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After upgrading project to C++20, hotspot shows incorrect flamegraph/stacktrace #635

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Waqar144 opened this issue May 13, 2024 · 7 comments
Open

After upgrading project to C++20, hotspot shows incorrect flamegraph/stacktrace #635

Waqar144 opened this issue May 13, 2024 · 7 comments
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bug needs_info not enough info

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@Waqar144
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Waqar144 commented May 13, 2024 •
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Describe the bug

Recently we updated Kate text editor to use C++20. After the switch, I noticed that the flamegraph being shown in hotspot was incorrect consistently. (I am not sure if this will be reproducible in any other C++20 app)

To Reproduce
Steps to reproduce the behavior:

  • Build kate using kdesrc-build (needs Qt6): kdesrc-build --include-dependencies kate
  • Source the prefix: source /path/to/kate/build/prefix.sh
  • start kate via perf: perf record --call-graph dwarf kate -b -n .
  • exit kate
  • open hotspot and see weird stacktraces

CMake flags used:

cmake-options -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ -DCMAKE_CXX_FLAGS="-fno-omit-frame-pointer" -DECM_ENABLE_SANITIZERS="address;leak" -DCMAKE_BUILD_TYPE=RelWithDebInfo

Expected behavior
The stacktrace is correct

Screenshots

image

output of perf report:

image

.perfparser file for the above screenshot: perf.data.perfparser.tar.gz

Version Info (please complete the following information):

  • Linux Kernel version: 6.6.26-1
  • perf version: 6.7-1
  • hotspot version: self-compiled, master branch
  • if self-compiled hotspot, what version of elfutils: 0.191-1
  • Qt version: 5.15.12
@Waqar144 Waqar144 added the bug label May 13, 2024
@GitMensch
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Just to recheck: is it better if you have the full QT debug info (looks like some symbols were missing)?

@lievenhey
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Can you share the orignal perf.data file? I tried reproducing the issue but I couldn't see those weird traces.

@lievenhey lievenhey added the needs_info not enough info label May 27, 2024
@lievenhey
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Could you try again with the appimage release? We had some problems with an old elfutils version.

@milianw
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milianw commented Jul 17, 2024

@Waqar144 do you still run into this? if so please reopen (and ideally provide a way to reproduce - we cannot so far)

@milianw milianw closed this as completed Jul 17, 2024
@Waqar144
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Yes, I am still running into this issue. Tried the latest appImage (1.5.1) as well as the latest master. Attaching the perf.data file: perf.zip

@Waqar144
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Waqar144 commented Jul 17, 2024 •
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Same result with the hotspot-continuous.AppImage

@milianw
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milianw commented Jul 18, 2024

the perf.data file is not relocatable, to analyze it we'd basically need your selfcompiled .so files too

@milianw milianw reopened this Jul 18, 2024
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@milianw @GitMensch @Waqar144 @lievenhey