[llvm-dev] Adding custom callback function before/after passes

[Neil Henning via llvm-dev]

If you are using the legacy PassManager and control when the PassManager is
created, you can do this with a little hack like:

struct MyPassManager final : llvm::legacy::PassManager
{
        void add(llvm::Pass* const pass) override
        {
            // Add your own pass which does a before callback
            llvm::legacy::PassManager::add(your_start_pass(pass));

            // Add the originally requested pass
            llvm::legacy::PassManager::add(pass);

            // Add your own pass which does an after callback
            llvm::legacy::PassManager::add(your_end_pass(pass));
        }
} passManager; // add new passes to this pass manager!

I've used this hack in the past (it is also something similar to how opt
lets you bail out on a certain pass).

Cheers,
-Neil.

On Tue, Dec 3, 2019 at 5:02 PM Juneyoung Lee via llvm-dev <
llvm-dev at lists.llvm.org> wrote:

> Hello all,
>
> Is there a way to register callback that runs before/after passes?
> PassTimingInfo seems to do a similar thing by calling
> PassInstrumentationCallbacks::registerBeforePassCallback /
> registerAfterPassCallback, but it is hard-wired with
> StandardInstrumentations class.
> Do we have something similar to RegisterStandardPasses, so custom
> callbacks can be added from somewhere outside LLVM?
>
> Thanks,
> Juneyoung Lee
>
>
> _______________________________________________
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> llvm-dev at lists.llvm.org
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>


-- 
Neil Henning
Senior Software Engineer Compiler
unity.com
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