[PATCH] D26769: [IR] Remove the DIExpression field from DIGlobalVariable.

[Duncan P. N. Exon Smith via llvm-commits]

> On 2016-Nov-18, at 16:21, David Blaikie <dblaikie at gmail.com> wrote:
> 
> 
> 
> On Fri, Nov 18, 2016 at 3:49 PM Adrian Prantl <aprantl at apple.com <mailto:aprantl at apple.com>> wrote:
>  
> Regardless of which implementation we choose we will also need to
> introduce a new bitcode record for DIExpressions with the
> corrected semantics in order to safely upgrade existing bitcode.
> 
> Ah, good point.

The first field in METADATA_EXPRESSION is effectively a bitfield, and we're only using the first bit (for isDistinct).  We can just use the second bit for "is-new-format"; no reason for a completely new record ID.  (Maybe you weren't suggesting that, and you just meant "new format, some way to distinguish, etc.", but I wanted to be sure we didn't use a new record ID unnecessarily.)
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20161119/04daee0a/attachment.html>