[analyzer] Add a CFG node for the allocator call in a C++ 'new' expression.

In an expression like "new (a, b) Foo(x, y)", two things happen:
- Memory is allocated by calling a function named 'operator new'.
- The memory is initialized using the constructor for 'Foo'.

Currently the analyzer only models the second event, though it has special
cases for both the default and placement forms of operator new. This patch
is the first step towards properly modeling both events: it changes the CFG
so that the above expression now generates the following elements.

1. a
2. b
3. (CFGNewAllocator)
4. x
5. y
6. Foo::Foo

The analyzer currently ignores the CFGNewAllocator element, but the next
step is to treat that as a call like any other.

The CFGNewAllocator element is not added to the CFG for analysis-based
warnings, since none of them take advantage of it yet.

llvm-svn: 199123

1 files changed, 29 insertions, 0 deletions

diff --git a/clang/lib/Analysis/CFG.cpp b/clang/lib/Analysis/CFG.cpp
index 5837d80b8d3..79966fd887d 100644
--- a/clang/lib/Analysis/CFG.cpp
+++ b/clang/lib/Analysis/CFG.cpp
@@ -363,6 +363,7 @@ private:
                                       AddStmtChoice asc);
   CFGBlock *VisitCXXCatchStmt(CXXCatchStmt *S);
   CFGBlock *VisitCXXConstructExpr(CXXConstructExpr *C, AddStmtChoice asc);
+  CFGBlock *VisitCXXNewExpr(CXXNewExpr *DE, AddStmtChoice asc);
   CFGBlock *VisitCXXDeleteExpr(CXXDeleteExpr *DE, AddStmtChoice asc);
   CFGBlock *VisitCXXForRangeStmt(CXXForRangeStmt *S);
   CFGBlock *VisitCXXFunctionalCastExpr(CXXFunctionalCastExpr *E,
@@ -459,6 +460,9 @@ private:
   void appendInitializer(CFGBlock *B, CXXCtorInitializer *I) {
     B->appendInitializer(I, cfg->getBumpVectorContext());
   }
+  void appendNewAllocator(CFGBlock *B, CXXNewExpr *NE) {
+    B->appendNewAllocator(NE, cfg->getBumpVectorContext());
+  }
   void appendBaseDtor(CFGBlock *B, const CXXBaseSpecifier *BS) {
     B->appendBaseDtor(BS, cfg->getBumpVectorContext());
   }
@@ -1122,6 +1126,9 @@ CFGBlock *CFGBuilder::Visit(Stmt * S, AddStmtChoice asc) {
     case Stmt::CXXConstructExprClass:
       return VisitCXXConstructExpr(cast<CXXConstructExpr>(S), asc);
 
+    case Stmt::CXXNewExprClass:
+      return VisitCXXNewExpr(cast<CXXNewExpr>(S), asc);
+
     case Stmt::CXXDeleteExprClass:
       return VisitCXXDeleteExpr(cast<CXXDeleteExpr>(S), asc);
 
@@ -3124,6 +3131,22 @@ CFGBlock *CFGBuilder::VisitCXXConstructExpr(CXXConstructExpr *C,
   return VisitChildren(C);
 }
 
+CFGBlock *CFGBuilder::VisitCXXNewExpr(CXXNewExpr *NE,
+                                      AddStmtChoice asc) {
+
+  autoCreateBlock();
+  appendStmt(Block, NE);
+  if (NE->getInitializer())
+    Block = VisitStmt(NE->getInitializer(), asc);
+  if (BuildOpts.AddCXXNewAllocator)
+    appendNewAllocator(Block, NE);
+  if (NE->isArray())
+    Block = VisitStmt(NE->getArraySize(), asc);
+  for (CXXNewExpr::arg_iterator I = NE->placement_arg_begin(),
+       E = NE->placement_arg_end(); I != E; ++I)
+    Block = VisitStmt(*I, asc);
+  return Block;
+}
 
 CFGBlock *CFGBuilder::VisitCXXDeleteExpr(CXXDeleteExpr *DE,
                                          AddStmtChoice asc) {
@@ -3426,6 +3449,7 @@ CFGImplicitDtor::getDestructorDecl(ASTContext &astContext) const {
   switch (getKind()) {
     case CFGElement::Statement:
     case CFGElement::Initializer:
+    case CFGElement::NewAllocator:
       llvm_unreachable("getDestructorDecl should only be used with "
                        "ImplicitDtors");
     case CFGElement::AutomaticObjectDtor: {
@@ -3789,6 +3813,11 @@ static void print_elem(raw_ostream &OS, StmtPrinterHelper &Helper,
     OS << ".~" << T->getAsCXXRecordDecl()->getName().str() << "()";
     OS << " (Implicit destructor)\n";
 
+  } else if (Optional<CFGNewAllocator> NE = E.getAs<CFGNewAllocator>()) {
+    OS << "CFGNewAllocator(";
+    if (const CXXNewExpr *AllocExpr = NE->getAllocatorExpr())
+      AllocExpr->getType().print(OS, PrintingPolicy(Helper.getLangOpts()));
+    OS << ")\n";
   } else if (Optional<CFGDeleteDtor> DE = E.getAs<CFGDeleteDtor>()) {
     const CXXRecordDecl *RD = DE->getCXXRecordDecl();
     if (!RD)