[llvm] RuntimeLibcalls: Add LibraryRef for dispatch-with-exclusion (PR #218869)

[Simon Pilgrim via llvm-commits]

================
@@ -670,21 +720,41 @@ void RuntimeLibcallEmitter::emitSystemRuntimeLibrarySetCalls(
       }
     }
 
-    // Split the top-level member list into named LibcallLibrary references,
-    // which are dispatched to their own setAvailableLibFuncs_<name> function
-    // under an isLibraryAvailable guard, and the remaining (bare impl /
-    // LibcallImpls) members, which are emitted inline via the flat path below.
+    // Split the top-level member list into named LibcallLibrary references
+    // (dispatched to their own setAvailableLibFuncs_<name> under an
+    // isLibraryAvailable guard) and the remaining bare impl / LibcallImpls
+    // members. A LibraryRef also records impls to drop.
+    struct DispatchLib {
+      StringRef Name;
+      std::vector<const RuntimeLibcallImpl *> Exclude;
----------------
RKSimon wrote:

Weird mix of SmallVector and std::vector?

https://github.com/llvm/llvm-project/pull/218869