[llvm-bugs] [Bug 49575] New: fix-irreducible pass crashes: Assertion `LI.isLoopHeader(Headers.front())' failed.

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=49575

            Bug ID: 49575
           Summary: fix-irreducible pass crashes: Assertion
                    `LI.isLoopHeader(Headers.front())' failed.
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Transformation Utilities
          Assignee: unassignedbugs at nondot.org
          Reporter: cszide at 163.com
                CC: llvm-bugs at lists.llvm.org

Created attachment 24640
  --> https://bugs.llvm.org/attachment.cgi?id=24640&action=edit
small.bc

$clang -v
clang version 13.0.0 (https://github.com/llvm/llvm-project.git
77394c12a48822bb7a9183408f922d90c1d563cd)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/jack-zhou/Documents/llvm/llvm_truck/llvm-project/build/bin
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/10
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8.5
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5.5.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6.5.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.5.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/8
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/10
Candidate multilib: .;@m64
Selected multilib: .;@m64

$clang -O3 -c -emit-llvm -femit-all-decls -mllvm -disable-llvm-optzns small.c
-o small.bc

$opt -fix-irreducible -simplifycfg -fix-irreducible small.bc -o small-opt.bc
opt:
/home/jack-zhou/Documents/llvm/llvm_truck/llvm-project/llvm/lib/Transforms/Utils/FixIrreducible.cpp:297:
bool makeReducible(llvm::LoopInfo&, llvm::DominatorTree&, Graph&&) [with Graph
= llvm::Loop&]: Assertion `LI.isLoopHeader(Headers.front())' failed.
PLEASE submit a bug report to https://bugs.llvm.org/ and include the crash
backtrace.
Stack dump:
0.      Program arguments:
/home/jack-zhou/Documents/llvm/llvm_truck/llvm-project/build/bin/opt
-fix-irreducible -simplifycfg -fix-irreducible small.bc -o small-opt.bc
1.      Running pass 'Function Pass Manager' on module 'small.bc'.
2.      Running pass 'Convert irreducible control-flow into natural loops' on
function '@c'
 #0 0x0000557d90d7a5ec llvm::sys::PrintStackTrace(llvm::raw_ostream&, int)
(/home/jack-zhou/Documents/llvm/llvm_truck/llvm-project/build/bin/opt+0x2e865ec)
 #1 0x0000557d90d782b4 llvm::sys::RunSignalHandlers()
(/home/jack-zhou/Documents/llvm/llvm_truck/llvm-project/build/bin/opt+0x2e842b4)
 #2 0x0000557d90d78423 SignalHandler(int) Signals.cpp:0:0
 #3 0x00007f62d2f8d8a0 __restore_rt
(/lib/x86_64-linux-gnu/libpthread.so.0+0x128a0)
 #4 0x00007f62d1bf4f47 raise
/build/glibc-2ORdQG/glibc-2.27/signal/../sysdeps/unix/sysv/linux/raise.c:51:0
 #5 0x00007f62d1bf68b1 abort /build/glibc-2ORdQG/glibc-2.27/stdlib/abort.c:81:0
 #6 0x00007f62d1be642a __assert_fail_base
/build/glibc-2ORdQG/glibc-2.27/assert/assert.c:89:0
 #7 0x00007f62d1be64a2 (/lib/x86_64-linux-gnu/libc.so.6+0x304a2)
 #8 0x0000557d90e00b16 FixIrreducibleImpl(llvm::Function&, llvm::LoopInfo&,
llvm::DominatorTree&) FixIrreducible.cpp:0:0
 #9 0x0000557d90529918 llvm::FPPassManager::runOnFunction(llvm::Function&)
(/home/jack-zhou/Documents/llvm/llvm_truck/llvm-project/build/bin/opt+0x2635918)
#10 0x0000557d9052a449 llvm::FPPassManager::runOnModule(llvm::Module&)
(/home/jack-zhou/Documents/llvm/llvm_truck/llvm-project/build/bin/opt+0x2636449)
#11 0x0000557d90529196 llvm::legacy::PassManagerImpl::run(llvm::Module&)
(/home/jack-zhou/Documents/llvm/llvm_truck/llvm-project/build/bin/opt+0x2635196)
#12 0x0000557d8e86ac0d main
(/home/jack-zhou/Documents/llvm/llvm_truck/llvm-project/build/bin/opt+0x976c0d)
#13 0x00007f62d1bd7b97 __libc_start_main
/build/glibc-2ORdQG/glibc-2.27/csu/../csu/libc-start.c:344:0
#14 0x0000557d8e933eaa _start
(/home/jack-zhou/Documents/llvm/llvm_truck/llvm-project/build/bin/opt+0xa3feaa)
Aborted (core dumped)

The source code of small.c is as follows.
--------------------------------------------------------
int a;
char(b)();
static short c() {
  if (b())
  d:;
  e:
    for (;;) {
      int f;
      if (a)
        goto e;
      for (; 0;)
        goto d;
    }
}

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