Date:   Sun, 19 Feb 2023 01:28:34 -0800
In-Reply-To: <20230219092848.639226-1-irogers@google.com>
Message-Id: <20230219092848.639226-38-irogers@google.com>
Mime-Version: 1.0
References: <20230219092848.639226-1-irogers@google.com>
Subject: [PATCH v1 37/51] perf expr: More explicit NAN handling
From:   Ian Rogers <irogers@google.com>
To:     Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>,
        Maxime Coquelin <mcoquelin.stm32@gmail.com>,
        Alexandre Torgue <alexandre.torgue@foss.st.com>,
        Zhengjun Xing <zhengjun.xing@linux.intel.com>,
        Sandipan Das <sandipan.das@amd.com>,
        James Clark <james.clark@arm.com>,
        Kajol Jain <kjain@linux.ibm.com>,
        John Garry <john.g.garry@oracle.com>,
        Kan Liang <kan.liang@linux.intel.com>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Andrii Nakryiko <andrii@kernel.org>,
        Eduard Zingerman <eddyz87@gmail.com>,
        Suzuki Poulouse <suzuki.poulose@arm.com>,
        Leo Yan <leo.yan@linaro.org>,
        Florian Fischer <florian.fischer@muhq.space>,
        Ravi Bangoria <ravi.bangoria@amd.com>,
        Jing Zhang <renyu.zj@linux.alibaba.com>,
        Sean Christopherson <seanjc@google.com>,
        Athira Rajeev <atrajeev@linux.vnet.ibm.com>,
        linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org,
        linux-stm32@st-md-mailman.stormreply.com,
        linux-arm-kernel@lists.infradead.org,
        Perry Taylor <perry.taylor@intel.com>,
        Caleb Biggers <caleb.biggers@intel.com>
Cc:     Stephane Eranian <eranian@google.com>,
        Ian Rogers <irogers@google.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

Comparison and logical operations on NAN won't ensure the result is
NAN. Ensure NANs are propogated so that threshold expressions like
"tma_fetch_latency > 0.1 & tma_frontend_bound > 0.15" don't yield a
number when the components are NAN.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/util/expr.y | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/expr.y b/tools/perf/util/expr.y
index 635e562350c5..250e444bf032 100644
--- a/tools/perf/util/expr.y
+++ b/tools/perf/util/expr.y
@@ -127,7 +127,11 @@ static struct ids handle_id(struct expr_parse_ctx *ctx, char *id,
 	if (!compute_ids || (is_const(LHS.val) && is_const(RHS.val))) { \
 		assert(LHS.ids == NULL);				\
 		assert(RHS.ids == NULL);				\
-		RESULT.val = (long)LHS.val OP (long)RHS.val;		\
+		if (isnan(LHS.val) || isnan(RHS.val)) {			\
+			RESULT.val = NAN;				\
+		} else {						\
+			RESULT.val = (long)LHS.val OP (long)RHS.val;	\
+		}							\
 		RESULT.ids = NULL;					\
 	} else {							\
 	        RESULT = union_expr(LHS, RHS);				\
@@ -137,7 +141,11 @@ static struct ids handle_id(struct expr_parse_ctx *ctx, char *id,
 	if (!compute_ids || (is_const(LHS.val) && is_const(RHS.val))) { \
 		assert(LHS.ids == NULL);				\
 		assert(RHS.ids == NULL);				\
-		RESULT.val = LHS.val OP RHS.val;			\
+		if (isnan(LHS.val) || isnan(RHS.val)) {			\
+			RESULT.val = NAN;				\
+		} else {						\
+			RESULT.val = LHS.val OP RHS.val;		\
+		}							\
 		RESULT.ids = NULL;					\
 	} else {							\
 	        RESULT = union_expr(LHS, RHS);				\
-- 
2.39.2.637.g21b0678d19-goog