<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=http://email.email.llvm.org/c/eJylVU2P2zYQ_TXyZWBBovwhH3zYJF0kQIFeWgTopaCkkcUNRQr8WK_76_tI29l8NT3UECyanBm-mfdm3NnhcvzINMlnpqfoAw3K9_aZHQ9U7Kr1GNTM6-Bkz_hJ0gw0KnypQGqe2XjWF5pYL2PUhajpvT0zvAvxlkbryNuZqbfzorQMyhqfDsLENDprAiMQ4itz8iQdk9RnefH0Nztb0u9T8nSO_WLNABuy3RP3Afdr9qRMr-PANEtzIS3dCUmwHNh5Oqsw0WyxNtQX4g0eRBo43Z0SUMYHaYKS4eYeeF6AjzM6b-kD9dKQsYE61gr5ALIMGVfCy6T8FVofSvrgcYqNYGFN_LJgl4cUCfmnrM5Mg034UzFgitUZ2Z-K5rGo3hXVw_UbLCTrVCzNIZU1Gh-T_wQ2Unht7adc1VTAxdlO81zS-3SaPG10KJFn93wtdc7VA44vmtsdtEZZgXWSywLuyBr6o4smRPpVmfhCL-3ur90mF_DmgM_6btNrCexg1yM81U1ZlfX6Wl9RCVHVeOrqIDbY2G-5acZ93YtBruti_wsKk153Q9HUVVWX2_a_7xFf34MrxKGu6kYIbIw8bOpmI2Qrxm_uyYZC1G29Kzdf5P8v4rMGJc8UpxJ_pbXM_p0c7CQJgQ9JWnVOugsVooWkgurvO1nmWRALVKI8tHcoP2P4OLG5xUpq4BfuY5BdugqRtPoEutkHyPHw035xvFgHsd3FqC8lPcAGirMjrK9tPcXT9_65vy63KKeIBtK3Nkrygvp3lef-1g8qeIgx4YJRLkaCdG-Hz3BuKJJTx72MnrNdar3UMTk6AqTpoiFA-L2W5DeINxvCy6fJ098Jx_or8q4UfVuOu6KVoYG7eMrid6xZAkUXlR78a_n51if8msd3ATuLIXJORGEiYjpcElPJHHievDVpGuKyfnLo6jxZMHhY6_xOA2gKYcmdJx7xnLAVuxKk44d00q8XLN4mpb9J6B6M1Bcg-XIiPJjraKWzjXpIYjo5lmCZkGySlcyDpl4Nx2Y4NAe5kjFM1h05TWYt4yo6ffwJDq2f76815slTJu9ReR_TKHzcNvvtbjUd5dhuqs2-7bpNxcN2v2laeWirrt3vZcNDs9ISc9Ifiy0YE4bPlENgXWzfrf4_AnXMUwMNXQu0-rbsq63oZdvVvNvKzdgWwDVLpcsUp7TutHLHHBJC8DjUCs30eii9VyfDnAEDYVBB8_HPH8oAGzN9-S-4yuCOGdk_HatpkQ>53756</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Zero frontend timings from -ftime-trace
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            new issue
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          emmenlau
      </td>
    </tr>
</table>

<pre>
    We have just discovered `-ftime-trace` and find it immensely helpful! However, for some compilations, the frontend timings are always zero. The corresponding object files include many large headers with modern c++ code, and instantiate many templates, so I can not believe that zero time is correct. Is this to be expected, or are we doing something wrong?

We are completely unsure where to look for the problem. Here are our observations and specs:
 - This happens on Ubuntu Linux x86_64 with
    - Ubuntu clang version 13.0.1-++20220120110924+75e33f71c2da-1~exp1~20220120231001.58
    - Ubuntu clang version 12.0.1-++20211029101322+fed41342a82f-1~exp1~20211029221816.4
 - The frontend timings are only zero for object files that are compiled into a library (static library, to be precise).
 - When compiling executables (like tests), the frontend timings are reported correctly. And we often have huge frontend timings. They are regularly larger than 60sec, so its unlikely that the zero timings are correct, because the code is largely overlapping.
 - Our code uses `c++20`
 - The zero frontend timings happens in debug and release builds
 - We observe the zero frontend timings both when displaying the `json` in chrome, as well as with https://github.com/aras-p/ClangBuildAnalyzer

Any help would be greatly appreciated!
</pre>
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