[analyzer] Add a checker to manage dynamic type propagation.

Instead of sprinkling dynamic type info propagation throughout
ExprEngine, the added checker would add the more precise type
information on known APIs (Ex: ObjC alloc, new) and propagate
the type info in other cases (ex: ObjC init method, casts (the second is
not implemented yet)).

Add handling of ObjC alloc, new and init to the checker.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@161357 91177308-0d34-0410-b5e6-96231b3b80d8

6 files changed, 127 insertions, 10 deletions

diff --git a/lib/StaticAnalyzer/Checkers/CMakeLists.txt b/lib/StaticAnalyzer/Checkers/CMakeLists.txt
index 66ee42f7e9..7fe51d3a4c 100644
--- a/lib/StaticAnalyzer/Checkers/CMakeLists.txt
+++ b/lib/StaticAnalyzer/Checkers/CMakeLists.txt
@@ -29,6 +29,7 @@ add_clang_library(clangStaticAnalyzerCheckers
   DebugCheckers.cpp
   DereferenceChecker.cpp
   DivZeroChecker.cpp
+  DynamicTypePropagation.cpp
   ExprInspectionChecker.cpp
   FixedAddressChecker.cpp
   GenericTaintChecker.cpp
diff --git a/lib/StaticAnalyzer/Checkers/Checkers.td b/lib/StaticAnalyzer/Checkers/Checkers.td
index 959c44f60d..8110bd0e18 100644
--- a/lib/StaticAnalyzer/Checkers/Checkers.td
+++ b/lib/StaticAnalyzer/Checkers/Checkers.td
@@ -84,6 +84,10 @@ def StackAddrEscapeChecker : Checker<"StackAddressEscape">,
   HelpText<"Check that addresses to stack memory do not escape the function">,
   DescFile<"StackAddrEscapeChecker.cpp">;
 
+def DynamicTypePropagation : Checker<"DynamicTypePropagation">,
+  HelpText<"Generate dynamic type information">,
+  DescFile<"DynamicTypePropagation.cpp">;
+
 } // end "core"
 
 let ParentPackage = CoreExperimental in {
diff --git a/lib/StaticAnalyzer/Checkers/DynamicTypePropagation.cpp b/lib/StaticAnalyzer/Checkers/DynamicTypePropagation.cpp
new file mode 100644
index 0000000000..56610b5818
--- /dev/null
+++ b/lib/StaticAnalyzer/Checkers/DynamicTypePropagation.cpp
@@ -0,0 +1,116 @@
+//== DynamicTypePropagation.cpp ----------------------------------- -*- C++ -*--=//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This checker defines the rules for dynamic type gathering and propagation.
+//
+//===----------------------------------------------------------------------===//
+
+#include "ClangSACheckers.h"
+#include "clang/StaticAnalyzer/Core/Checker.h"
+#include "clang/StaticAnalyzer/Core/CheckerManager.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
+#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
+#include "clang/Basic/Builtins.h"
+
+using namespace clang;
+using namespace ento;
+
+namespace {
+class DynamicTypePropagation : public Checker< check::PostCall > {
+  const ObjCObjectType *getObjectTypeForAllocAndNew(const ObjCMessageExpr *MsgE,
+                                                    CheckerContext &C) const;
+public:
+  void checkPostCall(const CallEvent &CE, CheckerContext &C) const;
+};
+}
+
+void DynamicTypePropagation::checkPostCall(const CallEvent &Call,
+                                           CheckerContext &C) const {
+  // We can obtain perfect type info for return values from some calls.
+  if (const ObjCMethodCall *Msg = dyn_cast<ObjCMethodCall>(&Call)) {
+
+    // Get the returned value if it's a region.
+    SVal Result = C.getSVal(Call.getOriginExpr());
+    const MemRegion *RetReg = Result.getAsRegion();
+    if (!RetReg)
+      return;
+
+    ProgramStateRef State = C.getState();
+
+    switch (Msg->getMethodFamily()) {
+    default:
+      break;
+
+    // We assume that the type of the object returned by alloc and new are the
+    // pointer to the object of the class specified in the receiver of the
+    // message.
+    case OMF_alloc:
+    case OMF_new: {
+      // Get the type of object that will get created.
+      const ObjCMessageExpr *MsgE = Msg->getOriginExpr();
+      const ObjCObjectType *ObjTy = getObjectTypeForAllocAndNew(MsgE, C);
+      if (!ObjTy)
+        return;
+      QualType DynResTy =
+                 C.getASTContext().getObjCObjectPointerType(QualType(ObjTy, 0));
+      C.addTransition(State->addDynamicTypeInfo(RetReg, DynResTy));
+      break;
+    }
+    case OMF_init: {
+      // Assume, the result of the init method has the same dynamic type as
+      // the receiver and propagate the dynamic type info.
+      const MemRegion *RecReg = Msg->getReceiverSVal().getAsRegion();
+      assert(RecReg);
+      DynamicTypeInfo RecDynType = State->getDynamicTypeInfo(RecReg);
+      C.addTransition(State->addDynamicTypeInfo(RetReg, RecDynType));
+      break;
+    }
+    }
+  }
+}
+
+const ObjCObjectType *
+DynamicTypePropagation::getObjectTypeForAllocAndNew(const ObjCMessageExpr *MsgE,
+                                                    CheckerContext &C) const {
+  if (MsgE->getReceiverKind() == ObjCMessageExpr::Class) {
+    if (const ObjCObjectType *ObjTy
+          = MsgE->getClassReceiver()->getAs<ObjCObjectType>())
+    return ObjTy;
+  }
+
+  if (MsgE->getReceiverKind() == ObjCMessageExpr::SuperClass) {
+    if (const ObjCObjectType *ObjTy
+          = MsgE->getSuperType()->getAs<ObjCObjectType>())
+      return ObjTy;
+  }
+
+  const Expr *RecE = MsgE->getInstanceReceiver();
+  if (!RecE)
+    return 0;
+
+  RecE= RecE->IgnoreParenImpCasts();
+  if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(RecE)) {
+    const StackFrameContext *SFCtx = C.getCurrentStackFrame();
+    // Are we calling [self alloc]? If this is self, get the type of the
+    // enclosing ObjC class.
+    if (DRE->getDecl() == SFCtx->getSelfDecl()) {
+      if (const ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(SFCtx->getDecl()))
+        if (const ObjCObjectType *ObjTy =
+            dyn_cast<ObjCObjectType>(MD->getClassInterface()->getTypeForDecl()))
+          return ObjTy;
+    }
+  }
+  return 0;
+}
+
+void ento::registerDynamicTypePropagation(CheckerManager &mgr) {
+  mgr.registerChecker<DynamicTypePropagation>();
+}
diff --git a/lib/StaticAnalyzer/Core/CallEvent.cpp b/lib/StaticAnalyzer/Core/CallEvent.cpp
index 05147670c1..396e0f6d8d 100644
--- a/lib/StaticAnalyzer/Core/CallEvent.cpp
+++ b/lib/StaticAnalyzer/Core/CallEvent.cpp
@@ -583,8 +583,8 @@ SVal ObjCMethodCall::getReceiverSVal() const {
   if (!isInstanceMessage())
     return UnknownVal();
     
-  if (const Expr *Base = getOriginExpr()->getInstanceReceiver())
-    return getSVal(Base);
+  if (const Expr *RecE = getOriginExpr()->getInstanceReceiver())
+    return getSVal(RecE);
 
   // An instance message with no expression means we are sending to super.
   // In this case the object reference is the same as 'self'.
@@ -676,8 +676,8 @@ const Decl *ObjCMethodCall::getRuntimeDefinition() const {
       if (!Receiver)
         return 0;
 
-      DynamicTypeInfo TI = getState()->getDynamicTypeInfo(Receiver);
-      ReceiverT = dyn_cast<ObjCObjectPointerType>(TI.getType().getTypePtr());
+      QualType DynType = getState()->getDynamicTypeInfo(Receiver).getType();
+      ReceiverT = dyn_cast<ObjCObjectPointerType>(DynType.getTypePtr());
     }
 
     // Lookup the method implementation.
@@ -715,7 +715,6 @@ void ObjCMethodCall::getInitialStackFrameContents(
   }
 }
 
-
 CallEventRef<SimpleCall>
 CallEventManager::getSimpleCall(const CallExpr *CE, ProgramStateRef State,
                                 const LocationContext *LCtx) {
diff --git a/lib/StaticAnalyzer/Core/ExprEngineC.cpp b/lib/StaticAnalyzer/Core/ExprEngineC.cpp
index 740dec5ec4..7ec151ef6d 100644
--- a/lib/StaticAnalyzer/Core/ExprEngineC.cpp
+++ b/lib/StaticAnalyzer/Core/ExprEngineC.cpp
@@ -308,9 +308,6 @@ void ExprEngine::VisitCast(const CastExpr *CastE, const Expr *Ex,
         const LocationContext *LCtx = Pred->getLocationContext();
         SVal V = state->getSVal(Ex, LCtx);
         V = svalBuilder.evalCast(V, T, ExTy);
-        if (const MemRegion *R = V.getAsRegion()) {
-          state = state->addDynamicTypeInfo(R, T);
-        }
         state = state->BindExpr(CastE, LCtx, V);
         Bldr.generateNode(CastE, Pred, state);
         continue;
diff --git a/lib/StaticAnalyzer/Core/ProgramState.cpp b/lib/StaticAnalyzer/Core/ProgramState.cpp
index b44c470a90..c916c1a020 100644
--- a/lib/StaticAnalyzer/Core/ProgramState.cpp
+++ b/lib/StaticAnalyzer/Core/ProgramState.cpp
@@ -762,12 +762,12 @@ DynamicTypeInfo ProgramState::getDynamicTypeInfo(const MemRegion *Reg) const {
 }
 
 ProgramStateRef ProgramState::addDynamicTypeInfo(const MemRegion *Reg,
-                                                 QualType NewTy) const {
+                                                 DynamicTypeInfo NewTy) const {
   if (const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(Reg)) {
     SymbolRef Sym = SR->getSymbol();
     // TODO: Instead of resetting the type info, check the old type info and
     // merge and pick the most precise type.
-    ProgramStateRef NewState = set<DynamicTypeMap>(Sym, DynamicTypeInfo(NewTy));
+    ProgramStateRef NewState = set<DynamicTypeMap>(Sym, NewTy);
     assert(NewState);
     return NewState;
   }