SILOptimizer: allow function pointers in static globals and static global arrays.

include/swift/SIL/SILBuilder.h

@@ -201,6 +201,8 @@ class SILBuilder {
   bool isInsertingIntoGlobal() const { return F == nullptr; }
 
   TypeExpansionContext getTypeExpansionContext() const {
+    if (!F)
+      return TypeExpansionContext::minimal();
     return TypeExpansionContext(getFunction());
   }
 
@@ -1027,7 +1029,7 @@ class SILBuilder {
                                              SILType Ty,
                                              bool WithoutActuallyEscaping) {
     return insert(ConvertFunctionInst::create(getSILDebugLocation(Loc), Op, Ty,
-                                              getFunction(), C.OpenedArchetypes,
+                                              getModule(), F, C.OpenedArchetypes,
                                               WithoutActuallyEscaping));
   }
 
@@ -1157,7 +1159,7 @@ class SILBuilder {
   ThinToThickFunctionInst *createThinToThickFunction(SILLocation Loc,
                                                      SILValue Op, SILType Ty) {
     return insert(ThinToThickFunctionInst::create(
-        getSILDebugLocation(Loc), Op, Ty, getFunction(), C.OpenedArchetypes));
+        getSILDebugLocation(Loc), Op, Ty, getModule(), F, C.OpenedArchetypes));
   }
 
   ThickToObjCMetatypeInst *createThickToObjCMetatype(SILLocation Loc,

include/swift/SIL/SILCloner.h

@@ -967,7 +967,7 @@ template<typename ImplClass>
 void
 SILCloner<ImplClass>::visitFunctionRefInst(FunctionRefInst *Inst) {
   SILFunction *OpFunction =
-      getOpFunction(Inst->getInitiallyReferencedFunction());
+      getOpFunction(Inst->getReferencedFunction());
   getBuilder().setCurrentDebugScope(getOpScope(Inst->getDebugScope()));
   recordClonedInstruction(Inst, getBuilder().createFunctionRef(
                                     getOpLocation(Inst->getLoc()), OpFunction));

include/swift/SIL/SILGlobalVariable.h

@@ -128,6 +128,10 @@ class SILGlobalVariable
   SILLinkage getLinkage() const { return SILLinkage(Linkage); }
   void setLinkage(SILLinkage linkage) { Linkage = unsigned(linkage); }
 
+  /// Returns true if the linkage of the SILFunction indicates that the global
+  /// might be referenced from outside the current compilation unit.
+  bool isPossiblyUsedExternally() const;
+
   /// Get this global variable's serialized attribute.
   IsSerialized_t isSerialized() const;
   void setSerialized(IsSerialized_t isSerialized);

include/swift/SIL/SILInstruction.h

@@ -2756,9 +2756,9 @@ class LiteralInst : public SingleValueInstruction {
 };
 
 class FunctionRefBaseInst : public LiteralInst {
+protected:
   SILFunction *f;
 
-protected:
   FunctionRefBaseInst(SILInstructionKind Kind, SILDebugLocation DebugLoc,
                       SILFunction *F, TypeExpansionContext context);
 
@@ -2819,6 +2819,9 @@ class FunctionRefInst : public FunctionRefBaseInst {
                   TypeExpansionContext context);
 
 public:
+  /// Return the referenced function.
+  SILFunction *getReferencedFunction() const { return f; }
+
   static bool classof(SILNodePointer node) {
     return node->getKind() == SILNodeKind::FunctionRefInst;
   }
@@ -4812,7 +4815,7 @@ class ConvertFunctionInst final
 
   static ConvertFunctionInst *create(SILDebugLocation DebugLoc,
                                      SILValue Operand, SILType Ty,
-                                     SILFunction &F,
+                                     SILModule &Mod, SILFunction *F,
                                      SILOpenedArchetypesState &OpenedArchetypes,
                                      bool WithoutActuallyEscaping);
 
@@ -5162,8 +5165,8 @@ class ThinToThickFunctionInst final
             Operand.getOwnershipKind()) {}
 
   static ThinToThickFunctionInst *
-  create(SILDebugLocation DebugLoc, SILValue Operand, SILType Ty,
-         SILFunction &F, SILOpenedArchetypesState &OpenedArchetypes);
+  create(SILDebugLocation DebugLoc, SILValue Operand, SILType Ty, SILModule &Mod,
+         SILFunction *F, SILOpenedArchetypesState &OpenedArchetypes);
 
 public:
   /// Return the callee of the thin_to_thick_function.

include/swift/SIL/TypeSubstCloner.h

@@ -69,7 +69,7 @@ class TypeSubstCloner : public SILClonerWithScopes<ImplClass> {
 
       if (!Cloner.Inlining) {
         FunctionRefInst *FRI = dyn_cast<FunctionRefInst>(AI.getCallee());
-        if (FRI && FRI->getInitiallyReferencedFunction() == AI.getFunction() &&
+        if (FRI && FRI->getReferencedFunction() == AI.getFunction() &&
             Subs == Cloner.SubsMap) {
           // Handle recursions by replacing the apply to the callee with an
           // apply to the newly specialized function, but only if substitutions

include/swift/SILOptimizer/PassManager/Passes.def

@@ -140,8 +140,8 @@ PASS(DCE, "dce",
      "Dead Code Elimination")
 PASS(DeadArgSignatureOpt, "dead-arg-signature-opt",
      "Dead Argument Elimination via Function Specialization")
-PASS(DeadFunctionElimination, "sil-deadfuncelim",
-     "Dead Function Elimination")
+PASS(DeadFunctionAndGlobalElimination, "sil-deadfuncelim",
+     "Dead Function and Global Variable Elimination")
 PASS(DeadObjectElimination, "deadobject-elim",
      "Dead Object Elimination for Classes with Trivial Destruction")
 PASS(DefiniteInitialization, "definite-init",
@@ -220,8 +220,8 @@ PASS(LICM, "licm",
      "Loop Invariant Code Motion")
 PASS(LateCodeMotion, "late-codemotion",
      "Late Code Motion with Release Hoisting")
-PASS(LateDeadFunctionElimination, "late-deadfuncelim",
-     "Late Dead Function Elimination")
+PASS(LateDeadFunctionAndGlobalElimination, "late-deadfuncelim",
+     "Late Dead Function and Global Elimination")
 PASS(LateInliner, "late-inline",
      "Late Function Inlining")
 PASS(LoopCanonicalizer, "loop-canonicalizer",

include/swift/SILOptimizer/Utils/BasicBlockOptUtils.h

@@ -320,7 +320,9 @@ class StaticInitCloner : public SILCloner<StaticInitCloner> {
   /// Add \p InitVal and all its operands (transitively) for cloning.
   ///
   /// Note: all init values must are added, before calling clone().
-  void add(SILInstruction *initVal);
+  /// Returns false if cloning is not possible, e.g. if we would end up cloning
+  /// a reference to a private function into a function which is serialized.
+  bool add(SILInstruction *initVal);
 
   /// Clone \p InitVal and all its operands into the initializer of the
   /// SILGlobalVariable.
@@ -332,7 +334,9 @@ class StaticInitCloner : public SILCloner<StaticInitCloner> {
   static void appendToInitializer(SILGlobalVariable *gVar,
                                   SingleValueInstruction *initVal) {
     StaticInitCloner cloner(gVar);
-    cloner.add(initVal);
+    bool success = cloner.add(initVal);
+    (void)success;
+    assert(success && "adding initVal cannot fail for a global variable");
     cloner.clone(initVal);
   }
 

lib/IRGen/GenConstant.cpp

@@ -22,6 +22,7 @@
 #include "GenTuple.h"
 #include "TypeInfo.h"
 #include "StructLayout.h"
+#include "Callee.h"
 #include "swift/Basic/Range.h"
 #include "swift/SIL/SILModule.h"
 
@@ -109,11 +110,67 @@ llvm::Constant *irgen::emitAddrOfConstantString(IRGenModule &IGM,
   llvm_unreachable("bad string encoding");
 }
 
-static llvm::Constant *emitConstantValue(IRGenModule &IGM, SILValue operand) {
+namespace {
+
+/// Fill in the missing values for padding.
+void insertPadding(SmallVectorImpl<llvm::Constant *> &Elements,
+                   llvm::StructType *sTy) {
+  // fill in any gaps, which are the explicit padding that swiftc inserts.
+  for (unsigned i = 0, e = Elements.size(); i != e; ++i) {
+    auto &elt = Elements[i];
+    if (elt == nullptr) {
+      auto *eltTy = sTy->getElementType(i);
+      assert(eltTy->isArrayTy() &&
+             eltTy->getArrayElementType()->isIntegerTy(8) &&
+             "Unexpected non-byte-array type for constant struct padding");
+      elt = llvm::UndefValue::get(eltTy);
+    }
+  }
+}
+
+template <typename InstTy, typename NextIndexFunc>
+llvm::Constant *emitConstantStructOrTuple(IRGenModule &IGM, InstTy inst,
+                                          NextIndexFunc nextIndex) {
+  auto type = inst->getType();
+  auto *sTy = cast<llvm::StructType>(IGM.getTypeInfo(type).getStorageType());
+
+  SmallVector<llvm::Constant *, 32> elts(sTy->getNumElements(), nullptr);
+
+  // run over the Swift initializers, putting them into the struct as
+  // appropriate.
+  for (unsigned i = 0, e = inst->getElements().size(); i != e; ++i) {
+    auto operand = inst->getOperand(i);
+    Optional<unsigned> index = nextIndex(IGM, type, i);
+    if (index.hasValue()) {
+      assert(elts[index.getValue()] == nullptr &&
+             "Unexpected constant struct field overlap");
+
+      elts[index.getValue()] = emitConstantValue(IGM, operand);
+    }
+  }
+  insertPadding(elts, sTy);
+  return llvm::ConstantStruct::get(sTy, elts);
+}
+} // end anonymous namespace
+
+llvm::Constant *irgen::emitConstantValue(IRGenModule &IGM, SILValue operand) {
   if (auto *SI = dyn_cast<StructInst>(operand)) {
-    return emitConstantStruct(IGM, SI);
+    // The only way to get a struct's stored properties (which we need to map to
+    // their physical/LLVM index) is to iterate over the properties
+    // progressively. Fortunately the iteration order matches the order of
+    // operands in a StructInst.
+    auto StoredProperties = SI->getStructDecl()->getStoredProperties();
+    auto Iter = StoredProperties.begin();
+
+    return emitConstantStructOrTuple(
+        IGM, SI, [&Iter](IRGenModule &IGM, SILType Type, unsigned _i) mutable {
+          (void)_i;
+          auto *FD = *Iter++;
+          return irgen::getPhysicalStructFieldIndex(IGM, Type, FD);
+        });
   } else if (auto *TI = dyn_cast<TupleInst>(operand)) {
-    return emitConstantTuple(IGM, TI);
+    return emitConstantStructOrTuple(IGM, TI,
+                                     irgen::getPhysicalTupleElementStructIndex);
   } else if (auto *ILI = dyn_cast<IntegerLiteralInst>(operand)) {
     return emitConstantInt(IGM, ILI);
   } else if (auto *FLI = dyn_cast<FloatLiteralInst>(operand)) {
@@ -159,73 +216,43 @@ static llvm::Constant *emitConstantValue(IRGenModule &IGM, SILValue operand) {
     auto *val = emitConstantValue(IGM, VTBI->getOperand());
     auto *sTy = IGM.getTypeInfo(VTBI->getType()).getStorageType();
     return llvm::ConstantExpr::getIntToPtr(val, sTy);
-  } else {
-    llvm_unreachable("Unsupported SILInstruction in static initializer!");
-  }
-}
 
-namespace {
+  } else if (auto *CFI = dyn_cast<ConvertFunctionInst>(operand)) {
+    return emitConstantValue(IGM, CFI->getOperand());
 
-/// Fill in the missing values for padding.
-void insertPadding(SmallVectorImpl<llvm::Constant *> &Elements,
-                   llvm::StructType *sTy) {
-  // fill in any gaps, which are the explicit padding that swiftc inserts.
-  for (unsigned i = 0, e = Elements.size(); i != e; ++i) {
-    auto &elt = Elements[i];
-    if (elt == nullptr) {
-      auto *eltTy = sTy->getElementType(i);
-      assert(eltTy->isArrayTy() &&
-             eltTy->getArrayElementType()->isIntegerTy(8) &&
-             "Unexpected non-byte-array type for constant struct padding");
-      elt = llvm::UndefValue::get(eltTy);
-    }
-  }
-}
+  } else if (auto *T2TFI = dyn_cast<ThinToThickFunctionInst>(operand)) {
+    SILType type = operand->getType();
+    auto *sTy = cast<llvm::StructType>(IGM.getTypeInfo(type).getStorageType());
 
-template <typename InstTy, typename NextIndexFunc>
-llvm::Constant *emitConstantStructOrTuple(IRGenModule &IGM, InstTy inst,
-                                          NextIndexFunc nextIndex) {
-  auto type = inst->getType();
-  auto *sTy = cast<llvm::StructType>(IGM.getTypeInfo(type).getStorageType());
+    auto *function = llvm::ConstantExpr::getBitCast(
+        emitConstantValue(IGM, T2TFI->getCallee()),
+        sTy->getTypeAtIndex((unsigned)0));
 
-  SmallVector<llvm::Constant *, 32> elts(sTy->getNumElements(), nullptr);
+    auto *context = llvm::ConstantExpr::getBitCast(
+        llvm::ConstantPointerNull::get(IGM.OpaquePtrTy),
+        sTy->getTypeAtIndex((unsigned)1));
+
+    return llvm::ConstantStruct::get(sTy, {function, context});
 
-  // run over the Swift initializers, putting them into the struct as
-  // appropriate.
-  for (unsigned i = 0, e = inst->getElements().size(); i != e; ++i) {
-    auto operand = inst->getOperand(i);
-    Optional<unsigned> index = nextIndex(IGM, type, i);
-    if (index.hasValue()) {
-      assert(elts[index.getValue()] == nullptr &&
-             "Unexpected constant struct field overlap");
+  } else if (auto *FRI = dyn_cast<FunctionRefInst>(operand)) {
+    SILFunction *fn = FRI->getReferencedFunction();
 
-      elts[index.getValue()] = emitConstantValue(IGM, operand);
+    llvm::Constant *fnPtr = IGM.getAddrOfSILFunction(fn, NotForDefinition);
+    assert(!fn->isAsync() && "TODO: support async functions");
+
+    CanSILFunctionType fnType = FRI->getType().getAs<SILFunctionType>();
+    auto authInfo = PointerAuthInfo::forFunctionPointer(IGM, fnType);
+    if (authInfo.isSigned()) {
+      auto constantDiscriminator =
+          cast<llvm::Constant>(authInfo.getDiscriminator());
+      assert(!constantDiscriminator->getType()->isPointerTy());
+      fnPtr = IGM.getConstantSignedPointer(fnPtr, authInfo.getKey(), nullptr,
+        constantDiscriminator);
     }
+    return fnPtr;
+  } else {
+    llvm_unreachable("Unsupported SILInstruction in static initializer!");
   }
-  insertPadding(elts, sTy);
-  return llvm::ConstantStruct::get(sTy, elts);
-}
-} // end anonymous namespace
-
-llvm::Constant *irgen::emitConstantStruct(IRGenModule &IGM, StructInst *SI) {
-  // The only way to get a struct's stored properties (which we need to map to
-  // their physical/LLVM index) is to iterate over the properties
-  // progressively. Fortunately the iteration order matches the order of
-  // operands in a StructInst.
-  auto StoredProperties = SI->getStructDecl()->getStoredProperties();
-  auto Iter = StoredProperties.begin();
-
-  return emitConstantStructOrTuple(
-      IGM, SI, [&Iter](IRGenModule &IGM, SILType Type, unsigned _i) mutable {
-        (void)_i;
-        auto *FD = *Iter++;
-        return irgen::getPhysicalStructFieldIndex(IGM, Type, FD);
-      });
-}
-
-llvm::Constant *irgen::emitConstantTuple(IRGenModule &IGM, TupleInst *TI) {
-  return emitConstantStructOrTuple(IGM, TI,
-                                   irgen::getPhysicalTupleElementStructIndex);
 }
 
 llvm::Constant *irgen::emitConstantObject(IRGenModule &IGM, ObjectInst *OI,

lib/IRGen/GenConstant.h

@@ -37,11 +37,8 @@ llvm::Constant *emitConstantFP(IRGenModule &IGM, FloatLiteralInst *FLI);
 llvm::Constant *emitAddrOfConstantString(IRGenModule &IGM,
                                          StringLiteralInst *SLI);
 
-/// Construct a struct literal from a StructInst containing constant values.
-llvm::Constant *emitConstantStruct(IRGenModule &IGM, StructInst *SI);
-
-/// Construct a struct literal from a TupleInst containing constant values.
-llvm::Constant *emitConstantTuple(IRGenModule &IGM, TupleInst *TI);
+/// Construct a constant from a SILValue containing constant values.
+llvm::Constant *emitConstantValue(IRGenModule &IGM, SILValue value);
 
 /// Construct an object (with a HeapObject header) from an ObjectInst
 /// containing constant values.

lib/IRGen/IRGenSIL.cpp

@@ -6414,17 +6414,8 @@ void IRGenModule::emitSILStaticInitializers() {
       continue;
     }
 
-    // Set the IR global's initializer to the constant for this SIL
-    // struct.
-    if (auto *SI = dyn_cast<StructInst>(InitValue)) {
-      IRGlobal->setInitializer(emitConstantStruct(*this, SI));
-      continue;
-    }
-
-    // Set the IR global's initializer to the constant for this SIL
-    // tuple.
-    auto *TI = cast<TupleInst>(InitValue);
-    IRGlobal->setInitializer(emitConstantTuple(*this, TI));
+    IRGlobal->setInitializer(
+      emitConstantValue(*this, cast<SingleValueInstruction>(InitValue)));
   }
 }
 

lib/SIL/IR/Linker.cpp

@@ -175,7 +175,7 @@ void SILLinkerVisitor::visitPartialApplyInst(PartialApplyInst *PAI) {
 }
 
 void SILLinkerVisitor::visitFunctionRefInst(FunctionRefInst *FRI) {
-  maybeAddFunctionToWorklist(FRI->getInitiallyReferencedFunction());
+  maybeAddFunctionToWorklist(FRI->getReferencedFunction());
 }
 
 void SILLinkerVisitor::visitDynamicFunctionRefInst(