Merge pull request #1829 from cachemeifyoucan/eng/reland-1825

Re-land [Planning] Avoid batching compile job twice

Author: cachemeifyoucan

Sources/SwiftDriver/Jobs/Planning.swift

@@ -90,16 +90,18 @@ extension Driver {
  incrementalCompilationState = nil
  }
 
- return try (
- // For compatibility with swiftpm, the driver produces batched jobs
- // for every job, even when run in incremental mode, so that all jobs
- // can be returned from `planBuild`.
- // But in that case, don't emit lifecycle messages.
- formBatchedJobs(jobsInPhases.allJobs,
- showJobLifecycle: showJobLifecycle && incrementalCompilationState == nil,
- jobCreatingPch: jobsInPhases.allJobs.first(where: {$0.kind == .generatePCH})),
- incrementalCompilationState
- )
+ let batchedJobs: [Job]
+ // If the jobs are batched during the incremental build, reuse the computation rather than computing the batches again.
+ if let incrementalState = incrementalCompilationState {
+ // For compatibility reasons, all the jobs planned will be returned, even the incremental state suggests the job is not mandatory.
+ batchedJobs = incrementalState.skippedJobs + incrementalState.mandatoryJobsInOrder + incrementalState.jobsAfterCompiles
+ } else {
+ batchedJobs = try formBatchedJobs(jobsInPhases.allJobs,
+ showJobLifecycle: showJobLifecycle,
+ jobCreatingPch: jobsInPhases.allJobs.first(where: {$0.kind == .generatePCH}))
+ }
+
+ return (batchedJobs, incrementalCompilationState)
  }
 
  /// If performing an explicit module build, compute an inter-module dependency graph.

Tests/SwiftDriverTests/IncrementalCompilationTests.swift

@@ -217,6 +217,25 @@ extension IncrementalCompilationTests {
  let expected = try AbsolutePath(validating: "\(module).autolink", relativeTo: derivedDataPath)
  XCTAssertEqual(outputs.first!.file.absolutePath, expected)
  }
+
+ // Null planning should not return an empty compile job for compatibility reason.
+ // `swift-build` wraps the jobs returned by swift-driver in `Executor` so returning an empty list of compile job will break build system.
+ func testNullPlanningCompatility() throws {
+ guard let sdkArgumentsForTesting = try Driver.sdkArgumentsForTesting() else {
+ throw XCTSkip("Cannot perform this test on this host")
+ }
+ var driver = try Driver(args: commonArgs + sdkArgumentsForTesting)
+ let initialJobs = try driver.planBuild()
+ try driver.run(jobs: initialJobs)
+
+ // Plan the build again without touching any file. This should be a null build but for compatibility reason,
+ // planBuild() should return all the jobs and supported build system will query incremental state for the actual
+ // jobs need to be executed.
+ let replanJobs = try driver.planBuild()
+ XCTAssertFalse(
+ replanJobs.filter { $0.kind == .compile }.isEmpty,
+ "more than one compile job needs to be planned")
+ }
 }
 
 // MARK: - Dot file tests