https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99579
Bug ID: 99579
Summary: gmon.out not created with -O0 but otherwise is
Product: gcc
Version: 9.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: wsnyder at wsnyder dot org
Target Milestone: ---
Created attachment 50382
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=50382&action=edit
Testcase
== Description
Type "make" in this tarball's directory.
This will show (extra lines omitted):
g++ -pg -O0 -c -o Vt_case_huge_prof__main.o Vt_case_huge_prof__main.ii
@@@@@ Did we get a gmon?
make: [Makefile:15: x] Error 1 (ignored)
g++ -pg -Os -c -o Vt_case_huge_prof__main.o Vt_case_huge_prof__main.ii
@@@@@ Did we get a gmon?
4554816 28 -rw-rw-r-- 1 user user 26943 Mar 13 11:33 ./gmon.out
g++ -pg -O0 -c -o Vt_case_huge_prof__main.o Vt_case_huge_prof__main__ok.ii
@@@@@ Did we get a gmon?
4554816 884 -rw-rw-r-- 1 user user 897414 Mar 13 11:33 ./gmon.out
In short gcc -pg with -O0 is not creating a gmon.
The problem goes away using -Os.
The problem goes away if line 60549 of ~/d/case/Vt_case_huge_prof__main.ii
std::array<CData , 16384> __Vtablechg1;
is changed into
CData __Vtablechg1[16384];
(The original program requires a unique class, not a std::array, so using
C-style arrays is unfortunately not a workaround in my application.)
While this "feels" like a memory corruption sort of bug,
the program is sanitizer and warning clean.
== gcc --version
gcc (Ubuntu 9.3.0-17ubuntu1~20.04) 9.3.0
Copyright (C) 2019 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
== cat /etc/*release
DISTRIB_DESCRIPTION="Ubuntu 20.04 LTS"
