clang crash for target BPF

clang crash for target BPF

[Andrei Matei]

Hello,

I've encountered an assertion failure / crash on clang master 
(5de09ef02e24) as well as the older version 11. Happens for "-target 
bpf", not otherwise.
I've reported it to clang but there's been no response so far. Alexei, I 
believe you've invited me to raise the issue here.
clang bugzilla: https://bugs.llvm.org/show_bug.cgi?id=48578


The repro program and instructions are in the bug report above.
The assertion failure reads:

clang: 
/home/andrei/src/llvm-project/llvm/lib/CodeGen/LiveVariables.cpp:130: 
void llvm::LiveVariables::HandleVirtRegUse(llvm::Register, 
llvm::MachineBasicBlock*, llvm::MachineInstr&): Assertion 
`MRI->getVRegDef(Reg) && "Register use before def!"' failed.
PLEASE submit a bug report to https://bugs.llvm.org/ and include the 
crash backtrace, preprocessed source, and associated run script.
Stack dump:
0.      Program arguments: bin/clang -O2 -target bpf -c -o probe.bpf.o 
/home/andrei/Downloads/probe.bpf.preprocessed.c
1.      <eof> parser at end of file
2.      Code generation
3.      Running pass 'Function Pass Manager' on module 
'/home/andrei/Downloads/probe.bpf.preprocessed.c'.
4.      Running pass 'Live Variable Analysis' on function '@probe'


Thanks!

Re: clang crash for target BPF

[Yonghong Song]

On 2/28/21 2:14 PM, Andrei Matei wrote:
> Hello,
> 
> I've encountered an assertion failure / crash on clang master 
> (5de09ef02e24) as well as the older version 11. Happens for "-target 
> bpf", not otherwise.
> I've reported it to clang but there's been no response so far. Alexei, I 
> believe you've invited me to raise the issue here.
> clang bugzilla: 
> https://bugs.llvm.org/show_bug.cgi?id=48578 
> 
> 
> The repro program and instructions are in the bug report above.
> The assertion failure reads:
> 
> clang: 
> /home/andrei/src/llvm-project/llvm/lib/CodeGen/LiveVariables.cpp:130: 
> void llvm::LiveVariables::HandleVirtRegUse(llvm::Register, 
> llvm::MachineBasicBlock*, llvm::MachineInstr&): Assertion 
> `MRI->getVRegDef(Reg) && "Register use before def!"' failed.
> PLEASE submit a bug report to 
> https://bugs.llvm.org/  
> and include the crash backtrace, preprocessed source, and associated run 
> script.
> Stack dump:
> 0.      Program arguments: bin/clang -O2 -target bpf -c -o probe.bpf.o 
> /home/andrei/Downloads/probe.bpf.preprocessed.c
> 1.      <eof> parser at end of file
> 2.      Code generation
> 3.      Running pass 'Function Pass Manager' on module 
> '/home/andrei/Downloads/probe.bpf.preprocessed.c'.
> 4.      Running pass 'Live Variable Analysis' on function '@probe'

Andrei, Thanks for reporting. I can reproduce with latest llvm trunk.
Will take a look and comment in the above bugzilla report whenever
I find anything. Thanks again!

> 
> 
> Thanks!
>