[Experimental] Integrate LTO works

include/swift/AST/SILOptions.h

@@ -166,6 +166,9 @@ class SILOptions {
   /// Enable large loadable types IRGen pass.
   bool EnableLargeLoadableTypes = true;
 
+  /// The path to combined module summary file
+  std::string ModuleSummaryPath;
+
   /// The name of the file to which the backend should save optimization
   /// records.
   std::string OptRecordFile;

include/swift/Frontend/FrontendOptions.h

@@ -70,6 +70,8 @@ class FrontendOptions {
   /// The path to which we should store indexing data, if any.
   std::string IndexStorePath;
 
+  /// The path to which we should emit combined module summary file
+  std::string ModuleSummaryOutputPath;
   /// The path to look in when loading a module interface file, to see if a
   /// binary module has already been built for use by the compiler.
   std::string PrebuiltModuleCachePath;

include/swift/Option/Options.td

@@ -445,6 +445,9 @@ def emit_module_summary_path :
   Flags<[FrontendOption, NoInteractiveOption, DoesNotAffectIncrementalBuild,
          ArgumentIsPath, SupplementaryOutput]>,
   MetaVarName<"<path>">, HelpText<"Output module summary file to <path>">;
+def module_summary_path : Separate<["-"], "module-summary-path">,
+    Flags<[FrontendOption, ArgumentIsPath]>, MetaVarName<"<path>">,
+    HelpText<"Combined module summary file <path>">;
 
 def emit_module_interface :
   Flag<["-"], "emit-module-interface">,

include/swift/SIL/ModuleSummary.h

@@ -0,0 +1,256 @@
+//===----- ModuleSummary.h --------------------------------------*- C++ -*-===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2020 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef SWIFT_SIL_MODULE_SUMMARY_H
+#define SWIFT_SIL_MODULE_SUMMARY_H
+
+#include "swift/AST/Decl.h"
+#include "swift/SIL/SILFunction.h"
+#include "llvm/Support/YAMLTraits.h"
+
+namespace swift {
+
+namespace modulesummary {
+
+using GUID = uint64_t;
+
+/// Compute globally unique identifier from the symbol.
+GUID getGUIDFromUniqueName(llvm::StringRef Name);
+
+/// Function summary information to help callee analysis
+class FunctionSummary {
+public:
+  /// Function call information
+  class Call {
+  public:
+    /// Kinds of callee reference.
+    enum KindTy {
+      /// The call references a function statically
+      Direct,
+      /// The call references a function via a witness table.
+      Witness,
+      /// The call references a function via a vtable.
+      VTable,
+      kindCount,
+    };
+
+  private:
+    // For import/export
+    friend llvm::yaml::MappingTraits<FunctionSummary::Call>;
+
+    /// The callee function GUID. This can be a static function or a virtual
+    /// function GUID.
+    GUID Callee;
+    /// The symbol name of the callee function only for debug and test purposes.
+    std::string Name;
+    /// Kind of the callee reference.
+    KindTy Kind;
+  public:
+    friend ::llvm::yaml::MappingTraits<Call>;
+    Call() = default;
+    Call(GUID callee, std::string name, KindTy kind)
+        : Callee(callee), Name(name), Kind(kind) {}
+
+    KindTy getKind() const { return Kind; }
+    GUID getCallee() const { return Callee; }
+    std::string getName() const { return Name; };
+  };
+
+  /// Function state flags
+  struct FlagsTy {
+    /// In per-module summary, always false.
+    /// In combined summary, indicates that the function is live.
+    bool Live;
+    /// Indicates that the function must be considered a live root for liveness
+    /// analysis.
+    bool Preserved;
+  };
+
+  using CallGraphEdgeListTy = std::vector<Call>;
+
+private:
+  // For import/export
+  friend llvm::yaml::MappingTraits<FunctionSummary>;
+
+  /// The function identity.
+  GUID Guid;
+  /// The function state flags.
+  FlagsTy Flags;
+  /// List of Call from this function.
+  CallGraphEdgeListTy CallGraphEdgeList;
+  /// The symbol name of the function only for debug and test purposes.
+  std::string Name;
+
+public:
+  FunctionSummary() = default;
+  FunctionSummary(GUID guid)
+      : Guid(guid), Flags({false, false}), CallGraphEdgeList(), Name("") {}
+
+  /// Add a call to the list.
+  void addCall(Call call) { CallGraphEdgeList.push_back(call); }
+
+  /// Return the list of Call from this function
+  ArrayRef<Call> calls() const { return CallGraphEdgeList; }
+
+  bool isLive() const { return Flags.Live; }
+  void setLive(bool Live) { Flags.Live = Live; }
+
+  bool isPreserved() const { return Flags.Preserved; }
+  void setPreserved(bool Preserved) { Flags.Preserved = Preserved; }
+
+  std::string getName() const { return Name; }
+  void setName(std::string name) { this->Name = name; }
+
+  GUID getGUID() const { return Guid; }
+};
+
+/// A slot in a set of virtual tables.
+struct VFuncSlot {
+  /// Kinds of table.
+  enum KindTy {
+    Witness,
+    VTable,
+    kindCount,
+  };
+
+  /// Kind of table.
+  KindTy Kind;
+  /// The virtual function GUID.
+  GUID VFuncID;
+
+  VFuncSlot(KindTy Kind, GUID VFuncID) : Kind(Kind), VFuncID(VFuncID) {}
+};
+
+struct VFuncImpl {
+  GUID Guid;
+  GUID TypeGuid;
+};
+
+using FunctionSummaryMapTy = std::map<GUID, std::unique_ptr<FunctionSummary>>;
+using VFuncToImplsMapTy = std::map<GUID, std::vector<VFuncImpl>>;
+
+/// Module summary that consists of function summaries and virtual function
+/// tables.
+class ModuleSummaryIndex {
+  // For import/export
+  friend llvm::yaml::MappingTraits<ModuleSummaryIndex>;
+
+  /// Map from function GUID to function summary.
+  FunctionSummaryMapTy FunctionSummaryMap;
+  /// Map from virtual function GUID to list of implementations for witness
+  /// tables.
+  VFuncToImplsMapTy WitnessTableMethodMap;
+  /// Map from virtual function GUID to list of implementations for vtables.
+  VFuncToImplsMapTy VTableMethodMap;
+  /// The symbol name of the module.
+  std::string Name;
+
+  VFuncToImplsMapTy &getVFuncMap(VFuncSlot::KindTy kind) {
+    switch (kind) {
+    case VFuncSlot::Witness:
+      return WitnessTableMethodMap;
+    case VFuncSlot::VTable:
+      return VTableMethodMap;
+    case VFuncSlot::kindCount: {
+      llvm_unreachable("impossible");
+    }
+    }
+  }
+  const VFuncToImplsMapTy &getVFuncMap(VFuncSlot::KindTy kind) const {
+    switch (kind) {
+    case VFuncSlot::Witness:
+      return WitnessTableMethodMap;
+    case VFuncSlot::VTable:
+      return VTableMethodMap;
+    case VFuncSlot::kindCount: {
+      llvm_unreachable("impossible");
+    }
+    }
+  }
+public:
+  friend ::llvm::yaml::MappingTraits<ModuleSummaryIndex>;
+  ModuleSummaryIndex() = default;
+
+  std::string getName() const { return this->Name; }
+  void setName(std::string name) { this->Name = name; }
+
+  /// Add a global value summary.
+  void addFunctionSummary(std::unique_ptr<FunctionSummary> summary) {
+    FunctionSummaryMap.insert(
+        std::make_pair(summary->getGUID(), std::move(summary)));
+  }
+
+  /// Return a FunctionSummary for GUID if it exists, otherwise return nullptr.
+  FunctionSummary *getFunctionSummary(GUID guid) const {
+    auto found = FunctionSummaryMap.find(guid);
+    if (found == FunctionSummaryMap.end()) {
+      return nullptr;
+    }
+    auto &entry = found->second;
+    return entry.get();
+  }
+
+  /// Record a implementation for the virtual function slot.
+  void addImplementation(VFuncSlot slot, GUID implGUID, GUID typeGUID) {
+    VFuncToImplsMapTy &table = getVFuncMap(slot.Kind);
+    auto found = table.find(slot.VFuncID);
+      VFuncImpl impl = {implGUID, typeGUID};
+    if (found == table.end()) {
+      table.insert(std::make_pair(slot.VFuncID, std::vector<VFuncImpl>{impl}));
+      return;
+    }
+    found->second.push_back(impl);
+  }
+
+  /// Return a list of implementations for the virtual function slot.
+  ArrayRef<VFuncImpl> getImplementations(VFuncSlot slot) const {
+    const VFuncToImplsMapTy &table = getVFuncMap(slot.Kind);
+    auto found = table.find(slot.VFuncID);
+    if (found == table.end()) {
+      return ArrayRef<VFuncImpl>();
+    }
+    return ArrayRef<VFuncImpl>(found->second);
+  }
+
+  const VFuncToImplsMapTy &getWitnessTableMethodMap() const {
+    return WitnessTableMethodMap;
+  }
+  const VFuncToImplsMapTy &getVTableMethodMap() const {
+    return VTableMethodMap;
+  }
+
+  FunctionSummaryMapTy::const_iterator functions_begin() const {
+    return FunctionSummaryMap.begin();
+  }
+  FunctionSummaryMapTy::const_iterator functions_end() const {
+    return FunctionSummaryMap.end();
+  }
+};
+
+/// Compute a \c ModuleSummaryIndex from the given SILModule.
+std::unique_ptr<ModuleSummaryIndex> buildModuleSummaryIndex(SILModule &M);
+
+/// Serializes a module summary to the given output file.
+///
+/// \returns false on success, true on error.
+bool writeModuleSummaryIndex(const ModuleSummaryIndex &index,
+                             DiagnosticEngine &diags, StringRef path);
+
+/// Attempt to deserialize the module summary.
+///
+/// \returns false on success, true on error.
+bool loadModuleSummaryIndex(llvm::MemoryBufferRef inputBuffer,
+                            ModuleSummaryIndex &moduleSummary);
+} // namespace modulesummary
+} // namespace swift
+
+#endif

include/swift/SIL/SILInstruction.h

@@ -2957,7 +2957,10 @@ class KeyPathPatternComponent {
   void visitReferencedFunctionsAndMethods(
       std::function<void (SILFunction *)> functionCallBack,
       std::function<void (SILDeclRef)> methodCallBack) const;
-
+
+  void clearReferencedFunctions_if(
+      llvm::function_ref<bool(SILFunction *)> predicate);
+
   void incrementRefCounts() const;
   void decrementRefCounts() const;
 

include/swift/SIL/SILProperty.h

@@ -67,7 +67,14 @@ class SILProperty : public llvm::ilist_node<SILProperty>,
   const Optional<KeyPathPatternComponent> &getComponent() const {
     return Component;
   }
-
+
+  void clearReferencedFunctions_if(
+      llvm::function_ref<bool(SILFunction *)> predicate) {
+    if (Component) {
+      Component->clearReferencedFunctions_if(predicate);
+    }
+  }
+
   void print(SILPrintContext &Ctx) const;
   void dump() const;
 

include/swift/SILOptimizer/PassManager/PassPipeline.def

@@ -24,6 +24,7 @@
 
 PASSPIPELINE(Diagnostic, "Guaranteed Passes")
 PASSPIPELINE(OwnershipEliminator, "Utility pass to just run the ownership eliminator pass")
+PASSPIPELINE(CrossModuleEliminator, "Passes run at -module-summary-path")
 PASSPIPELINE(Performance, "Passes run at -O")
 PASSPIPELINE(Onone, "Passes run at -Onone")
 PASSPIPELINE(InstCount, "Utility pipeline to just run the inst count pass")

include/swift/SILOptimizer/PassManager/Passes.def

@@ -66,6 +66,8 @@ PASS(AccessEnforcementWMO, "access-enforcement-wmo",
      "Access Enforcement Whole Module Optimization")
 PASS(CrossModuleSerializationSetup, "cross-module-serialization-setup",
      "Setup serialization flags for cross-module optimization")
+PASS(CrossDeadFunctionElimination, "sil-cross-deadfuncelim",
+     "Cross Dead Function Elimination")
 PASS(AccessSummaryDumper, "access-summary-dump",
      "Dump Address Parameter Access Summary")
 PASS(AccessedStorageAnalysisDumper, "accessed-storage-analysis-dump",

include/swift/SILOptimizer/PassManager/Passes.h

@@ -42,6 +42,8 @@ namespace swift {
   /// Run the SIL ownership eliminator pass on \p M.
   bool runSILOwnershipEliminatorPass(SILModule &M);
 
+  bool runSILCrossModuleEliminatorPass(SILModule &M);
+
   void runSILOptimizationPassesWithFileSpecification(SILModule &Module,
                                                      StringRef FileName);