[gcc r11-9896] gcov-profile: Allow negative counts of indirect calls [PR105282]

[Martin Liska <marxin@gcc.gnu.org>]

https://gcc.gnu.org/g:7b879564ec2bda6b5441fbaf231d70ec6359db01

commit r11-9896-g7b879564ec2bda6b5441fbaf231d70ec6359db01
Author: Sergei Trofimovich <siarheit@google.com>
Date:   Fri Apr 15 08:35:27 2022 +0100

    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.c:340
    
    gcc/ChangeLog:
    
            PR gcov-profile/105282
            * value-prof.c (stream_out_histogram_value): Allow negative counts
            on HIST_TYPE_INDIR_CALL.
    
    (cherry picked from commit 90a29845bfe7d6002e6c2fd49a97820b00fbc4a3)

Diff:
---
 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);