<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/112187>112187</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Different Behavior in Floating Point Division by Zero
        </td>
    </tr>

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

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

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

<pre>
    I am writing to report a potential bug in the Clang compiler regarding the behavior of floating point division by zero. The issue arises when compiling the following C code with different optimization levels:
```c
#include <stdio.h>

int f (int i, int k)
{
 if (k == 0)
    printf ("k = 0\n");
  return i/k;
}

int main (void)
{
  return f (1, 0);
}
```

Clang version:
```sh
# clang -vUbuntu clang version 19.0.0 (++20240301064251+dd426fa5f931-1~exp1~20240301184412.1845)
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/lib/llvm-19/bin
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4.7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.5.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/8
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7
Candidate multilib: .;@m64
Selected multilib: .;@m64
```

When compiled with clang -O0 or gcc -O1, the program results in a floating point exception (core dumped). However, when compiled with clang -O1, -O2, -O3, or -Os, the program prints "k = 0" as expected.

This inconsistency in behavior across different optimization levels is concerning and may indicate a bug in the optimization process or the handling of floating point operations.

Here is the command line:
```sh
gcc bugreport_0_1.c -O0 ; ./a.out 
```
k = 0
Floating point exception (core dumped)
https://godbolt.org/z/qE9E7eahz
```sh
clang bugreport_0_1.c -O0 ; ./a.out 
```
k = 0
Floating point exception (core dumped)
https://godbolt.org/z/os956srn7

```sh
clang bugreport_0_1.c -O1 ; ./a.out 
```
k = 0
https://godbolt.org/z/354nKzTG7

I would appreciate it if you could look into this issue and provide feedback on whether this is a known issue or if further investigation is needed.
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJzMVlFv2zYQ_jX0y8GCRMmW9eCH2K7aYg8ZsAwD9lJQ5FniQpEaSdlJHvrbB1K246Zp1wENMCCwpPC7jx_vjnfHnJOtRlyTxYYsdjM2-s7YtWQ900Y_9mZ03M0aIx7XH4H1cLTSS92CN2BxMNYDg8F41F4yBc3YgtTgO4StYroFbvpBKrRgsWVWRMsOocGOHaSxYPawV4ZFysFI7UHIg3TSaGge4QmtSeCuQ5DOjQjMSocOjh3qE_OZcG-UMsfwtQVuBMJR-g6E3O_RovZgBi97-cR8YFZ4QOVIfkPSHUlvyDKd_vjpm-ZSczUKBJJvnRfSJB3J351W429QugdCV-FFErqF8HJPaHVClZvpBWSE3QPJdyTfQXqBAAAMVmofAYTSiIGULLaaUBpw-ZkELPrR6rBTfX_5Nyl3LzX1TOpAdzBSvCLmzBO3zILs9HqfZ8KzS675p4ge0IbwfO09113cBzxC54ffm1H78fR5soSsStIknQ69IXRDU1qkeZqly4IuMkI3QhR0uWeLfZVn8-wzPgzZ5zMoWxVFRpNsVSwu57tjtkVP8ht4WC0_LYv5wOdK6vFh3urxBOksMgG9EagCcDBOPkxLH7XzTCkUO2nDEqH16CyhtZJN-FWHfp5VhNaN1JNFbUYtgDMtpGAe4f02hD-yxAR7haXlnND6JO9ZG62LpHgT0qR8C9rlm5C-hQve4PhlskjSn0-7mih_Q4Xco_gZp95ehPWj8jIY5TeQhHtepP2yeLHj90CvVoI_ngswiqnUnm78bQrGQss5zG9jfQnFebCmtawHi25U3oUOwV6WfXzgOMTqTOiKG4sgxn7AUMQS-GCOeEAb-I7f3jruN7-l0yMPD2Nhfute6ohV18FVyaUUmAN8GKJDkuuz3nUyKOZGO-k8av4Y9F8aGOPWOPf9TgPSATeao9XhwEwL6FmgEZKHILHrvvmF_WANR-fCOcJax7SILe_rtmkGtNHGfaH-A9rQPKM1N30f9lZS47fLd4hdM7ZTc_-UfsoSHsNK8g0khNYsMaOHV5Pj7M3pivxwfCd85_0QezKtQ4Yb0RjlE2NbQusnQuu_31XvSmTd0zd0T1nwf1RuXLVYOqvL68D8sP7sP-v_Nz35otC_PN29_0LPRziaUQlgw2CRy5CW0ofh5dGMwOOSMuY-jDkGfLwT00imRcjSgxQIe0TRMH4PRod76ju0ZygwuNfmqE9Wxgbq_WgjRuoDOi_bKeelA40oUCQzsc5FlVdshuuspKsqLVdFOevWZUqx4OWKpsuUlc0yWwlBq2yxyLMVr_Z8JtdhXsjSrMholhZlgkLsm2qJtOI5rnhGihR7JlUS2nvwzSwKW2cZzVblTLEGlYszMaUaj5PsMJUtdjO7jjNBM7aOFKmSzrtnGi-9wvXuUg4250IhNVwS69eYWLurSfdPtGY2WrV-ETzpu7FJuOlPk8h5IBms-Qu5J7SOyhyh9Un6YU3_CQAA__9xx6fV">