Add some documentation for C++ static analyzer.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@123313 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/StaticAnalyzer/README.txt b/lib/StaticAnalyzer/README.txt
index dd16ccc98057cba86421122370d16c81530f7c38..1406eca8c85ff14bee18cf5fe7aca42a0df6347f 100644 (file)
--- a/lib/StaticAnalyzer/README.txt
+++ b/lib/StaticAnalyzer/README.txt
@@ -67,6 +67,28 @@ finds a bug, it can tell the BugReporter object about the bug,
 providing it an ExplodedNode which is the last node in the path that
 triggered the problem.
 
+= Notes about C++ =
+
+Since now constructors are seen before the variable that is constructed 
+in the CFG, we create a temporary object as the destination region that 
+is constructed into. See ExprEngine::VisitCXXConstructExpr().
+
+In ExprEngine::processCallExit(), we always bind the object region to the
+evaluated CXXConstructExpr. Then in VisitDeclStmt(), we compute the
+corresponding lazy compound value if the variable is not a reference, and
+bind the variable region to the lazy compound value. If the variable
+is a reference, just use the object region as the initilizer value.
+
+Before entering a C++ method (or ctor/dtor), the 'this' region is bound
+to the object region. In ctors, we synthesize 'this' region with  
+CXXRecordDecl*, which means we do not use type qualifiers. In methods, we
+synthesize 'this' region with CXXMethodDecl*, which has getThisType() 
+taking type qualifiers into account. It does not matter we use qualified
+'this' region in one method and unqualified 'this' region in another
+method, because we only need to ensure the 'this' region is consistent 
+when we synthesize it and create it directly from CXXThisExpr in a single
+method call.
+
 = Working on the Analyzer =
 
 If you are interested in bringing up support for C++ expressions, the