<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/54425>54425</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            multiversioned static functions collision across translation units
        </td>
    </tr>

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

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

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

<pre>
    So, I was playing around with multi-versioned functions and, if I understand correctly, if there are two static multi-versioned functions:
-  with the same name
-  in separate compilation units,

one of them doesn't make its way to the final executable, and any call to it becomes a call the other.


Example ([static-mv.zip](https://github.com/llvm/llvm-project/files/8288671/static-mv.zip)): `foo.c`
```
__attribute__((target("default"))) static const char* boom(void) { return __FILE__ " default"; }
__attribute__((target("avx"))) static const char* boom(void) { return __FILE__ " avx"; }

const char* foo(void) { return boom(); }
```
`bar.c`:
```
#include <stdio.h>

__attribute__((target("default"))) static const char* boom(void) { return __FILE__ " default"; }
__attribute__((target("avx"))) static const char* boom(void) { return __FILE__ " avx"; }

const char* foo(void);
const char* bar(void) { return boom(); }

int main(void) {
    puts(foo());
    puts(bar());
}
```

Compile & run with `clang *.c && ./a.out`


Expected output (assuming avx is available):
```
foo.c avx
bar.c avx
```

Actual output:
```
bar.c avx
bar.c avx
```
We called from `foo.c` a static function defined in `bar.c`!

Tested with clang 10.0.0, 11.0.0 (from ubuntu in WSL2) and 13.0.0 (compiled by me from git.)

Looking at `nm a.out | grep boom`, it seems to be a name mangling issue:
```
0000000000201190 t boom
0000000000201210 t boom
00000000002011a0 t boom.avx
0000000000201220 t boom.avx
0000000000201020 i boom.ifunc
00000000002011b0 W boom.resolver
```
I would expect to see `boom_foo` and `boom_bar` or something to that effect.  

Same issue with compiling the files as C++ with `clang++`:
```
$ clang++ *.c && ./a.out && nm a.out | grep boom
clang-13: warning: treating 'c' input as 'c++' when in C++ mode, this behavior is deprecated [-Wdeprecated]
clang-13: warning: treating 'c' input as 'c++' when in C++ mode, this behavior is deprecated [-Wdeprecated]
bar.c avx
bar.c avx
0000000000201190 t _ZL4boomv
0000000000201210 t _ZL4boomv
00000000002011a0 t _ZL4boomv.avx
0000000000201220 t _ZL4boomv.avx
0000000000201020 i _ZL4boomv.ifunc
00000000002011b0 W _ZL4boomv.resolver
```

`g++` (9.4) emits two different names/aliases and the expected output:
```
$ g++ *.c && ./a.out && nm a.out | grep boom
foo.c avx
bar.c avx
00000000000017b9 t _ZL4boomv
0000000000001845 t _ZL4boomv
0000000000001813 i _ZL4boomv._GLOBAL____Z3barv.ifunc
0000000000001876 i _ZL4boomv._GLOBAL____Z3foov.ifunc
00000000000017ca t _ZL4boomv.avx
0000000000001856 t _ZL4boomv.avx
0000000000001813 t _ZL4boomv.resolver
0000000000001876 t _ZL4boomv.resolver
```
</pre>
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