SwiftCompilerSources: add a few utility APIs

SwiftCompilerSources/Sources/Optimizer/DataStructures/Set.swift

@@ -228,3 +228,16 @@ struct OperandSet : IntrusiveSet {
     context.freeOperandSet(bridged)
   }
 }
+
+extension IntrusiveSet {
+  mutating func insert(contentsOf source: some Sequence<Element>) {
+    for element in source {
+      _ = insert(element)
+    }
+  }
+
+  init(insertContentsOf source: some Sequence<Element>, _ context: some Context) {
+    self.init(context)
+    insert(contentsOf: source)
+  }
+}

SwiftCompilerSources/Sources/SIL/Operand.swift

@@ -150,6 +150,10 @@ extension Sequence where Element == Operand {
     self.lazy.filter { !($0.instruction is I) }
   }
 
+  public func ignore(user: Instruction) -> LazyFilterSequence<Self> {
+    self.lazy.filter { !($0.instruction == user) }
+  }
+
   public func getSingleUser<I: Instruction>(ofType: I.Type) -> I? {
     filterUsers(ofType: I.self).singleUse?.instruction as? I
   }

SwiftCompilerSources/Sources/SIL/Utilities/SequenceUtilities.swift

@@ -98,6 +98,8 @@ public extension CollectionLikeSequence {
     }
     return singleElement
   }
+
+  var first: Element? { first(where: { _ in true }) }
 }
 
 // Also make the lazy sequences a CollectionLikeSequence if the underlying sequence is one.