[Explicit Moduel Builds] Adapt to swift-driver's InterModuleDependencyOracle API for cross-target dependency tracking

Author: artemcm

Sources/Build/ManifestBuilder.swift

@@ -215,7 +215,7 @@ extension LLBuildManifestBuilder {
     ) throws {
         // Use the integrated Swift driver to compute the set of frontend
         // jobs needed to build this Swift target.
-        var commandLine = target.emitCommandLine();
+        var commandLine = target.emitCommandLine()
         commandLine.append("-driver-use-frontend-path")
         commandLine.append(buildParameters.toolchain.swiftCompiler.pathString)
         // FIXME: At some point SwiftPM should provide its own executor for
@@ -312,11 +312,9 @@ extension LLBuildManifestBuilder {
         }
         let allPackageDependencies = try! topologicalSort(nodes, successors: { $0.dependencies })
 
-        // All modules discovered so far as a part of this package manifest.
-        // This includes modules that correspond to the package's own targets, package dependency
-        // targets, and modules that are discovered as dependencies of the above in individual
-        // dependency scanning actions
-        var discoveredModulesMap : SwiftDriver.ModuleInfoMap = [:]
+        // Instantiate the inter-module dependency oracle which will cache commonly-scanned
+        // modules across targets' Driver instances.
+        let dependencyOracle = InterModuleDependencyOracle()
 
         // Create commands for all target descriptions in the plan.
         for dependency in allPackageDependencies.reversed() {
@@ -344,7 +342,7 @@ extension LLBuildManifestBuilder {
             switch description {
                 case .swift(let desc):
                     try createExplicitSwiftTargetCompileCommand(description: desc,
-                                                                discoveredModulesMap: &discoveredModulesMap)
+                                                                dependencyOracle: dependencyOracle)
                 case .clang(let desc):
                     createClangCompileCommand(desc)
             }
@@ -353,7 +351,7 @@ extension LLBuildManifestBuilder {
 
     private func createExplicitSwiftTargetCompileCommand(
         description: SwiftTargetBuildDescription,
-        discoveredModulesMap: inout SwiftDriver.ModuleInfoMap
+        dependencyOracle: InterModuleDependencyOracle
     ) throws {
         // Inputs.
         let inputs = computeSwiftCompileCmdInputs(description)
@@ -365,7 +363,7 @@ extension LLBuildManifestBuilder {
 
         // Commands.
         try addExplicitBuildSwiftCmds(description, inputs: inputs,
-                                      discoveredModulesMap: &discoveredModulesMap)
+                                      dependencyOracle: dependencyOracle)
 
         addTargetCmd(description, cmdOutputs: cmdOutputs)
         addModuleWrapCmd(description)
@@ -374,7 +372,7 @@ extension LLBuildManifestBuilder {
     private func addExplicitBuildSwiftCmds(
         _ targetDescription: SwiftTargetBuildDescription,
         inputs: [Node],
-        discoveredModulesMap: inout SwiftDriver.ModuleInfoMap
+        dependencyOracle: InterModuleDependencyOracle
     ) throws {
         // Pass the driver its external dependencies (target dependencies)
         var dependencyModulePathMap: SwiftDriver.ExternalTargetModulePathMap = [:]
@@ -384,7 +382,7 @@ extension LLBuildManifestBuilder {
 
         // Compute the set of frontend
         // jobs needed to build this Swift target.
-        var commandLine = targetDescription.emitCommandLine();
+        var commandLine = targetDescription.emitCommandLine()
         commandLine.append("-driver-use-frontend-path")
         commandLine.append(buildParameters.toolchain.swiftCompiler.pathString)
         commandLine.append("-experimental-explicit-module-build")
@@ -394,18 +392,10 @@ extension LLBuildManifestBuilder {
                                               env: ProcessEnv.vars)
         var driver = try Driver(args: commandLine, fileSystem: targetDescription.fs,
                                 executor: executor,
-                                externalBuildArtifacts: (dependencyModulePathMap, discoveredModulesMap))
-
+                                externalTargetModulePathMap: dependencyModulePathMap,
+                                interModuleDependencyOracle: dependencyOracle)
         let jobs = try driver.planBuild()
 
-        // Save the path to the target's module to be used by its dependents
-        // Save the dependency graph of this target to be used by its dependents
-        guard let dependencyGraph = driver.interModuleDependencyGraph else {
-            fatalError("Expected module dependency graph for target: \(targetDescription)")
-        }
-        try InterModuleDependencyGraph.mergeModules(from: dependencyGraph,
-                                                    into: &discoveredModulesMap)
-
         try addSwiftDriverJobs(for: targetDescription, jobs: jobs, inputs: inputs, resolver: resolver,
                                isMainModule: { driver.isExplicitMainModuleJob(job: $0)})
     }