r316399 - [analyzer] Fix handling of labels in getLValueElement

[Alexander Shaposhnikov via cfe-commits]

Author: alexshap
Date: Mon Oct 23 16:46:06 2017
New Revision: 316399

URL: http://llvm.org/viewvc/llvm-project?rev=316399&view=rev
Log:
[analyzer] Fix handling of labels in getLValueElement

In getLValueElement Base may represent the address of a label 
(as in the newly-added test case), in this case it's not a loc::MemRegionVal 
and Base.castAs<loc::MemRegionVal>() triggers an assert, this diff makes 
getLValueElement return UnknownVal instead.

Differential revision: https://reviews.llvm.org/D39174

Modified:
    cfe/trunk/lib/StaticAnalyzer/Core/Store.cpp
    cfe/trunk/test/Analysis/ptr-arith.c

Modified: cfe/trunk/lib/StaticAnalyzer/Core/Store.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/StaticAnalyzer/Core/Store.cpp?rev=316399&r1=316398&r2=316399&view=diff
==============================================================================
--- cfe/trunk/lib/StaticAnalyzer/Core/Store.cpp (original)
+++ cfe/trunk/lib/StaticAnalyzer/Core/Store.cpp Mon Oct 23 16:46:06 2017
@@ -440,7 +440,10 @@ SVal StoreManager::getLValueElement(Qual
   //  value. See also the similar FIXME in getLValueFieldOrIvar().
   if (Base.isUnknownOrUndef() || Base.getAs<loc::ConcreteInt>())
     return Base;
-
+  
+  if (Base.getAs<loc::GotoLabel>())
+    return UnknownVal();
+  
   const SubRegion *BaseRegion =
       Base.castAs<loc::MemRegionVal>().getRegionAs<SubRegion>();
 

Modified: cfe/trunk/test/Analysis/ptr-arith.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Analysis/ptr-arith.c?rev=316399&r1=316398&r2=316399&view=diff
==============================================================================
--- cfe/trunk/test/Analysis/ptr-arith.c (original)
+++ cfe/trunk/test/Analysis/ptr-arith.c Mon Oct 23 16:46:06 2017
@@ -342,3 +342,8 @@ void negativeIndex(char *str) {
   clang_analyzer_eval(*ptr3 == 'a'); // expected-warning{{UNKNOWN}}
 }
 
+void test_no_crash_on_pointer_to_label() {
+  char *a = &&label;
+  a[0] = 0;
+label:;
+}