<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/119556>119556</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Crash with -enable-ipra for trivial internal linkage functions for RISC-V/AArch64/Arm
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            backend:ARM,
            backend:AArch64,
            backend:RISC-V,
            ipo
      </td>
    </tr>

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

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

<pre>
    Reading #72129 it looks like there might have already been some related work looking at issues here - I'd really appreciate confirmation from @JanekvO / @arsenm on the status of this from an AMDGPU perspective and any other thoughts given it sounds like you've spent much more time looking into issues in this area. Many thanks in advance for any input.

Essentially, we see a crash for RISCV/AArch64/ARM for some internal linkage functions, notably even one that is just `ret void`. x86-64 and other targets don't fail. I've tracked down that disabling the machine outliner (i.e. `setMachineOutlin(false)` in RISCVTargetmachine) means there is no crash, and the function is completely elided, as it is for x86-64 and other targets.

Crash:
```
$ cat tc.ll 
define internal void @foo() {
  ret void
}
$ llc -mtriple=riscv64 -enable-ipra < tc.ll
llc: /home/asb/llvm-project/llvm/include/llvm/ADT/ilist_iterator.h:168: reference llvm::ilist_iterator<llvm::ilist_detail::node_options<llvm::MachineBasicBlock, true, false, void, false, void>, false, false>::operator*() const [OptionsT = llvm::ilist_detail::node_options<llvm::MachineBasicBlock, true, false, void, false, void>, IsReverse = false, IsConst = false]: Assertion `!NodePtr->isKnownSentinel()' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
Stack dump:
0.      Program arguments: ./build/default/bin/llc -mtriple=riscv64 -verify-machineinstrs -enable-ipra
1.      Running pass 'Function Pass Manager' on module '<stdin>'.
2.      Running pass 'RISC-V Assembly Printer' on function '@foo'
 #0 0x00007f66d4042e4d llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) /home/asb/llvm-project/llvm/lib/Support/Unix/Signals.inc:723:11
 #1 0x00007f66d404343b PrintStackTraceSignalHandler(void*) /home/asb/llvm-project/llvm/lib/Support/Unix/Signals.inc:798:1
 #2 0x00007f66d4041003 llvm::sys::RunSignalHandlers() /home/asb/llvm-project/llvm/lib/Support/Signals.cpp:105:5
 #3 0x00007f66d4043cd1 SignalHandler(int) /home/asb/llvm-project/llvm/lib/Support/Unix/Signals.inc:413:1
 #4 0x00007f66d6a5a770 (/usr/lib/libc.so.6+0x3c770)
 #5 0x00007f66d6aab32c (/usr/lib/libc.so.6+0x8d32c)
 #6 0x00007f66d6a5a6c8 raise (/usr/lib/libc.so.6+0x3c6c8)
 #7 0x00007f66d6a424b8 abort (/usr/lib/libc.so.6+0x244b8)
 #8 0x00007f66d6a423dc (/usr/lib/libc.so.6+0x243dc)
 #9 0x00007f66d6a52d46 (/usr/lib/libc.so.6+0x34d46)
#10 0x00007f66da81960f llvm::ilist_iterator<llvm::ilist_detail::node_options<llvm::MachineBasicBlock, true, false, void, false, void>, false, false>::operator*() const /home/asb/llvm-project/llvm/include/llvm/ADT/ilist_iterator.h:0:5
#11 0x00007f66da82bcef llvm::simple_ilist<llvm::MachineBasicBlock>::front() /home/asb/llvm-project/llvm/include/llvm/ADT/simple_ilist.h:144:30
#12 0x00007f66da81695c llvm::MachineFunction::front() /home/asb/llvm-project/llvm/include/llvm/CodeGen/MachineFunction.h:940:44
#13 0x00007f66da7fadda llvm::AsmPrinter::emitFunctionHeader() /home/asb/llvm-project/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp:963:11
#14 0x00007f66da7fea36 llvm::AsmPrinter::emitFunctionBody() /home/asb/llvm-project/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp:1783:3
#15 0x00007f66de471ea9 (anonymous namespace)::RISCVAsmPrinter::runOnMachineFunction(llvm::MachineFunction&) /home/asb/llvm-project/llvm/lib/Target/RISCV/RISCVAsmPrinter.cpp:476:3
#16 0x00007f66d8428a5c llvm::MachineFunctionPass::runOnFunction(llvm::Function&) /home/asb/llvm-project/llvm/lib/CodeGen/MachineFunctionPass.cpp:94:8
#17 0x00007f66d4af5ae5 llvm::FPPassManager::runOnFunction(llvm::Function&) /home/asb/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:1406:23
#18 0x00007f66d4afad4f llvm::FPPassManager::runOnModule(llvm::Module&) /home/asb/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:1452:16
#19 0x00007f66d4af64cb (anonymous namespace)::MPPassManager::runOnModule(llvm::Module&) /home/asb/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:1521:23
#20 0x00007f66d4af5fb4 llvm::legacy::PassManagerImpl::run(llvm::Module&) /home/asb/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:539:16
#21 0x00007f66d4afb051 llvm::legacy::PassManager::run(llvm::Module&) /home/asb/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:1648:3
#22 0x000055612c1f6ceb compileModule(char**, llvm::LLVMContext&) /home/asb/llvm-project/llvm/tools/llc/llc.cpp:753:9
#23 0x000055612c1f4d26 main /home/asb/llvm-project/llvm/tools/llc/llc.cpp:411:13
#24 0x00007f66d6a43cd0 (/usr/lib/libc.so.6+0x25cd0)
#25 0x00007f66d6a43d8a __libc_start_main (/usr/lib/libc.so.6+0x25d8a)
#26 0x000055612c1f4415 _start (./build/default/bin/llc+0x49415)
```

Successful compilation for x86-64:
```
$ llc -mtriple=x86_64 -verify-machineinstrs < tc.ll -enable-ipra
        .text
        .file   "<stdin>"
        .section        ".note.GNU-stack","",@progbits
```
</pre>
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