From 90a29845bfe7d6002e6c2fd49a97820b00fbc4a3 Mon Sep 17 00:00:00 2001
From: Sergei Trofimovich <siarheit@google.com>
Date: Fri, 15 Apr 2022 08:35:27 +0100
Subject: [PATCH] gcov-profile: Allow negative counts of indirect calls
[PR105282]
TOPN metrics are histograms that contain overall count and per-bucket
count. Overall count can be negative when two profiles merge and some
of per-bucket metrics are disacarded.
Noticed as an ICE on python PGO build where gcc crashes as:
during IPA pass: modref
a.c:36:1: ICE: in stream_out_histogram_value, at value-prof.cc:340
36 | }
| ^
stream_out_histogram_value(output_block*, histogram_value_t*)
gcc/value-prof.cc:340
gcc/ChangeLog:
PR gcov-profile/105282
* value-prof.cc (stream_out_histogram_value): Allow negative counts
on HIST_TYPE_INDIR_CALL.
---
gcc/value-prof.cc | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/gcc/value-prof.cc b/gcc/value-prof.cc
index 9785c7a03ea1..c240a1863369 100644
--- a/gcc/value-prof.cc
+++ b/gcc/value-prof.cc
@@ -336,6 +336,10 @@ stream_out_histogram_value (struct output_block *ob, histogram_value hist)
/* Note that the IOR counter tracks pointer values and these can have
sign bit set. */
;
+ else if (hist->type == HIST_TYPE_INDIR_CALL && i == 0)
+ /* 'all' counter overflow is stored as a negative value. Individual
+ counters and values are expected to be non-negative. */
+ ;
else
gcc_assert (value >= 0);
--
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