[Frontend] Remove TheSILModule

Now that SIL parsing is handled lazily, the
CompilerInstance no longer needs to hang onto a
SILModule.

Author: hamishknight

include/swift/Frontend/Frontend.h

@@ -425,7 +425,6 @@ class CompilerInstance {
   DiagnosticEngine Diagnostics{SourceMgr};
   std::unique_ptr<ASTContext> Context;
   std::unique_ptr<Lowering::TypeConverter> TheSILTypes;
-  std::unique_ptr<SILModule> TheSILModule;
   std::unique_ptr<DiagnosticVerifier> DiagVerifier;
 
   /// Null if no tracker.
@@ -498,8 +497,6 @@ class CompilerInstance {
 
   Lowering::TypeConverter &getSILTypes();
 
-  void createSILModule();
-
   void addDiagnosticConsumer(DiagnosticConsumer *DC) {
     Diagnostics.addConsumer(*DC);
   }
@@ -517,16 +514,6 @@ class CompilerInstance {
 
   UnifiedStatsReporter *getStatsReporter() const { return Stats.get(); }
 
-  SILModule *getSILModule() {
-    return TheSILModule.get();
-  }
-
-  std::unique_ptr<SILModule> takeSILModule();
-
-  bool hasSILModule() {
-    return static_cast<bool>(TheSILModule);
-  }
-
   ModuleDecl *getMainModule() const;
 
   MemoryBufferSerializedModuleLoader *
@@ -659,9 +646,6 @@ class CompilerInstance {
 public:
   void freeASTContext();
 
-  /// Frees up the SILModule that this instance is holding on to.
-  void freeSILModule();
-
 private:
   /// Load stdlib & return true if should continue, i.e. no error
   bool loadStdlib();

lib/Frontend/Frontend.cpp

@@ -186,14 +186,6 @@ Lowering::TypeConverter &CompilerInstance::getSILTypes() {
   return *tc;
 }
 
-void CompilerInstance::createSILModule() {
-  assert(MainModule && "main module not created yet");
-  // Assume WMO if a -primary-file option was not provided.
-  TheSILModule = SILModule::createEmptyModule(
-      getMainModule(), getSILTypes(), Invocation.getSILOptions(),
-      Invocation.getFrontendOptions().InputsAndOutputs.isWholeModule());
-}
-
 void CompilerInstance::recordPrimaryInputBuffer(unsigned BufID) {
   PrimaryBufferIDs.insert(BufID);
 }
@@ -679,10 +671,6 @@ CompilerInstance::openModuleDoc(const InputFile &input) {
   return None;
 }
 
-std::unique_ptr<SILModule> CompilerInstance::takeSILModule() {
-  return std::move(TheSILModule);
-}
-
 /// Implicitly import the SwiftOnoneSupport module in non-optimized
 /// builds. This allows for use of popular specialized functions
 /// from the standard library, which makes the non-optimized builds
@@ -760,14 +748,6 @@ void CompilerInstance::performSemaUpTo(SourceFile::ASTStage_t LimitStage) {
   ModuleDecl *mainModule = getMainModule();
   Context->LoadedModules[mainModule->getName()] = mainModule;
 
-  if (Invocation.getInputKind() == InputFileKind::SIL) {
-    assert(!InputSourceCodeBufferIDs.empty());
-    assert(InputSourceCodeBufferIDs.size() == 1);
-    assert(MainBufferID != NO_SUCH_BUFFER);
-    assert(isPrimaryInput(MainBufferID) || isWholeModuleCompilation());
-    createSILModule();
-  }
-
   if (Invocation.getImplicitStdlibKind() == ImplicitStdlibKind::Stdlib) {
     if (!loadStdlib())
       return;
@@ -989,8 +969,6 @@ void CompilerInstance::freeASTContext() {
   PrimarySourceFiles.clear();
 }
 
-void CompilerInstance::freeSILModule() { TheSILModule.reset(); }
-
 /// Perform "stable" optimizations that are invariant across compiler versions.
 static bool performMandatorySILPasses(CompilerInvocation &Invocation,
                                       SILModule *SM) {

lib/FrontendTool/FrontendTool.cpp

@@ -1461,30 +1461,24 @@ static bool validateTBDIfNeeded(const CompilerInvocation &Invocation,
   }
 }
 
-enum class DeallocatableResources {
-  None,
-  SILModule,
-  SILModuleAndASTContext,
-};
-static DeallocatableResources
-computeDeallocatableResources(const CompilerInstance &Instance) {
-  // If the stats reporter is installed, we need the ASTContext and SILModule
-  // to live through the entire compilation process.
+static void freeASTContextIfPossible(CompilerInstance &Instance) {
+  // If the stats reporter is installed, we need the ASTContext to live through
+  // the entire compilation process.
   if (Instance.getASTContext().Stats) {
-    return DeallocatableResources::None;
+    return;
   }
 
   // If we're going to dump the API of the module, we cannot tear down
   // the ASTContext, as that would cause the module to be freed prematurely.
   const auto &opts = Instance.getInvocation().getFrontendOptions();
   if (!opts.DumpAPIPath.empty()) {
-    return DeallocatableResources::SILModule;
+    return;
   }
 
   // Verifying incremental dependencies relies on access to the Swift Module's
-  // source files. We can still free the SIL module, though.
+  // source files.
   if (opts.EnableIncrementalDependencyVerifier) {
-    return DeallocatableResources::SILModule;
+    return;
   }
 
   // If there are multiple primary inputs it is too soon to free
@@ -1493,29 +1487,14 @@ computeDeallocatableResources(const CompilerInstance &Instance) {
   // unlikely to reduce the peak heap size. So, only optimize the
   // single-primary-case (or WMO).
   if (opts.InputsAndOutputs.hasMultiplePrimaryInputs()) {
-    return DeallocatableResources::SILModule;
+    return;
   }
 
-  return DeallocatableResources::SILModuleAndASTContext;
-}
-
-static void freeDeallocatableResourcesIfPossible(CompilerInstance &Instance) {
-  switch (computeDeallocatableResources(Instance)) {
-  case DeallocatableResources::None:
-    break;
-  case DeallocatableResources::SILModule:
-    Instance.freeSILModule();
-    break;
-  case DeallocatableResources::SILModuleAndASTContext:
-    Instance.freeSILModule();
-
-    // Make sure we emit dependencies now, because we can't do it after the
-    // context is gone.
-    emitReferenceDependenciesForAllPrimaryInputsIfNeeded(Instance);
+  // Make sure we emit dependencies now, because we can't do it after the
+  // context is gone.
+  emitReferenceDependenciesForAllPrimaryInputsIfNeeded(Instance);
 
-    Instance.freeASTContext();
-    break;
-  }
+  Instance.freeASTContext();
 }
 
 static bool generateCode(CompilerInstance &Instance, StringRef OutputFilename,
@@ -1528,7 +1507,7 @@ static bool generateCode(CompilerInstance &Instance, StringRef OutputFilename,
       Instance.getASTContext().LangOpts.EffectiveLanguageVersion;
 
   // Free up some compiler resources now that we have an IRModule.
-  freeDeallocatableResourcesIfPossible(Instance);
+  freeASTContextIfPossible(Instance);
 
   // Now that we have a single IR Module, hand it over to performLLVM.
   return performLLVM(opts, Instance.getDiags(), nullptr, HashGlobal, IRModule,