<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/119900>119900</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [VectorCombine] vectorizeLoadInsert - incorrect shuffle when folding from inserting into undef vector
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            llvm:transforms,
            miscompilation:undef
      </td>
    </tr>

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

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

<pre>
    As mentioned here by @nunoplopes: https://discourse.llvm.org/t/please-dont-use-undef-in-tests-part-2/83388/17?u=rksimon
```
; Transforms/VectorCombine/X86/load.ll

define <4 x float> @load_f32_insert_v4f32(ptr dereferenceable(16) align(16) %p) {
  %s = load float, ptr dereferenceable(16) align(16) %p, align 16
  %r = insertelement <4 x float> undef, float %s, i32 0
  ret <4 x float> %r
}
=>
define <4 x float> @load_f32_insert_v4f32(ptr dereferenceable(16) align(16) %p) {
  %#1 = load <4 x float>, ptr dereferenceable(16) align(16) %p, align 16
  %r = shufflevector <4 x float> %#1, <4 x float> poison, 0, 4294967295, 4294967295, 4294967295
  ret <4 x float> %r
}
Transformation doesn't verify! (unsound)
ERROR: Target is more poisonous than source

Source value: < poison, #x00000000 (+0.0), #x00000000 (+0.0), #x00000000 (+0.0) >
Target value: < poison, poison, poison, poison >
```
</pre>
<img width="1" height="1" alt="" src="http://email.email.llvm.org/o/eJy8VF2PqzYQ_TWTF4vIjCGEBx7YZJGqVqq096rq28rAOHFrbGSb9G5_fWXC3fvVrdqqahSBx3i-juccGYK-WKIGygdAfPr-nZ6cBUQozzu5xKvzzba569340rSBTWSjdpZGdiVPrH9hUHC7WDcbN1MA0bJrjHNaAHaA3ajD4BYfaG_Mbdo7fwHsImA3G5KBstHZmC2BssWOpDJts0ghhmyWPmYI2B2FOB4Bu7wC0S0gzv7XsNbJWzjw7c9bEA_svZc2KOenANj9REN0_uSmXlsC7H4-HgA74-S4NyY58HYkpS0xEKeCfWDKOBlBPKaO0rFnJfBZ20A-Pt8KJRDwOEfPRvKkyJMdSPaGAI_5AbBm0uiLfbUAy3l9Vw_AW5bswECcWQq95cIT-6cBT_ddlh8-RvVr1HudZChd0Dcdrdgm53VnrSVZWiDjaxxP3zql2Amn6rzCewbx-P9jBijyT7B9lfW_BDBcF6UM3dap-TMsUiXJ_etPs9MhsebEeHoUWBf1ocK6_Evrb4H-Os8ycY6NjoIFrCK7kdfqBTBngMfFBrfYEbAG3j4-Pf34lFj4XvoLRaYDm5ynrUq3BBav0rLgFj_QnQXv1jW7SbNQ8gRx-qwpQPGBb7-UDfCB73lK9q8_svskbRW-kfft1eb-Sv7d2IixFrXcUZNXosh5VWG5uzayPPRVxfPDoehpkHVRFIr6YhwVz0t1HHe6QY5FjrnID6LEck9HpZQquBIce1FVUHCapDav2rXTISzU5Hldc74zsicTNvlMR0C08TMNQsATIE5JAqdZm_UaQbQbHVed9U1yzPrlEhKHdIjhU7aoo1nl-UsxK8_sPqf6d_rByfG7lXAsY9oOznsa4sdxZr9dyTLlzKjthSnvpk0pkqltdHdp2MLtFm-aL-X7ouN16feDm5J4phbvr2z27hcakpCvkCTF3VC5NfhHAAAA__-nE-Y9">