<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/72720>72720</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [ARM][VPlan] Assertion with -mcpu=neoverse-v1 - Invalid operands for select instruction! 
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            vectorization,
            crash
      </td>
    </tr>

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

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

<pre>
    Possibly a side-effect from Issue #70988...

LoopVectorize is generating @llvm.get.active.lane.mask calls with a <1 x i1> return type. E.g.:

` 
%active.lane.mask.entry = call <1 x i1> @llvm.get.active.lane.mask.v1i1.i32(i32 0, i32 15)
`

The Verifier later blows up on this single element vector mask. E.g.:

`
Invalid operands for select instruction!
  %13 = select contract <1 x i1> %active.lane.mask, float %6, float -0.000000e+00
`

Test case to reproduce:

```
$ cat test.ll
source_filename = "test.ll"
target triple = "arm64-linux"

define dso_local void @foo() #0 {
entry:
  br label %loop

loop: ; preds = %loop, %entry
  %x.addr.0 = phi float [ undef, %entry ], [ %5, %loop ]
  %y.addr.0 = phi i32 [ 0, %entry ], [ %narrow, %loop ]
  %narrow = add nuw nsw i32 %y.addr.0, 1
  %0 = load i32, ptr null, align 4
  %1 = ashr i32 %0, 1
  %2 = sext i32 %1 to i64
  %3 = getelementptr float, ptr null, i64 %2
  %4 = load float, ptr %3, align 4
  %5 = fadd contract float %x.addr.0, %4
  %6 = icmp ult i32 %narrow, 15
  br i1 %6, label %loop, label %exit, !llvm.loop !0

exit: ; preds = %loop
  %.lcssa = phi float [ %5, %loop ]
  %7 = fadd contract float %.lcssa, 0.000000e+00
  store float %7, ptr null, align 4294967296
  ret void
}

!0 = distinct !{!0, !1}
!1 = !{!"llvm.loop.interleave.count", i32 2}

$ opt -passes=loop-vectorize -mcpu=neoverse-v1 -S test.ll
Invalid operands for select instruction!
  %13 = select contract <1 x i1> %active.lane.mask, float %6, float -0.000000e+00
Invalid operands for select instruction!
 %15 = select contract <1  i1> %active.lane.mask2, float %12, float -0.000000e+00
LLVM ERROR: Broken module found, compilation aborted!
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
Stack dump:
0.      Program arguments: opt -passes=loop-vectorize -mcpu=neoverse-v1 -S test.ll
 #0 0x0000aaaae5745b18 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (opt+0x1795b18)
 #1 0x0000aaaae5743b08 llvm::sys::RunSignalHandlers() (opt+0x1793b08)
 #2 0x0000aaaae5746388 SignalHandler(int) Signals.cpp:0:0
 #3 0x0000400007f1064c (linux-vdso.so.1+0x64c)
 #4 0x0000400008122c1c raise (/lib64/libc.so.6+0x32c1c)
 #5 0x00004000081107a8 abort (/lib64/libc.so.6+0x207a8)
 #6 0x0000aaaae56d1438 llvm::report_fatal_error(llvm::Twine const&, bool) (opt+0x1721438)
 #7 0x0000aaaae56d1264 llvm::report_fatal_error(llvm::Twine const&, bool) (opt+0x1721264)
 #8 0x0000aaaae5391834 llvm::VerifierPass::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (opt+0x13e1834)
 #9 0x0000aaaae5369778 llvm::PassManager<llvm::Module, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (opt+0x13b9778)
#10 0x0000aaaae44fd5e0 llvm::runPassPipeline(llvm::StringRef, llvm::Module&, llvm::TargetMachine*, llvm::TargetLibraryInfoImpl*, llvm::ToolOutputFile*, llvm::ToolOutputFile*, llvm::ToolOutputFile*, llvm::StringRef, llvm::ArrayRef<llvm::PassPlugin>, llvm::opt_tool::OutputKind, llvm::opt_tool::VerifierKind, bool, bool, bool, bool, bool, bool, bool) (opt+0x54d5e0)
#11 0x0000aaaae4509b30 main (opt+0x559b30)
#12 0x0000400008110be4 __libc_start_main (/lib64/libc.so.6+0x20be4)
#13 0x0000aaaae44f7d5c _start (opt+0x547d5c)
Aborted (core dumped)
```

@ktkachov-arm @paulwalker-arm @fhahn 
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJzMWFtv47oR_jX0y8CCRN3sBz84N3TRXZwgWeyrQVGUzYYiBZJy4v76YihfpMTJOduDAl1kbUmc-eabC4cjM-fkVguxIvkNye9mrPc7Y1ctl5opdZhVpj6sHo1zslIHYOBkLeaiaQT30FjTwjfnegGEpmW8XCyiKCLxHYnXw-d3Y7pfgntj5b8FSAdboYVlXuotkCxWat9GW-Ejxr3ci0gxLaKWuRfgTCkHr9LvgAFJbxN4A5mQ9B6s8L3V4A-diOA-2kYkXY9NkiKG4xXN3-NGQnt7AJLeBQtT5K8IRftEJpFMKaELmVKICb0FvEhyQpdny2MiP3cCfgkrGyksKOaFhUqZVwd9B0aD30kHTuqtEiCUaIX2sA-hgmDwE9-Gi296z5SswXTCMl07aIwFJxRmRWrnbc-9NJrQZJAHIDRP0uD4UYwb7S3j_l0MPsYMPW2UYR4Xi8vdPI7i8E8QehPH12MgnAfOnABvwIrOmrrn4opXw98xbRlw5sEL5yOlhofO9JaLTSOV0KwVwRFC6UmG0kHMM7sVHryVnToLMdsW2VxJ3b-dBYfPWjRSC6id2SjDmYK9kTXWQWMMoQtCl1jYMZDyZlAI5XOmD1BhZiuhMDTKmG4MHu7TNZD0BjoranfkMwjSW7wc8C4peotYXdsoDqLdTp4Cn99Ar2vRjNWA5HfhPr_BZ_lxDdHD0gX18B4VCxfV4i_wNLPWvH4OOqwHSFbXoPtX0O51gL6YRP1xDQ4clGE1hM10C523oHvM4S0wJbcasnHNDgbczp6QP0DSY1W_-ZNIgtUmizHOUPpb4Y9bDa2G2L6nIIssgI50swvniQrCXmedB40G43LeZuct9DYKDaKP9IqgJ3nbQa_O7lwykeSjwpPJeUNOa3D8QLxJPxhKQm8bEkmTyS4NQp9W6oVepLhz7Eptfl1-5VfRGDBR-Vo7AXDeWHERLz8pGbrMlkVJl8VJzwofdvPRz_Ju0nFoMhRiLZ2XGpsgTXCTY2CGaCUXFZokx4AcZQil52BGUnthlWB7EXHTa48t5ng20A9mMzCdh3nHnBOOpHeIMN-fD8h5y7uepHdamL2wTsz3Ccyfp53w_7b1_zYx5JV_zutzWnTCK6F_Quz7918_4P7p6Y8nLPIba16EhtbUvRLQmF7XqM9N20nFkCGwylgv6jPTx-_36-d7cH3VSg8Mqn6Lh5mxHhvNzvvO4ZlAHwh92Eq_66uIm5bQB6yS49e8s-ZfgntCHyROTI7QB2C6Bqm56msBfieAW-Z2UDH-gnEQx1Hq2TP-AnXfdueTJ45IvHy0ZmtZC8xue-xpSOLv19dw4sVvGEXGGBN5meVVsoDgTLom6dod3HDxaKX2gd5P5Evo4iJk2evGOG8FawkNtSNxc-CJujCdx_y8JeUSoc8TFNpO3tlOq_iq7adeP8utZuofTNdKWHc-sMfwqD2Bp-_gi3SxgAkQTngD0-Gxi3iHkY_D_zNQegTK8KNskrjIOBoPc8Z8XzsTORMlgUiR8QmJbKy7SCjlCQfLpMNBeoEVI6siG745whQBJkW5CVA-BUriki2G8v0SiKLcBKiYhKWokywdR32o9k3DPFMbYa2xk1z_fMUxihvt_DHXlTHqQzYook7Mlu_N0iL7H5ilGIOR2cXEbLpMFunY7Glqf2TuWGy21xPLD70-NrPh_D0vrDVTByfdD6bZVliS3l5RSu-D3pRmKpDFhOZySrNYluU4KUjvmp0fobX9dV5H-fQ-_F1z94T4G85eQK-4WqEnl_cmmiaTjpNlTZ2LeFwIvUZvH2UnlNTTRvPsrdTbp2E4_lPOP8Mbwg_GdwFnfW31u6wss4dvujHf2k59lDJG_dH7rvcPUl0B-VvLn7iztpYd8Ok4yCEmqt_KoabG8qbzG4-7IdwN9v4ph7PuM6lT3Z_kht30u9-TXOcZZnKS6kmDz_J4WaUxtEzqiV6Ojyd69H2vq0QGmw12to3zzPrNCeSLvleJbAKavqu7ss45DHBTN3DhrLkeBgSU4Die4tmM88Ly-gvt8JnFL_6F8Z3Zz5lt8S2zY716ZepF2NOTZsd2Gmb1Kq2X6ZLNxCop45gW2SLNZrtVmlK-jLO0SeNFyeOsybOkZLwsi0SkJStnckVjDHFS0jQrkyxalMsyzoosKfOGMlqRLBYtkyoKA6yx21mYRlYlLWk8C68NLvwUROlpbGBDo8Mpi1AaRhS8y-9mdhUmm6rfOpLFSjrvLrheehV-VVo__cD3gfzm16NimuR3sHZO2DBphR94rk4l8NfHSZj1Vq3--zEs-P6fAAAA__80sox_">