Add a test to check if OptionSet literals are fully folded

Author: eeckstein

test/SILOptimizer/optionset.swift

@@ -0,0 +1,34 @@
+// RUN: %target-swift-frontend  -parse-as-library -primary-file %s -O -sil-verify-all -module-name=test -emit-sil | %FileCheck %s
+// RUN: %target-swift-frontend  -parse-as-library -primary-file %s -Osize -sil-verify-all -module-name=test -emit-sil | %FileCheck %s
+// REQUIRES: swift_stdlib_no_asserts,optimized_stdlib
+
+public struct TestOptions: OptionSet {
+    public let rawValue: Int
+    public init(rawValue: Int) { self.rawValue = rawValue }
+
+    static let first    = TestOptions(rawValue: 1 << 0)
+    static let second  = TestOptions(rawValue: 1 << 1)
+    static let third   = TestOptions(rawValue: 1 << 2)
+    static let fourth   = TestOptions(rawValue: 1 << 3)
+}
+
+// CHECK:      sil @{{.*}}returnTestOptions{{.*}}
+// CHECK-NEXT: bb0:
+// CHECK-NEXT:   integer_literal {{.*}}, 15
+// CHECK-NEXT:   struct $Int
+// CHECK-NEXT:   struct $TestOptions
+// CHECK-NEXT:   return
+public func returnTestOptions() -> TestOptions {
+    return [.first, .second, .third, .fourth]
+}
+
+// CHECK:        alloc_global @{{.*}}globalTestOptions{{.*}}
+// CHECK-NEXT:   global_addr
+// CHECK-NEXT:   integer_literal {{.*}}, 15
+// CHECK-NEXT:   struct $Int
+// CHECK-NEXT:   struct $TestOptions
+// CHECK-NEXT:   store
+// CHECK-NEXT:   tuple
+// CHECK-NEXT:   return
+let globalTestOptions: TestOptions = [.first, .second, .third, .fourth]
+