[analyzer] Add very limited support for temporary destructors

This is an improved version of r186498. It enables ExprEngine to reason about
temporary object destructors.  However, these destructor calls are never
inlined, since this feature is still broken. Still, this is sufficient to
properly handle noreturn temporary destructors.

Now, the analyzer correctly handles expressions like "a || A()", and executes the
destructor of "A" only on the paths where "a" evaluted to false.

Temporary destructor processing is still off by default and one has to
explicitly request it by setting cfg-temporary-dtors=true.

Reviewers: jordan_rose

CC: cfe-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D1259

llvm-svn: 189746

1 files changed, 17 insertions, 5 deletions

diff --git a/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp b/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp
index 6aa9174ad6e..79139df786e 100644
--- a/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp
+++ b/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp
@@ -601,7 +601,15 @@ void ExprEngine::ProcessMemberDtor(const CFGMemberDtor D,
 
 void ExprEngine::ProcessTemporaryDtor(const CFGTemporaryDtor D,
                                       ExplodedNode *Pred,
-                                      ExplodedNodeSet &Dst) {}
+                                      ExplodedNodeSet &Dst) {
+
+  QualType varType = D.getBindTemporaryExpr()->getSubExpr()->getType();
+
+  // FIXME: Inlining of temporary destructors is not supported yet anyway, so we
+  // just put a NULL region for now. This will need to be changed later.
+  VisitCXXDestructor(varType, NULL, D.getBindTemporaryExpr(),
+                     /*IsBase=*/ false, Pred, Dst);
+}
 
 void ExprEngine::Visit(const Stmt *S, ExplodedNode *Pred,
                        ExplodedNodeSet &DstTop) {
@@ -1332,7 +1340,8 @@ void ExprEngine::processBranch(const Stmt *Condition, const Stmt *Term,
                                ExplodedNodeSet &Dst,
                                const CFGBlock *DstT,
                                const CFGBlock *DstF) {
-  PrettyStackTraceLocationContext StackCrashInfo(Pred->getLocationContext());
+  const LocationContext *LCtx = Pred->getLocationContext();
+  PrettyStackTraceLocationContext StackCrashInfo(LCtx);
   currBldrCtx = &BldCtx;
 
   // Check for NULL conditions; e.g. "for(;;)"
@@ -1347,10 +1356,14 @@ void ExprEngine::processBranch(const Stmt *Condition, const Stmt *Term,
   SVal TrueVal = SVB.makeTruthVal(true);
   SVal FalseVal = SVB.makeTruthVal(false);
 
-  // Resolve the condition in the precense of nested '||' and '&&'.
   if (const Expr *Ex = dyn_cast<Expr>(Condition))
     Condition = Ex->IgnoreParens();
-  Condition = ResolveCondition(Condition, BldCtx.getBlock());
+
+  // If the value is already available, we don't need to do anything.
+  if (Pred->getState()->getSVal(Condition, LCtx).isUnknownOrUndef()) {
+    // Resolve the condition in the presence of nested '||' and '&&'.
+    Condition = ResolveCondition(Condition, BldCtx.getBlock());
+  }
 
   // Cast truth values to the correct type.
   if (const Expr *Ex = dyn_cast<Expr>(Condition)) {
@@ -1360,7 +1373,6 @@ void ExprEngine::processBranch(const Stmt *Condition, const Stmt *Term,
                             getContext().getLogicalOperationType());
   }
 
-
   PrettyStackTraceLoc CrashInfo(getContext().getSourceManager(),
                                 Condition->getLocStart(),
                                 "Error evaluating branch");