[Explicit Module Builds][Target Variant] Refactor build planning to allow for a second, separte emit-module task for the target variant

This change allows builds that specify a variant triple and which must emit a target variant module to do so from within a single `swiftc` invocation when using Explicit Module Builds. This is an extensive refactor of the build planning procedure with respect to Explicit Module Builds: - Remove 'ExplicitDependencyBuildPlanner' global state from the 'Driver' instance - Instantiate a 'ExplicitDependencyBuildPlanner' instance at the beginning if build planning and propagate/thread this instance to all the required compilation task creation routines, all the way to 'addCommonFrontendOptions' - For '-target-variant' builds which emit a variant triple module, instantiate a whole separate explicit build planner, including performing a secondary dependency scan using the variant triple. Using this information: - Schedule variant triple module pre-compile dependency tasks - Schedule a variant triple PCH compilation task, if necessary - Schedule the variant emit-module task - Schedule the variant textual module verification task, if necessary

Author: artemcm

Sources/SwiftDriver/Driver/Driver.swift

@@ -341,38 +341,15 @@ public struct Driver {
  /// Original ObjC Header passed from command-line
  let originalObjCHeaderFile: VirtualPath.Handle?
 
-
  /// Enable bridging header chaining.
  let bridgingHeaderChaining: Bool
 
- /// The path to the imported Objective-C header.
- lazy var importedObjCHeader: VirtualPath.Handle? = {
- assert(explicitDependencyBuildPlanner != nil ||
- !parsedOptions.hasArgument(.driverExplicitModuleBuild) ||
- !inputFiles.contains { $0.type == .swift },
- "should not be queried before scanning")
- let chainedBridgingHeader = try? explicitDependencyBuildPlanner?.getChainedBridgingHeaderFile()
- return try? computeImportedObjCHeader(&parsedOptions, compilerMode: compilerMode,
- chainedBridgingHeader: chainedBridgingHeader) ?? originalObjCHeaderFile
- }()
-
  /// The directory to emit PCH file.
  lazy var bridgingPrecompiledHeaderOutputDir: VirtualPath? = {
  return try? computePrecompiledBridgingHeaderDir(&parsedOptions,
  compilerMode: compilerMode)
  }()
 
- /// The path to the pch for the imported Objective-C header.
- lazy var bridgingPrecompiledHeader: VirtualPath.Handle? = {
- let contextHash = try? explicitDependencyBuildPlanner?.getMainModuleContextHash()
- return computeBridgingPrecompiledHeader(&parsedOptions,
- compilerMode: compilerMode,
- importedObjCHeader: importedObjCHeader,
- outputFileMap: outputFileMap,
- outputDirectory: bridgingPrecompiledHeaderOutputDir,
- contextHash: contextHash)
- }()
-
  /// Path to the dependencies file.
  let dependenciesFilePath: VirtualPath.Handle?
 
@@ -621,14 +598,6 @@ public struct Driver {
  /// The mode the API digester should run in.
  let digesterMode: DigesterMode
 
- // FIXME: We should soon be able to remove this from being in the Driver's state.
- // Its only remaining use outside of actual dependency build planning is in
- // command-line input option generation for the explicit main module compile job.
- /// Planner for constructing module build jobs using Explicit Module Builds.
- /// Constructed during the planning phase only when all module dependencies will be prebuilt and treated
- /// as explicit inputs by the various compilation jobs.
- @_spi(Testing) public var explicitDependencyBuildPlanner: ExplicitDependencyBuildPlanner? = nil
-
  /// A reference to the instance of libSwiftScan which is shared with the driver's
  /// `InterModuleDependencyOracle`, but also used for non-scanning tasks, such as target info
  /// and supported compiler feature queries
@@ -1383,9 +1352,9 @@ public struct Driver {
  }
 
  public mutating func planBuild() throws -> [Job] {
- let (jobs, incrementalCompilationState, intermoduleDependencyGraph) = try planPossiblyIncrementalBuild()
+ let (jobs, incrementalCompilationState, explicitModulePlanner) = try planPossiblyIncrementalBuild()
  self.incrementalCompilationState = incrementalCompilationState
- self.intermoduleDependencyGraph = intermoduleDependencyGraph
+ self.intermoduleDependencyGraph = explicitModulePlanner?.dependencyGraph
  return jobs
  }
 }
@@ -1774,11 +1743,9 @@ extension Diagnostic.Message {
 }
 
 extension Driver {
- func explainModuleDependency(_ explainModuleName: String, allPaths: Bool) throws {
- guard let dependencyPlanner = explicitDependencyBuildPlanner else {
- fatalError("Cannot explain dependency without Explicit Build Planner")
- }
- guard let dependencyPaths = try dependencyPlanner.explainDependency(explainModuleName, allPaths: allPaths) else {
+ func explainModuleDependency(_ explainModuleName: String, allPaths: Bool,
+ moduleDependencyGraph: InterModuleDependencyGraph) throws {
+ guard let dependencyPaths = try moduleDependencyGraph.explainDependency(explainModuleName, allPaths: allPaths) else {
  diagnosticEngine.emit(.remark("No such module dependency found: '\(explainModuleName)'"))
  return
  }
@@ -1848,13 +1815,6 @@ extension Driver {
  return
  }
 
- // If we're only supposed to explain a dependency on a given module, do so now.
- if let explainModuleName = parsedOptions.getLastArgument(.explainModuleDependencyDetailed) {
- try explainModuleDependency(explainModuleName.asSingle, allPaths: true)
- } else if let explainModuleNameDetailed = parsedOptions.getLastArgument(.explainModuleDependency) {
- try explainModuleDependency(explainModuleNameDetailed.asSingle, allPaths: false)
- }
-
  if parsedOptions.contains(.driverPrintOutputFileMap) {
  if let outputFileMap = self.outputFileMap {
  stderrStream.send(outputFileMap.description)
@@ -2047,7 +2007,7 @@ extension Driver {
 
  // Put bridging header as first input if we have it
  let allInputs: [TypedVirtualPath]
- if let objcHeader = importedObjCHeader, bridgingPrecompiledHeader != nil {
+ if let objcHeader = originalObjCHeaderFile {
  allInputs = [TypedVirtualPath(file: objcHeader, type: .objcHeader)] + inputFiles
  } else {
  allInputs = inputFiles
@@ -2072,10 +2032,7 @@ extension Driver {
  // All input action IDs for this action.
  var inputIds = [UInt]()
 
- var jobInputs = job.primaryInputs.isEmpty ? job.inputs : job.primaryInputs
- if let pchPath = bridgingPrecompiledHeader, job.kind == .compile {
- jobInputs.append(TypedVirtualPath(file: pchPath, type: .pch))
- }
+ let jobInputs = job.primaryInputs.isEmpty ? job.inputs : job.primaryInputs
  // Collect input job IDs.
  for input in jobInputs {
  if let id = inputIdMap[input] {