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I am learning programming LLVM backends.

Currently I am interested in analysis passes, later program transformations. (I assume as I will be more fluent with analysis then will be time for program transformations).

Could you recommend resources for learning ? (I know LLVM Programmers manual and Dragon Book ;) ).

By resources I mean not only tutorials, books, but especially small well-written projects. I'd like to read code examples, compile them and play with them (hack a little bit) to learn more about practical implementation.

Those codes does not have to be restricted to analysis part. The topic is LLVM backend programming in general, while analysis and program transformations are most interesting.

Grzegorz Wierzowiecki
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    Slightly tangent: using the [Try Out LLVM](http://llvm.org/demo/index.cgi) page, one can ask to generate the equivalent LLVM C++ API source that would have generated the IR. It may help (or not) when looking for a particular translation. – Matthieu M. Jan 09 '12 at 16:13

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All LLVM transformations are organized as self-contained passes inside lib/Transforms dir, You can read its sources and run any arbitrary pass on your code using opt tool.

Also, there is nice tutorial on how to write your own pass and use it as loadable module without recompiling whole LLVM.

So there is pretty wide playground already.

arrowd
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    **I've asked about something more than documentation itself and llvm source. Especially I've wrote about small (even toy-examples of hacking LLVM) projects** . I've stressed about knowledge of [LLVM manual](http://llvm.org/docs/), which includes : [LLVM doxygen mentioned in "Programming" part](http://llvm.org/doxygen/) about programming out of source three in [LLVM CMake guide](http://llvm.org/docs/CMake.html#passdev), ... There is a lot of documentation and you can get good overall view on project. Nevertheless, in many respects documentation sucks, so there is question about sth more. – Grzegorz Wierzowiecki Jan 09 '12 at 10:54
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    As you are mentioning about documentation and *"without recompiling whole LLVM"* , I've wanted to let you know about how to make passes out of source tree : [Building LLVM with CMake: Developing LLVM pass out of source](http://llvm.org/docs/CMake.html#passdev) – Grzegorz Wierzowiecki Jan 09 '12 at 10:56
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    Okay, okay, sorry for irrelevant answer. As for developing pass out of tree, this feature was actually developed by me, lol. – arrowd Jan 09 '12 at 11:33
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    Cool man :). Great you've done it. Sorry, for down-voting, your answer is "just ok", but as you see irrelevant. I am afraid, that after up-voting there would be many other irrelevant answers. As you see, it's not point of topic to "just collect" links. Google, git-hub etc gave results ;). It's more about choosing **right, educational, for good learning curve, small, representative examples**. Isn't it ? :) I know we can learn from LLVM sources, but good can help in reading such sources and to propagate **best practices**. All the best @arrowdodger – Grzegorz Wierzowiecki Jan 09 '12 at 14:36
  • No problem. A few people do googling before asking on SO, so such obvious questions as mine are oftenly useful for them. – arrowd Jan 09 '12 at 15:21
  • Sure. Obvious answers and obvious info is useful. But I had experience when whole discussion when in wrong direction because of that. – Grzegorz Wierzowiecki Jan 09 '12 at 15:41
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I was looking for something similar, code that uses llvm libraries, and after long session in google I just found it in the llvm website under "llvm projects": http://llvm.org/ProjectsWithLLVM/

just download what you think relevant for you and play along.

keshchar
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As someone that did what you want to do 3 years ago: LLVM codebase has the best examples. Maybe a good place to start is dominator analysis, as it is well described in compiler books.

Check how it is done in LLVM: http://llvm.org/doxygen/Dominators_8h_source.html

Other place to look might be instruction scheduling.

mentatkgs
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