[analyzer] Anti-aliasing: different heap allocations do not alias

Add a concept of symbolic memory region belonging to heap memory space.
When comparing symbolic regions allocated on the heap, assume that they
do not alias. 

Use symbolic heap region to suppress a common false positive pattern in
the malloc checker, in code that relies on malloc not returning the
memory aliased to other malloc allocations, stack.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@158136 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 4 insertions, 0 deletions

diff --git a/lib/StaticAnalyzer/Core/MemRegion.cpp b/lib/StaticAnalyzer/Core/MemRegion.cpp
index 96905c081e..bcf7c3fe7d 100644
--- a/lib/StaticAnalyzer/Core/MemRegion.cpp
+++ b/lib/StaticAnalyzer/Core/MemRegion.cpp
@@ -849,6 +849,10 @@ const SymbolicRegion *MemRegionManager::getSymbolicRegion(SymbolRef sym) {
   return getSubRegion<SymbolicRegion>(sym, getUnknownRegion());
 }
 
+const SymbolicRegion *MemRegionManager::getSymbolicHeapRegion(SymbolRef Sym) {
+  return getSubRegion<SymbolicRegion>(Sym, getHeapRegion());
+}
+
 const FieldRegion*
 MemRegionManager::getFieldRegion(const FieldDecl *d,
                                  const MemRegion* superRegion){