Re: Illegal instruction error in some versions of valgrind

Paul Floyd via Valgrind-users <[email protected]> Tue, 24 Feb 2026 13:43:20 +0100
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Hi

On 24/02/2026 04:22, Steve Edmonds wrote:
>
> vex x86->IR: unhandled instruction bytes: 0x66 0xF 0x38 0x39
>
That ought to work

    case 0x39:
    case 0x3D:
       /* 66 0F 38 39 /r = PMINSD xmm1, xmm2/m128
          Minimum of Packed Signed Double Word Integers (XMM)
          66 0F 38 3D /r = PMAXSD xmm1, xmm2/m128
          Maximum of Packed Signed Double Word Integers (XMM)
       */
       if (have66noF2noF3(pfx) && sz == 2) {
          /* FIXME: this needs an alignment check */
          Bool isMAX = opc == 0x3D;
          delta = dis_SSEint_E_to_G(
                     vbi, pfx, delta,
                     isMAX ? "pmaxsd" : "pminsd",
                     isMAX ? Iop_Max32Sx4 : Iop_Min32Sx4,
                     False
                  );
          goto decode_success;
       }
       break;

It was also fairly recently added to x86 by Alexandra Hajkova. You will 
need to build Valgrind from source or wait for version 3.27 for that.

Would it be possible for me to build 'quasar'? Is it this 
https://quasar.dev/start/quasar-cli/ ?

Regards

Paul

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    <p>Hi</p>
    <div class="moz-cite-prefix">On 24/02/2026 04:22, Steve Edmonds
      wrote:<br>
    </div>
    <blockquote type="cite"
cite="mid:[email protected]"><span
        style="font-family:monospace"><span
          style="color:#000000;background-color:#ffffff;"> </span><br>
        <span style="color:#000000;background-color:#ffffff;">vex
          x86-&gt;IR: unhandled instruction bytes: 0x66 0xF 0x38 0x39</span><span
          style="color:#000000;background-color:#ffffff;"></span><br>
      </span><br>
    </blockquote>
    <p>That ought to work</p>
    <p>   case 0x39:<br>
         case 0x3D:<br>
            /* 66 0F 38 39 /r = PMINSD xmm1, xmm2/m128<br>
               Minimum of Packed Signed Double Word Integers (XMM)<br>
               66 0F 38 3D /r = PMAXSD xmm1, xmm2/m128<br>
               Maximum of Packed Signed Double Word Integers (XMM) <br>
            */<br>
            if (have66noF2noF3(pfx) &amp;&amp; sz == 2) {<br>
               /* FIXME: this needs an alignment check */<br>
               Bool isMAX = opc == 0x3D;<br>
               delta = dis_SSEint_E_to_G(<br>
                          vbi, pfx, delta, <br>
                          isMAX ? "pmaxsd" : "pminsd",<br>
                          isMAX ? Iop_Max32Sx4 : Iop_Min32Sx4,<br>
                          False<br>
                       );<br>
               goto decode_success;<br>
            }<br>
            break;<br>
    </p>
    <p>It was also fairly recently added to x86 by Alexandra Hajkova.
      You will need to build Valgrind from source or wait for version
      3.27 for that.<br>
      <br>
      Would it be possible for me to build 'quasar'? Is it this
      <a class="moz-txt-link-freetext" href="https://quasar.dev/start/quasar-cli/">https://quasar.dev/start/quasar-cli/</a> ?</p>
    <p>Regards</p>
    <p>Paul</p>
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