[PATCH] [analyzer] Fix FP warnings when binding a temporary to a local static variable

[Pavel Labath]

  Add tests, simplify VisitCXXConstructExpr, include thread_local references

Hi jordan_rose,

http://llvm-reviews.chandlerc.com/D1133

CHANGE SINCE LAST DIFF
  http://llvm-reviews.chandlerc.com/D1133?vs=2780&id=2837#toc

Files:
  include/clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h
  lib/StaticAnalyzer/Core/ExprEngine.cpp
  lib/StaticAnalyzer/Core/MemRegion.cpp
  test/Analysis/stack-addr-ps.cpp
  test/Analysis/temporaries.cpp

Index: include/clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h
===================================================================
--- include/clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h
+++ include/clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h
@@ -1272,6 +1272,11 @@
   const BlockDataRegion *getBlockDataRegion(const BlockTextRegion *bc,
                                             const LocationContext *lc = NULL);
 
+  /// Create a CXXTempObjectRegion for temporaries which are lifetime-extended
+  /// by static references. This differs from getCXXTempObjectRegion in the
+  /// super-region used.
+  const CXXTempObjectRegion *getCXXStaticTempObjectRegion(const Expr *Ex);
+
 private:
   template <typename RegionTy, typename A1>
   RegionTy* getRegion(const A1 a1);
Index: lib/StaticAnalyzer/Core/ExprEngine.cpp
===================================================================
--- lib/StaticAnalyzer/Core/ExprEngine.cpp
+++ lib/StaticAnalyzer/Core/ExprEngine.cpp
@@ -208,7 +208,18 @@
 
   // Create a temporary object region for the inner expression (which may have
   // a more derived type) and bind the value into it.
-  const TypedValueRegion *TR = MRMgr.getCXXTempObjectRegion(Inner, LC);
+  const TypedValueRegion *TR = NULL;
+  if (const MaterializeTemporaryExpr *MT =
+          dyn_cast<MaterializeTemporaryExpr>(Result)) {
+    clang::StorageDuration SD = MT->getStorageDuration();
+    // If this object is bound to a reference with static storage duration, we
+    // put it in a different region to prevent "address leakage" warnings.
+    if (SD == SD_Static || SD == SD_Thread)
+        TR = MRMgr.getCXXStaticTempObjectRegion(Inner);
+  }
+  if (!TR)
+    TR = MRMgr.getCXXTempObjectRegion(Inner, LC);
+
   SVal Reg = loc::MemRegionVal(TR);
 
   if (V.isUnknown())
Index: lib/StaticAnalyzer/Core/MemRegion.cpp
===================================================================
--- lib/StaticAnalyzer/Core/MemRegion.cpp
+++ lib/StaticAnalyzer/Core/MemRegion.cpp
@@ -864,6 +864,12 @@
   return getSubRegion<BlockDataRegion>(BC, LC, sReg);
 }
 
+const CXXTempObjectRegion *
+MemRegionManager::getCXXStaticTempObjectRegion(const Expr *Ex) {
+  return getSubRegion<CXXTempObjectRegion>(
+      Ex, getGlobalsRegion(MemRegion::GlobalInternalSpaceRegionKind, NULL));
+}
+
 const CompoundLiteralRegion*
 MemRegionManager::getCompoundLiteralRegion(const CompoundLiteralExpr *CL,
                                            const LocationContext *LC) {
Index: test/Analysis/stack-addr-ps.cpp
===================================================================
--- test/Analysis/stack-addr-ps.cpp
+++ test/Analysis/stack-addr-ps.cpp
@@ -20,6 +20,10 @@
   return s3; // expected-warning{{Address of stack memory associated with local variable 's1' returned}} expected-warning {{reference to stack memory associated with local variable 's1' returned}}
 }
 
+void g4() {
+  static const int &x = 3; // no warning
+}
+
 int get_value();
 
 const int &get_reference1() { return get_value(); } // expected-warning{{Address of stack memory associated with temporary object of type 'int' returned}} expected-warning {{returning reference to local temporary}}
Index: test/Analysis/temporaries.cpp
===================================================================
--- test/Analysis/temporaries.cpp
+++ test/Analysis/temporaries.cpp
@@ -109,3 +109,19 @@
   }
 }
 
+
+void testStaticMaterializeTemporaryExpr() {
+  static const Trivial &ref = getTrivial();
+  clang_analyzer_eval(ref.value == 42); // expected-warning{{TRUE}}
+
+  static const Trivial &directRef = Trivial(42);
+  clang_analyzer_eval(directRef.value == 42); // expected-warning{{TRUE}}
+
+#if __cplusplus >= 201103L
+  thread_local static const Trivial &threadRef = getTrivial();
+  clang_analyzer_eval(threadRef.value == 42); // expected-warning{{TRUE}}
+
+  thread_local static const Trivial &threadDirectRef = Trivial(42);
+  clang_analyzer_eval(threadDirectRef.value == 42); // expected-warning{{TRUE}}
+#endif
+}
-------------- next part --------------
A non-text attachment was scrubbed...
Name: D1133.2.patch
Type: text/x-patch
Size: 4011 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/cfe-commits/attachments/20130716/b4620114/attachment.bin>