1 files changed, 36 insertions, 9 deletions
diff --git a/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp b/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
index d9b58d0f51..5c3eb0d66a 100644
--- a/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
+++ b/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
@@ -1,9 +1,8 @@
 //== RangeConstraintManager.cpp - Manage range constraints.------*- C++ -*--==//
 //
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
@@ -174,6 +173,22 @@ RangeSet RangeSet::Intersect(BasicValueFactory &BV, Factory &F,
   return newRanges;
 }
 
+// Returns a set containing the values in the receiving set, intersected with
+// the range set passed as parameter.
+RangeSet RangeSet::Intersect(BasicValueFactory &BV, Factory &F,
+                             const RangeSet &Other) const {
+  PrimRangeSet newRanges = F.getEmptySet();
+
+  for (iterator i = Other.begin(), e = Other.end(); i != e; ++i) {
+    RangeSet newPiece = Intersect(BV, F, i->From(), i->To());
+    for (iterator j = newPiece.begin(), ee = newPiece.end(); j != ee; ++j) {
+      newRanges = F.add(newRanges, *j);
+    }
+  }
+
+  return newRanges;
+}
+
 // Turn all [A, B] ranges to [-B, -A]. Ranges [MIN, B] are turned to range set
 // [MIN, MIN] U [-B, MAX], when MIN and MAX are the minimal and the maximal
 // signed values of the type.
@@ -231,6 +246,11 @@ public:
   // Implementation for interface from ConstraintManager.
   //===------------------------------------------------------------------===//
 
+  bool haveEqualConstraints(ProgramStateRef S1,
+                            ProgramStateRef S2) const override {
+    return S1->get<ConstraintRange>() == S2->get<ConstraintRange>();
+  }
+
   bool canReasonAbout(SVal X) const override;
 
   ConditionTruthVal checkNull(ProgramStateRef State, SymbolRef Sym) override;
@@ -457,14 +477,21 @@ static RangeSet applyBitwiseConstraints(
 
 RangeSet RangeConstraintManager::getRange(ProgramStateRef State,
                                           SymbolRef Sym) {
-  if (ConstraintRangeTy::data_type *V = State->get<ConstraintRange>(Sym))
-    return *V;
-
-  BasicValueFactory &BV = getBasicVals();
+  ConstraintRangeTy::data_type *V = State->get<ConstraintRange>(Sym);
 
   // If Sym is a difference of symbols A - B, then maybe we have range set
   // stored for B - A.
-  if (const RangeSet *R = getRangeForMinusSymbol(State, Sym))
+  BasicValueFactory &BV = getBasicVals();
+  const RangeSet *R = getRangeForMinusSymbol(State, Sym);
+
+  // If we have range set stored for both A - B and B - A then calculate the
+  // effective range set by intersecting the range set for A - B and the
+  // negated range set of B - A.
+  if (V && R)
+    return V->Intersect(BV, F, R->Negate(BV, F));
+  if (V)
+    return *V;
+  if (R)
     return R->Negate(BV, F);
 
   // Lazily generate a new RangeSet representing all possible values for the