Store attributes in a global hash map instead.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@47191 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/AST/Decl.cpp b/AST/Decl.cpp
index 0ed028c..04d0d3c 100644
--- a/AST/Decl.cpp
+++ b/AST/Decl.cpp
@@ -15,6 +15,8 @@
 #include "clang/AST/DeclObjC.h"
 #include "clang/AST/Attr.h"
 #include "clang/Basic/IdentifierTable.h"
+#include "llvm/ADT/DenseMap.h"
+
 using namespace clang;
 
 // temporary statistics gathering
@@ -43,6 +45,12 @@
 
 static bool StatSwitch = false;
 
+// This keeps track of all decl attributes. Since so few decls have attrs, we
+// keep them in a hash map instead of wasting space in the Decl class.
+typedef llvm::DenseMap<const Decl*, Attr*> DeclAttrMapTy;
+
+static DeclAttrMapTy *DeclAttrs = 0;
+
 const char *Decl::getDeclKindName() const {
   switch (DeclKind) {
   default: assert(0 && "Unknown decl kind!");
@@ -251,6 +259,39 @@
 
 // Out-of-line virtual method providing a home for Decl.
 Decl::~Decl() {
+  if (!DeclAttrs)
+    return;
+  
+  DeclAttrMapTy::iterator it = DeclAttrs->find(this);
+  if (it != DeclAttrs->end()) {
+    delete it->second;
+    DeclAttrs->erase(it);
+    if (DeclAttrs->empty()) {
+      delete DeclAttrs;
+      DeclAttrs = 0;
+    }        
+  }
+}
+
+void Decl::addAttr(Attr *newattr)
+{
+  if (!DeclAttrs)
+    DeclAttrs = new llvm::DenseMap<const Decl*, Attr*>;
+  
+  Attr *&attr = DeclAttrs->FindAndConstruct(this).second;
+
+  newattr->setNext(attr);
+  attr = newattr;
+  
+  HasAttrs = true;
+}
+
+const Attr *Decl::getAttrs() const
+{
+  if (!HasAttrs || !DeclAttrs)
+    return 0;
+  
+  return DeclAttrs->find(this)->second;
 }
 
 const char *NamedDecl::getName() const {
@@ -259,12 +300,6 @@
   return "";
 }
 
-void ValueDecl::addAttr(Attr *attr)
-{
-  attr->setNext(Attrs);
-  Attrs = attr;
-}
-
 FunctionDecl::~FunctionDecl() {
   delete[] ParamInfo;
 }