<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/92182>92182</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            clang: "expected relocatable expression" when compiling large inline asm with -O0 and address sanitizer
        </td>
    </tr>

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

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

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

<pre>
    As in title: Bitcoin Core's sha256 Transform function in hand-written sse4 asm (implementing the algorithm from Intel's whitepaper) is unable to compile with optimizations disabled and address sanitizer enabled: [sha256_sse4.cpp](https://github.com/bitcoin/bitcoin/blob/master/src/crypto/sha256_sse4.cpp). The file is standalone and requires no other files.

Compile with: `clang++ -std=c++20 -fPIC -O0 -fsanitize=address -c crypto/sha256_sse4.cpp -o out.o`

> 
> crypto/sha256_sse4.cpp:44:9: error: expected relocatable expression
>         "shl    $0x6,%2;"
>         ^
> <inline asm>:1:1882: note: instantiated into assembly here
> crypto/sha256_sse4.cpp:44:9: error: expected relocatable expression
> "shl    $0x6,%2;"
>         ^
> <inline asm>:1:2580: note: instantiated into assembly here
> crypto/sha256_sse4.cpp:44:9: error: expected relocatable expression
>         "shl    $0x6,%2;"
> ^
> \<snip\>

It's no problem with optimizations at >= `-O1` or with asan off. gcc is able to compile it fine with the same options.

We intend to work around it by disabling asan for clang with no optimizations: https://github.com/bitcoin/bitcoin/pull/30097
</pre>
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