Create Pack Specialisation pass

benchmark/CMakeLists.txt

@@ -139,6 +139,7 @@ set(SWIFT_BENCH_MODULES
     single-source/ObserverUnappliedMethod
     single-source/OpaqueConsumingUsers
     single-source/OpenClose
+    single-source/ParameterPacks
     single-source/Phonebook
     single-source/PointerArithmetics
     single-source/PolymorphicCalls

benchmark/single-source/ParameterPacks.swift

@@ -0,0 +1,53 @@
+//===--- ParameterPacks.swift ---------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2025 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+// This benchmark serves to test the overhead of
+
+import TestsUtils
+
+public let benchmarks = [
+  BenchmarkInfo(
+    name: "ParameterPacks.VariadicFibonacci",
+    runFunction: run_ParameterPacksVariadicFibonacci,
+    tags: [.validation])
+]
+
+@inline(never)
+func numericLoop<each T: BinaryInteger>(xs: repeat each T) -> (repeat each T) {
+  return
+    (repeat { x in
+      // Recursive "Fibonacci" function prevents inlining
+      if x <= 1 {
+        return x
+      } else {
+        let (a, b) = numericLoop(xs: x - 1, x - 2)
+        return a + b
+      }
+    }(each xs)
+
+  )
+}
+
+let expectedResult = (610, 987, 1597)
+
+@inline(never)
+public func run_ParameterPacksVariadicFibonacci(_ n: Int) {
+  var result = (0, 0, 0)
+  for _ in 1...n {
+    result = numericLoop(xs: 15, 16, 17)
+    if result != expectedResult {
+      break
+    }
+  }
+
+  check(result == expectedResult)
+}

benchmark/utils/main.swift

@@ -143,6 +143,7 @@ import ObserverPartiallyAppliedMethod
 import ObserverUnappliedMethod
 import OpaqueConsumingUsers
 import OpenClose
+import ParameterPacks
 import Phonebook
 import PointerArithmetics
 import PolymorphicCalls
@@ -343,6 +344,7 @@ register(ObserverPartiallyAppliedMethod.benchmarks)
 register(ObserverUnappliedMethod.benchmarks)
 register(OpaqueConsumingUsers.benchmarks)
 register(OpenClose.benchmarks)
+register(ParameterPacks.benchmarks)
 register(Phonebook.benchmarks)
 register(PointerArithmetics.benchmarks)
 register(PolymorphicCalls.benchmarks)