[cfe-dev] Macro history (de-)serialization implementation, need help figuring out some things

Richard Smith richard at metafoo.co.uk
Wed Sep 5 20:03:00 PDT 2012

Hey Alex!

On Fri, Aug 31, 2012 at 4:36 PM, Alexander Kornienko <alexfh at google.com>wrote:

> Hi,
> I have a quick-and-dirty implementation of macro history
> (de-)serialization, but it is still not fully working. In particular, I
> still have to teach reading code to distinguish between identifiers that
> have macro definition currently, and those that had one before. I already
> taught ASTWriter to care about currently undefined macros, but I had to add
> HadMacro flag in IdentifierInfo for this purpose (hopefully there was one
> spare bit in 32-bit word for this).
> To complete this I have to gain much deeper understanding of things I'm
> changing, so I'd appreciate if someone explained me several things (or
> pointed me to the documentation if it exists): structure of PCH files and
> what is stored there, the idea behind chained PCHs and how they work, what
> are public/non-public macros (is it related to Objective C only?).

There is some documentation for PCH and the bitcode format it uses:


I don't think we have any documentation for PCH chaining.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/cfe-dev/attachments/20120905/bc8aa53f/attachment.html>

More information about the cfe-dev mailing list