[analyzer] Model and check unrepresentable left shifts

Patch by: Reka Nikolett Kovacs

Differential Revision: https://reviews.llvm.org/D41816

llvm-svn: 323115

1 files changed, 3 insertions, 3 deletions

diff --git a/clang/lib/StaticAnalyzer/Core/BasicValueFactory.cpp b/clang/lib/StaticAnalyzer/Core/BasicValueFactory.cpp
index ec7a7e9e4b1..11658816ed2 100644
--- a/clang/lib/StaticAnalyzer/Core/BasicValueFactory.cpp
+++ b/clang/lib/StaticAnalyzer/Core/BasicValueFactory.cpp
@@ -224,7 +224,6 @@ BasicValueFactory::evalAPSInt(BinaryOperator::Opcode Op,
       // FIXME: This logic should probably go higher up, where we can
       // test these conditions symbolically.
 
-      // FIXME: Expand these checks to include all undefined behavior.
       if (V1.isSigned() && V1.isNegative())
         return nullptr;
 
@@ -236,6 +235,9 @@ BasicValueFactory::evalAPSInt(BinaryOperator::Opcode Op,
       if (Amt >= V1.getBitWidth())
         return nullptr;
 
+      if (V1.isSigned() && Amt > V1.countLeadingZeros())
+          return nullptr;
+
       return &getValue( V1.operator<<( (unsigned) Amt ));
     }
 
@@ -244,8 +246,6 @@ BasicValueFactory::evalAPSInt(BinaryOperator::Opcode Op,
       // FIXME: This logic should probably go higher up, where we can
       // test these conditions symbolically.
 
-      // FIXME: Expand these checks to include all undefined behavior.
-
       if (V2.isSigned() && V2.isNegative())
         return nullptr;