<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/62402>62402</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [InstCombine] LLVM ERROR: instruction precedes `landingpad` intrinsic after optimization
        </td>
    </tr>

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

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

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

<pre>
    Reproducer: https://godbolt.org/z/sea53Wsda
Crashing input before optimization:
```llvm
define <4 x float> @bad3(float %a) {
  %t = insertelement <4 x float> poison, float %a, i32 0
  %out.i = callbr i32 asm "# $0", "=r,!i"()
          to label %direct.i [label %entry.indirect_crit_edge.i]

entry.indirect_crit_edge.i: ; preds = %0
  %1 = call i32 @llvm.callbr.landingpad.i32(i32 %out.i)
  %t6 = insertelement <4 x float> %t, float %a, i32 %1
  ret <4 x float> %t6

direct.i:                                         ; preds = %0
  unreachable
}
```

Crashing input after the InstCombine pass:
```llvm
define <4 x float> @bad3(float %a) {
  %out.i = callbr i32 asm "# $0", "=r,!i"() #1
          to label %direct.i [label %entry.indirect_crit_edge.i]

entry.indirect_crit_edge.i: ; preds = %0
  %t = insertelement <4 x float> poison, float %a, i64 0
  %1 = call i32 @llvm.callbr.landingpad.i32(i32 %out.i)
  %t6 = insertelement <4 x float> %t, float %a, i32 %1
  ret <4 x float> %t6

direct.i:                                         ; preds = %0
 unreachable
}
```

Here is the stack dump:
```
No other instructions may proceed intrinsic
  %1 = call i32 @llvm.callbr.landingpad.i32(i32 %out.i)
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/compiler-explorer/clang-assertions-trunk/bin/opt -o /app/output.s -S -passes=instcombine <source>
 #0 0x000055ac72b0cf8f llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x357cf8f)
 #1 0x000055ac72b0a6b4 SignalHandler(int) Signals.cpp:0:0
 #2 0x00007fd2fb1bc420 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x14420)
 #3 0x00007fd2fac8900b raise (/lib/x86_64-linux-gnu/libc.so.6+0x4300b)
 #4 0x00007fd2fac68859 abort (/lib/x86_64-linux-gnu/libc.so.6+0x22859)
 #5 0x000055ac6fe0913e llvm::SuffixTree::insertLeaf(llvm::SuffixTreeNode&, unsigned int, unsigned int) (.cold) SuffixTree.cpp:0:0
 #6 0x000055ac72a60f5e (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x34d0f5e)
 #7 0x000055ac72442753 (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x2eb2753)
 #8 0x000055ac6fef28f6 llvm::detail::PassModel<llvm::Module, llvm::VerifierPass, llvm::PreservedAnalyses, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x9628f6)
 #9 0x000055ac7240662d llvm::PassManager<llvm::Module, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x2e7662d)
#10 0x000055ac6fefe435 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) (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x96e435)
#11 0x000055ac6fe13d86 main (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x883d86)
#12 0x00007fd2fac6a083 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x24083)
#13 0x000055ac6fef1a0e _start (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x961a0e)
Compiler returned: 139
```
As the title says, it looks like the InstCombine pass moves the `insertelement` instruction in front of the `landingpad` intrinsic in the same basic block which triggers a verifier error. 
</pre>
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