On 4/19/22 21:28, Sergei Trofimovich wrote:
From: Sergei Trofimovich <siarh...@google.com>

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.

I'm fine with that but I think, as we're close to 11.3.0, it's up to release 
managers
who should approve that.

Cheers,
Martin


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.

(cherry picked from commit 90a29845bfe7d6002e6c2fd49a97820b00fbc4a3)
---
  gcc/value-prof.c | 4 ++++
  1 file changed, 4 insertions(+)

diff --git a/gcc/value-prof.c b/gcc/value-prof.c
index 42748771192..688089b04d2 100644
--- a/gcc/value-prof.c
+++ b/gcc/value-prof.c
@@ -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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