[llvm] [MemoryBuiltins] Add getBaseObjectSize() (NFCI) (PR #155911)

[Florian Hahn via llvm-commits]

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@@ -181,6 +181,13 @@ LLVM_ABI bool getObjectSize(const Value *Ptr, uint64_t &Size,
                             const DataLayout &DL, const TargetLibraryInfo *TLI,
                             ObjectSizeOpts Opts = {});
 
+/// Like getObjectSize(), but only supports base objects (like allocas,
+/// global variables and allocator calls). Requires ExactSizeFromOffset mode.
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fhahn wrote:

```suggestion
/// Like getObjectSize(), but only returns the size of base objects (like allocas,
/// global variables and allocator calls) and std::nullopt otherwise. Requires ExactSizeFromOffset mode.
```

https://github.com/llvm/llvm-project/pull/155911