[analyzer] Assume that reference symbols are non-null.

By doing this in the constraint managers, we can ensure that ANY reference
whose value we don't know gets the effect, even if it's not a top-level
parameter.

llvm-svn: 162246

2 files changed, 15 insertions, 1 deletions

diff --git a/clang/lib/StaticAnalyzer/Core/BasicConstraintManager.cpp b/clang/lib/StaticAnalyzer/Core/BasicConstraintManager.cpp
index 8897756a92d..fb6d4be09da 100644
--- a/clang/lib/StaticAnalyzer/Core/BasicConstraintManager.cpp
+++ b/clang/lib/StaticAnalyzer/Core/BasicConstraintManager.cpp
@@ -363,6 +363,10 @@ const llvm::APSInt* BasicConstraintManager::getSymVal(ProgramStateRef state,
 bool BasicConstraintManager::isNotEqual(ProgramStateRef state,
                                         SymbolRef sym,
                                         const llvm::APSInt& V) const {
+  // Special case: references are known to be non-zero.
+  if (sym->getType(getBasicVals().getContext())->isReferenceType())
+    if (V == 0)
+      return true;
 
   // Retrieve the NE-set associated with the given symbol.
   const ConstNotEqTy::data_type* T = state->get<ConstNotEq>(sym);
diff --git a/clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp b/clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
index 550404a5107..2b883cf9b9b 100644
--- a/clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
+++ b/clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
@@ -380,7 +380,17 @@ RangeConstraintManager::GetRange(ProgramStateRef state, SymbolRef sym) {
   // given symbol type.
   BasicValueFactory &BV = getBasicVals();
   QualType T = sym->getType(BV.getContext());
-  return RangeSet(F, BV.getMinValue(T), BV.getMaxValue(T));
+
+  RangeSet Result(F, BV.getMinValue(T), BV.getMaxValue(T));
+
+  // Special case: references are known to be non-zero.
+  if (T->isReferenceType()) {
+    APSIntType IntType = BV.getAPSIntType(T);
+    Result = Result.Intersect(BV, F, ++IntType.getZeroValue(),
+                                     --IntType.getZeroValue());
+  }
+
+  return Result;
 }
 
 //===------------------------------------------------------------------------===