[Lldb-commits] [PATCH] D112825: [lldb] Add MemoryTagMap class

David Spickett via Phabricator via lldb-commits lldb-commits at lists.llvm.org
Thu Jan 20 04:12:11 PST 2022

DavidSpickett added inline comments.

Comment at: lldb/include/lldb/Target/MemoryTagMap.h:29
+  ///     Non-null pointer to a memory tag manager.
+  MemoryTagMap(const MemoryTagManager *manager);
DavidSpickett wrote:
> JDevlieghere wrote:
> > If the pointer should be non-null, then should this take a reference instead?
> I would like to do that but in a later patch I have:
> ```
> static llvm::Optional<MemoryTagMap>
> GetMemoryTags(lldb::addr_t addr, size_t length,
>               ExecutionContextScope *exe_scope) {
> ```
> Can't have references in an optional.
> However looking again, I think I could check `.empty()` instead of using an Optional. I'll try that.
So the reason this doesn't work:
* Later we have a function that wants to return a memorytagmap.
* The current arch may not have tagging at all, so it wouldn't have any tag manager to reference.
* Hence Optional<MemoryTagManager> makes sense for the return type.
* Optionals cannot include references, so pointer is the best we can do.

On the plus side, this class only has a single user for now so ensuring the non-null part isn't difficult.

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