Merge pull request swiftlang#28767 from apple/revert-28702-only-one-dependency-file

Author: swift-ci

include/swift/Driver/Compilation.h

@@ -257,21 +257,6 @@ class Compilation {
   /// limit filelists will be used.
   size_t FilelistThreshold;
 
-  /// Because each frontend job outputs the same info in its .d file, only do it
-  /// on the first job that actually runs. Write out dummies for the rest of the
-  /// jobs. This hack saves a lot of time in the build system when incrementally
-  /// building a project with many files. Record if a scheduled job has already
-  /// added -emit-dependency-path.
-  bool HaveAlreadyAddedDependencyPath = false;
-
-  /// When set, only the first scheduled frontend job gets the argument needed
-  /// to produce a make-style dependency file. The other jobs create dummy files
-  /// in the driver. This hack speeds up incremental compilation by reducing the
-  /// time for the build system to read each dependency file, which are all
-  /// identical. This optimization can be disabled by passing
-  /// -disable-only-one-dependency-file on the command line.
-  const bool OnlyOneDependencyFile;
-
   /// Scaffolding to permit experimentation with finer-grained dependencies and
   /// faster rebuilds.
   const bool EnableFineGrainedDependencies;
@@ -324,7 +309,6 @@ class Compilation {
               bool SaveTemps = false,
               bool ShowDriverTimeCompilation = false,
               std::unique_ptr<UnifiedStatsReporter> Stats = nullptr,
-              bool OnlyOneDependencyFile = false,
               bool EnableFineGrainedDependencies = false,
               bool VerifyFineGrainedDependencyGraphAfterEveryImport = false,
               bool EmitFineGrainedDependencyDotFileAfterEveryImport = false,
@@ -443,14 +427,6 @@ class Compilation {
     return FilelistThreshold;
   }
 
-  /// Called to decide whether to add a dependency path argument, or whether to
-  /// create a dummy file. Responds by invoking one of the two passed-in
-  /// functions.
-  void addDependencyPathOrCreateDummy(
-      const CommandOutput &Output,
-      function_ref<void(StringRef)> addDependencyPath,
-      function_ref<void(StringRef)> createDummy);
-
   UnifiedStatsReporter *getStatsReporter() const {
     return Stats.get();
   }

include/swift/Option/Options.td

@@ -139,11 +139,6 @@ def enable_fine_grained_dependencies :
 Flag<["-"], "enable-fine-grained-dependencies">, Flags<[FrontendOption, HelpHidden]>,
 HelpText<"Experimental work-in-progress to be more selective about incremental recompilation">;
 
-
-def disable_only_one_dependency_file :
-Flag<["-"], "disable-only-one-dependency-file">, Flags<[DoesNotAffectIncrementalBuild]>,
- HelpText<"Disables incremental build optimization that only produces one dependencies file">;
-
 def enable_source_range_dependencies :
 Flag<["-"], "enable-source-range-dependencies">, Flags<[]>,
 HelpText<"Try using source range information">;

lib/Driver/Compilation.cpp

@@ -121,15 +121,13 @@ Compilation::Compilation(DiagnosticEngine &Diags,
                          bool SaveTemps,
                          bool ShowDriverTimeCompilation,
                          std::unique_ptr<UnifiedStatsReporter> StatsReporter,
-                         bool OnlyOneDependencyFile,
                          bool EnableFineGrainedDependencies,
                          bool VerifyFineGrainedDependencyGraphAfterEveryImport,
                          bool EmitFineGrainedDependencyDotFileAfterEveryImport,
                          bool FineGrainedDependenciesIncludeIntrafileOnes,
                          bool EnableSourceRangeDependencies,
                          bool CompareIncrementalSchemes,
-                         StringRef CompareIncrementalSchemesPath
-                         )
+                         StringRef CompareIncrementalSchemesPath)
   : Diags(Diags), TheToolChain(TC),
     TheOutputInfo(OI),
     Level(Level),
@@ -151,16 +149,14 @@ Compilation::Compilation(DiagnosticEngine &Diags,
     ShowDriverTimeCompilation(ShowDriverTimeCompilation),
     Stats(std::move(StatsReporter)),
     FilelistThreshold(FilelistThreshold),
-    OnlyOneDependencyFile(OnlyOneDependencyFile),
     EnableFineGrainedDependencies(EnableFineGrainedDependencies),
     VerifyFineGrainedDependencyGraphAfterEveryImport(
       VerifyFineGrainedDependencyGraphAfterEveryImport),
     EmitFineGrainedDependencyDotFileAfterEveryImport(
       EmitFineGrainedDependencyDotFileAfterEveryImport),
     FineGrainedDependenciesIncludeIntrafileOnes(
       FineGrainedDependenciesIncludeIntrafileOnes),
-    EnableSourceRangeDependencies(EnableSourceRangeDependencies)
-    {
+    EnableSourceRangeDependencies(EnableSourceRangeDependencies) {
     if (CompareIncrementalSchemes)
       IncrementalComparator.emplace(
       // Ensure the references are to inst vars, NOT arguments
@@ -2036,19 +2032,3 @@ unsigned Compilation::countSwiftInputs() const {
       ++inputCount;
   return inputCount;
 }
-
-void Compilation::addDependencyPathOrCreateDummy(
-    const CommandOutput &Output,
-    function_ref<void(StringRef)> addDependencyPath,
-    function_ref<void(StringRef)> createDummy) {
-  StringRef path =
-      Output.getAdditionalOutputForType(file_types::TY_Dependencies);
-  if (path.empty())
-    return;
-  if (HaveAlreadyAddedDependencyPath && OnlyOneDependencyFile)
-    createDummy(path);
-  else {
-    addDependencyPath(path);
-    HaveAlreadyAddedDependencyPath = true;
-  }
-}

lib/Driver/Driver.cpp

@@ -951,11 +951,7 @@ Driver::buildCompilation(const ToolChain &TC,
         ArgList->hasArg(options::OPT_driver_time_compilation);
     std::unique_ptr<UnifiedStatsReporter> StatsReporter =
         createStatsReporter(ArgList.get(), Inputs, OI, DefaultTargetTriple);
-
-    const bool OnlyOneDependencyFile =
-        !ArgList->hasArg(options::OPT_disable_only_one_dependency_file);
     // relies on the new dependency graph
-
     const bool EnableFineGrainedDependencies =
         ArgList->hasArg(options::OPT_enable_fine_grained_dependencies);
 
@@ -988,7 +984,6 @@ Driver::buildCompilation(const ToolChain &TC,
         SaveTemps,
         ShowDriverTimeCompilation,
         std::move(StatsReporter),
-        OnlyOneDependencyFile,
         EnableFineGrainedDependencies,
         VerifyFineGrainedDependencyGraphAfterEveryImport,
         EmitFineGrainedDependencyDotFileAfterEveryImport,

lib/Driver/ToolChains.cpp

@@ -34,8 +34,6 @@
 #include "llvm/Support/Process.h"
 #include "llvm/Support/Program.h"
 
-#include <fstream>
-
 using namespace swift;
 using namespace swift::driver;
 using namespace llvm::opt;
@@ -673,17 +671,8 @@ void ToolChain::JobContext::addFrontendSupplementaryOutputArguments(
            "mode!");
   }
 
-  C.addDependencyPathOrCreateDummy(
-      Output,
-      [&](StringRef) {
-        addOutputsOfType(arguments, Output, Args, file_types::TY_Dependencies,
-                         "-emit-dependencies-path");
-      },
-      [&](StringRef dependencyFile) {
-        // Create an empty file
-        std::ofstream(dependencyFile.str().c_str());
-      });
-
+  addOutputsOfType(arguments, Output, Args, file_types::TY_Dependencies,
+                   "-emit-dependencies-path");
   addOutputsOfType(arguments, Output, Args, file_types::TY_SwiftDeps,
                    "-emit-reference-dependencies-path");
   addOutputsOfType(arguments, Output, Args, file_types::TY_SwiftRanges,