Split libAnalysis into two libraries: libAnalysis and libChecker.

(1) libAnalysis is a generic analysis library that can be used by
    Sema.  It defines the CFG, basic dataflow analysis primitives, and
    inexpensive flow-sensitive analyses (e.g. LiveVariables).

(2) libChecker contains the guts of the static analyzer, incuding the
    path-sensitive analysis engine and domain-specific checks.

Now any clients that want to use the frontend to build their own tools
don't need to link in the entire static analyzer.

This change exposes various obvious cleanups that can be made to the
layout of files and headers in libChecker.  More changes pending.  :)

This change also exposed a layering violation between AnalysisContext
and MemRegion.  BlockInvocationContext shouldn't explicitly know about
BlockDataRegions.  For now I've removed the BlockDataRegion* from
BlockInvocationContext (removing context-sensitivity; although this
wasn't used yet).  We need to have a better way to extend
BlockInvocationContext (and any LocationContext) to add
context-sensitivty.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@94406 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 349 insertions, 0 deletions

diff --git a/lib/Checker/BugReporterVisitors.cpp b/lib/Checker/BugReporterVisitors.cpp
new file mode 100644
index 0000000000..98261943a8
--- /dev/null
+++ b/lib/Checker/BugReporterVisitors.cpp
@@ -0,0 +1,349 @@
+// BugReporterVisitors.cpp - Helpers for reporting bugs -----------*- C++ -*--//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file defines a set of BugReporter "visitors" which can be used to
+//  enhance the diagnostics reported for a bug.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/AST/Expr.h"
+#include "clang/AST/ExprObjC.h"
+#include "clang/Checker/PathSensitive/BugReporter.h"
+#include "clang/Checker/PathDiagnostic.h"
+#include "clang/Checker/PathSensitive/GRState.h"
+
+using namespace clang;
+
+//===----------------------------------------------------------------------===//
+// Utility functions.
+//===----------------------------------------------------------------------===//
+
+const Stmt *clang::bugreporter::GetDerefExpr(const ExplodedNode *N) {
+  // Pattern match for a few useful cases (do something smarter later):
+  //   a[0], p->f, *p
+  const Stmt *S = N->getLocationAs<PostStmt>()->getStmt();
+
+  if (const UnaryOperator *U = dyn_cast<UnaryOperator>(S)) {
+    if (U->getOpcode() == UnaryOperator::Deref)
+      return U->getSubExpr()->IgnoreParenCasts();
+  }
+  else if (const MemberExpr *ME = dyn_cast<MemberExpr>(S)) {
+    return ME->getBase()->IgnoreParenCasts();
+  }
+  else if (const ArraySubscriptExpr *AE = dyn_cast<ArraySubscriptExpr>(S)) {
+    // Retrieve the base for arrays since BasicStoreManager doesn't know how
+    // to reason about them.
+    return AE->getBase();
+  }
+
+  return NULL;
+}
+
+const Stmt*
+clang::bugreporter::GetReceiverExpr(const ExplodedNode *N){
+  const Stmt *S = N->getLocationAs<PostStmt>()->getStmt();
+  if (const ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(S))
+    return ME->getReceiver();
+  return NULL;
+}
+
+const Stmt*
+clang::bugreporter::GetDenomExpr(const ExplodedNode *N) {
+  const Stmt *S = N->getLocationAs<PreStmt>()->getStmt();
+  if (const BinaryOperator *BE = dyn_cast<BinaryOperator>(S))
+    return BE->getRHS();
+  return NULL;
+}
+
+const Stmt*
+clang::bugreporter::GetCalleeExpr(const ExplodedNode *N) {
+  // Callee is checked as a PreVisit to the CallExpr.
+  const Stmt *S = N->getLocationAs<PreStmt>()->getStmt();
+  if (const CallExpr *CE = dyn_cast<CallExpr>(S))
+    return CE->getCallee();
+  return NULL;
+}
+
+const Stmt*
+clang::bugreporter::GetRetValExpr(const ExplodedNode *N) {
+  const Stmt *S = N->getLocationAs<PostStmt>()->getStmt();
+  if (const ReturnStmt *RS = dyn_cast<ReturnStmt>(S))
+    return RS->getRetValue();
+  return NULL;
+}
+
+//===----------------------------------------------------------------------===//
+// Definitions for bug reporter visitors.
+//===----------------------------------------------------------------------===//
+
+namespace {
+class FindLastStoreBRVisitor : public BugReporterVisitor {
+  const MemRegion *R;
+  SVal V;
+  bool satisfied;
+  const ExplodedNode *StoreSite;
+public:
+  FindLastStoreBRVisitor(SVal v, const MemRegion *r)
+  : R(r), V(v), satisfied(false), StoreSite(0) {}
+
+  PathDiagnosticPiece* VisitNode(const ExplodedNode *N,
+                                 const ExplodedNode *PrevN,
+                                 BugReporterContext& BRC) {
+
+    if (satisfied)
+      return NULL;
+
+    if (!StoreSite) {
+      const ExplodedNode *Node = N, *Last = NULL;
+
+      for ( ; Node ; Last = Node, Node = Node->getFirstPred()) {
+
+        if (const VarRegion *VR = dyn_cast<VarRegion>(R)) {
+          if (const PostStmt *P = Node->getLocationAs<PostStmt>())
+            if (const DeclStmt *DS = P->getStmtAs<DeclStmt>())
+              if (DS->getSingleDecl() == VR->getDecl()) {
+                Last = Node;
+                break;
+              }
+        }
+
+        if (Node->getState()->getSVal(R) != V)
+          break;
+      }
+
+      if (!Node || !Last) {
+        satisfied = true;
+        return NULL;
+      }
+
+      StoreSite = Last;
+    }
+
+    if (StoreSite != N)
+      return NULL;
+
+    satisfied = true;
+    std::string sbuf;
+    llvm::raw_string_ostream os(sbuf);
+
+    if (const PostStmt *PS = N->getLocationAs<PostStmt>()) {
+      if (const DeclStmt *DS = PS->getStmtAs<DeclStmt>()) {
+
+        if (const VarRegion *VR = dyn_cast<VarRegion>(R)) {
+          os << "Variable '" << VR->getDecl()->getNameAsString() << "' ";
+        }
+        else
+          return NULL;
+
+        if (isa<loc::ConcreteInt>(V)) {
+          bool b = false;
+          ASTContext &C = BRC.getASTContext();
+          if (R->isBoundable()) {
+            if (const TypedRegion *TR = dyn_cast<TypedRegion>(R)) {
+              if (TR->getValueType(C)->isObjCObjectPointerType()) {
+                os << "initialized to nil";
+                b = true;
+              }
+            }
+          }
+
+          if (!b)
+            os << "initialized to a null pointer value";
+        }
+        else if (isa<nonloc::ConcreteInt>(V)) {
+          os << "initialized to " << cast<nonloc::ConcreteInt>(V).getValue();
+        }
+        else if (V.isUndef()) {
+          if (isa<VarRegion>(R)) {
+            const VarDecl *VD = cast<VarDecl>(DS->getSingleDecl());
+            if (VD->getInit())
+              os << "initialized to a garbage value";
+            else
+              os << "declared without an initial value";
+          }
+        }
+      }
+    }
+
+    if (os.str().empty()) {
+      if (isa<loc::ConcreteInt>(V)) {
+        bool b = false;
+        ASTContext &C = BRC.getASTContext();
+        if (R->isBoundable()) {
+          if (const TypedRegion *TR = dyn_cast<TypedRegion>(R)) {
+            if (TR->getValueType(C)->isObjCObjectPointerType()) {
+              os << "nil object reference stored to ";
+              b = true;
+            }
+          }
+        }
+
+        if (!b)
+          os << "Null pointer value stored to ";
+      }
+      else if (V.isUndef()) {
+        os << "Uninitialized value stored to ";
+      }
+      else if (isa<nonloc::ConcreteInt>(V)) {
+        os << "The value " << cast<nonloc::ConcreteInt>(V).getValue()
+           << " is assigned to ";
+      }
+      else
+        return NULL;
+
+      if (const VarRegion *VR = dyn_cast<VarRegion>(R)) {
+        os << '\'' << VR->getDecl()->getNameAsString() << '\'';
+      }
+      else
+        return NULL;
+    }
+
+    // FIXME: Refactor this into BugReporterContext.
+    const Stmt *S = 0;
+    ProgramPoint P = N->getLocation();
+
+    if (BlockEdge *BE = dyn_cast<BlockEdge>(&P)) {
+      CFGBlock *BSrc = BE->getSrc();
+      S = BSrc->getTerminatorCondition();
+    }
+    else if (PostStmt *PS = dyn_cast<PostStmt>(&P)) {
+      S = PS->getStmt();
+    }
+
+    if (!S)
+      return NULL;
+
+    // Construct a new PathDiagnosticPiece.
+    PathDiagnosticLocation L(S, BRC.getSourceManager());
+    return new PathDiagnosticEventPiece(L, os.str());
+  }
+};
+
+
+static void registerFindLastStore(BugReporterContext& BRC, const MemRegion *R,
+                                  SVal V) {
+  BRC.addVisitor(new FindLastStoreBRVisitor(V, R));
+}
+
+class TrackConstraintBRVisitor : public BugReporterVisitor {
+  DefinedSVal Constraint;
+  const bool Assumption;
+  bool isSatisfied;
+public:
+  TrackConstraintBRVisitor(DefinedSVal constraint, bool assumption)
+  : Constraint(constraint), Assumption(assumption), isSatisfied(false) {}
+
+  PathDiagnosticPiece* VisitNode(const ExplodedNode *N,
+                                 const ExplodedNode *PrevN,
+                                 BugReporterContext& BRC) {
+    if (isSatisfied)
+      return NULL;
+
+    // Check if in the previous state it was feasible for this constraint
+    // to *not* be true.
+    if (PrevN->getState()->Assume(Constraint, !Assumption)) {
+
+      isSatisfied = true;
+
+      // As a sanity check, make sure that the negation of the constraint
+      // was infeasible in the current state.  If it is feasible, we somehow
+      // missed the transition point.
+      if (N->getState()->Assume(Constraint, !Assumption))
+        return NULL;
+
+      // We found the transition point for the constraint.  We now need to
+      // pretty-print the constraint. (work-in-progress)
+      std::string sbuf;
+      llvm::raw_string_ostream os(sbuf);
+
+      if (isa<Loc>(Constraint)) {
+        os << "Assuming pointer value is ";
+        os << (Assumption ? "non-null" : "null");
+      }
+
+      if (os.str().empty())
+        return NULL;
+
+      // FIXME: Refactor this into BugReporterContext.
+      const Stmt *S = 0;
+      ProgramPoint P = N->getLocation();
+
+      if (BlockEdge *BE = dyn_cast<BlockEdge>(&P)) {
+        CFGBlock *BSrc = BE->getSrc();
+        S = BSrc->getTerminatorCondition();
+      }
+      else if (PostStmt *PS = dyn_cast<PostStmt>(&P)) {
+        S = PS->getStmt();
+      }
+
+      if (!S)
+        return NULL;
+
+      // Construct a new PathDiagnosticPiece.
+      PathDiagnosticLocation L(S, BRC.getSourceManager());
+      return new PathDiagnosticEventPiece(L, os.str());
+    }
+
+    return NULL;
+  }
+};
+} // end anonymous namespace
+
+static void registerTrackConstraint(BugReporterContext& BRC,
+                                    DefinedSVal Constraint,
+                                    bool Assumption) {
+  BRC.addVisitor(new TrackConstraintBRVisitor(Constraint, Assumption));
+}
+
+void clang::bugreporter::registerTrackNullOrUndefValue(BugReporterContext& BRC,
+                                                       const void *data,
+                                                       const ExplodedNode* N) {
+
+  const Stmt *S = static_cast<const Stmt*>(data);
+
+  if (!S)
+    return;
+
+  GRStateManager &StateMgr = BRC.getStateManager();
+  const GRState *state = N->getState();
+
+  if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(S)) {
+    if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) {
+      const VarRegion *R =
+      StateMgr.getRegionManager().getVarRegion(VD, N->getLocationContext());
+
+      // What did we load?
+      SVal V = state->getSVal(S);
+
+      if (isa<loc::ConcreteInt>(V) || isa<nonloc::ConcreteInt>(V)
+          || V.isUndef()) {
+        registerFindLastStore(BRC, R, V);
+      }
+    }
+  }
+
+  SVal V = state->getSValAsScalarOrLoc(S);
+
+  // Uncomment this to find cases where we aren't properly getting the
+  // base value that was dereferenced.
+  // assert(!V.isUnknownOrUndef());
+
+  // Is it a symbolic value?
+  if (loc::MemRegionVal *L = dyn_cast<loc::MemRegionVal>(&V)) {
+    const SubRegion *R = cast<SubRegion>(L->getRegion());
+    while (R && !isa<SymbolicRegion>(R)) {
+      R = dyn_cast<SubRegion>(R->getSuperRegion());
+    }
+
+    if (R) {
+      assert(isa<SymbolicRegion>(R));
+      registerTrackConstraint(BRC, loc::MemRegionVal(R), false);
+    }
+  }
+}