Fix a crash by division by zero in analyzer

Patch by takeshi-yoshimura!

Differential Revision: http://reviews.llvm.org/D10145

llvm-svn: 240643

clang/lib/StaticAnalyzer/Core/BasicValueFactory.cpp

@@ -154,9 +154,13 @@ BasicValueFactory::evalAPSInt(BinaryOperator::Opcode Op,
       return &getValue( V1 * V2 );
 
     case BO_Div:
+      if (V2 == 0) // Avoid division by zero
+        return nullptr;
       return &getValue( V1 / V2 );
 
     case BO_Rem:
+      if (V2 == 0) // Avoid division by zero
+        return nullptr;
       return &getValue( V1 % V2 );
 
     case BO_Add:

clang/test/Analysis/division-by-zero.c

@@ -0,0 +1,7 @@
+// RUN: %clang_cc1 -analyze -analyzer-checker=unix.Malloc %s
+// Do not crash due to division by zero
+
+int f(unsigned int a) {
+  if (a <= 0) return 1 / a;
+  return a;
+}