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

[Artem Dergachev via cfe-commits]

NoQ created this revision.
NoQ added a reviewer: dcoughlin.
NoQ added a subscriber: cfe-commits.

Or, more importantly, tell the users that there's a way to discover the region, value of which - at some moment of time - the symbol was introduced to represent. Idea proposed by Devin Coughlin.

Right now this is a simple code de-duplication, but in fact maybe it should be extended to support SymbolMetadata, SymbolExtent, and maybe, even more importantly, SymbolConjured (if the latter is created during invalidation of a region, *and* the symbol's structure is modified to remember that region - which i think is a useful idea, but that's another story; there's not much we could do for conjured-return-value symbols, even though sometimes even they should probably be tied to temporary object regions).

http://reviews.llvm.org/D22242

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

Index: lib/StaticAnalyzer/Core/SymbolManager.cpp
===================================================================
--- lib/StaticAnalyzer/Core/SymbolManager.cpp
+++ lib/StaticAnalyzer/Core/SymbolManager.cpp
@@ -147,6 +147,14 @@
   return R;
 }
 
+const MemRegion *SymExpr::getOriginRegion() const {
+  if (const SymbolRegionValue *SRV = dyn_cast<SymbolRegionValue>(this))
+    return SRV->getRegion();
+  else if (const SymbolDerived *SD = dyn_cast<SymbolDerived>(this))
+    return SD->getRegion();
+  return nullptr;
+}
+
 const SymbolRegionValue*
 SymbolManager::getRegionValueSymbol(const TypedValueRegion* R) {
   llvm::FoldingSetNodeID profile;
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/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 +78,7 @@
   static symbol_iterator symbol_end() { return symbol_iterator(); }
 
   unsigned computeComplexity() const;
+  const MemRegion *getOriginRegion() const;
 };
 
 typedef const SymExpr *SymbolRef;


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