'[llvm-bugs] [Bug 43507] New: v8i1 build_vector legalizer miscompile'

[prev in list] [next in list] [prev in thread] [next in thread] 

List:       llvm-bugs
Subject:    [llvm-bugs] [Bug 43507] New: v8i1 build_vector legalizer miscompile
From:       via llvm-bugs <llvm-bugs () lists ! llvm ! org>
Date:       2019-09-30 15:42:37
Message-ID: bug-43507-206 () http ! bugs ! llvm ! org/
[Download RAW message or body]

--1569858157.d13a3B71.32240
Date: Mon, 30 Sep 2019 08:42:37 -0700
MIME-Version: 1.0
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
X-Bugzilla-URL: http://bugs.llvm.org/
Auto-Submitted: auto-generated

https://bugs.llvm.org/show_bug.cgi?id=43507

            Bug ID: 43507
           Summary: v8i1 build_vector legalizer miscompile
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: Backend: X86
          Assignee: unassignedbugs@nondot.org
          Reporter: benny.kra@gmail.com
                CC: craig.topper@gmail.com, llvm-bugs@lists.llvm.org,
                    llvm-dev@redking.me.uk, spatel+llvm@rotateright.com

$ cat t.ll
define <8 x i1> @ham(i64 %arg) {
  %tmp = trunc i64 %arg to i1
  %tmp1 = insertelement <8 x i1> undef, i1 %tmp, i32 0
  %tmp2 = shufflevector <8 x i1> %tmp1, <8 x i1> undef, <8 x i32>
zeroinitializer
  ret <8 x i1> %tmp2
}

$ llc -mcpu=skx < t.ll
ham:
        xorl    %eax, %eax
        testb   %dil, %dil
        movl    $255, %ecx
        cmovel  %eax, %ecx
        kmovd   %ecx, %k0
        vpmovm2w        %k0, %xmm0
        retq

This drops the trunc to i1, giving wrong results for all even inputs > 0. I'd
expect `testb $1, %dil` here.

-- 
You are receiving this mail because:
You are on the CC list for the bug.
--1569858157.d13a3B71.32240
Date: Mon, 30 Sep 2019 08:42:37 -0700
MIME-Version: 1.0
Content-Type: text/html; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
X-Bugzilla-URL: http://bugs.llvm.org/
Auto-Submitted: auto-generated

<html>
    <head>
      <base href="https://bugs.llvm.org/">
    </head>
    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - v8i1 build_vector legalizer miscompile"
   href="https://bugs.llvm.org/show_bug.cgi?id=43507">43507</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>v8i1 build_vector legalizer miscompile
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>libraries
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>trunk
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>PC
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>Linux
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>normal
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>P
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>Backend: X86
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>unassignedbugs&#64;nondot.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>benny.kra&#64;gmail.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>craig.topper&#64;gmail.com, llvm-bugs&#64;lists.llvm.org, \
llvm-dev&#64;redking.me.uk, spatel+llvm&#64;rotateright.com  </td>
        </tr></table>
      <p>
        <div>
        <pre>$ cat t.ll
define &lt;8 x i1&gt; &#64;ham(i64 %arg) {
  %tmp = trunc i64 %arg to i1
  %tmp1 = insertelement &lt;8 x i1&gt; undef, i1 %tmp, i32 0
  %tmp2 = shufflevector &lt;8 x i1&gt; %tmp1, &lt;8 x i1&gt; undef, &lt;8 x i32&gt;
zeroinitializer
  ret &lt;8 x i1&gt; %tmp2
}

$ llc -mcpu=skx &lt; t.ll
ham:
        xorl    %eax, %eax
        testb   %dil, %dil
        movl    $255, %ecx
        cmovel  %eax, %ecx
        kmovd   %ecx, %k0
        vpmovm2w        %k0, %xmm0
        retq

This drops the trunc to i1, giving wrong results for all even inputs &gt; 0. I'd
expect `testb $1, %dil` here.</pre>
        </div>
      </p>

      <hr>
      <span>You are receiving this mail because:</span>

      <ul>
          <li>You are on the CC list for the bug.</li>
      </ul>
    </body>
</html>
--1569858157.d13a3B71.32240--

[Attachment #3 (text/plain)]

_______________________________________________
llvm-bugs mailing list
llvm-bugs@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-bugs

[prev in list] [next in list] [prev in thread] [next in thread] 