linux-kernel - [PATCH v1 32/51] perf jevents: Add rand support to metrics

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Message-Id: <20230219092848.639226-33-irogers@google.com>
Date:   Sun, 19 Feb 2023 01:28:29 -0800
From:   Ian Rogers <irogers@...gle.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Zhengjun Xing <zhengjun.xing@...ux.intel.com>,
        Sandipan Das <sandipan.das@....com>,
        James Clark <james.clark@....com>,
        Kajol Jain <kjain@...ux.ibm.com>,
        John Garry <john.g.garry@...cle.com>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Andrii Nakryiko <andrii@...nel.org>,
        Eduard Zingerman <eddyz87@...il.com>,
        Suzuki Poulouse <suzuki.poulose@....com>,
        Leo Yan <leo.yan@...aro.org>,
        Florian Fischer <florian.fischer@...q.space>,
        Ravi Bangoria <ravi.bangoria@....com>,
        Jing Zhang <renyu.zj@...ux.alibaba.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Athira Rajeev <atrajeev@...ux.vnet.ibm.com>,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org,
        Perry Taylor <perry.taylor@...el.com>,
        Caleb Biggers <caleb.biggers@...el.com>
Cc:     Stephane Eranian <eranian@...gle.com>,
        Ian Rogers <irogers@...gle.com>
Subject: [PATCH v1 32/51] perf jevents: Add rand support to metrics

rand (reverse and) is useful in the parsing of metric
thresholds. Update the documentation on operator precedence to clarify
the simple expression parser and python differences wrt binary/logical
operators.

Signed-off-by: Ian Rogers <irogers@...gle.com>
---
 tools/perf/pmu-events/metric.py | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/tools/perf/pmu-events/metric.py b/tools/perf/pmu-events/metric.py
index 77ea6ff98538..8ec0ba884673 100644
--- a/tools/perf/pmu-events/metric.py
+++ b/tools/perf/pmu-events/metric.py
@@ -44,6 +44,9 @@ class Expression:
   def __and__(self, other: Union[int, float, 'Expression']) -> 'Operator':
     return Operator('&', self, other)
 
+  def __rand__(self, other: Union[int, float, 'Expression']) -> 'Operator':
+    return Operator('&', other, self)
+
   def __lt__(self, other: Union[int, float, 'Expression']) -> 'Operator':
     return Operator('<', self, other)
 
@@ -88,7 +91,10 @@ def _Constify(val: Union[bool, int, float, Expression]) -> Expression:
 
 
 # Simple lookup for operator precedence, used to avoid unnecessary
-# brackets. Precedence matches that of python and the simple expression parser.
+# brackets. Precedence matches that of the simple expression parser
+# but differs from python where comparisons are lower precedence than
+# the bitwise &, ^, | but not the logical versions that the expression
+# parser doesn't have.
 _PRECEDENCE = {
     '|': 0,
     '^': 1,
-- 
2.39.2.637.g21b0678d19-goog