<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 - [AVX512] Incorrect register argument to test instruction"
   href="https://bugs.llvm.org/show_bug.cgi?id=37396">37396</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>[AVX512] Incorrect register argument to test instruction
          </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>All
          </td>
        </tr>

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

        <tr>
          <th>Severity</th>
          <td>enhancement
          </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@nondot.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>keno@alumni.harvard.edu
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>craig.topper@gmail.com, llvm-bugs@lists.llvm.org
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Consider the following bugpoint-reduced reproducer of
<a href="https://github.com/JuliaLang/julia/issues/27032">https://github.com/JuliaLang/julia/issues/27032</a>:

```
define void @japi1_foo2_34617() {
pass2:                                            ; preds = %top
  br label %if5

L174:                                             ; preds = %if5
  %tmp = icmp sgt <2 x i64> undef, zeroinitializer
  %tmp1 = icmp sle <2 x i64> undef, undef
  %tmp2 = and <2 x i1> %tmp, %tmp1
  %tmp3 = extractelement <2 x i1> %tmp2, i32 0
  %tmp4 = extractelement <2 x i1> %tmp2, i32 1
  %tmp106 = and i1 %tmp4, %tmp3
  %tmp107 = zext i1 %tmp106 to i8
  %tmp108 = and i8 %tmp122, %tmp107
  %tmp109 = icmp eq i8 %tmp108, 0
  br i1 %tmp109, label %L188, label %L190

if5:                                              ; preds = %if5, %pass2
  %b.055 = phi i8 [ 1, %pass2 ], [ %tmp122, %if5 ]
  %tmp118 = icmp sgt i64 undef, 0
  %tmp119 = icmp sle i64 undef, undef
  %tmp120 = and i1 %tmp118, %tmp119
  %tmp121 = zext i1 %tmp120 to i8
  %tmp122 = and i8 %b.055, %tmp121
  br i1 undef, label %L174, label %if5

L188:                                             ; preds = %L174
  unreachable

L190:                                             ; preds = %L174
  ret void
}
```

Running llc on trunk (and 6.0) gives:
```
$ llc -mcpu=skylake-avx512 bug.ll -o -
        .text
        .file   "wip.ll"
        .globl  japi1_foo2_34617        # -- Begin function japi1_foo2_34617
        .p2align        4, 0x90
        .type   japi1_foo2_34617,@function
japi1_foo2_34617:                       # @japi1_foo2_34617
        .cfi_startproc
# %bb.0:                                # %L174
        testq   %rax, %rax
        setg    %al
        vpxor   %xmm0, %xmm0, %xmm0
        vpcmpgtq        %xmm0, %xmm0, %k0
        kshiftrw        $1, %k0, %k1
        kandd   %k0, %k1, %k0
        testb   %k0, %al
        je      .LBB0_1
# %bb.2:                                # %L190
        retq
.LBB0_1:                                # %L188
.Lfunc_end0:
        .size   japi1_foo2_34617, .Lfunc_end0-japi1_foo2_34617
        .cfi_endproc
                                        # -- End function

        .section        ".note.GNU-stack","",@progbits
```

llvm-mc says it best:
```
$ llvm-mc bug.s
bug.s:15:8: error: invalid operand for instruction
        testb   %k0, %al
                ^~~
```

If we try to generate code directly rather than go through textual assembly,
we end up generating `testb %al, %al`, which was the cause of the above linked
bug report.</pre>
        </div>
      </p>


      <hr>
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      <ul>
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