[PATCH] D49209: CodeGen: specify alignment for automatic variable initialization

[Eli Friedman via Phabricator via cfe-commits]

efriedma accepted this revision.
efriedma added a comment.
This revision is now accepted and ready to land.

LGTM



================
Comment at: lib/CodeGen/CGBuilder.h:260
+                            CharUnits::fromQuantity(Offset.getSExtValue())));
+  }
+
----------------
jfb wrote:
> efriedma wrote:
> > Not sure about the new helper.  We already have CreateStructGEP and CreateConstArrayGEP which do approximately what you want.
> It's close to doing what we want, but not quite? It seems like the original code would have used them otherwise.
> 
> To use them we'd have to:
> 
>   - branch on struct / array
>     - for struct calculate the offset there (which the new helper does)
>     - for array get the element size
> 
> Seems simpler to use GEP2_32 and more fool-proof to (internal to the helper) use GEP's own idea of what the offset is, no?
Okay.

(Actually, I think this ends up conservatively underestimating the alignment in some cases involving nested structs, but it's unlikely to matter.)


Repository:
  rC Clang

https://reviews.llvm.org/D49209