<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/107305>107305</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            LoadStoreVectorizer hits assert, miscompiles with asserts disabled in corner case
        </td>
    </tr>

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

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

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

<pre>
    Miscompilation (assertions disabled): https://godbolt.org/z/8hPsxfneP

Crash (assertions enabled): https://godbolt.org/z/4vM9eqoqG

IR Input:

```
define void @shrink_after_gep(i32 addrspace(3)* %p) {
entry:
  %a.ascast = addrspacecast i32 addrspace(3)* %p to i32*
 %b.ascast = addrspacecast i32 addrspace(3)* %p to i32*
  %gep1 = getelementptr inbounds i32, i32* %a.ascast, i64 8589934592 ;0x2000000000000000
  %gep2 = getelementptr inbounds i32, i32* %b.ascast, i64 17179869185 ;0x4000000000000001
  %tmp1 = load i32, i32* %gep1, align 8
  %tmp2 = load i32, i32* %gep2, align 8
 unreachable
}
```

`stripAndAccumulateInBoundsConstantOffsets` truncates the offset to the lower 32 bits, upon which the difference between offsets becomes 1. However, the addresses are not really consecutive. 

```
Stack dump:

0.      Program arguments: /home/ce/llvm-install/bin/opt -o /tmp/compiler-explorer-compiler202484-1060-14c40xj.p8sq/output.s -S -passes=load-store-vectorizer <source>

1.      Running pass "function(load-store-vectorizer)" on module "<source>"

2.      Running pass "load-store-vectorizer" on function "shrink_after_gep"

 #0 0x000055be4aba7dd0 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/home/ce/llvm-install/bin/opt+0x5587dd0)

 #1 0x000055be4aba4def llvm::sys::RunSignalHandlers() (/home/ce/llvm-install/bin/opt+0x5584def)

 #2 0x000055be4aba4f45 SignalHandler(int) Signals.cpp:0:0

 #3 0x00007ff54339f520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)

 #4 0x00007ff5433f39fc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969fc)

 #5 0x00007ff54339f476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)

 #6 0x00007ff5433857f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)

 #7 0x00007ff54338571b (/lib/x86_64-linux-gnu/libc.so.6+0x2871b)

 #8 0x00007ff543396e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)

 #9 0x000055be49a95cb7 (anonymous namespace)::Vectorizer::getConstantOffset(llvm::Value*, llvm::Value*, llvm::Instruction*, unsigned int) LoadStoreVectorizer.cpp:0:0

#10 0x000055be49a9a659 (anonymous namespace)::Vectorizer::gatherChains(llvm::ArrayRef<llvm::Instruction*>) LoadStoreVectorizer.cpp:0:0

#11 0x000055be49a9bf75 (anonymous namespace)::Vectorizer::run() LoadStoreVectorizer.cpp:0:0

#12 0x000055be49a9e380 llvm::LoadStoreVectorizerPass::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/home/ce/llvm-install/bin/opt+0x447e380)

#13 0x000055be469d5df6 llvm::detail::PassModel<llvm::Function, llvm::LoadStoreVectorizerPass, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/home/ce/llvm-install/bin/opt+0x13b5df6)

#14 0x000055be4a989f2f llvm::PassManager<llvm::Function, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/home/ce/llvm-install/bin/opt+0x5369f2f)

#15 0x000055be469d5e96 llvm::detail::PassModel<llvm::Function, llvm::PassManager<llvm::Function, llvm::AnalysisManager<llvm::Function>>, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/home/ce/llvm-install/bin/opt+0x13b5e96)

#16 0x000055be4a988cf7 llvm::ModuleToFunctionPassAdaptor::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/home/ce/llvm-install/bin/opt+0x5368cf7)

#17 0x000055be469d4d96 llvm::detail::PassModel<llvm::Module, llvm::ModuleToFunctionPassAdaptor, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/home/ce/llvm-install/bin/opt+0x13b4d96)

#18 0x000055be4a9871e5 llvm::PassManager<llvm::Module, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/home/ce/llvm-install/bin/opt+0x53671e5)

#19 0x000055be4648ffe4 llvm::runPassPipeline(llvm::StringRef, llvm::Module&, llvm::TargetMachine*, llvm::TargetLibraryInfoImpl*, llvm::ToolOutputFile*, llvm::ToolOutputFile*, llvm::ToolOutputFile*, llvm::StringRef, llvm::ArrayRef<llvm::PassPlugin>, llvm::ArrayRef<std::function<void (llvm::PassBuilder&)>>, llvm::opt_tool::OutputKind, llvm::opt_tool::VerifierKind, bool, bool, bool, bool, bool, bool, bool) (/home/ce/llvm-install/bin/opt+0xe6ffe4)

#20 0x000055be464805ad optMain (/home/ce/llvm-install/bin/opt+0xe605ad)

#21 0x00007ff543386d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)

#22 0x00007ff543386e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)

#23 0x000055be464740b5 _start (/home/ce/llvm-install/bin/opt+0xe540b5)

Compiler returned: -1
```
</pre>
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