Add performance measurement with instructions count

Author: kimdv

Package.swift

@@ -290,7 +290,7 @@ let package = Package(
 
     .testTarget(
       name: "PerformanceTest",
-      dependencies: ["SwiftIDEUtils", "SwiftParser", "SwiftSyntax"],
+      dependencies: ["_InstructionCounter", "SwiftIDEUtils", "SwiftParser", "SwiftSyntax"],
       exclude: ["Inputs"]
     ),
   ]

Tests/PerformanceTest/ParsingPerformanceTests.swift

@@ -25,7 +25,7 @@ public class ParsingPerformanceTests: XCTestCase {
 
   func testNativeParsingPerformance() throws {
     try XCTSkipIf(ProcessInfo.processInfo.environment["SKIP_LONG_TESTS"] == "1")
-    measure {
+    measureInscructions(baseline: 5_850_081_534) {
       do {
         let source = try String(contentsOf: inputFile)
         _ = Parser.parse(source: source)

Tests/PerformanceTest/XCTestCase+InstructionsCount.swift

@@ -0,0 +1,37 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2023 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
+//
+//===----------------------------------------------------------------------===//
+
+import XCTest
+import _InstructionCounter
+
+extension XCTestCase {
+  func measureInscructions(baseline: UInt64, block: () -> Void, file: StaticString = #file, line: UInt = #line) {
+    let startInstructions = getInstructionsExecuted()
+    block()
+    let endInstructions = getInstructionsExecuted()
+    let numberOfInstructions = endInstructions - startInstructions
+
+    let lowerBaseline = UInt64(Double(baseline) * 0.97)
+    let upperBaseline = UInt64(Double(baseline) * 1.03)
+    let baselineRange = lowerBaseline...upperBaseline
+
+    XCTAssertTrue(
+      baselineRange.contains(numberOfInstructions),
+      """
+      Number of instructions '\(numberOfInstructions)'
+      is not within range \(lowerBaseline)-\(upperBaseline)
+      """,
+      file: file,
+      line: line
+    )
+  }
+}