[BatchMode] Store -{enable,disable}-batch-mode as a flag in Compilation.

Author: graydon

include/swift/Driver/Compilation.h

@@ -156,6 +156,11 @@ class Compilation {
   /// of date.
   bool EnableIncrementalBuild;
 
+  /// Indicates whether groups of parallel frontend jobs should be merged
+  /// together and run in composite "batch jobs" when possible, to reduce
+  /// redundant work.
+  bool EnableBatchMode;
+
   /// True if temporary files should not be deleted.
   bool SaveTemps;
 
@@ -197,6 +202,7 @@ class Compilation {
               StringRef ArgsHash, llvm::sys::TimePoint<> StartTime,
               unsigned NumberOfParallelCommands = 1,
               bool EnableIncrementalBuild = false,
+              bool EnableBatchMode = false,
               bool SkipTaskExecution = false,
               bool SaveTemps = false,
               bool ShowDriverTimeCompilation = false,
@@ -254,7 +260,11 @@ class Compilation {
   void disableIncrementalBuild() {
     EnableIncrementalBuild = false;
   }
-  
+
+  bool getBatchModeEnabled() const {
+    return EnableBatchMode;
+  }
+
   bool getContinueBuildingAfterErrors() const {
     return ContinueBuildingAfterErrors;
   }

lib/Driver/Compilation.cpp

@@ -24,6 +24,7 @@
 #include "swift/Driver/Driver.h"
 #include "swift/Driver/Job.h"
 #include "swift/Driver/ParseableOutput.h"
+#include "swift/Driver/ToolChain.h"
 #include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/MapVector.h"
 #include "llvm/ADT/StringExtras.h"
@@ -94,6 +95,7 @@ Compilation::Compilation(DiagnosticEngine &Diags,
                          StringRef ArgsHash, llvm::sys::TimePoint<> StartTime,
                          unsigned NumberOfParallelCommands,
                          bool EnableIncrementalBuild,
+                         bool EnableBatchMode,
                          bool SkipTaskExecution,
                          bool SaveTemps,
                          bool ShowDriverTimeCompilation,
@@ -108,6 +110,7 @@ Compilation::Compilation(DiagnosticEngine &Diags,
     NumberOfParallelCommands(NumberOfParallelCommands),
     SkipTaskExecution(SkipTaskExecution),
     EnableIncrementalBuild(EnableIncrementalBuild),
+    EnableBatchMode(EnableBatchMode),
     SaveTemps(SaveTemps),
     ShowDriverTimeCompilation(ShowDriverTimeCompilation),
     Stats(std::move(StatsReporter)) {

lib/Driver/Driver.cpp

@@ -540,6 +540,10 @@ Driver::buildCompilation(const ToolChain &TC,
     Incremental = false;
   }
 
+  bool BatchMode = ArgList->hasFlag(options::OPT_enable_batch_mode,
+                                    options::OPT_disable_batch_mode,
+                                    false);
+
   bool SaveTemps = ArgList->hasArg(options::OPT_save_temps);
   bool ContinueBuildingAfterErrors =
     ArgList->hasArg(options::OPT_continue_building_after_errors);
@@ -679,6 +683,7 @@ Driver::buildCompilation(const ToolChain &TC,
                                                  ArgsHash, StartTime,
                                                  NumberOfParallelCommands,
                                                  Incremental,
+                                                 BatchMode,
                                                  DriverSkipExecution,
                                                  SaveTemps,
                                                  ShowDriverTimeCompilation,