[analyzer] Use Clang's evaluation for global constants and default arguments.

Previously, we were handling only simple integer constants for globals and
the smattering of implicitly-valued expressions handled by Environment for
default arguments. Now, we can use any integer constant expression that
Clang can evaluate, in addition to everything we handled before.

PR15094 / <rdar://problem/12830437>

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@175026 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 41 insertions, 10 deletions

diff --git a/lib/StaticAnalyzer/Core/Environment.cpp b/lib/StaticAnalyzer/Core/Environment.cpp
index b6c44bf5d6..2b069a04a5 100644
--- a/lib/StaticAnalyzer/Core/Environment.cpp
+++ b/lib/StaticAnalyzer/Core/Environment.cpp
@@ -37,9 +37,6 @@ static const Expr *ignoreTransparentExprs(const Expr *E) {
   case Stmt::SubstNonTypeTemplateParmExprClass:
     E = cast<SubstNonTypeTemplateParmExpr>(E)->getReplacement();
     break;
-  case Stmt::CXXDefaultArgExprClass:
-    E = cast<CXXDefaultArgExpr>(E)->getExpr();
-    break;
   default:
     // This is the base case: we can't look through more than we already have.
     return E;
@@ -75,7 +72,6 @@ SVal Environment::getSVal(const EnvironmentEntry &Entry,
 
   switch (S->getStmtClass()) {
   case Stmt::CXXBindTemporaryExprClass:
-  case Stmt::CXXDefaultArgExprClass:
   case Stmt::ExprWithCleanupsClass:
   case Stmt::GenericSelectionExprClass:
   case Stmt::OpaqueValueExprClass:
diff --git a/lib/StaticAnalyzer/Core/ExprEngine.cpp b/lib/StaticAnalyzer/Core/ExprEngine.cpp
index f092f1a3d8..18ac0964aa 100644
--- a/lib/StaticAnalyzer/Core/ExprEngine.cpp
+++ b/lib/StaticAnalyzer/Core/ExprEngine.cpp
@@ -639,7 +639,6 @@ void ExprEngine::Visit(const Stmt *S, ExplodedNode *Pred,
     case Stmt::StringLiteralClass:
     case Stmt::ObjCStringLiteralClass:
     case Stmt::CXXBindTemporaryExprClass:
-    case Stmt::CXXDefaultArgExprClass:
     case Stmt::SubstNonTypeTemplateParmExprClass:
     case Stmt::CXXNullPtrLiteralExprClass: {
       Bldr.takeNodes(Pred);
@@ -650,6 +649,39 @@ void ExprEngine::Visit(const Stmt *S, ExplodedNode *Pred,
       break;
     }
 
+    case Stmt::CXXDefaultArgExprClass: {
+      Bldr.takeNodes(Pred);
+      ExplodedNodeSet PreVisit;
+      getCheckerManager().runCheckersForPreStmt(PreVisit, Pred, S, *this);
+
+      ExplodedNodeSet Tmp;
+      StmtNodeBuilder Bldr2(PreVisit, Tmp, *currBldrCtx);
+
+      const LocationContext *LCtx = Pred->getLocationContext();
+      const Expr *ArgE = cast<CXXDefaultArgExpr>(S)->getExpr();
+
+      // Avoid creating and destroying a lot of APSInts.
+      SVal V;
+      llvm::APSInt Result;
+
+      for (ExplodedNodeSet::iterator I = PreVisit.begin(), E = PreVisit.end();
+           I != E; ++I) {
+        ProgramStateRef State = (*I)->getState();
+
+        if (ArgE->EvaluateAsInt(Result, getContext()))
+          V = svalBuilder.makeIntVal(Result);
+        else
+          V = State->getSVal(ArgE, LCtx);
+
+        State = State->BindExpr(S, LCtx, V);
+        Bldr2.generateNode(S, *I, State);
+      }
+
+      getCheckerManager().runCheckersForPostStmt(Dst, Tmp, S, *this);
+      Bldr.addNodes(Dst);
+      break;
+    }
+
     case Expr::ObjCArrayLiteralClass:
     case Expr::ObjCDictionaryLiteralClass:
       // FIXME: explicitly model with a region and the actual contents
diff --git a/lib/StaticAnalyzer/Core/RegionStore.cpp b/lib/StaticAnalyzer/Core/RegionStore.cpp
index 399f9ebae8..9572f64865 100644
--- a/lib/StaticAnalyzer/Core/RegionStore.cpp
+++ b/lib/StaticAnalyzer/Core/RegionStore.cpp
@@ -1524,11 +1524,14 @@ SVal RegionStoreManager::getBindingForVar(RegionBindingsConstRef B,
     QualType CT = Ctx.getCanonicalType(T);
     if (CT.isConstQualified()) {
       if (const Expr *Init = VD->getInit()) {
-        if (const IntegerLiteral *IL =
-            dyn_cast<IntegerLiteral>(Init->IgnoreParenCasts())) {
-          const nonloc::ConcreteInt &V = svalBuilder.makeIntVal(IL);
-          return svalBuilder.evalCast(V, Init->getType(), IL->getType());
-        }
+        llvm::APSInt Result;
+        if (Init->EvaluateAsInt(Result, Ctx))
+          return svalBuilder.makeIntVal(Result);
+
+        if (Init->isNullPointerConstant(Ctx, Expr::NPC_ValueDependentIsNotNull))
+          return svalBuilder.makeNull();
+
+        // FIXME: Handle other possible constant expressions.
       }
     }