[llvm] [IR] Introduce captures attribute (PR #116990)

[Alexander Richardson via llvm-commits]

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@@ -273,6 +273,107 @@ raw_ostream &operator<<(raw_ostream &OS, MemoryEffects RMRB);
 // Legacy alias.
 using FunctionModRefBehavior = MemoryEffects;
 
+/// Components of the pointer that may be captured.
+enum class CaptureComponents : uint8_t {
+  None = 0,
+  AddressIsNull = (1 << 0),
+  Address = (1 << 1) | AddressIsNull,
+  ReadProvenance = (1 << 2),
+  Provenance = (1 << 3) | ReadProvenance,
+  All = Address | Provenance,
+  LLVM_MARK_AS_BITMASK_ENUM(Provenance),
+};
+
+inline bool capturesNothing(CaptureComponents CC) {
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arichardson wrote:

I'm not sure what the following commits look like but maybe it would it be better for IDE code completion to have a struct wrapper with these as member functions?

https://github.com/llvm/llvm-project/pull/116990