[PATCH] D29670: [DebugInfo] Emit address space with DW_AT_address_class attribute for pointer and reference types

[Adrian Prantl via Phabricator via llvm-commits]

aprantl added inline comments.


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Comment at: lib/Bitcode/Reader/MetadataLoader.cpp:1117
+    Optional<unsigned> AddressSpace = None;
+    if (Record.size() > 12 && Record[12] != ~0U)
+      AddressSpace = Record[12];
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kzhuravl wrote:
> dblaikie wrote:
> > What's the magical ~0U value about?
> I used it as a sentinel value to represent "None" optional dwarf address space in the bitcode (we always generate and read address space record, if it is ~0U, then we pass None when creating DIDerivedType).
> 
> Would it be better to not write address space record if it is None?
> 
> We can also use UINT24_MAX + 1 (we would need to define UINT24_MAX). or ADDRESS_SPACE_MAX?
I'm pretty sure we prefer bitcode records from the same LLVM revision to always have the same number of elements.
Typically we use 0 as the default value and omit it in the textual IR.
What would you think about encoding the address space as n+1, with 0 being the default=None value?


https://reviews.llvm.org/D29670