[llvm-bugs] [Bug 42422] New: newgvn crashes with "opt -functionattrs -simplifycfg -gvn -newgvn": Assertion `BeforeCC->isEquivalentTo(AfterCC) && "Value number changed after main loop completed!"' failed.

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=42422

            Bug ID: 42422
           Summary: newgvn crashes with "opt -functionattrs -simplifycfg
                    -gvn -newgvn":  Assertion
                    `BeforeCC->isEquivalentTo(AfterCC) && "Value number
                    changed after main loop completed!"' failed.
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Scalar Optimizations
          Assignee: unassignedbugs at nondot.org
          Reporter: cszide at 163.com
                CC: llvm-bugs at lists.llvm.org

Created attachment 22152
  --> https://bugs.llvm.org/attachment.cgi?id=22152&action=edit
.bc file of the source code

$clang -v
clang version 9.0.0 (trunk 363125)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/jack-zhou/Documents/llvm/llvm_truck/llvm2/build1/bin
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/8
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/7.4.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/8
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.4.0
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Candidate multilib: x32;@mx32
Selected multilib: .;@m64


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

$opt -functionattrs -simplifycfg -gvn -newgvn  small.bc -o small-opt.bc
opt:
/home/jack-zhou/Documents/llvm/llvm_truck/llvm2/lib/Transforms/Scalar/NewGVN.cpp:3296:
void {anonymous}::NewGVN::verifyIterationSettled(llvm::Function&): Assertion
`BeforeCC->isEquivalentTo(AfterCC) && "Value number changed after main loop
completed!"' failed.
Stack dump:
0.      Program arguments:
/home/jack-zhou/Documents/llvm/llvm_truck/llvm2/build1/bin/opt -functionattrs
-simplifycfg -gvn -newgvn small.bc -o small-opt.bc 
1.      Running pass 'CallGraph Pass Manager' on module 'small.bc'.
2.      Running pass 'Global Value Numbering' on function '@d'
 #0 0x000055ad55b3f87a llvm::sys::PrintStackTrace(llvm::raw_ostream&)
(/home/jack-zhou/Documents/llvm/llvm_truck/llvm2/build1/bin/opt+0x257887a)
 #1 0x000055ad55b3d534 llvm::sys::RunSignalHandlers()
(/home/jack-zhou/Documents/llvm/llvm_truck/llvm2/build1/bin/opt+0x2576534)
 #2 0x000055ad55b3d672 SignalHandler(int)
(/home/jack-zhou/Documents/llvm/llvm_truck/llvm2/build1/bin/opt+0x2576672)
 #3 0x00007f1105787890 __restore_rt
(/lib/x86_64-linux-gnu/libpthread.so.0+0x12890)
 #4 0x00007f1104439e97 raise
/build/glibc-OTsEL5/glibc-2.27/signal/../sysdeps/unix/sysv/linux/raise.c:51:0
 #5 0x00007f110443b801 abort /build/glibc-OTsEL5/glibc-2.27/stdlib/abort.c:81:0
 #6 0x00007f110442b39a __assert_fail_base
/build/glibc-OTsEL5/glibc-2.27/assert/assert.c:89:0
 #7 0x00007f110442b412 (/lib/x86_64-linux-gnu/libc.so.6+0x30412)
 #8 0x000055ad559e61e2 (anonymous namespace)::NewGVN::runGVN()
(/home/jack-zhou/Documents/llvm/llvm_truck/llvm2/build1/bin/opt+0x241f1e2)
 #9 0x000055ad559e7abf (anonymous
namespace)::NewGVNLegacyPass::runOnFunction(llvm::Function&) (.part.1399)
(/home/jack-zhou/Documents/llvm/llvm_truck/llvm2/build1/bin/opt+0x2420abf)
#10 0x000055ad554f8189 llvm::FPPassManager::runOnFunction(llvm::Function&)
(/home/jack-zhou/Documents/llvm/llvm_truck/llvm2/build1/bin/opt+0x1f31189)
#11 0x000055ad54de2793 (anonymous
namespace)::CGPassManager::runOnModule(llvm::Module&)
(/home/jack-zhou/Documents/llvm/llvm_truck/llvm2/build1/bin/opt+0x181b793)
#12 0x000055ad554f73e1 llvm::legacy::PassManagerImpl::run(llvm::Module&)
(/home/jack-zhou/Documents/llvm/llvm_truck/llvm2/build1/bin/opt+0x1f303e1)
#13 0x000055ad53de00a9 main
(/home/jack-zhou/Documents/llvm/llvm_truck/llvm2/build1/bin/opt+0x8190a9)
#14 0x00007f110441cb97 __libc_start_main
/build/glibc-OTsEL5/glibc-2.27/csu/../csu/libc-start.c:344:0
#15 0x000055ad53e653fa _start
(/home/jack-zhou/Documents/llvm/llvm_truck/llvm2/build1/bin/opt+0x89e3fa)
Aborted (core dumped)

----------------------------------------------
int a, b, c;
char d() {
  long e;
  for (;;) {
    int f = 0;
    for (; f <= 1; f++) {
      long g = 4;
      for (; a;)
        return 4;
      for (;;) {
        int h;
        if (b)
          break;
        e = 0;
        for (; e <= 1; e++)
          ;
        if (g)
          return c;
      }
    }
  }
}

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