Analyzer: Teach analyzer how to handle TypeTraitExpr

Summary:
`TypeTraitExpr`s are not supported by the ExprEngine today. Analyzer
creates a sink, and aborts the block. Therefore, certain bugs that
involve type traits intrinsics cannot be detected (see PR24710).

This patch creates boolean `SVal`s for `TypeTraitExpr`s, which are
evaluated by the compiler.

Test within the patch is a summary of PR24710.

Reviewers: zaks.anna, dcoughlin, krememek

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D12482

llvm-svn: 248314

3 files changed, 8 insertions, 2 deletions

diff --git a/clang/lib/StaticAnalyzer/Core/Environment.cpp b/clang/lib/StaticAnalyzer/Core/Environment.cpp
index 508f5d31196..d55858db576 100644
--- a/clang/lib/StaticAnalyzer/Core/Environment.cpp
+++ b/clang/lib/StaticAnalyzer/Core/Environment.cpp
@@ -90,6 +90,7 @@ SVal Environment::getSVal(const EnvironmentEntry &Entry,
   case Stmt::CXXNullPtrLiteralExprClass:
   case Stmt::ObjCStringLiteralClass:
   case Stmt::StringLiteralClass:
+  case Stmt::TypeTraitExprClass:
     // Known constants; defer to SValBuilder.
     return svalBuilder.getConstantVal(cast<Expr>(S)).getValue();
 
diff --git a/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp b/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp
index 00d9c7a9616..0865189193d 100644
--- a/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp
+++ b/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp
@@ -756,7 +756,6 @@ void ExprEngine::Visit(const Stmt *S, ExplodedNode *Pred,
     case Stmt::MSPropertyRefExprClass:
     case Stmt::CXXUnresolvedConstructExprClass:
     case Stmt::DependentScopeDeclRefExprClass:
-    case Stmt::TypeTraitExprClass:
     case Stmt::ArrayTypeTraitExprClass:
     case Stmt::ExpressionTraitExprClass:
     case Stmt::UnresolvedLookupExprClass:
@@ -902,7 +901,8 @@ void ExprEngine::Visit(const Stmt *S, ExplodedNode *Pred,
     case Stmt::CXXPseudoDestructorExprClass:
     case Stmt::SubstNonTypeTemplateParmExprClass:
     case Stmt::CXXNullPtrLiteralExprClass:
-    case Stmt::OMPArraySectionExprClass: {
+    case Stmt::OMPArraySectionExprClass:
+    case Stmt::TypeTraitExprClass: {
       Bldr.takeNodes(Pred);
       ExplodedNodeSet preVisit;
       getCheckerManager().runCheckersForPreStmt(preVisit, Pred, S, *this);
diff --git a/clang/lib/StaticAnalyzer/Core/SValBuilder.cpp b/clang/lib/StaticAnalyzer/Core/SValBuilder.cpp
index d853286d7fa..4f8ccd0329d 100644
--- a/clang/lib/StaticAnalyzer/Core/SValBuilder.cpp
+++ b/clang/lib/StaticAnalyzer/Core/SValBuilder.cpp
@@ -259,6 +259,11 @@ Optional<SVal> SValBuilder::getConstantVal(const Expr *E) {
   case Stmt::CXXBoolLiteralExprClass:
     return makeBoolVal(cast<CXXBoolLiteralExpr>(E));
 
+  case Stmt::TypeTraitExprClass: {
+    const TypeTraitExpr *TE = cast<TypeTraitExpr>(E);
+    return makeTruthVal(TE->getValue(), TE->getType());
+  }
+
   case Stmt::IntegerLiteralClass:
     return makeIntVal(cast<IntegerLiteral>(E));