[IR] Make Attributes and AttributeLists trivially destructible and BumpPtrAllocate them

llvm/lib/IR/AttributeImpl.h

@@ -54,8 +54,6 @@ public:
   AttributeImpl(const AttributeImpl &) = delete;
   AttributeImpl &operator=(const AttributeImpl &) = delete;
 
-  virtual ~AttributeImpl();
-
   bool isEnumAttribute() const { return KindID == EnumAttrEntry; }
   bool isIntAttribute() const { return KindID == IntAttrEntry; }
   bool isStringAttribute() const { return KindID == StringAttrEntry; }
@@ -104,6 +102,9 @@ public:
   }
 };
 
+static_assert(std::is_trivially_destructible<AttributeImpl>::value,
+              "AttributeImpl should be trivially destructible");
+
 //===----------------------------------------------------------------------===//
 /// \class
 /// A set of classes that contain the value of the
@@ -112,8 +113,6 @@ public:
 /// attribute enties, which are for target-dependent attributes.
 
 class EnumAttributeImpl : public AttributeImpl {
-  virtual void anchor();
-
   Attribute::AttrKind Kind;
 
 protected:
@@ -130,8 +129,6 @@ public:
 class IntAttributeImpl : public EnumAttributeImpl {
   uint64_t Val;
 
-  void anchor() override;
-
 public:
   IntAttributeImpl(Attribute::AttrKind Kind, uint64_t Val)
       : EnumAttributeImpl(IntAttrEntry, Kind), Val(Val) {
@@ -142,24 +139,43 @@ public:
   uint64_t getValue() const { return Val; }
 };
 
-class StringAttributeImpl : public AttributeImpl {
-  virtual void anchor();
+class StringAttributeImpl final
+    : public AttributeImpl,
+      private TrailingObjects<StringAttributeImpl, char> {
+  friend TrailingObjects;
 
-  std::string Kind;
-  std::string Val;
+  unsigned KindSize;
+  unsigned ValSize;
+  size_t numTrailingObjects(OverloadToken<char>) const {
+    return KindSize + 1 + ValSize + 1;
+  }
 
 public:
   StringAttributeImpl(StringRef Kind, StringRef Val = StringRef())
-      : AttributeImpl(StringAttrEntry), Kind(std::string(Kind)),
-        Val(std::string(Val)) {}
+      : AttributeImpl(StringAttrEntry), KindSize(Kind.size()),
+        ValSize(Val.size()) {
+    char *TrailingString = getTrailingObjects<char>();
+    // Some users rely on zero-termination.
+    llvm::copy(Kind, TrailingString);
+    TrailingString[KindSize] = '\0';
+    llvm::copy(Val, &TrailingString[KindSize + 1]);
+    TrailingString[KindSize + 1 + ValSize] = '\0';
+  }
 
-  StringRef getStringKind() const { return Kind; }
-  StringRef getStringValue() const { return Val; }
+  StringRef getStringKind() const {
+    return StringRef(getTrailingObjects<char>(), KindSize);
+  }
+  StringRef getStringValue() const {
+    return StringRef(getTrailingObjects<char>() + KindSize + 1, ValSize);
+  }
+
+  static size_t totalSizeToAlloc(StringRef Kind, StringRef Val) {
+    return TrailingObjects::totalSizeToAlloc<char>(Kind.size() + 1 +
+                                                   Val.size() + 1);
+  }
 };
 
 class TypeAttributeImpl : public EnumAttributeImpl {
-  void anchor() override;
-
   Type *Ty;
 
 public:
@@ -265,8 +281,6 @@ public:
   AttributeListImpl(const AttributeListImpl &) = delete;
   AttributeListImpl &operator=(const AttributeListImpl &) = delete;
 
-  void operator delete(void *p) { ::operator delete(p); }
-
   /// Get the context that created this AttributeListImpl.
   LLVMContext &getContext() { return Context; }
 
@@ -287,6 +301,9 @@ public:
   void dump() const;
 };
 
+static_assert(std::is_trivially_destructible<AttributeListImpl>::value,
+              "AttributeListImpl should be trivially destructible");
+
 } // end namespace llvm
 
 #endif // LLVM_LIB_IR_ATTRIBUTEIMPL_H

llvm/lib/IR/Attributes.cpp

@@ -92,9 +92,9 @@ Attribute Attribute::get(LLVMContext &Context, Attribute::AttrKind Kind,
     // If we didn't find any existing attributes of the same shape then create a
     // new one and insert it.
     if (!Val)
-      PA = new EnumAttributeImpl(Kind);
+      PA = new (pImpl->Alloc) EnumAttributeImpl(Kind);
     else
-      PA = new IntAttributeImpl(Kind, Val);
+      PA = new (pImpl->Alloc) IntAttributeImpl(Kind, Val);
     pImpl->AttrsSet.InsertNode(PA, InsertPoint);
   }
 
@@ -114,7 +114,10 @@ Attribute Attribute::get(LLVMContext &Context, StringRef Kind, StringRef Val) {
   if (!PA) {
     // If we didn't find any existing attributes of the same shape then create a
     // new one and insert it.
-    PA = new StringAttributeImpl(Kind, Val);
+    void *Mem =
+        pImpl->Alloc.Allocate(StringAttributeImpl::totalSizeToAlloc(Kind, Val),
+                              alignof(StringAttributeImpl));
+    PA = new (Mem) StringAttributeImpl(Kind, Val);
     pImpl->AttrsSet.InsertNode(PA, InsertPoint);
   }
 
@@ -135,7 +138,7 @@ Attribute Attribute::get(LLVMContext &Context, Attribute::AttrKind Kind,
   if (!PA) {
     // If we didn't find any existing attributes of the same shape then create a
     // new one and insert it.
-    PA = new TypeAttributeImpl(Kind, Ty);
+    PA = new (pImpl->Alloc) TypeAttributeImpl(Kind, Ty);
     pImpl->AttrsSet.InsertNode(PA, InsertPoint);
   }
 
@@ -554,17 +557,6 @@ void Attribute::Profile(FoldingSetNodeID &ID) const {
 // AttributeImpl Definition
 //===----------------------------------------------------------------------===//
 
-// Pin the vtables to this file.
-AttributeImpl::~AttributeImpl() = default;
-
-void EnumAttributeImpl::anchor() {}
-
-void IntAttributeImpl::anchor() {}
-
-void StringAttributeImpl::anchor() {}
-
-void TypeAttributeImpl::anchor() {}
-
 bool AttributeImpl::hasAttribute(Attribute::AttrKind A) const {
   if (isStringAttribute()) return false;
   return getKindAsEnum() == A;
@@ -1040,8 +1032,9 @@ AttributeList AttributeList::getImpl(LLVMContext &C,
   // create a new one and insert it.
   if (!PA) {
     // Coallocate entries after the AttributeListImpl itself.
-    void *Mem = ::operator new(
-        AttributeListImpl::totalSizeToAlloc<AttributeSet>(AttrSets.size()));
+    void *Mem = pImpl->Alloc.Allocate(
+        AttributeListImpl::totalSizeToAlloc<AttributeSet>(AttrSets.size()),
+        alignof(AttributeListImpl));
     PA = new (Mem) AttributeListImpl(C, AttrSets);
     pImpl->AttrsLists.InsertNode(PA, InsertPoint);
   }

llvm/lib/IR/LLVMContextImpl.cpp

@@ -104,21 +104,6 @@ LLVMContextImpl::~LLVMContextImpl() {
     delete CDSConstant.second;
   CDSConstants.clear();
 
-  // Destroy attributes.
-  for (FoldingSetIterator<AttributeImpl> I = AttrsSet.begin(),
-         E = AttrsSet.end(); I != E; ) {
-    FoldingSetIterator<AttributeImpl> Elem = I++;
-    delete &*Elem;
-  }
-
-  // Destroy attribute lists.
-  for (FoldingSetIterator<AttributeListImpl> I = AttrsLists.begin(),
-                                             E = AttrsLists.end();
-       I != E;) {
-    FoldingSetIterator<AttributeListImpl> Elem = I++;
-    delete &*Elem;
-  }
-
   // Destroy attribute node lists.
   for (FoldingSetIterator<AttributeSetNode> I = AttrsSetNodes.begin(),
          E = AttrsSetNodes.end(); I != E; ) {