phases

Author: David Ungar

Sources/SwiftDriver/IncrementalCompilation/InitialStateComputer.swift

@@ -167,7 +167,7 @@ extension IncrementalCompilationState.InitialStateComputer {
   private func buildInitialGraphFromSwiftDepsAndCollectInputsInvalidatedByChangedExternals(
   ) -> (ModuleDependencyGraph, Set<TypedVirtualPath>)?
   {
-    let graph = ModuleDependencyGraph(self)
+    let graph = ModuleDependencyGraph(self, .buildingWithoutAPrior)
     assert(outputFileMap.onlySourceFilesHaveSwiftDeps())
     guard graph.populateInputDependencySourceMap() else {
       return nil
@@ -215,9 +215,13 @@ extension IncrementalCompilationState.InitialStateComputer {
         batchJobFormer.formBatchedJobs(
           mandatoryCompileGroupsInOrder.flatMap {$0.allJobs()},
           showJobLifecycle: showJobLifecycle)
+
+      moduleDependencyGraph.phase = .buildingAfterEachCompilation
       return (skippedCompileGroups: [:],
               mandatoryJobsInOrder: mandatoryJobsInOrder)
     }
+    moduleDependencyGraph.phase = .updatingAfterCompilation
+
 
     let skippedInputs = computeSkippedCompilationInputs(
       inputsInvalidatedByExternals: inputsInvalidatedByExternals,

Sources/SwiftDriver/IncrementalCompilation/ModuleDependencyGraph.swift

@@ -35,12 +35,16 @@ import SwiftOptions
   /// For debugging, something to write out files for visualizing graphs
   let dotFileWriter: DependencyGraphDotFileWriter?
 
-  public init(_ info: IncrementalCompilationState.InitialStateComputer
+  var phase: Phase
+
+  public init(_ info: IncrementalCompilationState.InitialStateComputer,
+              _ phase: Phase
   ) {
     self.info = info
     self.dotFileWriter = info.emitDependencyDotFileAfterEveryImport
     ? DependencyGraphDotFileWriter(info)
     : nil
+    self.phase = phase
   }
 
   private func addMapEntry(_ input: TypedVirtualPath, _ dependencySource: DependencySource) {
@@ -65,6 +69,25 @@ import SwiftOptions
   }
 }
 
+extension ModuleDependencyGraph {
+  public enum Phase {
+    case
+    buildingWithoutAPrior,
+    updatingFromAPrior,
+    updatingAfterCompilation,
+    buildingAfterEachCompilation
+
+    var isUpdating: Bool {
+      switch self {
+      case .buildingWithoutAPrior, .buildingAfterEachCompilation:
+        return false
+      case .updatingAfterCompilation, .updatingFromAPrior:
+        return true
+      }
+    }
+  }
+}
+
 // MARK: - Building from swiftdeps
 extension ModuleDependencyGraph {
   /// Integrates `input` as needed and returns any inputs that were invalidated by external dependencies
@@ -462,7 +485,7 @@ extension ModuleDependencyGraph {
 
       init(_ info: IncrementalCompilationState.InitialStateComputer) {
         self.fileSystem = info.fileSystem
-        self.graph = ModuleDependencyGraph(info)
+        self.graph = ModuleDependencyGraph(info, .updatingFromAPrior)
       }
 
       func finalizeGraph() -> ModuleDependencyGraph {

Tests/SwiftDriverTests/ModuleDependencyGraphTests.swift

@@ -942,7 +942,7 @@ extension ModuleDependencyGraph {
     mock diagnosticEngine: DiagnosticsEngine,
     options: IncrementalCompilationState.Options = [ .verifyDependencyGraphAfterEveryImport ]
   ) {
-    self.init(IncrementalCompilationState.InitialStateComputer.mock())
+    self.init(IncrementalCompilationState.InitialStateComputer.mock(), .buildingWithoutAPrior)
   }