[error] Uh oh! Mull corrupted LLVM module (Tarantool, tzcode)

[ligurio]

How to reproduce:

$ git clone https://github/tarantool/tarantool
$ cd tarantool/src/lib/tzcode
$ mkdir build
$ cmake -DCMAKE_C_FLAGS="-fembed-bitcode -g -O0  -fexperimental-new-pass-manager -fpass-plugin=/usr/lib/mull-ir-frontend-12 -grecord-command-line" -DCMAKE_CXX_FLAGS="-fembed-bitcode -g -O0  -fexperimental-new-pass-manager -fpass-plugin=/usr/lib/mull-ir-frontend-12 -grecord-command-line" -DCMAKE_BUILD_TYPE=Debug  -DCMAKE_EXPORT_COMPILE_COMMANDS=ON  -DCMAKE_C_COMPILER="/usr/bin/clang-12" -DCMAKE_CXX_COMPILER="/usr/bin/clang++-12" ..

$ make
...
       [################################] 1/1. Finished in 0ms
[info] Applying mutations (threads: 1)
       [################################] 32/32. Finished in 11ms
[error] Uh oh! Mull corrupted LLVM module.
Please, report the following error message here https://github.com/mull-project/mull/issues
Underlying error message:
PHINode should have one entry for each predecessor of its parent basic block!
  %422 = phi i1 [ false, %410 ], [ false, %407 ], [ %420, %415 ], !dbg !3013 

[error] Error messages are treated as fatal errors. Exiting now.
make[2]: *** [CMakeFiles/tzcode.dir/build.make:95: CMakeFiles/tzcode.dir/strptime.c.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:95: CMakeFiles/tzcode.dir/all] Error 2
make: *** [Makefile:103: all] Error 2

mull.yml:

sergeyb@pony:~/sources/MRG/tarantool/build$ cat ../mull.yml 
mutators:
 - cxx_logical
includePaths:
 - src
excludePaths:
 - third_party
 - test
 - src/lib/small
quiet: false

Source: https://github.com/tarantool/tarantool/blob/master/src/lib/tzcode/strptime.c

$ mull-runner-12 --version
Mull: Practical mutation testing for C and C++
Home: https://github.com/mull-project/mull
Docs: https://mull.readthedocs.io
Version: 0.17.1
Commit: ac98382
Date: 17 Mar 2022
LLVM: 12.0.0

[AlexDenisov]

There is an issue with cxx_logical_and_to_or.

I'll keep investigating it, but as a temporary workaround I can suggest not using this specific mutator: you can replace cxx_logical with cxx_logical_or_to_and and cxx_remove_negation.

[ligurio]

@AlexDenisov I'll try, thanks!

[AlexDenisov]

Smallest reproducer I could get:

void a() {
  int c;
  c = c && c && c;
}

with the following mull.yml

mutators:
  - cxx_logical_and_to_or

and this command:

> clang -g -O0  -fexperimental-new-pass-manager -fpass-plugin=/usr/local/lib/mull-ir-frontend-12 -grecord-command-line -c test.c
[error] Uh oh! Mull corrupted LLVM module.
Please, report the following error message here https://github.com/mull-project/mull/issues
Underlying error message:
PHINode should have one entry for each predecessor of its parent basic block!
  %11 = phi i1 [ false, %4 ], [ false, %0 ], [ %9, %7 ], !dbg !18

[error] Error messages are treated as fatal errors. Exiting now.

@stanislaw do you have any ideas? Seems like a 'trivial' case (or a family of cases) is not handled 😃

[AlexDenisov]

Actually, the same happens with cxx_logical_or_to_and and

void a() {
  int c;
  c = c || c || c;
}

[AlexDenisov]

This specific issue is fixed here #998.
I'll add a few more features to debug/workaround such issues in the future and then will cut a new release.

[AlexDenisov]

Btw, @ligurio you can ignore certain mutators via the following config:

ignoreMutators:
 - cxx_logical_or_to_and
 - cxx_logical_and_to_or

[ligurio]

Sure, similar issues happen in other files too and I workaround them in config:

mutators:
 - cxx_logical
includePaths:
 - src
excludePaths:
 - third_party      # https://github.com/mull-project/mull/issues/996
 - test
 - src/lib/small
 - src/lib/tzcode   # https://github.com/mull-project/mull/issues/994
 - src/lib/core
 - src/lib/json     # json.c
 - src/box          # xlog.c
quiet: false