Remove ProgramState::getSymVal(). It was being misused by Checkers,

with at least one subtle bug in MacOSXKeyChainAPIChecker where the
calling the method was a substitute for assuming a symbolic value
was null (which is not the case).

We still keep ConstraintManager::getSymVal(), but we use that as
an optimization in SValBuilder and ProgramState::getSVal() to
constant-fold SVals.  This is only if the ConstraintManager can
provide us with that information, which is no longer a requirement.
As part of this, introduce a default implementation of
ConstraintManager::getSymVal() which returns null.

For Checkers, introduce ConstraintManager::isNull(), which queries
the state to see if the symbolic value is constrained to be a null
value.  It does this without assuming it has been implicitly constant
folded.

llvm-svn: 163428

5 files changed, 56 insertions, 8 deletions

diff --git a/clang/lib/StaticAnalyzer/Core/CMakeLists.txt b/clang/lib/StaticAnalyzer/Core/CMakeLists.txt
index 97cb977861a..91f15b31da6 100644
--- a/clang/lib/StaticAnalyzer/Core/CMakeLists.txt
+++ b/clang/lib/StaticAnalyzer/Core/CMakeLists.txt
@@ -14,6 +14,7 @@ add_clang_library(clangStaticAnalyzerCore
   CheckerHelpers.cpp
   CheckerManager.cpp
   CheckerRegistry.cpp
+  ConstraintManager.cpp
   CoreEngine.cpp
   Environment.cpp
   ExplodedGraph.cpp
diff --git a/clang/lib/StaticAnalyzer/Core/ConstraintManager.cpp b/clang/lib/StaticAnalyzer/Core/ConstraintManager.cpp
new file mode 100644
index 00000000000..075c771f0df
--- /dev/null
+++ b/clang/lib/StaticAnalyzer/Core/ConstraintManager.cpp
@@ -0,0 +1,46 @@
+//== ConstraintManager.cpp - Constraints on symbolic values -----*- C++ -*--==//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file defined the interface to manage constraints on symbolic values.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
+#include "llvm/Support/SaveAndRestore.h"
+
+using namespace clang;
+using namespace ento;
+
+ConstraintManager::~ConstraintManager() {}
+
+static DefinedSVal getLocFromSymbol(const ProgramStateRef &State,
+                                    SymbolRef Sym) {
+  const MemRegion *R = State->getStateManager().getRegionManager()
+                                               .getSymbolicRegion(Sym);
+  return loc::MemRegionVal(R);
+}
+
+/// Convenience method to query the state to see if a symbol is null or
+/// not null, or neither assumption can be made.
+ConditionTruthVal ConstraintManager::isNull(ProgramStateRef State,
+                                            SymbolRef Sym) {
+  // Disable recursive notification of clients.
+  llvm::SaveAndRestore<bool> DisableNotify(NotifyAssumeClients, false);
+  
+  ProgramStateManager &Mgr = State->getStateManager();
+  QualType Ty = Sym->getType(Mgr.getContext());
+  DefinedSVal V = Loc::isLocType(Ty) ? getLocFromSymbol(State, Sym)
+                                     : nonloc::SymbolVal(Sym);
+  const ProgramStatePair &P = assumeDual(State, V);
+  if (P.first && !P.second)
+    return ConditionTruthVal(false);
+  if (!P.first && P.second)
+    return ConditionTruthVal(true);
+  return ConditionTruthVal();
+}
diff --git a/clang/lib/StaticAnalyzer/Core/ProgramState.cpp b/clang/lib/StaticAnalyzer/Core/ProgramState.cpp
index 78554c4e891..ed8e1dc9ec1 100644
--- a/clang/lib/StaticAnalyzer/Core/ProgramState.cpp
+++ b/clang/lib/StaticAnalyzer/Core/ProgramState.cpp
@@ -22,10 +22,6 @@
 using namespace clang;
 using namespace ento;
 
-// Give the vtable for ConstraintManager somewhere to live.
-// FIXME: Move this elsewhere.
-ConstraintManager::~ConstraintManager() {}
-
 namespace clang { namespace  ento {
 /// Increments the number of times this state is referenced.
 
@@ -238,7 +234,9 @@ SVal ProgramState::getSVal(Loc location, QualType T) const {
   // about).
   if (!T.isNull()) {
     if (SymbolRef sym = V.getAsSymbol()) {
-      if (const llvm::APSInt *Int = getSymVal(sym)) {
+      if (const llvm::APSInt *Int = getStateManager()
+                                    .getConstraintManager()
+                                    .getSymVal(this, sym)) {
         // FIXME: Because we don't correctly model (yet) sign-extension
         // and truncation of symbolic values, we need to convert
         // the integer value to the correct signedness and bitwidth.
diff --git a/clang/lib/StaticAnalyzer/Core/SimpleConstraintManager.cpp b/clang/lib/StaticAnalyzer/Core/SimpleConstraintManager.cpp
index 5568f1ca555..da52a17ceff 100644
--- a/clang/lib/StaticAnalyzer/Core/SimpleConstraintManager.cpp
+++ b/clang/lib/StaticAnalyzer/Core/SimpleConstraintManager.cpp
@@ -67,7 +67,9 @@ ProgramStateRef SimpleConstraintManager::assume(ProgramStateRef state,
 ProgramStateRef SimpleConstraintManager::assume(ProgramStateRef state, Loc cond,
                                                bool assumption) {
   state = assumeAux(state, cond, assumption);
-  return SU.processAssume(state, cond, assumption);
+  if (NotifyAssumeClients)
+    return SU.processAssume(state, cond, assumption);
+  return state;
 }
 
 ProgramStateRef SimpleConstraintManager::assumeAux(ProgramStateRef state,
diff --git a/clang/lib/StaticAnalyzer/Core/SimpleSValBuilder.cpp b/clang/lib/StaticAnalyzer/Core/SimpleSValBuilder.cpp
index 6a70309a21d..967e95bb603 100644
--- a/clang/lib/StaticAnalyzer/Core/SimpleSValBuilder.cpp
+++ b/clang/lib/StaticAnalyzer/Core/SimpleSValBuilder.cpp
@@ -507,7 +507,8 @@ SVal SimpleSValBuilder::evalBinOpNN(ProgramStateRef state,
       } else if (isa<SymbolData>(Sym)) {
         // Does the symbol simplify to a constant?  If so, "fold" the constant
         // by setting 'lhs' to a ConcreteInt and try again.
-        if (const llvm::APSInt *Constant = state->getSymVal(Sym)) {
+        if (const llvm::APSInt *Constant = state->getConstraintManager()
+                                                  .getSymVal(state, Sym)) {
           lhs = nonloc::ConcreteInt(*Constant);
           continue;
         }
@@ -942,7 +943,7 @@ const llvm::APSInt *SimpleSValBuilder::getKnownValue(ProgramStateRef state,
     return &X->getValue();
 
   if (SymbolRef Sym = V.getAsSymbol())
-    return state->getSymVal(Sym);
+    return state->getConstraintManager().getSymVal(state, Sym);
 
   // FIXME: Add support for SymExprs.
   return NULL;