Revert "[IR] Move optional data in llvm::Function into a hungoff uselist"

This reverts commit r256090.

This broke llvm-clang-lld-x86_64-debian-fast.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@256091 91177308-0d34-0410-b5e6-96231b3b80d8

8 files changed, 168 insertions, 91 deletions

diff --git a/include/llvm/IR/Function.h b/include/llvm/IR/Function.h
index 2a983930bf4..2843cf2cce3 100644
--- a/include/llvm/IR/Function.h
+++ b/include/llvm/IR/Function.h
@@ -64,7 +64,7 @@ private:
    * bit 0      : HasLazyArguments
    * bit 1      : HasPrefixData
    * bit 2      : HasPrologueData
-   * bit 3      : HasPersonalityFn
+   * bit 3      : [reserved]
    * bits 4-13  : CallingConvention
    * bits 14-15 : [reserved]
    */
@@ -110,7 +110,7 @@ private:
 public:
   static Function *Create(FunctionType *Ty, LinkageTypes Linkage,
                           const Twine &N = "", Module *M = nullptr) {
-    return new Function(Ty, Linkage, N, M);
+    return new(1) Function(Ty, Linkage, N, M);
   }
 
   ~Function() override;
@@ -118,6 +118,14 @@ public:
   /// \brief Provide fast operand accessors
   DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
 
+  /// \brief Get the personality function associated with this function.
+  bool hasPersonalityFn() const { return getNumOperands() != 0; }
+  Constant *getPersonalityFn() const {
+    assert(hasPersonalityFn());
+    return cast<Constant>(Op<0>());
+  }
+  void setPersonalityFn(Constant *C);
+
   Type *getReturnType() const;           // Return the type of the ret val
   FunctionType *getFunctionType() const; // Return the FunctionType for me
 
@@ -517,30 +525,17 @@ public:
   size_t arg_size() const;
   bool arg_empty() const;
 
-  /// \brief Check whether this function has a personality function.
-  bool hasPersonalityFn() const {
-    return getSubclassDataFromValue() & (1<<3);
-  }
-
-  /// \brief Get the personality function associated with this function.
-  Constant *getPersonalityFn() const;
-  void setPersonalityFn(Constant *Fn);
-
-  /// \brief Check whether this function has prefix data.
   bool hasPrefixData() const {
     return getSubclassDataFromValue() & (1<<1);
   }
 
-  /// \brief Get the prefix data associated with this function.
   Constant *getPrefixData() const;
   void setPrefixData(Constant *PrefixData);
 
-  /// \brief Check whether this function has prologue data.
   bool hasPrologueData() const {
     return getSubclassDataFromValue() & (1<<2);
   }
 
-  /// \brief Get the prologue data associated with this function.
   Constant *getPrologueData() const;
   void setPrologueData(Constant *PrologueData);
 
@@ -635,15 +630,11 @@ public:
   DISubprogram *getSubprogram() const;
 
 private:
-  void allocHungoffUselist();
-  template<int Idx> void setHungoffOperand(Constant *C);
-
   // Shadow Value::setValueSubclassData with a private forwarding method so that
   // subclasses cannot accidentally use it.
   void setValueSubclassData(unsigned short D) {
     Value::setValueSubclassData(D);
   }
-  void setValueSubclassDataBit(unsigned Bit, bool On);
 
   bool hasMetadataHashEntry() const {
     return getGlobalObjectSubClassData() & HasMetadataHashEntryBit;
@@ -656,7 +647,7 @@ private:
 };
 
 template <>
-struct OperandTraits<Function> : public HungoffOperandTraits<3> {};
+struct OperandTraits<Function> : public OptionalOperandTraits<Function> {};
 
 DEFINE_TRANSPARENT_OPERAND_ACCESSORS(Function, Value)
 
diff --git a/include/llvm/IR/User.h b/include/llvm/IR/User.h
index 885ae197d22..639dc5c01c8 100644
--- a/include/llvm/IR/User.h
+++ b/include/llvm/IR/User.h
@@ -170,6 +170,19 @@ public:
     NumUserOperands = NumOps;
   }
 
+  /// Set the number of operands on a Function.
+  ///
+  /// Function always allocates space for a single operands, but
+  /// doesn't always use it.
+  ///
+  /// FIXME: As that the number of operands is used to find the start of
+  /// the allocated memory in operator delete, we need to always think we have
+  /// 1 operand before delete.
+  void setFunctionNumOperands(unsigned NumOps) {
+    assert(NumOps <= 1 && "Function can only have 0 or 1 operands");
+    NumUserOperands = NumOps;
+  }
+
   /// \brief Subclasses with hung off uses need to manage the operand count
   /// themselves.  In these instances, the operand count isn't used to find the
   /// OperandList, so there's no issue in having the operand count change.
diff --git a/lib/Bitcode/Writer/ValueEnumerator.cpp b/lib/Bitcode/Writer/ValueEnumerator.cpp
index faf82a7926e..2a9b4490ffb 100644
--- a/lib/Bitcode/Writer/ValueEnumerator.cpp
+++ b/lib/Bitcode/Writer/ValueEnumerator.cpp
@@ -87,9 +87,15 @@ static OrderMap orderModule(const Module &M) {
     if (!isa<GlobalValue>(A.getAliasee()))
       orderValue(A.getAliasee(), OM);
   for (const Function &F : M) {
-    for (const Use &U : F.operands())
-      if (!isa<GlobalValue>(U.get()))
-        orderValue(U.get(), OM);
+    if (F.hasPrefixData())
+      if (!isa<GlobalValue>(F.getPrefixData()))
+        orderValue(F.getPrefixData(), OM);
+    if (F.hasPrologueData())
+      if (!isa<GlobalValue>(F.getPrologueData()))
+        orderValue(F.getPrologueData(), OM);
+    if (F.hasPersonalityFn())
+      if (!isa<GlobalValue>(F.getPersonalityFn()))
+        orderValue(F.getPersonalityFn(), OM);
   }
   OM.LastGlobalConstantID = OM.size();
 
@@ -267,8 +273,12 @@ static UseListOrderStack predictUseListOrder(const Module &M) {
   for (const GlobalAlias &A : M.aliases())
     predictValueUseListOrder(A.getAliasee(), nullptr, OM, Stack);
   for (const Function &F : M) {
-    for (const Use &U : F.operands())
-      predictValueUseListOrder(U.get(), nullptr, OM, Stack);
+    if (F.hasPrefixData())
+      predictValueUseListOrder(F.getPrefixData(), nullptr, OM, Stack);
+    if (F.hasPrologueData())
+      predictValueUseListOrder(F.getPrologueData(), nullptr, OM, Stack);
+    if (F.hasPersonalityFn())
+      predictValueUseListOrder(F.getPersonalityFn(), nullptr, OM, Stack);
   }
 
   return Stack;
@@ -311,10 +321,20 @@ ValueEnumerator::ValueEnumerator(const Module &M,
   for (const GlobalAlias &GA : M.aliases())
     EnumerateValue(GA.getAliasee());
 
-  // Enumerate any optional Function data.
+  // Enumerate the prefix data constants.
   for (const Function &F : M)
-    for (const Use &U : F.operands())
-      EnumerateValue(U.get());
+    if (F.hasPrefixData())
+      EnumerateValue(F.getPrefixData());
+
+  // Enumerate the prologue data constants.
+  for (const Function &F : M)
+    if (F.hasPrologueData())
+      EnumerateValue(F.getPrologueData());
+
+  // Enumerate the personality functions.
+  for (Module::const_iterator I = M.begin(), E = M.end(); I != E; ++I)
+    if (I->hasPersonalityFn())
+      EnumerateValue(I->getPersonalityFn());
 
   // Enumerate the metadata type.
   //
diff --git a/lib/IR/AsmWriter.cpp b/lib/IR/AsmWriter.cpp
index 124fc56e78f..51a0faee81c 100644
--- a/lib/IR/AsmWriter.cpp
+++ b/lib/IR/AsmWriter.cpp
@@ -103,9 +103,17 @@ static OrderMap orderModule(const Module *M) {
     orderValue(&A, OM);
   }
   for (const Function &F : *M) {
-    for (const Use &U : F.operands())
-      if (!isa<GlobalValue>(U.get()))
-        orderValue(U.get(), OM);
+    if (F.hasPrefixData())
+      if (!isa<GlobalValue>(F.getPrefixData()))
+        orderValue(F.getPrefixData(), OM);
+
+    if (F.hasPrologueData())
+      if (!isa<GlobalValue>(F.getPrologueData()))
+        orderValue(F.getPrologueData(), OM);
+
+    if (F.hasPersonalityFn())
+      if (!isa<GlobalValue>(F.getPersonalityFn()))
+        orderValue(F.getPersonalityFn(), OM);
 
     orderValue(&F, OM);
 
@@ -255,8 +263,8 @@ static UseListOrderStack predictUseListOrder(const Module *M) {
   for (const GlobalAlias &A : M->aliases())
     predictValueUseListOrder(A.getAliasee(), nullptr, OM, Stack);
   for (const Function &F : *M)
-    for (const Use &U : F.operands())
-      predictValueUseListOrder(U.get(), nullptr, OM, Stack);
+    if (F.hasPrefixData())
+      predictValueUseListOrder(F.getPrefixData(), nullptr, OM, Stack);
 
   return Stack;
 }
diff --git a/lib/IR/Function.cpp b/lib/IR/Function.cpp
index f41f7619e7d..5e4d2d2054e 100644
--- a/lib/IR/Function.cpp
+++ b/lib/IR/Function.cpp
@@ -279,6 +279,9 @@ Function::~Function() {
 
   // Remove the function from the on-the-side GC table.
   clearGC();
+
+  // FIXME: needed by operator delete
+  setFunctionNumOperands(1);
 }
 
 void Function::BuildLazyArguments() const {
@@ -325,14 +328,14 @@ void Function::dropAllReferences() {
   while (!BasicBlocks.empty())
     BasicBlocks.begin()->eraseFromParent();
 
-  // Drop uses of any optional data (real or placeholder).
-  if (getNumOperands()) {
-    User::dropAllReferences();
-    setNumHungOffUseOperands(0);
-  }
+  // Prefix and prologue data are stored in a side table.
+  setPrefixData(nullptr);
+  setPrologueData(nullptr);
 
   // Metadata is stored in a side-table.
   clearMetadata();
+
+  setPersonalityFn(nullptr);
 }
 
 void Function::addAttribute(unsigned i, Attribute::AttrKind attr) {
@@ -422,12 +425,18 @@ void Function::copyAttributesFrom(const GlobalValue *Src) {
     setGC(SrcF->getGC());
   else
     clearGC();
-  if (SrcF->hasPersonalityFn())
-    setPersonalityFn(SrcF->getPersonalityFn());
   if (SrcF->hasPrefixData())
     setPrefixData(SrcF->getPrefixData());
+  else
+    setPrefixData(nullptr);
   if (SrcF->hasPrologueData())
     setPrologueData(SrcF->getPrologueData());
+  else
+    setPrologueData(nullptr);
+  if (SrcF->hasPersonalityFn())
+    setPersonalityFn(SrcF->getPersonalityFn());
+  else
+    setPersonalityFn(nullptr);
 }
 
 /// \brief This does the actual lookup of an intrinsic ID which
@@ -935,67 +944,61 @@ bool Function::callsFunctionThatReturnsTwice() const {
   return false;
 }
 
-Constant *Function::getPersonalityFn() const {
-  assert(hasPersonalityFn() && getNumOperands());
-  return cast<Constant>(Op<0>());
-}
-
-void Function::setPersonalityFn(Constant *Fn) {
-  if (Fn)
-    setHungoffOperand<0>(Fn);
-  setValueSubclassDataBit(3, Fn != nullptr);
+static Constant *
+getFunctionData(const Function *F,
+                const LLVMContextImpl::FunctionDataMapTy &Map) {
+  const auto &Entry = Map.find(F);
+  assert(Entry != Map.end());
+  return cast<Constant>(Entry->second->getReturnValue());
+}
+
+/// setFunctionData - Set "Map[F] = Data". Return an updated SubclassData value
+/// in which Bit is low iff Data is null.
+static unsigned setFunctionData(Function *F,
+                                LLVMContextImpl::FunctionDataMapTy &Map,
+                                Constant *Data, unsigned SCData, unsigned Bit) {
+  ReturnInst *&Holder = Map[F];
+  if (Data) {
+    if (Holder)
+      Holder->setOperand(0, Data);
+    else
+      Holder = ReturnInst::Create(F->getContext(), Data);
+    return SCData | (1 << Bit);
+  } else {
+    delete Holder;
+    Map.erase(F);
+    return SCData & ~(1 << Bit);
+  }
 }
 
 Constant *Function::getPrefixData() const {
-  assert(hasPrefixData() && getNumOperands());
-  return cast<Constant>(Op<1>());
+  assert(hasPrefixData());
+  return getFunctionData(this, getContext().pImpl->PrefixDataMap);
 }
 
 void Function::setPrefixData(Constant *PrefixData) {
-  if (PrefixData)
-    setHungoffOperand<1>(PrefixData);
-  setValueSubclassDataBit(1, PrefixData != nullptr);
+  if (!PrefixData && !hasPrefixData())
+    return;
+
+  unsigned SCData = getSubclassDataFromValue();
+  SCData = setFunctionData(this, getContext().pImpl->PrefixDataMap, PrefixData,
+                           SCData, /*Bit=*/1);
+  setValueSubclassData(SCData);
 }
 
 Constant *Function::getPrologueData() const {
-  assert(hasPrologueData() && getNumOperands());
-  return cast<Constant>(Op<2>());
+  assert(hasPrologueData());
+  return getFunctionData(this, getContext().pImpl->PrologueDataMap);
 }
 
 void Function::setPrologueData(Constant *PrologueData) {
-  if (PrologueData)
-    setHungoffOperand<2>(PrologueData);
-  setValueSubclassDataBit(2, PrologueData != nullptr);
-}
-
-void Function::allocHungoffUselist() {
-  // If we've already allocated a uselist, stop here.
-  if (getNumOperands())
+  if (!PrologueData && !hasPrologueData())
     return;
 
-  allocHungoffUses(3, /*IsPhi=*/ false);
-  setNumHungOffUseOperands(3);
-
-  // Initialize the uselist with placeholder operands to allow traversal.
-  auto *CPN = ConstantPointerNull::get(Type::getInt1PtrTy(getContext(), 0));
-  Op<0>().set(CPN);
-  Op<1>().set(CPN);
-  Op<2>().set(CPN);
-}
-
-template <int Idx>
-void Function::setHungoffOperand(Constant *C) {
-  assert(C && "Cannot set hungoff operand to nullptr");
-  allocHungoffUselist();
-  Op<Idx>().set(C);
-}
-
-void Function::setValueSubclassDataBit(unsigned Bit, bool On) {
-  assert(Bit < 16 && "SubclassData contains only 16 bits");
-  if (On)
-    setValueSubclassData(getSubclassDataFromValue() | (1 << Bit));
-  else
-    setValueSubclassData(getSubclassDataFromValue() & ~(1 << Bit));
+  unsigned SCData = getSubclassDataFromValue();
+  SCData = setFunctionData(this, getContext().pImpl->PrologueDataMap,
+                           PrologueData, SCData, /*Bit=*/2);
+  setValueSubclassData(SCData);
 }
 
 void Function::setEntryCount(uint64_t Count) {
@@ -1013,3 +1016,22 @@ Optional<uint64_t> Function::getEntryCount() const {
       }
   return None;
 }
+
+void Function::setPersonalityFn(Constant *C) {
+  if (!C) {
+    if (hasPersonalityFn()) {
+      // Note, the num operands is used to compute the offset of the operand, so
+      // the order here matters.  Clearing the operand then clearing the num
+      // operands ensures we have the correct offset to the operand.
+      Op<0>().set(nullptr);
+      setFunctionNumOperands(0);
+    }
+  } else {
+    // Note, the num operands is used to compute the offset of the operand, so
+    // the order here matters.  We need to set num operands to 1 first so that
+    // we get the correct offset to the first operand when we set it.
+    if (!hasPersonalityFn())
+      setFunctionNumOperands(1);
+    Op<0>().set(C);
+  }
+}
diff --git a/lib/IR/LLVMContextImpl.h b/lib/IR/LLVMContextImpl.h
index a24114d0a0a..ae987e65bcb 100644
--- a/lib/IR/LLVMContextImpl.h
+++ b/lib/IR/LLVMContextImpl.h
@@ -1014,6 +1014,17 @@ public:
   /// instructions in different blocks at the same location.
   DenseMap<std::pair<const char *, unsigned>, unsigned> DiscriminatorTable;
 
+  typedef DenseMap<const Function *, ReturnInst *> FunctionDataMapTy;
+
+  /// \brief Mapping from a function to its prefix data, which is stored as the
+  /// operand of an unparented ReturnInst so that the prefix data has a Use.
+  FunctionDataMapTy PrefixDataMap;
+
+  /// \brief Mapping from a function to its prologue data, which is stored as
+  /// the operand of an unparented ReturnInst so that the prologue data has a
+  /// Use.
+  FunctionDataMapTy PrologueDataMap;
+
   int getOrAddScopeRecordIdxEntry(MDNode *N, int ExistingIdx);
   int getOrAddScopeInlinedAtIdxEntry(MDNode *Scope, MDNode *IA,int ExistingIdx);
 
diff --git a/lib/IR/TypeFinder.cpp b/lib/IR/TypeFinder.cpp
index b5bdab0865b..2ea0550ba45 100644
--- a/lib/IR/TypeFinder.cpp
+++ b/lib/IR/TypeFinder.cpp
@@ -44,8 +44,14 @@ void TypeFinder::run(const Module &M, bool onlyNamed) {
   for (Module::const_iterator FI = M.begin(), E = M.end(); FI != E; ++FI) {
     incorporateType(FI->getType());
 
-    for (const Use &U : FI->operands())
-      incorporateValue(U.get());
+    if (FI->hasPrefixData())
+      incorporateValue(FI->getPrefixData());
+
+    if (FI->hasPrologueData())
+      incorporateValue(FI->getPrologueData());
+
+    if (FI->hasPersonalityFn())
+      incorporateValue(FI->getPersonalityFn());
 
     // First incorporate the arguments.
     for (Function::const_arg_iterator AI = FI->arg_begin(),
diff --git a/lib/Transforms/IPO/GlobalDCE.cpp b/lib/Transforms/IPO/GlobalDCE.cpp
index 9b276ed28e2..1cc657458d6 100644
--- a/lib/Transforms/IPO/GlobalDCE.cpp
+++ b/lib/Transforms/IPO/GlobalDCE.cpp
@@ -215,8 +215,14 @@ void GlobalDCE::GlobalIsNeeded(GlobalValue *G) {
     // any globals used will be marked as needed.
     Function *F = cast<Function>(G);
 
-    for (Use &U : F->operands())
-      MarkUsedGlobalsAsNeeded(cast<Constant>(U.get()));
+    if (F->hasPrefixData())
+      MarkUsedGlobalsAsNeeded(F->getPrefixData());
+
+    if (F->hasPrologueData())
+      MarkUsedGlobalsAsNeeded(F->getPrologueData());
+
+    if (F->hasPersonalityFn())
+      MarkUsedGlobalsAsNeeded(F->getPersonalityFn());
 
     for (BasicBlock &BB : *F)
       for (Instruction &I : BB)