Add some notes for SCA.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@58597 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 31 insertions, 0 deletions

diff --git a/lib/Analysis/NOTES.TXT b/lib/Analysis/NOTES.TXT
index 97b7bf7c01..54ce078c1d 100644
--- a/lib/Analysis/NOTES.TXT
+++ b/lib/Analysis/NOTES.TXT
@@ -22,3 +22,34 @@ One is PredefinedExpr.
 //===----------------------------------------------------------------------===//
 
 Remove PersistentSValPairs and PersistentSVals?
+
+//===----------------------------------------------------------------------===//
+
+If the pointer is symbolic, we should expand it to a full region with symbolic
+values. This can eliminate the following false warning.
+
+struct file {
+  int lineno;
+};
+
+struct file *fileinfo;
+
+void f10() {
+  int i;
+  int *p = 0;
+  
+  if (fileinfo->lineno)
+    p = &i;
+  
+  if (fileinfo->lineno)
+    *p = 3; // false warning
+}
+
+Now we return a symbolic region for fileinfo->lineno in RegionStore. Loading
+from it returns an UnknownVal. Therefore the path condition is not recorded.
+
+Where should we call this ExpandSymbolicPointer method? Perhaps in
+GRExprEngine::VisitMemberExpr().
+
+Problem: The base expr of MemberExpr can be in various form. How do we get the 
+pointer varregion(or other kind of region) to be changed?