Catch uses of undefined values when they are used in assignment, thus catching such bugs closer to the source.

llvm-svn: 86003

1 files changed, 59 insertions, 0 deletions

diff --git a/clang/lib/Analysis/UndefinedAssignmentChecker.cpp b/clang/lib/Analysis/UndefinedAssignmentChecker.cpp
new file mode 100644
index 00000000000..9df58844dc3
--- /dev/null
+++ b/clang/lib/Analysis/UndefinedAssignmentChecker.cpp
@@ -0,0 +1,59 @@
+//===--- UndefinedAssignmentChecker.h ---------------------------*- C++ -*--==//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This defines UndefinedAssginmentChecker, a builtin check in GRExprEngine that
+// checks for assigning undefined values.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Analysis/PathSensitive/Checkers/UndefinedAssignmentChecker.h"
+#include "clang/Analysis/PathSensitive/BugReporter.h"
+
+using namespace clang;
+
+void *UndefinedAssignmentChecker::getTag() {
+  static int x = 0;
+  return &x;
+}
+
+void UndefinedAssignmentChecker::PreVisitBind(CheckerContext &C, 
+                                              const Stmt *S,
+                                              SVal location,
+                                              SVal val) {
+  if (!val.isUndef())
+    return;
+
+  ExplodedNode *N = C.GenerateNode(S, true);
+
+  if (!N)
+    return;
+
+  if (!BT)
+    BT = new BugType("Assigned value is garbage or undefined",
+                     "Logic error");
+
+  // Generate a report for this bug.
+  EnhancedBugReport *R = new EnhancedBugReport(*BT, BT->getName().c_str(), N);
+  const Expr *ex = 0;
+
+  if (const BinaryOperator *B = dyn_cast<BinaryOperator>(S))
+    ex = B->getRHS();
+  else if (const DeclStmt *DS = dyn_cast<DeclStmt>(S)) {
+    const VarDecl* VD = dyn_cast<VarDecl>(DS->getSingleDecl());
+    ex = VD->getInit();
+  }
+
+  if (ex) {
+    R->addRange(ex->getSourceRange());
+    R->addVisitorCreator(bugreporter::registerTrackNullOrUndefValue, ex);
+  }
+
+  C.EmitReport(R);
+}  
+