Add support for load-pass-plugin option

`Options.swift` has been regenerated so as to
include `load-pass-plugin` option as well.

Sources/SwiftDriver/Jobs/FrontendJobHelpers.swift

@@ -489,6 +489,11 @@ extension Driver {
       commandLine.appendFlag(.pluginPath)
       commandLine.appendPath(pluginPathRoot.localPluginPath)
     }
+
+    if let passPluginPath = parsedOptions.getLastArgument(.loadPassPluginEQ),
+        isFrontendArgSupported(.loadPassPluginEQ) {
+      commandLine.appendFlag("-load-pass-plugin=\(passPluginPath.asSingle)")
+    }
   }
 
   mutating func addBridgingHeaderPCHCacheKeyArguments(commandLine: inout [Job.ArgTemplate],

Sources/SwiftOptions/Options.swift

@@ -572,6 +572,7 @@ extension Option {
   public static let linkObjcRuntime: Option = Option("-link-objc-runtime", .flag, attributes: [.doesNotAffectIncrementalBuild], helpText: "Deprecated")
   public static let lldbRepl: Option = Option("-lldb-repl", .flag, attributes: [.helpHidden, .noBatch], helpText: "LLDB-enhanced REPL mode", group: .modes)
   public static let reuseDependencyScanCache: Option = Option("-load-dependency-scan-cache", .flag, attributes: [.frontend, .noDriver], helpText: "After performing a dependency scan, serialize the scanner's internal state.")
+  public static let loadPassPluginEQ: Option = Option("-load-pass-plugin=", .joined, attributes: [.frontend, .argumentIsPath], metaVar: "<path>", helpText: "Load LLVM pass plugin from a dynamic shared object file.")
   public static let loadPluginExecutable: Option = Option("-load-plugin-executable", .separate, attributes: [.frontend, .doesNotAffectIncrementalBuild, .argumentIsPath], metaVar: "<path>#<module-names>", helpText: "Path to a compiler plugin executable and a comma-separated list of module names where the macro types are declared", group: .pluginSearch)
   public static let loadPluginLibrary: Option = Option("-load-plugin-library", .separate, attributes: [.frontend, .doesNotAffectIncrementalBuild, .argumentIsPath], metaVar: "<path>", helpText: "Path to a dynamic library containing compiler plugins such as macros", group: .pluginSearch)
   public static let locale: Option = Option("-locale", .separate, attributes: [.frontend, .doesNotAffectIncrementalBuild], metaVar: "<locale-code>", helpText: "Choose a language for diagnostic messages")
@@ -1416,6 +1417,7 @@ extension Option {
       Option.linkObjcRuntime,
       Option.lldbRepl,
       Option.reuseDependencyScanCache,
+      Option.loadPassPluginEQ,
       Option.loadPluginExecutable,
       Option.loadPluginLibrary,
       Option.locale,

Tests/SwiftDriverTests/SwiftDriverTests.swift

@@ -7771,6 +7771,21 @@ final class SwiftDriverTests: XCTestCase {
     }
     try assertNoDriverDiagnostics(args: "swiftc", "foo.swift", "-emit-module", "-cache-compile-job", "-explicit-module-build")
   }
+
+  func testFrontendLoadPassPlugin() throws {
+#if os(Windows)
+    throw XCTSkip("'-load-pass-plugin' is not available on Windows.")
+#else
+    var driver = try Driver(args: ["swiftc", "foo.swift", "-load-pass-plugin=/path/to/plugin"])
+    guard driver.isFrontendArgSupported(.loadPassPluginEQ) else {
+      throw XCTSkip("Skipping: compiler does not support '-load-pass-plugin'.")
+    }
+    let plannedJobs = try driver.planBuild()
+    XCTAssertEqual(plannedJobs[0].kind, .compile)
+    XCTAssertTrue(plannedJobs[0].tool.name.hasSuffix("swift-frontend"))
+    XCTAssertTrue(plannedJobs[0].commandLine.contains(.flag("-load-pass-plugin=/path/to/plugin")))
+#endif
+  }
 }
 
 func assertString(