[PATCH] D144870: [Clang][DebugInfo] Emit zero size bitfields in the debug info to delimit bitfields in different allocation units.

[Paul Robinson via Phabricator via cfe-commits]

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

One entirely optional suggestion on the test. LGTM.



================
Comment at: clang/lib/CodeGen/CGDebugInfo.cpp:1563
+
+  assert(PreviousBitfield->isBitField());
+
----------------
jmmartinez wrote:
> probinson wrote:
> > Is this true for cases like
> > ```
> > struct nonadjacent {
> >   char a : 8;
> >   char : 0;
> >   int b;
> >   char d : 8;
> > };
> > ```
> > where the field `d` has a predecessor that is not a bitfield? (This might be my ignorance of how Decls are put together, but asserting that `advance` is guaranteed to get you a bitfield just seems a little odd.)
> In that case the assert is never reached.
> 
> When emiting the debug-info for `d`, when looking at the metadata generated for the previous field the function should exit early on this condition:
> ```
>   if (!PreviousMDField || !PreviousMDField->isBitField() ||
>       PreviousMDField->getSizeInBits() == 0)
>     return nullptr;
> ```
Ah, you are right. Thanks!


================
Comment at: clang/test/CodeGen/debug-info-bitfield-0-struct.c:40
+struct SecondDuplicate {
+  // BOTH-DAG: ![[SECONDD:[0-9]+]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "SecondDuplicate", file: !{{[0-9]+}}, line: {{[0-9]+}}, size: 64, elements: ![[SECONDD_ELEMENTS:[0-9]+]])
+
----------------
Maybe use something like `SECONDDUP` instead of `SECONDD` which can look like a typo.


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https://reviews.llvm.org/D144870