<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/167243>167243</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [LV] Assert "all accumulators in chain must have same scale factor"
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            vectorizers,
            crash-on-valid,
            llvm:transforms
      </td>
    </tr>

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

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

<pre>
    This IR:

```
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128-Fn32"
target triple = "aarch64-unknown-linux-gnu"

define void @_Z1fv() #0 {
entry:
 br label %for.body

for.cond.loopexit.loopexit:                       ; preds = %for.body
  ret void

for.body: ; preds = %for.body, %entry
  %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
  %add15.lcssa1921 = phi i32 [ 0, %entry ], [ %add.1, %for.body ]
  %conv8 = sext i16 0 to i32
  %add = add i32 %add15.lcssa1921, %conv8
  %conv8.1 = sext i16 0 to i32
  %add.1 = add i32 %add, %conv8.1
  store i32 %add.1, ptr null, align 4
  %indvars.iv.next = add i64 %indvars.iv, 1
  %0 = and i64 %indvars.iv.next, 255
  %exitcond.not = icmp eq i64 %0, 0
  br i1 %exitcond.not, label %for.cond.loopexit.loopexit, label %for.body
}

attributes #0 = { "target-cpu"="grace" }
```

Triggers this assert:

```
opt: /root/llvm-project/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp:8181: llvm::VPRecipeBase* llvm::VPRecipeBuilder::tryToCreatePartialReduction(llvm::VPInstruction*, unsigned int): Assertion `ScaleFactor == vputils::getVFScaleFactor(Accumulator->getDefiningRecipe()) && "all accumulators in chain must have same scale factor"' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace and instructions to reproduce the bug.
Stack dump:
0.      Program arguments: /opt/compiler-explorer/clang-assertions-trunk/bin/opt -o /app/output.s -S -S -passes=loop-vectorize <source>
1.      Running pass "function(loop-vectorize<no-interleave-forced-only;no-vectorize-forced-only;>)" on module "<source>"
2.      Running pass "loop-vectorize<no-interleave-forced-only;no-vectorize-forced-only;>" on function "_Z1fv"
 #0 0x00000000059ad0e8 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x59ad0e8)
 #1 0x00000000059a9f94 SignalHandler(int, siginfo_t*, void*) Signals.cpp:0:0
 #2 0x00007efe89442520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
 #3 0x00007efe894969fc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969fc)
 #4 0x00007efe89442476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
 #5 0x00007efe894287f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
 #6 0x00007efe8942871b (/lib/x86_64-linux-gnu/libc.so.6+0x2871b)
 #7 0x00007efe89439e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
 #8 0x00000000036b2f1b llvm::VPRecipeBuilder::tryToCreatePartialReduction(llvm::VPInstruction*, unsigned int) (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x36b2f1b)
 #9 0x00000000036b599f llvm::VPRecipeBuilder::tryToCreateWidenRecipe(llvm::VPSingleDefRecipe*, llvm::VFRange&) (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x36b599f)
#10 0x00000000036d4e5e llvm::LoopVectorizationPlanner::tryToBuildVPlanWithVPRecipes(std::unique_ptr<llvm::VPlan, std::default_delete<llvm::VPlan>>, llvm::VFRange&, llvm::LoopVersioning*) (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x36d4e5e)
#11 0x00000000036d63a8 llvm::LoopVectorizationPlanner::buildVPlansWithVPRecipes(llvm::ElementCount, llvm::ElementCount) (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x36d63a8)
```

Compile with: `opt -S -passes=loop-vectorize`, see also: https://godbolt.org/z/7oedf34Pq

Reproduced from this C reproducer:

```
int a, b;
extern char e;
int *c;
short *d;
void f() {
  for (int g;;)
    for (char h; h < 20; h++) {
      a = c[h];
 for (int i = 0; i < 22; i += 3) {
        e = 0;
        b += d[g];
 }
    }
}
```
</pre>
<img width="1" height="1" alt="" src="http://email.email.llvm.org/o/eJy8WF-P4jgS_zTmxQpKbBLCAw8BGt1K-9DqHs1K99JykkrwjLEztsN076c_lRMgMD2717ejQ2k6jqt-9cdVlSqEc7LVAGuSbki6m4neH4xduy8GbH0E-QXsrDT12_rTQTr62xPhBYnDlcXjFRde2BY8rYUXSryZ3lPCd5QwBtGR8AKiji1jwgvOwhcuk9sl3mWL8BXJnPAiH7ZkkhFehC9cXUgShgQJyyPNB97oGVd7XDJ21clb2Sk46yOErQ7ZIur1V22-60hJ3b9Gre4HHhIXNTRSAz0ZWVOyiF_-nTQnwnLCVpQwHlOy3JC4AO3t2-AKWlqqRAmKEpY2xs7RWwMWriqj67kypoNX6S83hBf0_Q_hG9pZqN2o8hSSUgs-qHbFD1u8-As-tsXloDFiEJZKXZ-EdXN5CtTdQVKZLShJNzSe0lOS7sI63dyyzTW8-pHyLCgQjwJEXSfpXFXOiWTFkqsUzv5WiqjrefIX2JXRpzwgOnj1VCYZjak3iD0RHwjwfxD5g0YjfsC6AZ4nfws9ktyCTwHnSaB23liYkAxWdd5S3SuF90LJVtPFj8cS_HuVgmcz3Ube5MwVD3T6HbrLMbE0PZNj-IWg1GaQIKtjR-HbmTscTRyoS0tlcs-D2zfx_pMIvyc7p8VyNwSv8N7KsvfgxsTCsF1iBLAhdaOqC2nJd4Sx1ooKCGN05J8UHxIXn6xsW7COeixSwjmw_t1CZbqQeoTtrUFT9kqdjlFnzReozkv8J0vC9p-s0K4x9ugI23-Gyhsr_wTC9r8b013W86rrsF4lOZY0GhB4QXjx-fEJKtnBRjgg7N2dXqoa7PDQ27dPZmtBeHgU1kuhnqDuKy-NJiyfMv-mnbfnnQId3etQxGsqtSdshXoUwQnSaEqy-LkSCvYCNUY_o6tPXe-lcgNmC_7zfkJEWF5UVX_slfDGRoQ_tOB3WBmlbgfdh5o4lMWMsCxUV6WouPI5KjWtDkJqeuydpwdxAurEEahDUbQZZTHClrQRUkE9J3Hx-PtD8fxAXV8epaeCln1LLXTGekzFg_dd0JrtCdu30h_6cl6Z4-Twbo9UOtcDnuCQIrpSfQ3UH4BWVrgDLUX11WN0jfsX3zoUZ6Gzpu6rgaPsW9Tw2YvqK637YzcEWTwn8erRmtaKIxW27Y-gvRsDDUOO7Stz7KQCG8Frp4wFi8-U0G0kzgflIm97_ZWwfSn1wEgjgxCi63Dd-673c0ej53B1yOkI32HKRadzPFLCt870tgLCH0hcJKjcU6_x6Cjy4Ek1vb5E1g034VttIqk9WAXiBFFjbAV1ZLR6I3yjzZX0bgulYUAwajQ9mrrHty6m70Sb8JJl7yn0S7UIKpxNRPTxLR6KeCg28Wt8_qQrUceQT9LTvY1p8Wil9uGwPw3lZ5KGVnx_Mc5bEMeQANsx92hIjH906oRt4tdRLXTpoHRyp_SqWS3os2y1UP8SulYIngcdttTJVurGvPixPoSWAW9XI4cbq1Yc_gYBbBSwhAby1WLBUhaP1gz18DXPXrLFtGfCjWruzDwLOgeWq8b8FnCVrZqKdv5gQdQvX6VSH0MP_Ff0xb26i2VGWxfM-6jai2V2BU5vgVm-bDgVJdafD8EGxits9gNsUn4YMCmvgMtbQL6CVfYxwMByBcynEcazkjVJ-X98a_2qzBk1v9q1urMrXa2aD9j1h6xBX156U75nqVsFO2jOu8GsCcX-SegWQn34leahAYN5WBfiW_PqBaQwUWLarAgEflRC6xs7g-Wf8fkf0h_O_nCE5c7XA12v5bceXjpvCd9OfaCEDhXnTFhDI3rlX2pQ4OEdYv4QavTP_LT9QXXrpMF3xVjAfpkbg6Oubkzu3Jhxkf_XbiwvHnT3LrxCPCjAxmBr-qFK_2znV9qIVow23rbM2wGWfpf-EDqVLA4Nx88bC2TFkwagQjmDTHfNmKlLo_zc2Jaw_Z-E7ZcG6oYvHr8NMp_OzVRNG2uOQ7e-vfZY9t2eXWpPBUou8f0eF_DqwYbG0lIYHiEJYUU1rNxhqNVFPazDLN-ch_gwv1PaYCscXpi0DX3DZiwY9LIXJBxwsD5gU0VZHO4J24TrioUfEQaYiqSbA86qQfBUiAz7AUEOaGy8Zxvc4feAlMKFZfKwPDPUJN20V1HDXBR-QRgmpNs5aVaveb3iKzGDdbLM2DLJ84TPDuuGx8sc8iRveCmgZCAqlpfpMi7TnDclzOSaxSxNknjF4jhL-XyZLFgcc87zZsE4y8kihqOQao7xjIc_Cy33OsmWbMFnYQh04eclxi7BZF3o-7eEsdCGR0ZHJ6GwTRkfj9nhJ0MYI-luZtehwS_71pFFrKTz7irZS6_CT1m_fybpbhyC_sloMuutWv_vM8fog9Oa_ScAAP__B2XVHg">