<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/55412>55412</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [AArch64][SVE] No way to convert scalable vector into fixed sized vector
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            new issue
      </td>
    </tr>

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

    <tr>
      <th>Reporter</th>
      <td>
          stevesuzuki-arm
      </td>
    </tr>
</table>

<pre>
    https://godbolt.org/z/ab5YGK595
```
define <8 x i32> @to_fixed_sized_vector_i32x8_1(<vscale x 8 x i32> %a) #0{
  %1 = call <8 x i32> @llvm.experimental.vector.extract.v832.nxv832(<vscale x 8 x i32> %a, i64 0)
  ret <8 x i32> %1
}
declare <8 x i32> @llvm.experimental.vector.extract.v832.nxv832(<vscale x 8 x i32>, i64)
```
Crashes with target triple = "aarch64-linux-gnu" -mattr=+sve2 -O3
`LLVM ERROR: Extracting a fixed-length vector from an illegal scalable vector is not yet supported`

I tried two workaround to avoid illegal length as follows, however both of them resulted in the same crash.
```
define void @to_fixed_sized_vector_i32x8_2(<vscale x 8 x i32> %a, <8 x i32>* %p1) #0{
    %step = tail call <vscale x 8 x i32> @llvm.experimental.stepvector.nxv8i32()
    %1 = call <vscale x 4 x i32> @llvm.experimental.vector.extract.nxv4i32.nxv8i32(<vscale x 8 x i32> %step, i64 0)
    %2 = call <4 x i32> @llvm.experimental.vector.extract.v4i32.nxv4i32(<vscale x 4 x i32> %1, i64 0)

    %3 = call <vscale x 4 x i32> @llvm.experimental.vector.extract.nxv4i32.nxv8i32(<vscale x 8 x i32> %step, i64 4)
    %4 = call <4 x i32> @llvm.experimental.vector.extract.v4i32.nxv4i32(<vscale x 4 x i32> %3, i64 0)

    %5 = shufflevector <4 x i32> %2, <4 x i32> %4, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7>

    store <8 x i32> %5, <8 x i32>* %p1, align 32
  ret void
}
```
```
define void @to_fixed_sized_vector_i32x8_3(<vscale x 8 x i32> %a110, <8 x i32>* %p1) #0 {
  %a165 = tail call <vscale x 8 x i32> @llvm.experimental.stepvector.nxv8i32()
  %a166 = add nsw <vscale x 8 x i32> %a165, %a110
  %a167 = extractelement <vscale x 8 x i32> %a166, i64 0
  %a168 = insertelement <8 x i32> undef, i32 %a167, i64 0
  %a169 = extractelement <vscale x 8 x i32> %a166, i64 1
  %a170 = insertelement <8 x i32> %a168, i32 %a169, i64 1
  %a171 = extractelement <vscale x 8 x i32> %a166, i64 2
  %a172 = insertelement <8 x i32> %a170, i32 %a171, i64 2
  %a173 = extractelement <vscale x 8 x i32> %a166, i64 3
  %a174 = insertelement <8 x i32> %a172, i32 %a173, i64 3
  %a175 = extractelement <vscale x 8 x i32> %a166, i64 4
  %a176 = insertelement <8 x i32> %a174, i32 %a175, i64 4
  %a177 = extractelement <vscale x 8 x i32> %a166, i64 5
  %a178 = insertelement <8 x i32> %a176, i32 %a177, i64 5
  %a179 = extractelement <vscale x 8 x i32> %a166, i64 6
  %a180 = insertelement <8 x i32> %a178, i32 %a179, i64 6
  %a181 = extractelement <vscale x 8 x i32> %a166, i64 7
  %a182 = insertelement <8 x i32> %a180, i32 %a181, i64 7
  store <8 x i32> %a182, <8 x i32>* %p1, align 32
  ret void
}
```
```
LLVM ERROR: Extracting a fixed-length vector from an illegal scalable vector is not yet supported
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
Stack dump:
0.      Program arguments: /opt/compiler-explorer/clang-assertions-trunk/bin/llc -o /app/output.s -x86-asm-syntax=intel -mattr=+sve2 -O3 <source>
1.      Running pass 'Function Pass Manager' on module '<source>'.
2.      Running pass 'AArch64 Instruction Selection' on function '@to_fixed_sized_vector_i32x8_1'
 #0 0x0000560a927bbb6f PrintStackTraceSignalHandler(void*) Signals.cpp:0:0
 #1 0x0000560a927b95dc SignalHandler(int) Signals.cpp:0:0
 #2 0x00007fdb640983c0 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x143c0)
 #3 0x00007fdb63b6503b raise (/lib/x86_64-linux-gnu/libc.so.6+0x4303b)
 #4 0x00007fdb63b44859 abort (/lib/x86_64-linux-gnu/libc.so.6+0x22859)
 #5 0x0000560a926fdce8 llvm::report_fatal_error(llvm::Twine const&, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x30fdce8)
 #6 0x0000560a926fde58 (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x30fde58)
 #7 0x0000560a92638b65 llvm::DAGTypeLegalizer::SplitVecOp_EXTRACT_SUBVECTOR(llvm::SDNode*) (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x3038b65)
 #8 0x0000560a9263e08b llvm::DAGTypeLegalizer::SplitVectorOperand(llvm::SDNode*, unsigned int) (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x303e08b)
 #9 0x0000560a9261d9ee llvm::DAGTypeLegalizer::run() (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x301d9ee)
#10 0x0000560a9261e8c6 llvm::SelectionDAG::LegalizeTypes() (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x301e8c6)
#11 0x0000560a925b1a03 llvm::SelectionDAGISel::CodeGenAndEmitDAG() (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x2fb1a03)
#12 0x0000560a925b54c3 llvm::SelectionDAGISel::SelectAllBasicBlocks(llvm::Function const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x2fb54c3)
#13 0x0000560a925b6bf8 llvm::SelectionDAGISel::runOnMachineFunction(llvm::MachineFunction&) (.part.962) SelectionDAGISel.cpp:0:0
#14 0x0000560a91af98d6 llvm::MachineFunctionPass::runOnFunction(llvm::Function&) (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x24f98d6)
#15 0x0000560a91faae16 llvm::FPPassManager::runOnFunction(llvm::Function&) (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x29aae16)
#16 0x0000560a91fab169 llvm::FPPassManager::runOnModule(llvm::Module&) (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x29ab169)
#17 0x0000560a91fabac9 llvm::legacy::PassManagerImpl::run(llvm::Module&) (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x29abac9)
#18 0x0000560a9014ea08 compileModule(char**, llvm::LLVMContext&) llc.cpp:0:0
#19 0x0000560a900a9557 main (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0xaa9557)
#20 0x00007fdb63b460b3 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x240b3)
#21 0x0000560a901453da _start (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0xb453da)
Compiler returned: 139
```
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJzFmV1z4rgShn8NuVFB2fL3RS4IIbNTO7NJJdmpc64o2ZbBJ8JySTaQ-fXbkg1YBgYmw5lNBbCl-O2npZbUTWKevt8uqqqUA2c8wA_wO-dpzFk14mIOd9_hRWLvv5_-9CJvYN0PrPHAt9pffZvSLC8oGjiTEG1Q7uCBM0UD16r4LMs3NJ3J_Du8r2hScTGD_k04swc4hAdWMiGMwlPdJ7FHBjiCT8caBHeNDaSabbBxj-AJdmiMsdVyRDclFfmSFhVho8YetFWCJNVoFTp4VGzUxznbE5T7LrIAYmtc0KpvEnDa0Qjut-OQMCKODMRV2FqsHVRvEiaCyAWVaJ1XC1QRMQfiSuQlo3rQBhgTIpKF7w5ZXtSb4byooQ0Nl6SqBPzFAN_JFYWGR2en_-XLt69o-vz8-AyxgaYNbF7MEUF6YoeMFnMw13iDMsGXiBQoZ4zOCUPKBxIDQNufS1TwCr0DmazLkouKpjv-5v2zYqYpqtYcrbl4I4LXBdxyRFY8T3fSrWEiUcYZ42upRmfB13RFBYo5dPEMVQu6hJmTNQNDKC9UA5JkSVGiBmv0o2DW1s7E8AVxZITCAI9VR2kfiW4d37KipZ6tiuRsF-dH9Y8FlXq8DSwVS3kTTPsgPrKGdtruzwUs6Lt5G7P5mQWlsI6tKY2DDZyfpNgxuIcMbm-pHgAYGM6_Oipuf1Tc3zMqzplR8TSGXNRZxmi7iHs8MINtnJut7kH0qzu4UrYmqgnZ2wu8vXC2F-72wtte-NuLQC2kHqoEsINtF_B_tAIniLB8XiBo7-zxatn3dvXe_vDx7cL58XZh29b5HQOZByKxfe__uGE0FnxtgaQpKuT6pH4Doz1onTFEAi3ShihlVBH8WMvfB6ehFGqlvJBUdIU6z8OJQbNtvLTmT4hFH8eyDaXAOovV4ptg0Qk5--Ng2FTCl4EFlgEW2CfknI-DOaaSeyEYNsGcE3Lex8FcU8m_EMw1wbwTcr8Q-p6pdD70WwdMsOCE3C8Ev28ohRcGf2AGfxCdkPuF4A9MpQuDPzSDP7QP5E4cMcrEbzhlfkcirg09fZmOX6bQGi_zCtTjeg7E6i9UDt4rE6HSqONRwpdwow6X9mNYCv4_MAS3uZQ1hdz8AWhUBp6wOqU6DdcZOIpJ8qZ8oW0u_lJBA0rrZams6CYLuqInweeCgE9iXqs5VBAwxA-8VFaAoMwZFUM43BhMk1BtjBTzIZFq4nNeyGEl6uINOuK80JwJGnIlQcpSCdVVWVcjiYab0IfHlkP5DkfkBqInLyByjtZJatYlr0VCdzmJrWif66JQk1OCeTARPNRFoiDQk2r4SgoyV4wBgqYlT2tVouHAEMNBOyL4mOB4rCs59LmQ4Faj_QLhra9a4WxrVEmfrcW3ca5zDGtjwY_nWyTCQRzHfoaeBAyDnp1XNV0vENOE_QGTypQnoQ5oPFZZStMlR0mp5tDSr5223dOOvDRBfTGwdFYIt0JBlsa-a0Whk1hoNoNiT63TGYSrzmQeWB7DO8zpzCx8VUdZLQQl6UjyESz_O2tju6CyT3_AjNM148S-ZzkxEiSX9AL9RCn7Wtl14EFD2TWVXTf0IkRifhF5RxljeNBQ9owx9rM0oSHSyxOWlDNuVvMsI5AAzqgQXA35vvt1rdLZBFYMTILeVWPOWZN-hr-44jSwY2kiA9nvI1MvvKY9kDPsBaY9J4SZ7QzR_fjT63tJv6i9E1aLaFpfSpZX32jyWM6m_3l9Hk9eZy9_332bTl5hV-4O4cv9Xzyl7XK4mhca0vAi7HlBrTC-2AtYJo9QCcCiO8U-gTxawhrUX51U1_VFoRq-RKYvdhpRetYXUG_qleuRacP7Yhh2LKtHRsPE75Dttl1AbFq2kApYXp1PmTf4zC3Vi21iOSf4PsNN0zqBSf5Ei3GRTuGcV-hX5cSZxjA4cY_Tc5PznE3rmLE7IvPkjvHkTRrxujta9zvWNb1QkIYXTs8LP87Cs16A-mPxlSQL2Fq3wIYXB31bN0YlEdUo8rE-EHvihyejInS7hDbJojDtxmvPlMpIOpBH6Q6xrjK6rkYzRtc4uuyMEGp32R-eFO42f_p3qCMNZVD7PepYfa1wnvqrzvzMOGibrkwc668ZOsRBn5gkXWJVNCTvzXWH_fOy3Af0b-EGLIPbOPEs26XEClFrYzecyYIIfYDpM2wPqWqoCYdkfrPdJ8DU8TVknEYWvDwvQEuSF9dyjmjJrm_Y6iWEvhU7kNGqbG8mK9gGZh2AS5NDF0QMK3ZvBD0nJajRv5ZvsRbdWZ20SqrwrQVkE6p0s53-P7Fu0lsnjZyI3FR5xejtwLtrq5yBdw83L9-mcIH-4mhN3lUtChv-CkAOa9sCOnWpg3Sp07bf1IL1_835E_Wr57k2vlnceqkdxpnlu74Xh1bqBxCi1PODiOI0iFL_Blgokwp_gHFB10hLwDXQ3-S32MLY8mxsR7bv4ZGHswD2kzS1s8hxqQuFGoVpZiP9XS0X8xtxq5GgDpfqK9xcVnLfCXOhEjQ9Wkqf1NWCi1tZ0RWV9ff6LR8SsbzRCLfahX8Ajw7GIw">