[llvm-dev] How to port symcc to clang/llvm-13?
Douglas Chen [陳鍵源] via llvm-dev
llvm-dev at lists.llvm.org
Sat Dec 18 08:25:38 PST 2021
Hi Min:
I am interested in the discussion. I modified the code from clang-tutor to
register with `PassPipeline::registerPipelineStartEPCallback`. The plugin
can be loaded with clang with `-fpass-plugin=<path to plugin>` option.
Thank you for your suggestions and help.
-- Douglas Chen
On Sat, Dec 18, 2021 at 5:03 PM Min-Yih Hsu via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
>
>
> On Dec 18, 2021, at 4:36 PM, Alberto Barbaro <barbaro.alberto at gmail.com>
> wrote:
>
> Hi,
> I think I got confused. Just clarify: my main goal is to be able to port
> symcc[1] to llvm-13.
>
> Since I'm confused I went back to the beginning I have experimented with
> and HelloWorld [2] LLVM pass. As you can see in the following paragraph all
> went well:
>
> root at eaa014e3667a:~/llvm-tutor/build# opt-13 -load-pass-plugin
> ./libHelloWorld.so -passes=hello-world -disable-output output.ll
> (llvm-tutor) Hello from: foo
> (llvm-tutor) number of arguments: 1
> (llvm-tutor) Hello from: bar
> (llvm-tutor) number of arguments: 2
> (llvm-tutor) Hello from: fez
> (llvm-tutor) number of arguments: 3
> (llvm-tutor) Hello from: main
> (llvm-tutor) number of arguments: 2
> root at eaa014e3667a:~/llvm-tutor/build#
>
> At this point I wanted to load directly the plugin via clang using the
> -fplugin parameter
>
>
> Correct, that is expected, `-fplugin` is for Clang plugin not LLVM pass
> plugin.
>
> but I wasn't able to do it. I tried the following command:
>
>
> root at eaa014e3667a:~/llvm-tutor/build# clang
> -fpass-plugin=/root/llvm-tutor/build/libHelloWorld.so
> ../inputs/input_for_hello.c -o hello
> root at eaa014e3667a:~/llvm-tutor/build# file hello
> hello: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically
> linked, interpreter /lib64/ld-linux-x86-64.so.2,
> BuildID[sha1]=ba237b79f2b2bcd362e894657b1e203af914aa9c, for GNU/Linux
> 3.2.0, not stripped
> root at eaa014e3667a:~/llvm-tutor/build#
>
> I was expecting the same output as before where the number of parameters
> were printed.
>
>
> The HelloWorld example you mentioned is using
> `llvm::PassBuilder::registerPipelineParsingCallback`. Passes registered in
> this way are not visible to clang.
> More specifically, if you registered a Pass via `
> registerPipelineParsingCallback`, you need to call
> `PassBuilder::parsePassPipeline` with a textual pass pipeline description.
> But clang doesn’t use that function at all. The opt tool is using it (via
> the `—passes` flag) though.
>
> Try to use other `PassPipline` registration functions like
> `PassPipeline::registerPipelineStartEPCallback` or
> `PassPipeline::registerOptimizerLastEPCallback`.
>
> Also, when the optimization level is set to -O0 (which is the default
> one), every IR function is annotated with `optnone`, which prevents a
> function from being visited by any LLVM Pass. So be sure to add `-Xclang
> -disable-O0-optnone` flag on clang to turn this off (or using optimization
> levels other than -O0).
>
> Best,
> -Min
>
>
> With some verbosity the interesting part was
>
> "/usr/lib/llvm-13/bin/clang" -cc1 -triple x86_64-pc-linux-gnu -emit-obj
> -mrelax-all --mrelax-relocations -disable-free -disable-llvm-verifier
> -discard-value-names -main-file-name input_for_hello.c -mrelocation-model
> static -mframe-pointer=all -fmath-errno -fno-rounding-math
> -mconstructor-aliases -munwind-tables -target-cpu x86-64 -tune-cpu generic
> -debugger-tuning=gdb -v -fcoverage-compilation-dir=/root/llvm-tutor/build
> -resource-dir /usr/lib/llvm-13/lib/clang/13.0.1 -internal-isystem
> /usr/lib/llvm-13/lib/clang/13.0.1/include -internal-isystem
> /usr/local/include -internal-isystem
> /usr/bin/../lib/gcc/x86_64-linux-gnu/10/../../../../x86_64-linux-gnu/include
> -internal-externc-isystem /usr/include/x86_64-linux-gnu
> -internal-externc-isystem /include -internal-externc-isystem /usr/include
> -fdebug-compilation-dir=/root/llvm-tutor/build -ferror-limit 19
> -fgnuc-version=4.2.1 -fcolor-diagnostics
> *-fpass-plugin=/root/llvm-tutor/build/libHelloWorld.so* -faddrsig
> -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/input_for_hello-c52362.o -x c
> ../inputs/input_for_hello.c
>
> symcc loads the plugin in this way:
>
> ➜ build git:(master) ✗ tail -n 8 symcc
>
>
> exec $compiler \
> -Xclang -load -Xclang "$pass" \
> "$@" \
> -L"$runtime_dir" \
> -lSymRuntime \
> -Wl,-rpath,"$runtime_dir" \
> -Qunused-arguments
> ➜ build git:(master) ✗
>
>
>
> How am I supposed to load the plugin via clang so I can just have the same
> output? I want to *avoid* the use of opt.
>
> Thanks a lot for your help
> Alberto
>
>
> [1] https://github.com/eurecom-s3/symcc
> [2] https://github.com/banach-space/llvm-tutor
>
> Il giorno sab 18 dic 2021 alle ore 00:52 Min-Yih Hsu <minyihh at uci.edu> ha
> scritto:
>
>> Both links you provided are for Clang plugin not LLVM plugin. Examples of
>> clang plugins including modifying AST or registering custom `#pragma`
>> directives.
>>
>> To my best understanding your original question was asking about LLVM
>> plugin, which works on LLVM IR.
>>
>> Best,
>> -Min
>>
>> On Dec 17, 2021, at 2:56 PM, Alberto Barbaro <barbaro.alberto at gmail.com>
>> wrote:
>>
>> Hi Min-Yih,
>> thanks for your email. I have searched online on how to build clang
>> plugins and I found [1]. I wanted to use the example that prints all the
>> function names but, despite the fact that I followed the instructions, I
>> could not compile it :)
>>
>> I searched again and I found [2] and hopefully In this case I could build
>> and run the basic hello-world example. I then tried to just replace the
>> HelloWorld.cpp with the example that print the functions names but no luck.
>> I compile but I have an error message. The following paragraph shows the
>> entire test:
>>
>> ➜ build git:(main) ✗ make
>> Scanning dependencies of target HelloWorld
>> [ 50%] Building CXX object CMakeFiles/HelloWorld.dir/HelloWorld.cpp.o
>> [100%] Linking CXX shared library libHelloWorld.so
>> [100%] Built target HelloWorld
>> ➜ build git:(main) ✗ clang-13 -cc1 -load ./libHelloWorld.so -plugin
>> hello-world $CLANG_TUTOR_DIR/test/HelloWorld-basic.cpp
>> ➜ build git:(main) ✗ $Clang_DIR/bin/clang -cc1 -load ./libHelloWorld.so
>> -plugin hello-world $CLANG_TUTOR_DIR/test/HelloWorld-basic.cpp
>> (clang-tutor) file:
>> /home/alberto/Desktop/projects/llvm/clang-tutor//test/HelloWorld-basic.cpp
>> (clang-tutor) count: 3
>> ➜ build git:(main) ✗ cd ..
>> ➜ HelloWorld git:(main) ✗ wget
>> https://raw.githubusercontent.com/llvm/llvm-project/main/clang/examples/PrintFunctionNames/PrintFunctionNames.cpp
>> --2021-12-17 06:45:54--
>> https://raw.githubusercontent.com/llvm/llvm-project/main/clang/examples/PrintFunctionNames/PrintFunctionNames.cpp
>> Resolving raw.githubusercontent.com (raw.githubusercontent.com)...
>> 185.199.110.133, 185.199.109.133, 185.199.108.133, ...
>> Connecting to raw.githubusercontent.com (raw.githubusercontent.com)|185.199.110.133|:443...
>> connected.
>> HTTP request sent, awaiting response... 200 OK
>> Length: 4504 (4.4K) [text/plain]
>> Saving to: ‘PrintFunctionNames.cpp’
>>
>> PrintFunctionNames.cp 100%[========================>] 4.40K --.-KB/s
>> in 0s
>>
>> 2021-12-17 06:45:54 (11.3 MB/s) - ‘PrintFunctionNames.cpp’ saved
>> [4504/4504]
>>
>> ➜ HelloWorld git:(main) ✗ mv HelloWorld.cpp HelloWorld.cpp.backup
>> ➜ HelloWorld git:(main) ✗ mv PrintFunctionNames.cpp HelloWorld.cpp
>>
>> ➜ HelloWorld git:(main) ✗ rm -rf build
>> ➜ HelloWorld git:(main) ✗ take build
>> ➜ build git:(main) ✗ cmake ../
>> -- The C compiler identification is GNU 10.2.1
>> -- The CXX compiler identification is GNU 10.2.1
>> -- Detecting C compiler ABI info
>> -- Detecting C compiler ABI info - done
>> -- Check for working C compiler: /usr/bin/cc - skipped
>> -- Detecting C compile features
>> -- Detecting C compile features - done
>> -- Detecting CXX compiler ABI info
>> -- Detecting CXX compiler ABI info - done
>> -- Check for working CXX compiler: /usr/bin/c++ - skipped
>> -- Detecting CXX compile features
>> -- Detecting CXX compile features - done
>> -- Performing Test Terminfo_LINKABLE
>> -- Performing Test Terminfo_LINKABLE - Success
>> -- Found Terminfo: /usr/lib/x86_64-linux-gnu/libtinfo.so
>> -- Found ZLIB: /usr/local/lib/libz.so (found version "1.2.11")
>> -- Configuring done
>> -- Generating done
>> -- Build files have been written to:
>> /home/alberto/Desktop/progetti/llvm/clang-tutor/HelloWorld/build
>> ➜ build git:(main) ✗ make
>> Scanning dependencies of target HelloWorld
>> [ 50%] Building CXX object CMakeFiles/HelloWorld.dir/HelloWorld.cpp.o
>> [100%] Linking CXX shared library libHelloWorld.so
>> [100%] Built target HelloWorld
>> ➜ build git:(main) ✗ $Clang_DIR/bin/clang -cc1 -load ./libHelloWorld.so
>> -plugin hello-world $CLANG_TUTOR_DIR/test/HelloWorld-basic.cpp
>> error: unable to find plugin 'hello-world'
>> ➜ build git:(main) ✗
>>
>> Any idea on how to solve it? I think a little github repo with an example
>> on how to do it as standalone project would be beneficial to others as well.
>>
>> Thanks a lot for all
>> Alberto
>>
>> [1] https://clang.llvm.org/docs/ClangPlugins.html
>> [2] https://github.com/banach-space/clang-tutor
>>
>> Il giorno ven 17 dic 2021 alle ore 01:11 Min-Yih Hsu <minyihh at uci.edu>
>> ha scritto:
>>
>>> It’s a lot easier to load custom pass plugins into clang with the new
>>> PassManager actually:
>>> ```
>>> clang -fpass-plugin=<path to plugin> ...
>>> ```
>>> Note that <path to plugin> needs to be an absolute path.
>>>
>>> -Min
>>>
>>> On Dec 17, 2021, at 6:38 AM, Alberto Barbaro via llvm-dev <
>>> llvm-dev at lists.llvm.org> wrote:
>>>
>>> Hi all,
>>> Few days ago I have discovered the symcc[1] project. This project, via
>>> an llvm pass, is able to modify the IR code and to inject calls to a
>>> backend which allows symbolic execution. I can use it with clang/llvm 11
>>> but not with the version 13.
>>>
>>> I was wondering if maybe the new pass manager uses llvm passes in a
>>> different way .. so I have created a small pass which injects a call to
>>> printf in each function and I'm able to use it via opt. Now my question is:
>>> is it possible to run the same pass via clang and just obtain the modified
>>> IR code? I'd like to avoid to use opt if not mandatory. Is it possible to
>>> do it or the new pass manager forces me to use opt?
>>>
>>> How would you fix this situation in symcc?
>>>
>>> If someone could tell me how to load a ModulePass in clang-13 would be
>>> great.
>>>
>>> Thanks a lot
>>> Alberto
>>>
>>> [1] https://github.com/eurecom-s3/symcc
>>>
>>> _______________________________________________
>>> LLVM Developers mailing list
>>> llvm-dev at lists.llvm.org
>>> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>>
>>>
>>>
>>
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