How to pass addition arguments to llvm pass registered by new pass manager

[LeoneChen]

When I use clang-13 -fpass-plugin to load pass, and use mllvm to provide addition arguments

Then I get error

But when I use clang-13 -flegacy-pass-manager -Xclang -load -Xclang to load it, everything is OK

[Chordp]

Same question

[viroulep]

At the moment the only way to be able to register options and still use the new PM is to provide both the -Xclang -load -Xclang lib.so and -Xclang -fpass-plugin=lib.so.

The first load will make sure the options defined in the library will be registered before command line arguments are parsed.

[LeoneChen]

OK, thanks~

[OfekShilon]

@viroulep On clang 16 I'm getting "Bad options: -load" with this. Has the workaround changed since writing this?

[viroulep]

I don't think so, the load option seems to be still here, I just compiled the Bye example plugin and ran it over some very basic IR and the workaround seemed to still work:

foo@d366b74ba893:~/llvm/tmp/tests/Bye/build$ clang-16 -Xclang -load -Xclang ./Bye.so -fpass-plugin=./Bye.so -mllvm -wave-goodbye foo.ll -S
Bye: g
Bye: f
Bye: main

While looking at the code I also realized the frontend turns -fplugin into the appropriate load so this works too:

foo@d366b74ba893:~/llvm/dockers/tests/Bye/build$ clang-16 -fplugin=./Bye.so -fpass-plugin=./Bye.so -mllvm -wave-goodbye foo.ll -S
Bye: g
Bye: f
Bye: main

[OfekShilon]

@viroulep Thank you! Perhaps invoking plugins this way works only on IR? If I change foo.ll into some toy foo.cpp I can no longer see "Bye: foo"

[viroulep]

I think it works on cpp as well:

foo@cf52f006f235:~/llvm/dockers/tests/Bye/build$ cat main.cpp 
int main() { return 0; }
foor@cf52f006f235:~/llvm/dockers/tests/Bye/build$ clang-16 -O1 -fplugin=./Bye.so -fpass-plugin=./Bye.so -mllvm -wave-goodbye main.cpp 
Bye: main

If the driver doesn't complain about an unknown option then the plugin is surely loaded and maybe it's just because you compile with -O0?
If you don't specify a -O then -O0 is assumed and clang will add an optnone attribute to the functions, and therefore Bye will not run over them (because the pass implemented in the Bye plugin doesn't implement the isRequired function).

[OfekShilon]

@viroulep Thanks - you're right of course. I now think my problem is different: our plugin implements 2 passes (say "pass1" and "opass2") and according to the existing docs -mllvm -passes=pass1 should have made just pass1 apply. Is it possible this doesn't work in the new pass manager?