[clang] Fix tbaa.struct metadata for bitfields using big endian. (PR #87753)

[Julian Nagele via cfe-commits]

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@@ -319,7 +320,10 @@ CodeGenTBAA::CollectFields(uint64_t BaseOffset,
       // base type.
       if ((*i)->isBitField()) {
         const CGBitFieldInfo &Info = CGRL.getBitFieldInfo(*i);
-        if (Info.Offset != 0)
+        bool IsBE = Context.getTargetInfo().isBigEndian();
+        bool IsFirst = IsBE ? Info.StorageSize - (Info.Offset + Info.Size) == 0
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juliannagele wrote:

Agreed, and that's what I had originally, but then saw https://github.com/llvm/llvm-project/blob/0b7362c257ff7b656c31266b4f9b8485a7ba4033/clang/lib/CodeGen/CGRecordLayoutBuilder.cpp#L759 so thought I'd go with the same structure, but no strong feelings either way.

https://github.com/llvm/llvm-project/pull/87753