<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=http://email.email.llvm.org/c/eJytVU1v4zgM_TXOhbDhz8Q55NA2U6BAZ7uHAeYYyDYbayJLhj6adH_9UnK8SdrZAQa7gSPZFiU-PvLRjereN996boAb45BG0CiYxQ6sAtsjvCoh1JHLPbyhNlxJaLluGeRpTldWRsVdlG6j9DwC_VrBrsyzKkmTFKK87q0djbfPH-nac9u7JmnVQA9CvM1TPGr1A1ubkAGUiHmZNvUyrSt8Xaddnra4KjJWFmVer-q06rJsjSzK1xf_35jeoyVHcKqXu2UZO3mQ6ihjwaU7xXvprmx7jayDQXUo_I5RGX66LD9JY5kQ2G259suE0RntkaqWCZobLq_D_94jEaSGkQtP2S2BLTmBI4UNL1mUP5x56hQakMoS8dZpCUx2ZCktYVXOiHf_YNxARm6kRUBa0khvNX7gPqrubykembbqmEgiI38M3uZ595LtGrffzVlM_uJjVG1_O0n0-MoFGprrdJnX6_UvPcxZmsYn6NkbgkB7pkI7SXRpYI1yFiSXCL1y2kCD9Bq9eWBVQUNZOySUPQQ8jQQEuzPt6BFyeQDLBwyn2WDEhlHglAIq8smDVm7fE8OKHA3Et8XkYy07gzoq04G1vYcTrb7Q-UelD2ZkLf5bsFQn5QRgYIcAUdvDjjCLnUVjP0glyu_pgnjEjlFy2xi1VhR1_J1Kj0Y8Wc387F9DbGwXFdt22pVlEL_QX31y8ulF0o4jxM-XEuYNxIJOa2cAYrggi6ovDx58qPrq_ivd-kzTY-E1_zmmaktqsYTRjdarne8l5ay7Ueblzu_zc1WuhqpMVsvC3JLu53SgzpGWVyvm3cA_K1llbso_jH8oGzBvnZ4V6MsqJOMJOt4FramGXFDtMUn66ikHJC8ugzUblJNk8QoDDkq_U_FN4g0q7KB5D2ZTxZIMWjTmpmziX_6uLX35hoo8l64J4vfVa2BKtn8-Mi09gleNSKVK3JI47-6en6cbUARHgxopRG6Y9T1X4BsKc7akXLykvt-85GEsfEqmrbM8SA5ERodEDUU4d26iIER5E92j097f4PVo_x_8P0E-A7tunsGFnnycIZoPHTCGWUxlUkCSQJbNC9dKywIdWXG9ddFtim5drNmCOdsrvbnTzPR_hg66cFpsfrsxhi-q74xVUefLRb9hK6QeWSLDZVWkDVvVTdngal1Vq3ZZLNlCsIaC35DcSE2L_-6Sb-aGlFF3LvOkqfKybvIyW3dlRj_qbDgwLhJ_TqL0fqE34UhqZoYWBTfWXBaZMaRqxBmh5Vbg5iEoIXwnDRxvP4Dnr91PcrwIWDcB6N-2oq4P>53826</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Clang stalls when compiling with O1 optimisation level
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
      </td>
    </tr>

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

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

<pre>
    This issue is related to the following version circa 20220214:

    clang version 15.0.0 (https://github.com/llvm/llvm-project.git 4ee240b86085ef90d20ce731a434287805d119ea)
    Target: x86_64-unknown-linux-gnu
    Thread model: posix
    InstalledDir: /usr/local/bin

When compiling the following code with O1, clang does not return and continuously consumes up an entire core:

[https://partow.net/clang/clang_O1_bug_20220214.zip](https://github.com/llvm/llvm-project/files/8062899/clang_O1_bug_20220214.zip)

I have let clang run for about nine hours before having to break. The expected compile/link time for the example code is about roughly one minute.

    user@machine ~/workspace/clang_O1_bug_20220214 $ time make exprtk_real_test
    clang++ -pedantic-errors -Wall -Wextra -Werror -std=c++11 -O1 -o exprtk_real_test exprtk_real_test.cpp -L/usr/lib -lstdc++ -lm
    ^Cmake: [Makefile:34: exprtk_real_test] Interrupt (ignored)
    
    real    547m54.763s
    user    0m0.004s
    sys     0m0.015s


Note: During the run time I did not observe any changes in the amount of memory being consumed by the clang process.

------------------------------

The code compiles and links error and warning free on **ALL** other optimisation levels **(O0, O2, O3)** for the above denoted version of clang.

Furthermore the code compiles and links error and warning free on **ALL** optimisation levels for the following compilers and versions:

- g++ 4.3 .. 11
- clang++ 10, 13


</pre>
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