r230423 - Wrap clang module files in a Mach-O, ELF, or COFF container.

[Adrian Prantl]

On Feb 24, 2015, at 6:28 PM, Adrian Prantl <aprantl at apple.com> wrote:
> You are correct. I need to remove the use of PCHGenerator from ModuleContainerGenerator.
>> On Feb 24, 2015, at 6:11 PM, NAKAMURA Takumi <geek4civic at gmail.com> wrote:
>> It still has circular dependencies between clangCodeGen and clangFrontend.

After some deliberation, I noticed that there is actually more to be done here in order to resolve the cyclic dependencies. Here is a graph of (a simplified subset of) the dependencies after this commit:
- Pretty much all of CodeGen depends on CodeGenOptions, which is currently part of Frontend.
- BackendUtil and CodeGenAction depend on both CodeGen and Frontend.
- CodeGenModuleContainer introduces a cyclic dependency between Frontend and CodeGen.



The above cycle can be resolved by reversing the CodeGen->Frontend dependency and splitting out the common dependencies CodeGenOptions and frontend::utils::BuryPointer into a separate library that I’m calling FrontendSupport for lack of a better name. After this, the only remaining CodeGen->Frontend dependencies are CodeGen/BackendUtil.cpp and CodeGen/CodeGenAction.cpp:
- CodeGenAction looks like it could safely be moved into FrontendTool, which is its only user.
- BackendUtil can stay were it is, it is needed by CodeGenAction and (via CodeGenModuleContainer) by Frontend. The dependency on Frontend can be eliminated by splitting BuryPointer out from Utils.
The new picture then looks like this:
  


I’ll try and implement it this way; hopefully I didn’t miss any other edges in the graph.
-- adrian

> 
> thanks for noticing!
> -- adrian

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/cfe-commits/attachments/20150225/35302c24/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: before.png
Type: image/png
Size: 92586 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/cfe-commits/attachments/20150225/35302c24/attachment.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: after.png
Type: image/png
Size: 96787 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/cfe-commits/attachments/20150225/35302c24/attachment-0001.png>