Overhaul of Stmt allocation:
- Made allocation of Stmt objects using vanilla new/delete a *compiler
  error* by making this new/delete "protected" within class Stmt.
- Now the only way to allocate Stmt objects is by using the new
  operator that takes ASTContext& as an argument.  This ensures that
  all Stmt nodes are allocated from the same (pool) allocator.
- Naturally, these two changes required that *all* creation sites for
  AST nodes use new (ASTContext&).  This is a large patch, but the
  majority of the changes are just this mechanical adjustment.
- The above changes also mean that AST nodes can no longer be
  deallocated using 'delete'.  Instead, one most do
  StmtObject->Destroy(ASTContext&) or do
  ASTContextObject.Deallocate(StmtObject) (the latter not running the
  'Destroy' method).

Along the way I also...
- Made CompoundStmt allocate its array of Stmt* using the allocator in
  ASTContext (previously it used std::vector).  There are a whole
  bunch of other Stmt classes that need to be similarly changed to
  ensure that all memory allocated for ASTs comes from the allocator
  in ASTContext.
- Added a new smart pointer ExprOwningPtr to Sema.h.  This replaces
  the uses of llvm::OwningPtr within Sema, as llvm::OwningPtr used
  'delete' to free memory instead of a Stmt's 'Destroy' method.

Big thanks to Doug Gregor for helping with the acrobatics of making
'new/delete' private and the new smart pointer ExprOwningPtr!


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@63997 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/Expr.cpp b/lib/AST/Expr.cpp
index 89fdbe3..d686167 100644
--- a/lib/AST/Expr.cpp
+++ b/lib/AST/Expr.cpp
@@ -54,8 +54,8 @@
 }
 
 void StringLiteral::Destroy(ASTContext &C) {
-  C.Deallocate(const_cast<char*>(StrData));
   this->~StringLiteral();
+  C.Deallocate(const_cast<char*>(StrData));
 }
 
 bool UnaryOperator::isPostfix(Opcode Op) {
@@ -104,8 +104,8 @@
 // Postfix Operators.
 //===----------------------------------------------------------------------===//
 
-CallExpr::CallExpr(StmtClass SC, Expr *fn, Expr **args, unsigned numargs, 
-                   QualType t, SourceLocation rparenloc)
+CallExpr::CallExpr(StmtClass SC, Expr *fn, Expr **args,
+                   unsigned numargs, QualType t, SourceLocation rparenloc)
   : Expr(SC, t, 
          fn->isTypeDependent() || hasAnyTypeDependentArguments(args, numargs),
          fn->isValueDependent() || hasAnyValueDependentArguments(args, numargs)),
@@ -133,14 +133,14 @@
 /// setNumArgs - This changes the number of arguments present in this call.
 /// Any orphaned expressions are deleted by this, and any new operands are set
 /// to null.
-void CallExpr::setNumArgs(unsigned NumArgs) {
+void CallExpr::setNumArgs(ASTContext& C, unsigned NumArgs) {
   // No change, just return.
   if (NumArgs == getNumArgs()) return;
   
   // If shrinking # arguments, just delete the extras and forgot them.
   if (NumArgs < getNumArgs()) {
     for (unsigned i = NumArgs, e = getNumArgs(); i != e; ++i)
-      delete getArg(i);
+      getArg(i)->Destroy(C);
     this->NumArgs = NumArgs;
     return;
   }
@@ -154,7 +154,7 @@
   for (unsigned i = getNumArgs()+ARGS_START; i != NumArgs+ARGS_START; ++i)
     NewSubExprs[i] = 0;
   
-  delete[] SubExprs;
+  delete [] SubExprs;
   SubExprs = NewSubExprs;
   this->NumArgs = NumArgs;
 }
@@ -1391,10 +1391,10 @@
   // will iterate over the size expression. However, this expression belongs
   // to the type, not to this, so we don't want to delete it.
   // We still want to delete this expression.
-  // FIXME: Same as in Stmt::Destroy - will be eventually in ASTContext's
-  // pool allocator.
-  if (isArgumentType())
-    delete this;
+  if (isArgumentType()) {
+    this->~SizeOfAlignOfExpr();
+    C.Deallocate(this);
+  }
   else
     Expr::Destroy(C);
 }
diff --git a/lib/AST/ExprCXX.cpp b/lib/AST/ExprCXX.cpp
index b328c1e..801a0f2 100644
--- a/lib/AST/ExprCXX.cpp
+++ b/lib/AST/ExprCXX.cpp
@@ -20,10 +20,10 @@
   // FIXME: Cannot destroy the decl here, because it is linked into the
   // DeclContext's chain.
   //getVarDecl()->Destroy(C);
-  delete this;
+  this->~CXXConditionDeclExpr();
+  C.Deallocate(this);
 }
 
-
 //===----------------------------------------------------------------------===//
 //  Child Iterators for iterating over subexpressions/substatements
 //===----------------------------------------------------------------------===//
diff --git a/lib/AST/Stmt.cpp b/lib/AST/Stmt.cpp
index 541bb04..49c8c80 100644
--- a/lib/AST/Stmt.cpp
+++ b/lib/AST/Stmt.cpp
@@ -219,7 +219,7 @@
 
 // CompoundStmt
 Stmt::child_iterator CompoundStmt::child_begin() { return &Body[0]; }
-Stmt::child_iterator CompoundStmt::child_end() { return &Body[0]+Body.size(); }
+Stmt::child_iterator CompoundStmt::child_end() { return &Body[0]+NumStmts; }
 
 // CaseStmt
 Stmt::child_iterator CaseStmt::child_begin() { return &SubExprs[0]; }
diff --git a/lib/AST/StmtSerialization.cpp b/lib/AST/StmtSerialization.cpp
index 8d6636d..92713cc 100644
--- a/lib/AST/StmtSerialization.cpp
+++ b/lib/AST/StmtSerialization.cpp
@@ -483,7 +483,8 @@
   S.EmitOwnedPtr(Init);
 }
 
-CompoundLiteralExpr* CompoundLiteralExpr::CreateImpl(Deserializer& D, ASTContext& C) {
+CompoundLiteralExpr* CompoundLiteralExpr::CreateImpl(Deserializer& D,
+                                                     ASTContext& C) {
   QualType Q = QualType::ReadVal(D);
   SourceLocation L = SourceLocation::ReadVal(D);
   bool fileScope = D.ReadBool();
@@ -495,10 +496,8 @@
 void CompoundStmt::EmitImpl(Serializer& S) const {
   S.Emit(LBracLoc);
   S.Emit(RBracLoc);
-  S.Emit(Body.size());
-  
-  for (const_body_iterator I=body_begin(), E=body_end(); I!=E; ++I)
-    S.EmitOwnedPtr(*I);
+  S.Emit(NumStmts);
+  if (NumStmts) S.BatchEmitOwnedPtrs(NumStmts, &Body[0]);
 }
 
 CompoundStmt* CompoundStmt::CreateImpl(Deserializer& D, ASTContext& C) {
@@ -507,13 +506,15 @@
   unsigned size = D.ReadInt();
   
   CompoundStmt* stmt = new (C, llvm::alignof<CompoundStmt>())
-    CompoundStmt(NULL, 0, LB, RB);
+    CompoundStmt(C, NULL, 0, LB, RB);
+
+  stmt->NumStmts = size;
   
-  stmt->Body.reserve(size);
-  
-  for (unsigned i = 0; i < size; ++i)
-    stmt->Body.push_back(D.ReadOwnedPtr<Stmt>(C));
-  
+  if (size) {
+    stmt->Body = new (C) Stmt*[size];
+    D.BatchReadOwnedPtrs(size, &stmt->Body[0], C);
+  }
+
   return stmt;
 }
 
@@ -1306,7 +1307,7 @@
   Expr *B = D.ReadOwnedPtr<Expr>(C);
   IdentifierInfo *A = D.ReadPtr<IdentifierInfo>();
   SourceLocation AL = SourceLocation::ReadVal(D);
-  return new ExtVectorElementExpr(T, B, *A, AL);
+  return new (C) ExtVectorElementExpr(T, B, *A, AL);
 }
 
 void BlockExpr::EmitImpl(Serializer& S) const {