[llvm] [LLVM] Add a C API for creating instructions with custom syncscopes. (PR #104775)

[Nikita Popov via llvm-commits]

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@@ -4942,6 +4942,25 @@ inline std::optional<SyncScope::ID> getAtomicSyncScopeID(const Instruction *I) {
   llvm_unreachable("unhandled atomic operation");
 }
 
+/// A helper function that sets an atomic operation's sync scope.
+/// Does nothing if it is not an atomic operation.
+inline void setAtomicSyncScopeID(Instruction *I, SyncScope::ID SSID) {
+  if (!I->isAtomic())
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nikic wrote:

I think I'd prefer an `assert(I->isAtomic())` here. Silently discarding a set seems like a bad idea. The caller can do an isAtomic() check if it wants that behavior.

https://github.com/llvm/llvm-project/pull/104775