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astor86
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Joined: 19 Feb 2016
Posts: 57
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 Posted: Thu Jan 25, 2018 3:05 pm Post subject: [solved] gprof not working with PIE |
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[Moderator edit: Changed title to reflect the apparent solution: gprof and PIE do not mix; previous title was [solved] gprof not working with gcc >= 6. -Hu]
Hi,
gprof does not work, meaning that it does not display function names, function calls. It either print nothing
| Code: | $ gprof -Q a.out gmon.out
Flat profile:
Each sample counts as 0.01 seconds.
no time accumulated
% cumulative self self total
time seconds seconds calls Ts/call Ts/call name
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or (different code actually)
| Code: | $ gprof -Q ../a.out gmon.out
Flat profile:
Each sample counts as 0.01 seconds.
% cumulative self self total
time seconds seconds calls Ts/call Ts/call name
100.31 2.79 2.79 data_start
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Do I need to have proper use flags somewhere?
Thanks
Last edited by astor86 on Fri Jan 26, 2018 8:47 am; edited 1 time in total |
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mike155
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Joined: 17 Sep 2010
Posts: 4438
Location: Frankfurt, Germany
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astor86
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Joined: 19 Feb 2016
Posts: 57
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| Posted: Thu Jan 25, 2018 5:50 pm Post subject: |
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dear mike155,
I know how to use gprof  and indeed on an another machine it gives me the right information. so I am sure there is something wrong with my installation.. |
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Hu
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Joined: 06 Mar 2007
Posts: 21586
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| Posted: Fri Jan 26, 2018 2:52 am Post subject: |
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| What commands did you use to generate a.out? |
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astor86
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Joined: 19 Feb 2016
Posts: 57
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| Posted: Fri Jan 26, 2018 8:26 am Post subject: |
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Dear Hu
| Quote: | | What commands did you use to generate a.out? |
| Code: | | gcc -g -pg source_file.c |
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astor86
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Joined: 19 Feb 2016
Posts: 57
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| Posted: Fri Jan 26, 2018 8:38 am Post subject: |
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I tried to compile with clang and gprof displays the right things.. So it may be an issue on the gcc I have. I tried both with gcc-6.4.0 and gcc-7.2.0 but without success.
I also found this bug report..
https://bugs.launchpad.net/ubuntu/+source/gcc-6/+bug/1678510 |
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astor86
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Joined: 19 Feb 2016
Posts: 57
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| Posted: Fri Jan 26, 2018 8:46 am Post subject: |
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If I add -no-pie to both compile and link flags I got the right results both with gcc-6 and gcc-7. For the sake of completeness I need to compile as follows
| Code: | gcc -no-pie -g -pg -c source_file.c
gcc -no-pie -pg source_file.o -lother_libs |
in this way gprof will like a.out
Thanks to everybody |
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mike155
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Joined: 17 Sep 2010
Posts: 4438
Location: Frankfurt, Germany
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| Posted: Fri Jan 26, 2018 11:08 am Post subject: |
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| Quote: | | If I add -no-pie to both compile and link flags I got the right results both with gcc-6 and gcc-7. |
Thanks for sharing this! I use gprof once or twice a year - and I'm sure your post will save me a couple of hours the next time I will use gprof!
But it's probably not a 'feature' or 'bug' of GCC 6 or 7. It's the consequence of the switch to profile 17.0, which enables generation of position independent code by default. |
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