def ToPerfJson(self):
return (f'{self.Bracket(self.lhs, self.lhs.ToPerfJson())} {self.operator} '
f'{self.Bracket(self.rhs, self.rhs.ToPerfJson(), True)}')
def ToPython(self):
return (f'{self.Bracket(self.lhs, self.lhs.ToPython())} {self.operator} '
f'{self.Bracket(self.rhs, self.rhs.ToPython(), True)}')
def Simplify(self) -> Expression:
lhs = self.lhs.Simplify()
rhs = self.rhs.Simplify()
if isinstance(lhs, Constant) and isinstance(rhs, Constant):
return Constant(ast.literal_eval(lhs + self.operator + rhs))
if isinstance(self.lhs, Constant):
if self.operator in ('+', '|') and lhs.value == '0':
return rhs
# Simplify multiplication by 0 except for the slot event which
# is deliberately introduced using this pattern.
if self.operator == '*' and lhs.value == '0' and (
not isinstance(rhs, Event) or 'slots' not in rhs.name.lower()):
return Constant(0)
if self.operator == '*' and lhs.value == '1':
return rhs
if isinstance(rhs, Constant):
if self.operator in ('+', '|') and rhs.value == '0':
return lhs
if self.operator == '*' and rhs.value == '0':
return Constant(0)
if self.operator == '*' and self.rhs.value == '1':
return lhs
return Operator(self.operator, lhs, rhs)
def Equals(self, other: Expression) -> bool:
if isinstance(other, Operator):
return self.operator == other.operator and self.lhs.Equals(
other.lhs) and self.rhs.Equals(other.rhs)
return False
class Select(Expression):
"""Represents a select ternary in the parse tree."""
def __init__(self, true_val: Union[int, float, Expression],
cond: Union[int, float, Expression],
false_val: Union[int, float, Expression]):
self.true_val = _Constify(true_val)
self.cond = _Constify(cond)
self.false_val = _Constify(false_val)
def ToPerfJson(self):
true_str = self.true_val.ToPerfJson()
cond_str = self.cond.ToPerfJson()
false_str = self.false_val.ToPerfJson()
return f'({true_str} if {cond_str} else {false_str})'
def ToPython(self):
return (f'Select({self.true_val.ToPython()}, {self.cond.ToPython()}, '
f'{self.false_val.ToPython()})')
def Simplify(self) -> Expression:
cond = self.cond.Simplify()
true_val = self.true_val.Simplify()
false_val = self.false_val.Simplify()
if isinstance(cond, Constant):
return false_val if cond.value == '0' else true_val
if true_val.Equals(false_val):
return true_val
return Select(true_val, cond, false_val)
def Equals(self, other: Expression) -> bool:
if isinstance(other, Select):
return self.cond.Equals(other.cond) and self.false_val.Equals(
other.false_val) and self.true_val.Equals(other.true_val)
return False
class Function(Expression):
"""A function in an expression like min, max, d_ratio."""
def __init__(self,
fn: str,
lhs: Union[int, float, Expression],
rhs: Optional[Union[int, float, Expression]] = None):
self.fn = fn
self.lhs = _Constify(lhs)
self.rhs = _Constify(rhs)
def ToPerfJson(self):
if self.rhs:
return f'{self.fn}({self.lhs.ToPerfJson()}, {self.rhs.ToPerfJson()})'
return f'{self.fn}({self.lhs.ToPerfJson()})'
def ToPython(self):
if self.rhs:
return f'{self.fn}({self.lhs.ToPython()}, {self.rhs.ToPython()})'
return f'{self.fn}({self.lhs.ToPython()})'
def Simplify(self) -> Expression:
lhs = self.lhs.Simplify()
rhs = self.rhs.Simplify() if self.rhs else None
if isinstance(lhs, Constant) and isinstance(rhs, Constant):
if self.fn == 'd_ratio':
if rhs.value == '0':
return Constant(0)
Constant(ast.literal_eval(f'{lhs} / {rhs}'))
return Constant(ast.literal_eval(f'{self.fn}({lhs}, {rhs})'))
return Function(self.fn, lhs, rhs)
def Equals(self, other: Expression) -> bool:
if isinstance(other, Function):
return self.fn == other.fn and self.lhs.Equals(
other.lhs) and self.rhs.Equals(other.rhs)
return False
def _FixEscapes(s: str) -> str:
s = re.sub(r'([^\\]),', r'\1\\,', s)
return re.sub(r'([^\\])=', r'\1\\=', s)
class Event(Expression):
"""An event in an expression."""
def __init__(self, name: str, legacy_name: str = ''):
self.name = _FixEscapes(name)
self.legacy_name = _FixEscapes(legacy_name)
def ToPerfJson(self):
result = re.sub('/', '@', self.name)
return result
def ToPython(self):
return f'Event(r"{self.name}")'
def Simplify(self) -> Expression:
return self
def Equals(self, other: Expression) -> bool:
return isinstance(other, Event) and self.name == other.name
class Constant(Expression):
"""A constant within the expression tree."""
def __init__(self, value: Union[float, str]):
ctx = decimal.Context()
ctx.prec = 20
dec = ctx.create_decimal(repr(value) if isinstance(value, float) else value)
self.value = dec.normalize().to_eng_string()
self.value = self.value.replace('+', '')
self.value = self.value.replace('E', 'e')
def ToPerfJson(self):
return self.value
def ToPython(self):
return f'Constant({self.value})'
def Simplify(self) -> Expression:
return self
def Equals(self, other: Expression) -> bool:
return isinstance(other, Constant) and self.value == other.value
class Literal(Expression):
"""A runtime literal within the expression tree."""
def __init__(self, value: str):
self.value = value
def ToPerfJson(self):
return self.value
def ToPython(self):
return f'Literal({self.value})'
def Simplify(self) -> Expression:
return self
def Equals(self, other: Expression) -> bool:
return isinstance(other, Literal) and self.value == other.value
def min(lhs: Union[int, float, Expression], rhs: Union[int, float,
Expression]) -> Function:
# pylint: disable=redefined-builtin
# pylint: disable=invalid-name
return Function('min', lhs, rhs)
def max(lhs: Union[int, float, Expression], rhs: Union[int, float,
Expression]) -> Function:
# pylint: disable=redefined-builtin
# pylint: disable=invalid-name
return Function('max', lhs, rhs)
def d_ratio(lhs: Union[int, float, Expression],
rhs: Union[int, float, Expression]) -> Function:
# pylint: disable=redefined-builtin
# pylint: disable=invalid-name
return Function('d_ratio', lhs, rhs)
def source_count(event: Event) -> Function:
# pylint: disable=redefined-builtin
# pylint: disable=invalid-name
return Function('source_count', event)
class Metric:
"""An individual metric that will specifiable on the perf command line."""
groups: Set[str]
expr: Expression
scale_unit: str
constraint: bool
def __init__(self,
name: str,
description: str,
expr: Expression,
scale_unit: str,
constraint: bool = False):
self.name = name
self.description = description
self.expr = expr.Simplify()
# Workraound valid_only_metric hiding certain metrics based on unit.
scale_unit = scale_unit.replace('/sec', ' per sec')
if scale_unit[0].isdigit():
self.scale_unit = scale_unit
else:
self.scale_unit = f'1{scale_unit}'
self.constraint = constraint
self.groups = set()
def __lt__(self, other):
"""Sort order."""
return self.name < other.name
def AddToMetricGroup(self, group):
"""Callback used when being added to a MetricGroup."""
self.groups.add(group.name)
def Flatten(self) -> Set['Metric']:
"""Return a leaf metric."""
return set([self])
def ToPerfJson(self) -> Dict[str, str]:
"""Return as dictionary for Json generation."""
result = {
'MetricName': self.name,
'MetricGroup': ';'.join(sorted(self.groups)),
'BriefDescription': self.description,
'MetricExpr': self.expr.ToPerfJson(),
'ScaleUnit': self.scale_unit
}
if self.constraint:
result['MetricConstraint'] = 'NO_NMI_WATCHDOG'
return result
class _MetricJsonEncoder(json.JSONEncoder):
"""Special handling for Metric objects."""
def default(self, o):
if isinstance(o, Metric):
return o.ToPerfJson()
return json.JSONEncoder.default(self, o)
class MetricGroup:
"""A group of metrics.
Metric groups may be specificd on the perf command line, but within
the json they aren't encoded. Metrics may be in multiple groups
which can facilitate arrangements similar to trees.
"""
def __init__(self, name: str, metric_list: List[Union[Metric,
'MetricGroup']]):
self.name = name
self.metric_list = metric_list
for metric in metric_list:
metric.AddToMetricGroup(self)
def AddToMetricGroup(self, group):
"""Callback used when a MetricGroup is added into another."""
for metric in self.metric_list:
metric.AddToMetricGroup(group)
def Flatten(self) -> Set[Metric]:
"""Returns a set of all leaf metrics."""
result = set()
for x in self.metric_list:
result = result.union(x.Flatten())
return result
def ToPerfJson(self) -> str:
return json.dumps(sorted(self.Flatten()), indent=2, cls=_MetricJsonEncoder)
def __str__(self) -> str:
return self.ToPerfJson()
class _RewriteIfExpToSelect(ast.NodeTransformer):
def visit_IfExp(self, node):
# pylint: disable=invalid-name
self.generic_visit(node)
call = ast.Call(
func=ast.Name(id='Select', ctx=ast.Load()),
args=[node.body, node.test, node.orelse],
keywords=[])
ast.copy_location(call, node.test)
return call
def ParsePerfJson(orig: str) -> Expression:
"""A simple json metric expression decoder.
Converts a json encoded metric expression by way of python's ast and
eval routine. First tokens are mapped to Event calls, then
accidentally converted keywords or literals are mapped to their
appropriate calls. Python's ast is used to match if-else that can't
be handled via operator overloading. Finally the ast is evaluated.
Args:
orig (str): String to parse.
Returns:
Expression: The parsed string.
"""
# pylint: disable=eval-used
py = orig.strip()
py = re.sub(r'([a-zA-Z][^-+/\* \\\(\),]*(?:\\.[^-+/\* \\\(\),]*)*)',
r'Event(r"\1")', py)
py = re.sub(r'#Event\(r"([^"]*)"\)', r'Literal("#\1")', py)
py = re.sub(r'([0-9]+)Event\(r"(e[0-9]+)"\)', r'\1\2', py)
keywords = ['if', 'else', 'min', 'max', 'd_ratio', 'source_count']
for kw in keywords:
py = re.sub(rf'Event\(r"{kw}"\)', kw, py)
parsed = ast.parse(py, mode='eval')
_RewriteIfExpToSelect().visit(parsed)
parsed = ast.fix_missing_locations(parsed)
return _Constify(eval(compile(parsed, orig, 'eval')))

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@ -0,0 +1,157 @@
# SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
import unittest
from metric import Constant
from metric import Event
from metric import ParsePerfJson
class TestMetricExpressions(unittest.TestCase):
def test_Operators(self):
a = Event('a')
b = Event('b')
self.assertEqual((a | b).ToPerfJson(), 'a | b')
self.assertEqual((a ^ b).ToPerfJson(), 'a ^ b')
self.assertEqual((a & b).ToPerfJson(), 'a & b')
self.assertEqual((a < b).ToPerfJson(), 'a < b')
self.assertEqual((a > b).ToPerfJson(), 'a > b')
self.assertEqual((a + b).ToPerfJson(), 'a + b')
self.assertEqual((a - b).ToPerfJson(), 'a - b')
self.assertEqual((a * b).ToPerfJson(), 'a * b')
self.assertEqual((a / b).ToPerfJson(), 'a / b')
self.assertEqual((a % b).ToPerfJson(), 'a % b')
one = Constant(1)
self.assertEqual((a + one).ToPerfJson(), 'a + 1')
def test_Brackets(self):
a = Event('a')
b = Event('b')
c = Event('c')
self.assertEqual((a * b + c).ToPerfJson(), 'a * b + c')
self.assertEqual((a + b * c).ToPerfJson(), 'a + b * c')
self.assertEqual(((a + a) + a).ToPerfJson(), 'a + a + a')
self.assertEqual(((a + b) * c).ToPerfJson(), '(a + b) * c')
self.assertEqual((a + (b * c)).ToPerfJson(), 'a + b * c')
self.assertEqual(((a / b) * c).ToPerfJson(), 'a / b * c')
self.assertEqual((a / (b * c)).ToPerfJson(), 'a / (b * c)')
def test_ParsePerfJson(self):
# Based on an example of a real metric.
before = '(a + b + c + d) / (2 * e)'
after = before
self.assertEqual(ParsePerfJson(before).ToPerfJson(), after)
# Parsing should handle events with '-' in their name. Note, in
# the json file the '\' are doubled to '\\'.
before = r'topdown\-fe\-bound / topdown\-slots - 1'
after = before
self.assertEqual(ParsePerfJson(before).ToPerfJson(), after)
# Parsing should handle escaped modifiers. Note, in the json file
# the '\' are doubled to '\\'.
before = r'arb@event\=0x81\,umask\=0x1@ + arb@event\=0x84\,umask\=0x1@'
after = before
self.assertEqual(ParsePerfJson(before).ToPerfJson(), after)
# Parsing should handle exponents in numbers.
before = r'a + 1e12 + b'
after = before
self.assertEqual(ParsePerfJson(before).ToPerfJson(), after)
def test_IfElseTests(self):
# if-else needs rewriting to Select and back.
before = r'Event1 if #smt_on else Event2'
after = f'({before})'
self.assertEqual(ParsePerfJson(before).ToPerfJson(), after)
before = r'Event1 if 0 else Event2'
after = f'({before})'
self.assertEqual(ParsePerfJson(before).ToPerfJson(), after)
before = r'Event1 if 1 else Event2'
after = f'({before})'
self.assertEqual(ParsePerfJson(before).ToPerfJson(), after)
# Ensure the select is evaluate last.
before = r'Event1 + 1 if Event2 < 2 else Event3 + 3'
after = (r'Select(Event(r"Event1") + Constant(1), Event(r"Event2") < '
r'Constant(2), Event(r"Event3") + Constant(3))')
self.assertEqual(ParsePerfJson(before).ToPython(), after)
before = r'Event1 > 1 if Event2 < 2 else Event3 > 3'
after = (r'Select(Event(r"Event1") > Constant(1), Event(r"Event2") < '
r'Constant(2), Event(r"Event3") > Constant(3))')
self.assertEqual(ParsePerfJson(before).ToPython(), after)
before = r'min(a + b if c > 1 else c + d, e + f)'
after = r'min((a + b if c > 1 else c + d), e + f)'
self.assertEqual(ParsePerfJson(before).ToPerfJson(), after)
before =3D r'a if b else c if d else e'
after =3D r'(a if b else (c if d else e))'
self.assertEqual(ParsePerfJson(before).ToPerfJson(), after)
def test_ToPython(self):
# pylint: disable=eval-used
# Based on an example of a real metric.
before = '(a + b + c + d) / (2 * e)'
py = ParsePerfJson(before).ToPython()
after = eval(py).ToPerfJson()
self.assertEqual(before, after)
def test_Simplify(self):
before = '1 + 2 + 3'
after = '6'
self.assertEqual(ParsePerfJson(before).Simplify().ToPerfJson(), after)
before = 'a + 0'
after = 'a'
self.assertEqual(ParsePerfJson(before).Simplify().ToPerfJson(), after)
before = '0 + a'
after = 'a'
self.assertEqual(ParsePerfJson(before).Simplify().ToPerfJson(), after)
before = 'a | 0'
after = 'a'
self.assertEqual(ParsePerfJson(before).Simplify().ToPerfJson(), after)
before = '0 | a'
after = 'a'
self.assertEqual(ParsePerfJson(before).Simplify().ToPerfJson(), after)
before = 'a * 0'
after = '0'
self.assertEqual(ParsePerfJson(before).Simplify().ToPerfJson(), after)
before = '0 * a'
after = '0'
self.assertEqual(ParsePerfJson(before).Simplify().ToPerfJson(), after)
before = 'a * 1'
after = 'a'
self.assertEqual(ParsePerfJson(before).Simplify().ToPerfJson(), after)
before = '1 * a'
after = 'a'
self.assertEqual(ParsePerfJson(before).Simplify().ToPerfJson(), after)
before = 'a if 0 else b'
after = 'b'
self.assertEqual(ParsePerfJson(before).Simplify().ToPerfJson(), after)
before = 'a if 1 else b'
after = 'a'
self.assertEqual(ParsePerfJson(before).Simplify().ToPerfJson(), after)
before = 'a if b else a'
after = 'a'
self.assertEqual(ParsePerfJson(before).Simplify().ToPerfJson(), after)
# Pattern used to add a slots event to metrics that require it.
before = '0 * SLOTS'
after = '0 * SLOTS'
self.assertEqual(ParsePerfJson(before).Simplify().ToPerfJson(), after)
if __name__ == '__main__':
unittest.main()