Schauveau cmake

[schauveau]

Here is a global cmake build system with a few sample libraries and programs.

f18 and the library files previously added in the repository are currently not handled by cmake (and I erased the top level CMakeList.txt). You can use lib/Sema and the tools/flang-info as examples to create your own CMakeList.txt. I followed the Clang and LLVM naming style for libraries (so in CamelCase) which mean that some files may have to be moved around (e.g. lib/parser vs lib/Parser).

I wrote a quick README for the installation. The principle is very similar to the old flang installation.

If you want to try without waiting for mypush, use my branch schauveau_cmake
https://github.com/ThePortlandGroup/f18/tree/schauveau_cmake

[schauveau]

There are plenty of unnecessary things especially in the top CMakeLists.txt and in the TableGen files. A lot was copied from Clang. I commented out or removed some useless parts but I also left some pieces of codes that may be useful in the future. So no need to comment about that!

[tskeith]

I was able to follow the instructions in the README to build LLVM and then build f18 on your branch. I made changes to the cmake files to build the lib/parser and lib/semantics and the f18 executable.

For the stuff that "may be useful in the future", I would really like to see examples. For example, if we're going to use .td files for diagnostics, a sample diagnostic and a source file that uses it. And if we're going to use gtest, a sample unit test.

I think everything else should be removed.

[schauveau]

I also want a Diagnostic example but this is slightly harder that one may imagine. The problem is that the Diagnostic subsystem depends of other classes in the Basic library ; SourceLocation, SourceManager, ...
I think that we will eventually copy the Diagnostic classes but that will require a bit of cleanup to get something working.
Anyways, this is outside the scope of that pull request which is to provide the global CMake infrastructure.

[sscalpone]

Can we break this up into several pull requests? In particular, can we not combine the directory structure and cmake changes with the speculative stuff (tbl gen) or the C++ diagnostic messages yet?

[schauveau]

Sorry! I just merged without noticing your remark. I was not expecting one at that time. Working late? :-)

I do not see why it should matter to separate tblgen from the cmake pull request. We can always remove tablegen later if we decide that we do not need it.

[sscalpone]

I don't want to get in the habit of merging things we don't need.