[analyzer] operator new: Add a new checker callback, check::NewAllocator.

The callback runs after operator new() and before the construction and allows
the checker to access the casted return value of operator new() (in the
sense of r322780) which is not available in the PostCall callback for the
allocator call.

Update MallocChecker to use the new callback instead of PostStmt<CXXNewExpr>,
which gets called after the constructor.

Differential Revision: https://reviews.llvm.org/D41406
rdar://problem/12180598

llvm-svn: 322787

1 files changed, 55 insertions, 25 deletions

diff --git a/clang/lib/StaticAnalyzer/Checkers/MallocChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/MallocChecker.cpp
index ca4be178c85..a1a540c4b96 100644
--- a/clang/lib/StaticAnalyzer/Checkers/MallocChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/MallocChecker.cpp
@@ -162,6 +162,7 @@ class MallocChecker : public Checker<check::DeadSymbols,
                                      check::PreCall,
                                      check::PostStmt<CallExpr>,
                                      check::PostStmt<CXXNewExpr>,
+                                     check::NewAllocator,
                                      check::PreStmt<CXXDeleteExpr>,
                                      check::PostStmt<BlockExpr>,
                                      check::PostObjCMessage,
@@ -207,6 +208,8 @@ public:
   void checkPreCall(const CallEvent &Call, CheckerContext &C) const;
   void checkPostStmt(const CallExpr *CE, CheckerContext &C) const;
   void checkPostStmt(const CXXNewExpr *NE, CheckerContext &C) const;
+  void checkNewAllocator(const CXXNewExpr *NE, SVal Target,
+                         CheckerContext &C) const;
   void checkPreStmt(const CXXDeleteExpr *DE, CheckerContext &C) const;
   void checkPostObjCMessage(const ObjCMethodCall &Call, CheckerContext &C) const;
   void checkPostStmt(const BlockExpr *BE, CheckerContext &C) const;
@@ -281,10 +284,18 @@ private:
   bool isStandardNewDelete(const FunctionDecl *FD, ASTContext &C) const;
   ///@}
 
+  /// \brief Process C++ operator new()'s allocation, which is the part of C++
+  /// new-expression that goes before the constructor.
+  void processNewAllocation(const CXXNewExpr *NE, CheckerContext &C,
+                            SVal Target) const;
+
   /// \brief Perform a zero-allocation check.
+  /// The optional \p RetVal parameter specifies the newly allocated pointer
+  /// value; if unspecified, the value of expression \p E is used.
   ProgramStateRef ProcessZeroAllocation(CheckerContext &C, const Expr *E,
                                         const unsigned AllocationSizeArg,
-                                        ProgramStateRef State) const;
+                                        ProgramStateRef State,
+                                        Optional<SVal> RetVal = None) const;
 
   ProgramStateRef MallocMemReturnsAttr(CheckerContext &C,
                                        const CallExpr *CE,
@@ -300,7 +311,7 @@ private:
                                       AllocationFamily Family = AF_Malloc);
 
   static ProgramStateRef addExtentSize(CheckerContext &C, const CXXNewExpr *NE,
-                                       ProgramStateRef State);
+                                       ProgramStateRef State, SVal Target);
 
   // Check if this malloc() for special flags. At present that means M_ZERO or
   // __GFP_ZERO (in which case, treat it like calloc).
@@ -309,9 +320,12 @@ private:
                       const ProgramStateRef &State) const;
 
   /// Update the RefState to reflect the new memory allocation.
+  /// The optional \p RetVal parameter specifies the newly allocated pointer
+  /// value; if unspecified, the value of expression \p E is used.
   static ProgramStateRef
   MallocUpdateRefState(CheckerContext &C, const Expr *E, ProgramStateRef State,
-                       AllocationFamily Family = AF_Malloc);
+                       AllocationFamily Family = AF_Malloc,
+                       Optional<SVal> RetVal = None);
 
   ProgramStateRef FreeMemAttr(CheckerContext &C, const CallExpr *CE,
                               const OwnershipAttr* Att,
@@ -949,13 +963,15 @@ void MallocChecker::checkPostStmt(const CallExpr *CE, CheckerContext &C) const {
 }
 
 // Performs a 0-sized allocations check.
-ProgramStateRef MallocChecker::ProcessZeroAllocation(CheckerContext &C,
-                                               const Expr *E,
-                                               const unsigned AllocationSizeArg,
-                                               ProgramStateRef State) const {
+ProgramStateRef MallocChecker::ProcessZeroAllocation(
+    CheckerContext &C, const Expr *E, const unsigned AllocationSizeArg,
+    ProgramStateRef State, Optional<SVal> RetVal) const {
   if (!State)
     return nullptr;
 
+  if (!RetVal)
+    RetVal = C.getSVal(E);
+
   const Expr *Arg = nullptr;
 
   if (const CallExpr *CE = dyn_cast<CallExpr>(E)) {
@@ -987,8 +1003,7 @@ ProgramStateRef MallocChecker::ProcessZeroAllocation(CheckerContext &C,
       State->assume(SvalBuilder.evalEQ(State, *DefArgVal, Zero));
 
   if (TrueState && !FalseState) {
-    SVal retVal = C.getSVal(E);
-    SymbolRef Sym = retVal.getAsLocSymbol();
+    SymbolRef Sym = RetVal->getAsLocSymbol();
     if (!Sym)
       return State;
 
@@ -1049,9 +1064,9 @@ static bool treatUnusedNewEscaped(const CXXNewExpr *NE) {
   return false;
 }
 
-void MallocChecker::checkPostStmt(const CXXNewExpr *NE,
-                                  CheckerContext &C) const {
-
+void MallocChecker::processNewAllocation(const CXXNewExpr *NE,
+                                         CheckerContext &C,
+                                         SVal Target) const {
   if (NE->getNumPlacementArgs())
     for (CXXNewExpr::const_arg_iterator I = NE->placement_arg_begin(),
          E = NE->placement_arg_end(); I != E; ++I)
@@ -1071,37 +1086,48 @@ void MallocChecker::checkPostStmt(const CXXNewExpr *NE,
   // MallocUpdateRefState() instead of MallocMemAux() which breakes the
   // existing binding.
   State = MallocUpdateRefState(C, NE, State, NE->isArray() ? AF_CXXNewArray
-                                                           : AF_CXXNew);
-  State = addExtentSize(C, NE, State);
-  State = ProcessZeroAllocation(C, NE, 0, State);
+                                                           : AF_CXXNew, Target);
+  State = addExtentSize(C, NE, State, Target);
+  State = ProcessZeroAllocation(C, NE, 0, State, Target);
   C.addTransition(State);
 }
 
+void MallocChecker::checkPostStmt(const CXXNewExpr *NE,
+                                  CheckerContext &C) const {
+  if (!C.getAnalysisManager().getAnalyzerOptions().mayInlineCXXAllocator())
+    processNewAllocation(NE, C, C.getSVal(NE));
+}
+
+void MallocChecker::checkNewAllocator(const CXXNewExpr *NE, SVal Target,
+                                      CheckerContext &C) const {
+  if (!C.wasInlined)
+    processNewAllocation(NE, C, Target);
+}
+
 // Sets the extent value of the MemRegion allocated by
 // new expression NE to its size in Bytes.
 //
 ProgramStateRef MallocChecker::addExtentSize(CheckerContext &C,
                                              const CXXNewExpr *NE,
-                                             ProgramStateRef State) {
+                                             ProgramStateRef State,
+                                             SVal Target) {
   if (!State)
     return nullptr;
   SValBuilder &svalBuilder = C.getSValBuilder();
   SVal ElementCount;
-  const LocationContext *LCtx = C.getLocationContext();
   const SubRegion *Region;
   if (NE->isArray()) {
     const Expr *SizeExpr = NE->getArraySize();
     ElementCount = C.getSVal(SizeExpr);
     // Store the extent size for the (symbolic)region
     // containing the elements.
-    Region = (State->getSVal(NE, LCtx))
-                 .getAsRegion()
+    Region = Target.getAsRegion()
                  ->getAs<SubRegion>()
-                 ->getSuperRegion()
+                 ->StripCasts()
                  ->getAs<SubRegion>();
   } else {
     ElementCount = svalBuilder.makeIntVal(1, true);
-    Region = (State->getSVal(NE, LCtx)).getAsRegion()->getAs<SubRegion>();
+    Region = Target.getAsRegion()->getAs<SubRegion>();
   }
   assert(Region);
 
@@ -1261,18 +1287,22 @@ ProgramStateRef MallocChecker::MallocMemAux(CheckerContext &C,
 ProgramStateRef MallocChecker::MallocUpdateRefState(CheckerContext &C,
                                                     const Expr *E,
                                                     ProgramStateRef State,
-                                                    AllocationFamily Family) {
+                                                    AllocationFamily Family,
+                                                    Optional<SVal> RetVal) {
   if (!State)
     return nullptr;
 
   // Get the return value.
-  SVal retVal = C.getSVal(E);
+  if (!RetVal)
+    RetVal = C.getSVal(E);
 
   // We expect the malloc functions to return a pointer.
-  if (!retVal.getAs<Loc>())
+  if (!RetVal->getAs<Loc>())
     return nullptr;
 
-  SymbolRef Sym = retVal.getAsLocSymbol();
+  SymbolRef Sym = RetVal->getAsLocSymbol();
+  // This is a return value of a function that was not inlined, such as malloc()
+  // or new(). We've checked that in the caller. Therefore, it must be a symbol.
   assert(Sym);
 
   // Set the symbol's state to Allocated.