Creating and implementing an analysis group out of tree

Hello all,

I’m trying to follow the guide http://llvm.org/docs/WritingAnLLVMPass.html to build an some passes and analysis groups out of tree. However, I’m having some trouble with crashes when I try to follow the guide.
The first section provides a very useful example of what the whole .cpp file should look like for the HelloWorld pass. Obviously it’s a bit more complex to write the whole setup with an analysis group, an analysis pass, and a transform pass that uses the analysis, but example code would be extremely helpful, and could serve as a good starting point for anyone who wants to do something similar. Is there anywhere i could find such example code, perhaps as part of a project, that demonstrates how to define and use an analysis group out of tree?

Thanks,

Jeremy

It's not entirely clear which part you're having a problem with. If it's
creating an analysis group, there should be samples within the LLVM source
code. If it's building out-of-tree, take a look at
https://github.com/eliben/llvm-clang-samples -- it's a repository with a
bunch of LLVM/Clang samples, all built out of tree. It keeps pretty close
track to ToT, as well as having branches for prior releases (3.3 and 3.4,
for now).

Eli

Hi Eli,

Thanks for the link! I’m able to compile a standalone pass outside of the source tree, and I’m obviously ably to compile analysis groups inside the source tree. However, the problem comes when I try to do what the tutorial suggests to create an analysis group outside of the source tree.

My understanding is that building out of tree requires different methods to register the passes. For example, the class RegisterPass, which the tutorial instructs you to use (and is used by sample repository you linked), never shows up in the source tree. Likewise for RegisterAnalysisGroup. Furthermore I’ve found that just copying the way it’s done in the source tree and not using RegisterPass causes opt to not recognize your command-line arguments.

Do you know of any other projects that will demonstrate how to build passes out of tree, only creating an analysis group as well?

Thanks

Jeremy

Hi Eli,

Thanks for the link! I'm able to compile a standalone pass outside of the
source tree, and I'm obviously ably to compile analysis groups inside the
source tree. However, the problem comes when I try to do what the tutorial
suggests to create an analysis group outside of the source tree.

My understanding is that building out of tree requires different methods
to register the passes.

I don't think so; or I may be misunderstanding what you mean by "out of
tree"?

For example, the class RegisterPass, which the tutorial instructs you to
use (and is used by sample repository you linked), never shows up in the
source tree. Likewise for RegisterAnalysisGroup.

What makes you say that? Both appear there.

Furthermore I've found that just copying the way it's done in the source
tree and not using RegisterPass causes opt to not recognize your
command-line arguments.

Do you know of any other projects that will demonstrate how to build
passes out of tree, only creating an analysis group as well?

Nope, sorry.

Eli

The poolalloc and SAFECode projects have analysis groups. For directions on downloading the code, please see . Regards, John Criswell

Eli, I’m referring to building a project in its own directory, without a copy of the llvm source being involved at all. If I grep for RegisterAnalysisGroup it only shows up in the header file it’s defined, and in the docs directory. (RegisterPass does show up however, just not in all of the passes).

John, thanks, I’m taking a look at poolalloc. It doesn’t seem to compile with the latest SVN, but hopefully the code regarding analysis groups is up to date[1]

Jeremy

[1] I had to make some changes for headers being moved around, but after doing so, I still got error messages

Thank you John,

I was able to get my code to work by copying poolalloc. The crucial part I was missing is the third line here

static RegisterPass B(“paheur-AllButUnreachableFromMemory”, “Pool allocate all reachable from memory objects”);

static RegisterAnalysisGroup HeuristicGroup(“Pool Allocation Heuristic”);
RegisterAnalysisGroup Heuristic2(B);

As I mentioned above, RegisterAnalysisGroup is never used in the llvm source tree, and the tutorial tells you about the usage on the second line, but it tells you to use INITIALIZE_AG_PASS instead of the third line and makes no mention of using RegisterAnalysisGroup this way. I’m not sure how one was expected to find out about this usage, perhaps someone could update the tutorial to include this?

Jeremy