Re: [PATCH] D22242: [analyzer] De-duplicate some code for discovering the origin of the symbol.

[Artem Dergachev via cfe-commits]

NoQ updated this revision to Diff 63688.
NoQ marked an inline comment as done.
NoQ added a comment.

Added a doxygen comment, made the function virtual instead of branching.


http://reviews.llvm.org/D22242

Files:
  include/clang/StaticAnalyzer/Core/PathSensitive/SymExpr.h
  include/clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h
  lib/StaticAnalyzer/Checkers/CheckObjCDealloc.cpp
  lib/StaticAnalyzer/Checkers/RetainCountChecker.cpp


Index: lib/StaticAnalyzer/Checkers/RetainCountChecker.cpp
===================================================================
--- lib/StaticAnalyzer/Checkers/RetainCountChecker.cpp
+++ lib/StaticAnalyzer/Checkers/RetainCountChecker.cpp
@@ -2833,23 +2833,15 @@
   C.addTransition(State);
 }
 
-static bool wasLoadedFromIvar(SymbolRef Sym) {
-  if (auto DerivedVal = dyn_cast<SymbolDerived>(Sym))
-    return isa<ObjCIvarRegion>(DerivedVal->getRegion());
-  if (auto RegionVal = dyn_cast<SymbolRegionValue>(Sym))
-    return isa<ObjCIvarRegion>(RegionVal->getRegion());
-  return false;
-}
-
 void RetainCountChecker::checkPostStmt(const ObjCIvarRefExpr *IRE,
                                        CheckerContext &C) const {
   Optional<Loc> IVarLoc = C.getSVal(IRE).getAs<Loc>();
   if (!IVarLoc)
     return;
 
   ProgramStateRef State = C.getState();
   SymbolRef Sym = State->getSVal(*IVarLoc).getAsSymbol();
-  if (!Sym || !wasLoadedFromIvar(Sym))
+  if (!Sym || !dyn_cast_or_null<ObjCIvarRegion>(Sym->getOriginRegion()))
     return;
 
   // Accessing an ivar directly is unusual. If we've done that, be more
Index: lib/StaticAnalyzer/Checkers/CheckObjCDealloc.cpp
===================================================================
--- lib/StaticAnalyzer/Checkers/CheckObjCDealloc.cpp
+++ lib/StaticAnalyzer/Checkers/CheckObjCDealloc.cpp
@@ -315,15 +315,7 @@
 /// Returns nullptr if the instance symbol cannot be found.
 const ObjCIvarRegion *
 ObjCDeallocChecker::getIvarRegionForIvarSymbol(SymbolRef IvarSym) const {
-  const MemRegion *RegionLoadedFrom = nullptr;
-  if (auto *DerivedSym = dyn_cast<SymbolDerived>(IvarSym))
-    RegionLoadedFrom = DerivedSym->getRegion();
-  else if (auto *RegionSym = dyn_cast<SymbolRegionValue>(IvarSym))
-    RegionLoadedFrom = RegionSym->getRegion();
-  else
-    return nullptr;
-
-  return dyn_cast<ObjCIvarRegion>(RegionLoadedFrom);
+  return dyn_cast_or_null<ObjCIvarRegion>(IvarSym->getOriginRegion());
 }
 
 /// Given a symbol for an ivar, return a symbol for the instance containing
Index: include/clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h
===================================================================
--- include/clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h
+++ include/clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h
@@ -58,6 +58,7 @@
   }
 
   void dumpToStream(raw_ostream &os) const override;
+  const MemRegion *getOriginRegion() const override { return getRegion(); }
 
   QualType getType() const override;
 
@@ -127,6 +128,7 @@
   QualType getType() const override;
 
   void dumpToStream(raw_ostream &os) const override;
+  const MemRegion *getOriginRegion() const override { return getRegion(); }
 
   static void Profile(llvm::FoldingSetNodeID& profile, SymbolRef parent,
                       const TypedValueRegion *r) {
Index: include/clang/StaticAnalyzer/Core/PathSensitive/SymExpr.h
===================================================================
--- include/clang/StaticAnalyzer/Core/PathSensitive/SymExpr.h
+++ include/clang/StaticAnalyzer/Core/PathSensitive/SymExpr.h
@@ -22,6 +22,8 @@
 namespace clang {
 namespace ento {
 
+class MemRegion;
+
 /// \brief Symbolic value. These values used to capture symbolic execution of
 /// the program.
 class SymExpr : public llvm::FoldingSetNode {
@@ -76,6 +78,18 @@
   static symbol_iterator symbol_end() { return symbol_iterator(); }
 
   unsigned computeComplexity() const;
+
+  /// \brief Find the region from which this symbol originates.
+  ///
+  /// Whenever the symbol was constructed to denote an unknown value of
+  /// a certain memory region, return this region. This method
+  /// allows checkers to make decisions depending on the origin of the symbol.
+  /// Symbol classes for which the origin region is known include
+  /// SymbolRegionValue which denotes the value of the region before
+  /// the beginning of the analysis, and SymbolDerived which denotes the value
+  /// of a certain memory region after its super region (a memory space or
+  /// a larger record region) is default-bound with a certain symbol.
+  virtual const MemRegion *getOriginRegion() const { return nullptr; }
 };
 
 typedef const SymExpr *SymbolRef;

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