[PATCH] WIP: DI: Fold constant arguments into a single MDString

[Duncan P. N. Exon Smith]

This patch addresses the first stage of PR17891 by folding constant
arguments together into a single MDString.  Integers are stringified and
a `\0` character is used as a separator.

----

Known defects:

  - I've only barely started to update testcases.
  - There are bound to be bugs ~~~~~~~~~~~~^
  - I deleted dead code (I'll separate that out before committing).

I'd really appreciate some early feedback on this nevertheless.  I'm
finding the testcases painful enough to update that I don't want to do it
twice.

 1. I think `\0` is cleaner than `,`.  Bike shed?

 2. I'm using hex for the tags.  Good idea?

 3. I didn't add a prefix, which David suggested just now in PR17891.
    This would be the time to do it, but is the hex tag sufficient?

 4. Anything (other than testcases) I've missed updating?

 5. Do you have specific advice on automating the testcase update flow?
    My next step is building tool support, so suggestions (and starter
    scripts) are welcome.

-------------- next part --------------
A non-text attachment was scrubbed...
Name: 0001-DI-Fold-constant-arguments-into-a-single-MDString.patch
Type: application/octet-stream
Size: 116406 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20140909/501de565/attachment.obj>