[PATCH] D42254: Add optional DICompileUnit to DIBuilder and make outlined debug info use that CU

[Justin Bogner via llvm-commits]

Jessica Paquette via Phabricator via llvm-commits
<llvm-commits at lists.llvm.org> writes:
> paquette created this revision.
> paquette added reviewers: aprantl, probinson, dblaikie.
> Herald added a subscriber: JDevlieghere.
>
> Previously, I committed a change to the outliner which added some
> debug information to outlined functions. This wasn't entirely great
> because DIBuilder only sets its CU using createCompileUnit. As a
> result, the outliner had to make a second compile unit just for the
> outlined sequences.
>
> This sparked an e-mail discussion on the topic, so I'm putting the
> patch up here just because it's a bit easier to read + discuss.
>
> The only change to DIBuilder is an added optional parameter in the
> constructor which allows you to set the CU if you already know what
> you want. There are no functional changes to it otherwise. The rest of
> the changes are in the outliner. It works like this:
>
> 1. Keep track of the MachineFunction that each Candidate appears
> in. Use that to get a CU for that Candidate if possible.
> 2. To find a CU for an OutlinedFunction, grab the first CU belonging
> to some Candidate associated with that function.
> 3. When you create a function, see if it has a potential CU. If it
> does, then generate debug info for the outlined function.

Drive by style nit:

> +  /// \brief If there is a DICompileUnit for any Candidate for this outlined
> +  /// function, then return it. Otherwise, return nullptr.
> +  DICompileUnit *getCUIfExists() const {
> +    DICompileUnit *CU = nullptr;
> +    for (auto &C : Candidates) {
> +      CU = C->getCUIfExists();
> +      if (CU)
> +        break;
> +    }
> +    return CU;
> +  }

  DICompileUnit *getCUIfExists() const {
    for (auto &C : Candidates)
      if (DICompileUnit *CU = C->getCUIfExists())
        return CU;
    return nullptr;
  }