<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/119182>119182</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [RISCV] error in generating assembly for compressed instruction
        </td>
    </tr>

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

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

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

<pre>
    ` int a=20, b=10; `
   ` asm volatile ("c.sub %0, %1":
        "=r"(a):
        "r"(b)
    );    `


Clang generates the below assembly sequence for the above code

`li      a0, 20 `
`sw      a0, -20(s0) `
`li      a0, 10`
`sw      a0, -24(s0) `
`lw a0, -24(s0) `
`sub     a0, a0, a0`
`sw      a0, -20(s0) `


which is subtraction of `b` from `b` ie ` (b-b) ` whereas subtraction of `b` from `a` ie `(a-b) ` is expected 

see it on [godbolt](https://godbolt.org/z/z8xdPdaKW)


### expected assembly

`li a0, 20 `
`sw      a0, -20(s0) `
`li      a0, 10`
`sw      a0, -24(s0) `
`lw      a0, -24(s0) `
`lw      a1, -20(s0) `
`sub     a1, a1, a0`
`sw a0, -20(s0) `


</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJzEVEFv6zYM_jXyhUggU7ZjH3xoGgQYdhk2YDtLFhNrk61MkpN2v36Q7Tbt9trX2wsYKfHHj6T1kZIhmPNI1LJyz8pDJqfYO9_KfiAdevmXsTZTTj-3rOJgxgiSiQNyho-gmDjknIk9sIoz_gCQfoAMA1ydldFYAoY1Q-y2YVLAsJx5DMucITLxsJDmz_zg4NOGtWTY_A9eMZWwBZi99rDkZfxhsUcrxzOcaSQvIwWIPYEi624gQ6BB2WcI9PdEY0dwcn7GpXJXgs5pWsNU3Jols5xrRv6So-Lh9hbZpMOoA2fY3F3ek3P-Ibf4Bvf2GZoO8h7gdf1ybbPdetP1YAKESUUvu2jcCO6UfFSS8OTd8PrH0CxrOvqNWiPBrSdP8rsB5D1AkvXONwHo6UJdJA1LTYEITAQ3Aiv3Z6eVs5GVB4Z1H-MlpHbAI8PjCm2dPzM8_pO-9ZP-Rcuf_1g6YzUUi93zvMj_VuIfoe6XXfIPK3jtgtllXd_V8UkDZLoVuhGNzKjNd0LshKgbkfWtrPSpbnaSThzLSpXdri51kXe6LLhsOpGZFjkWOfKG10VRim3VVbtaNycthSKkmhWcBmns1trrkCTKTAgTtXne5DVmViqyYb5qEEe6wYymuS4PmW8TaaOmc2AFtybEcA8TTbTzHfXrT789_s7KA5D3zoMZXybdjOf7gKe57txw8RQCaTBjiH6auzSbvG3_01Em9pPadm5geEwZ121z8e5P6iLD41xnYHhcX-Ta4r8BAAD__3hVZYg">