[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 added a comment.

Still one question, and haven't dug into the test in detail yet.



================
Comment at: clang/lib/CodeGen/CGDebugInfo.cpp:1552
+
+  auto *PreviousMDEntry =
+      PreviousFieldsDI.empty() ? nullptr : PreviousFieldsDI.back();
----------------
Maybe a comment here,
`// If we already emitted metadata for a 0-length bitfield, nothing to do here.`
(I was briefly confused by "if the previous field is a 0-length bitfield, do nothing" until I realized this is looking at the metadata not the decl.


================
Comment at: clang/lib/CodeGen/CGDebugInfo.cpp:1563
+
+  assert(PreviousBitfield->isBitField());
+
----------------
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.)


================
Comment at: clang/lib/CodeGen/CGDebugInfo.h:324
 
-  /// Create new bit field member.
-  llvm::DIType *createBitFieldType(const FieldDecl *BitFieldDecl,
-                                   llvm::DIScope *RecordTy,
-                                   const RecordDecl *RD);
+  /// Create new bit field member
+  llvm::DIDerivedType *createBitFieldType(const FieldDecl *BitFieldDecl,
----------------
Please keep that final `.`


================
Comment at: clang/lib/CodeGen/CGDebugInfo.h:330
+  /// Create an anonnymous zero-size separator for bit-field-decl if needed on
+  /// the target
+  llvm::DIDerivedType *createBitFieldSeparatorIfNeeded(
----------------



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