[PATCH] D104616: [analyzer][WIP] Model comparision methods of std::unique_ptr

[Deep Majumder via Phabricator via cfe-commits]

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This patch handles all the comparision methods (defined via overloaded
operators) on std::unique_ptr. These operators compare the underlying
pointers, which makes it difficult to model the result.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D104616

Files:
  clang/lib/StaticAnalyzer/Checkers/SmartPtrModeling.cpp


Index: clang/lib/StaticAnalyzer/Checkers/SmartPtrModeling.cpp
===================================================================
--- clang/lib/StaticAnalyzer/Checkers/SmartPtrModeling.cpp
+++ clang/lib/StaticAnalyzer/Checkers/SmartPtrModeling.cpp
@@ -68,6 +68,7 @@
   bool updateMovedSmartPointers(CheckerContext &C, const MemRegion *ThisRegion,
                                 const MemRegion *OtherSmartPtrRegion) const;
   void handleBoolConversion(const CallEvent &Call, CheckerContext &C) const;
+  bool handleComparisionOp(const CallEvent &Call, CheckerContext &C) const;
 
   using SmartPtrMethodHandlerFn =
       void (SmartPtrModeling::*)(const CallEvent &Call, CheckerContext &) const;
@@ -264,6 +265,9 @@
   if (handleAssignOp(Call, C))
     return true;
 
+  if (handleComparisionOp(Call, C))
+    return true;
+
   const SmartPtrMethodHandlerFn *Handler = SmartPtrMethodHandlers.lookup(Call);
   if (!Handler)
     return false;
@@ -272,6 +276,26 @@
   return C.isDifferent();
 }
 
+bool SmartPtrModeling::handleComparisionOp(const CallEvent &Call,
+                                           CheckerContext &C) const {
+  const auto *MC = llvm::dyn_cast<CXXMemberOperatorCall>(&Call);
+  if (!MC)
+    return false;
+  const OverloadedOperatorKind OOK = MC->getOverloadedOperator();
+  if (!(OOK == OO_Equal || OOK == OO_ExclaimEqual || OOK == OO_Less ||
+        OOK == OO_LessEqual || OOK == OO_Greater || OOK == OO_GreaterEqual ||
+        OOK == OO_Spaceship))
+    return false;
+
+  // TODO: We had better put some useful modelling here.
+  // But the problem is that all these operators act on the raw
+  // inner pointer (there are special cases for comparision with nullptr).
+  // So, we are not really comparing the value pointed to by the pointer
+  // but the *pointer* itself, which is just an address, which is not
+  // something that symbolic evaluation is concerned about.
+  return true;
+}
+
 void SmartPtrModeling::checkDeadSymbols(SymbolReaper &SymReaper,
                                         CheckerContext &C) const {
   ProgramStateRef State = C.getState();


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